SOLUTIONS MANUAL FOR Anatomy & Physiology 9th Edition. Kevin Patton by digitaldownload87

Anatomy & Physiology 9e Kevin Patton (Solutions Manual All Chapters, 100% Original Verified, A+ Grade) Instructor’s Resource Material for

1 Organization of the Body ANSWER KEYS Answers to Quick Check Questions 1. Science develops new principles by using detailed observations and vigorous tests, or experiments, to analyze each idea or hypothesis until a reasonable conclusion can be made. As more testing is done, eliminating outside influences or biases and ensuring consistent results, scientists begin to have more confidence in the principle and then call it a theory or law. 2. Anatomy is the study of the structure of an organism and the relationships of its parts. Physiology is the scientific study of the body functions of the living organism and its parts. 3. Physiology can be divided into (1) the type of organism involved, (2) the organizational level studied, and (3) a specific, or systemic, function being studied. 4. The study of the body that focuses on groups of organs that have a common function is called systemic anatomy. 5. An eponym is a term that is based on a person’s name. 6. Autopoiesis defines life; organisms are self-organizing or self-maintaining, and nonliving structures are not. 7. Metabolism is the sum of all physical and chemical reactions in the body. Each characteristic of life is related to these reactions. 8. The seven levels of organization are chemical, organelle, cellular, tissue, organ, system, and organism. 9. Answers may include any of the following: mitochondria, Golgi apparatus, nucleus, ribosome, endoplasmic reticulum, vacuole, and lysosome. 10. The four major tissue types are epithelial, connective, muscular, and nerve. 11. The 11 major organ systems are integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive. 12. In the anatomical position, the body is in an erect, or standing, posture with the arms at the sides and palms turned forward. The head and feet are also pointing forward. This position is a reference position that gives meaning to the directional terms used to describe the body parts and regions. 13. The two major subdivisions of the body as a whole are axial and appendicular. 14. The two major body cavities and their subdivisions are (1) ventral cavity (thoracic and abdominopelvic cavities) and (2) dorsal cavity (cranial and spinal cavities). 15. The nine abdominopelvic regions are right hypochondriac, epigastric, left hypochondriac, right lumbar, umbilical, left lumbar, right iliac, hypogastric, and left iliac. The four abdominal quadrants are right upper, left upper, right lower, and left lower. 16. Superior is toward the head or upper or above; inferior: toward the feet or lower or below; anterior is front or “in front of;” posterior is back or “in back of;” medial is toward the midline of the body; lateral is toward the side of the body; dorsal is toward the back; and ventral is toward the belly. 17. Anatomical left is opposite of your left as you face the structure. 18. The rosette is used as a compass similar to those used on geographical maps. Rather than being labeled, N, S, E, and W, the anatomical rosette is labeled with abbreviated anatomical directions.

Anatomy and Physiology, 9th ed. Patton

Chapter 1 | Organization of the Body _________________________________________________________

19. The three major planes used to divide the body into parts are the sagittal, coronal (frontal), and transverse planes. A sagittal plane is any lengthwise plane running from front to back and top to bottom, dividing the body or any of its parts into right and left sides. A coronal (or frontal) plane is any lengthwise plane running from side to side and top to bottom, dividing the body or any of its parts into anterior and posterior portions. A transverse plane is any crosswise plan that divides the body or any of its parts into upper and lower parts. 20. “Complementarity of structure and function” refers to the fact that anatomical structures seem “designed” (size, shape, form, or placement) to efficiently perform specific functions. 21. DNA “directs” the differentiation of specialized cells during development so that they can effectively contribute to a specific function. For example, in the lungs, the cilia, which cover the exposed surface of cells that form the tissues lining the respiratory passageways, help trap and eliminate inhaled contaminants.

Answers to Case Study Questions (p. 19) 1. b: The abdominopelvic cavity can be divided into quarters, or quadrants. Health care professionals commonly refer to these quadrants as a standard way to describe the location of pain or an injury on a patient. 2. c: The liver is a large organ that fills the majority of the right upper quadrant. A stab wound to this area will most likely affect the liver. 3. c: Proximal means closer to the trunk. So, the part of the lower extremity proximal to the knee would be the thigh region, also referred to as the femoral region. If the contusion is “just proximal” to the knee, it is just above the knee. 4. c: The proximal part of the upper extremity is referred to as the brachial region—the arm, which is where the humerus bone is located. (You’ll also find the brachial nerve and the brachial artery in this area.)

Answers to Review Questions (p. 22) 1. Anatomy is the study of the body’s structure and the relationship of its parts. Physiology is the study of functions of the living organism and its parts. 2. Chemical level: Atoms, molecules, and macromolecules that make up the body. The text uses cytoplasm as an example of the chemical level. Organelle level: Collections of molecules organized in such a way that they can perform an individual function. Mitochondria, Golgi apparatus, endoplasmic reticulum, or any other organelles are examples. Cellular level: Cells are the smallest units that possess and exhibit the basic characteristics of living matter. Each cell is surrounded by a membrane and contains a single nucleus surrounded by cytoplasm. The cytoplasm contains numerous organelles. Muscle, bone, nerve, or any other cells are examples. Tissue level: An organization of many similar cells specialized to perform a certain function. Epithelial, muscle, connective, and nervous tissues are examples. Organ level: An organization of several different tissues arranged so that together they can perform a specialized function. Lung, heart, brain, or any other organs are examples. System level: Varying numbers and kinds of organs arranged so that together they can perform complex functions for the body. Integumentary, skeletal, muscular, or any other organ systems are examples. Organism level: An integrated assemblage of interactive structures able to survive and flourish. Human beings or any other organisms are examples. 3. Integumentary system: The primary function is protection. Other functions include regulating body temperature, synthesizing chemicals, and acting as a sense organ. Skeletal system: The primary function is to support the body. Other functions include protection, allowance for movement, mineral storage, and blood cell formation. Muscular system: The primary function is movement of the body. Muscles also generate heat for the body. Nervous system: The primary functions are communication, integration, and control of body functions. Endocrine system: The primary functions are also communication, integration, and control of body functions but in a slower, longer-lasting form than the nervous system provides. Cardiovascular system: The primary function is the transport of substances to various parts of the body.

Anatomy and Physiology, 9th ed. Patton

_________________________________________________________ Chapter 1 | Organization of the Body

Lymphatic/immune system: The primary function of the lymphatic system is the movement of tissue fluid and large molecules back to general circulation. The primary function of the immune system is conferring protection and resistance to disease. Respiratory system: The primary function is the exchange of oxygen for carbon dioxide. Digestive system: The primary function is the digestion of food, absorption of food, and elimination of undigested residue. Urinary system: The primary function is to clean the blood of waste products. Other functions are to maintain the electrolyte, water, and acid-base balance of the body. Reproductive system: The primary function is to ensure the survival of the genetic code and the species. 4. Anatomical position is a position in which the body is standing erect with arms at the side, palms forward, and the head and feet pointing forward. This is the reference position that gives meaning to the directional terms used to describe the body parts and regions. 5. Bilateral symmetry means that the right and left sides of the body are mirror images of each other, and only one plane can divide the body into left and right sides. Ipsilateral refers to a body part on the same side of the body. Contralateral refers to a body part on the opposite side of the body. 6. Somatotype is used to describe a particular category of body build or physique. The three major somatotype categories are endomorph, mesomorph, and ectomorph. Endomorphs are more round shaped, mesomorphs are more muscular, and ectomorphs are more lean and linear. 7. Anterior: The front or in front of Distal: Away from or farthest from the trunk or point of origin of a body part Sagittal plane: A lengthwise plane running from front to back, dividing the body into right and left sides Medial: Toward the midline of the body Dorsal: Toward the back Coronal plane: A lengthwise plane running from side to side, dividing the body into anterior and posterior sections Organ: Several different kinds of tissues arranged so that together they can perform a special function Parietal peritoneum: The membrane lining the inside of the abdominal cavity Superior: Toward the head or above Tissue: A group of similar cells specialized to perform a certain function 8. The mediastinum is located in the midpoint of the thoracic cavity between the right and left pleural cavities. 9. The principle of complementarity of structure and function states that each structure has a particular size, shape, form, or placement in the body that makes it especially efficient at performing a unique, specialized activity.

Answers to Critical Thinking Questions (p. 22) 1. Digestion is the process by which complex food particles are broken down into simpler substances. Through the circulatory system, these substances (nutrients) are transported from one body part to another. Growth occurs as a result of these nutrients increasing the size or number of cells. 2. An endomorph with a waist-to-hip ratio of 1:2 would be predisposed to heart disease, stroke, high blood pressure, and diabetes. 3. The abdominopelvic regions included in the x-ray would be right iliac, right lumbar, right hypochondriac, epigastric, left hypochondriac, and umbilical region. The more correct answer would include all nine regions. 4. From the largest to the smallest, the urinary bladder can be placed in the following cavities: ventral cavity, abdominopelvic cavity, and pelvic cavity.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

2 Homeostasis ANSWER KEYS

Answers to Quick Check Questions 1. The body’s internal environment is a watery fluid that surrounds the cells of the body. 2. Homeostasis is the relatively constant state maintained by the body. 3. In physiology, a set point value for a physiological variable is the value at which the body’s control systems have “set” as the normal value. 4. Because the human body is essentially a group of many living cells living in a bag (of skin) filled with body fluid, one can use the analogy of a fishbowl, where the cells living in body fluid are like fish living in water. Like the fishbowl accessories that maintain a stable environment for the health of fish, our organs maintain a stable fluid environment in our body. 5. The basic components of every feedback control system are the sensor mechanism, the integrator or control center, the effector mechanism, and the feedback. The variable is the physiology characteristic being controlled by the feedback loop and the set point value is the “normal” value for the variable. 6. Room temperature (variable) is kept stable by a thermostat (sensor-integrator) that feeds back information about room temperature to a controller that turns on the furnace (effector) if the room temperature dips below the value set on the thermostat (set point value). 7. A feedback loop is “negative” when its response reverses the direction of change (in the variable) detected by sensors. 8. Negative feedback control systems are inhibitory. They produce an action that is opposite to the change that activated the system. Negative feedback control systems stabilize physiological variables. Positive feedback control systems are stimulatory. Positive feedback tends to amplify or reinforce the change that is occurring. Typically, such responses result in instability and disrupt homeostasis. 9. Examples of such circumstances include bacterial infection, when a higher temperature benefits the fight against infection, and when variables need to be higher or lower than average during particular times of the day in order to maintain normal function of the body. 10. A circadian rhythm is a daily pattern in body function, such as a daily drop in body temperature while sleeping. 11. Any time the body responds to a change that has not happened, but is likely to happen, is a feed-forward response—like when the stomach becomes active and begins producing digestive juices just before a meal. 12. Intracellular control mechanisms operate at the cell level. These mechanisms regulate functions within the cells. Intrinsic control mechanisms operate at the tissue and organ levels. They often make use of chemical signals. Extrinsic control mechanisms operate at the system and organism levels. These usually involve nervous and endocrine regulation.

Answers to Case Study Questions (p. 35) 1. b: An adrenaline boost causes a number of physical symptoms, including rapid pulse and breathing, which are all designed to urge the body into action. The term flight-or-flight response is used to describe an adrenaline release, because it addresses the body’s reaction to the increase in hormone production. 2. d: When Anniston ran her race, skeletal muscles (particularly her legs) worked extensively thus using energy at a very high rate. This increase in muscle contraction produced a substantial amount of heat, which raised her core body temperature. In attempt to cool the body down from this increase in temperature, her sweat glands were activated to produce/secrete sweat (water). This secretion of sweat reduced her body water levels.

Anatomy and Physiology, 9th ed. Patton

Chapter 2 | Homeostasis ___________________________________________________________________

3. b: This is an example of negative feedback. As the level of water in the blood falls, negative feedback ensures that the amount of ADH rises. As the level of water in the blood rises, negative feedback ensures that the amount of ADH falls.

Answers to Review Questions (pp. 36-37) 1. Homeostasis is the relatively constant state maintained by the body (relative uniformity of the normal body’s internal environment). Examples include the following: the body maintains a constant internal temperature, the blood and body fluid must maintain a constant chemical composition, or any other occurrence that demonstrates the body’s homeostatic regulation. 2. Homeostatic control mechanisms are devices for maintaining or restoring homeostasis. Feedback control loops are systems that respond to changing internal environments and restore and maintain a healthy internal environment. 3. The four basic components of a control loop are (1) a sensor mechanism, (2) an integrator or control center, (3) an effector mechanism, and (4) feedback. 4. A negative feedback loop causes a reversal of a change that is occurring in the body, thus stabilizing a controlled variable near a set point value. A positive feedback loop, on the other hand, works in the opposite manner—amplifying a change in the controlled variable and thus promoting further movement away from the set point. 5. A drop in body temperature below the set point temperature acts as a stimulus, which promotes the response of muscle shivering. Shivering produces heat that moves the body temperature back toward the set point temperature. 6. Examples mentioned in this chapter include: regulation of body temperature, blood oxygen concentration, blood carbon dioxide concentration, blood acid levels (pH), and water content of body tissues. 7. Examples mentioned in this chapter include: regulation of labor contractions during childbirth, immune system response to infection, and formation of a blood clot. 8. A circadian rhythm is regular daily pattern in the body, such as highs and lows of temperature, blood pressure, or hormone concentrations in the blood. 9. Feed-forward is the concept that information may flow ahead to another process to trigger a change in anticipation of an event that will follow. It allows the body to react to anticipated changes in the body, rather than reacting only to changes after they have happened. 10. The three levels of homeostatic control in the body are intracellular, intrinsic, and extrinsic control mechanisms. Intracellular control mechanisms operate at the cell level. Intrinsic control mechanisms operate at the tissue and organ levels. Extrinsic control means “outside” control and operates at the system and organism levels. 11. Health usually involves an overall stability of the body maintained by homeostatic feedback loops. Disease is often the result of some disruption of homeostasis when abnormal changes to the body cannot be easily returned to normal ranges. 12. Risk factors mentioned in this chapter include: genetic factors, age, lifestyle, stress, environmental factors, microorganisms, and preexisting conditions. 13. A pathogen is an agent that causes disease. Examples mentioned in this chapter include: prions, viruses, bacteria, fungi, protozoa, and animals.

Answers to Critical Thinking Questions (p. 37) 1. Just as an aquarium filter removes toxic fish wastes, keeping the toxin levels relatively constant at a low, safe level, the kidneys remove toxic cellular wastes from the blood—thus keeping toxin levels in the blood at a relatively constant safe (low) level.

Anatomy and Physiology, 9th ed. Patton

__________________________________________________________________ Chapter 2 | Homeostasis

2. Your eyes (seeing you are drifting out of your lane) are the sensory mechanism. Your brain is the integrator or control center. Your arms and hands are the effector mechanism. This is a negative feedback loop because the response opposes the change that stimulated it and returns it to set point (your own lane). 3. As blood glucose levels drop below the set point value, sensors detect this and provide the information to integrator mechanisms. Integrators respond by using regulatory mechanisms (such as, hormones) to push the glucose back up to normal concentrations. 4. This is negative feedback, because it reverses the drop in tissue oxygen levels by increasing the flow of blood to the local tissues (by dilating the nearby vessels). It is an example of intrinsic control, because it is happening at the tissue level, using cell-to-cell communication.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

3 Chemical Basis of Life ANSWER KEYS Answers to Quick Check Questions 1. Biochemistry is the specialized area of chemistry that deals with living organisms and life processes. 2. An element is a substance that cannot be broken down or decomposed into two or more different substances. A compound is two or more elements joined to form chemical combinations. 3. Carbon, oxygen, hydrogen, and nitrogen make up 96% of the human body. 4. The three most important types of subatomic particles are proton, neutron, and electron. A proton is a subatomic particle with a positive charge located in the nucleus. A neutron is a subatomic particle with no charge located in the nucleus. An electron is a subatomic particle with negative charge located outside the nucleus. 5. The atomic number is the number of protons in the atom’s nucleus. Atomic weight refers to the mass of a single atom. It equals the number of protons plus the number of neutrons in the atom’s nucleus. 6. Energy levels are the shells or concentric circles with electrons surrounding each atom. 7. The tendency of atoms with fewer or more than eight electrons in the outer energy level to attempt to lose, gain, or share electrons with other atoms is called the octet rule. 8. Isotopes are atoms with the same number of protons, but differing numbers of neutrons. Isotopes have the same basic chemical properties as any other atom of the same element, and they also have the same atomic number. However, because they have a different number of neutrons, they differ in mass number. 9. The two types of chemical bonds between atoms are ionic and covalent bonds. Ionic bonds are formed by the transfer of electrons from one atom to another. Covalent bonds are formed when atoms share electrons. 10. Hydrogen bonds attract one molecule to another. 11. The three basic types of chemical reactions are as follows: Synthesis: A + B → AB. Decomposition: AB → A + B + energy. Exchange: AB + CD → AD + CB. 12. The term metabolism is used to describe all the chemical reactions that occur in the body’s cells. 13. Anabolism refers to the chemical reactions that join simple molecules together to form more complex biomolecules. Catabolism refers to chemical reactions that not only break down relatively complex compounds into simpler ones but also release energy from them. 14. ATP transfers energy to cell components, which makes it possible for them to do work. 15. Polar water molecules attract other polar compounds, causing them to dissociate. Hydrogen bonds absorb heat when they break and release heat when they form, minimizing temperature changes. Many hydrogen bonds must be broken before water can evaporate. Hydrogen bonds hold molecules of water together. The critical role that water plays as a solvent permits the transportation of many essential materials within the body. Water has a high specific heat property. This means that water can lose and gain large amounts of heat with little change in temperature. Finally, water has a high heat of vaporization. This characteristic requires the absorption of significant amounts of heat to change water from a liquid to a gas. 16. Electrolytes are substances that break up in a solution to form charged particles or ions. 17. Acids and bases are chemical opposites. Although they both dissociate in solution, both release different types of ions. Acids release hydrogen ions, and bases are electrolytes that shift the H +/OH− balance in favor of OH−. 18. The term pH is a symbol used to mean the H+ ion concentration of a solution; pH stands for the negative logarithm of the H+ ion concentration.

Anatomy and Physiology, 9th ed. Patton

Chapter 3 | Chemical Basis of Life ___________________________________________________________

Answers to Case Study Questions (p. 52) 1. c: Your stomach contents are very acidic. When you vomit, you are “losing” that acid content to the outside. Your overall body fluid is usually well balanced between acids and bases. (Your blood is just on the basic side at a pH of about 7.36 to 7.41.) A decrease in acid content body-wide (as with prolonged vomiting) could possibly lead to alkalosis or the body chemistry being too basic. Many reactions cannot occur when the pH is unbalanced, that is, the body cannot function properly, regardless of whether the imbalance is too acidic or too basic. 2. d: The concentration of hydrogen ions is reflected in the pH measure. More hydrogen ions translates to more acidic and a lower number on the pH scale. Fewer hydrogen ions translate to more basic and a higher number on the pH scale. A pH of 7.0 is neutral. 3. a: Remember your body is not simply a bag of water; it is a vessel containing specifically calibrated fluids in a number of different compartments. If you lose electrolytes (i.e., sodium, potassium, and chloride) through vomiting or sweating or any other means, you need to replace them in appropriate amounts. 4. b: Carbohydrates are the body’s primary source of energy. Simple sugars (monosaccharides) can be absorbed and used immediately by the body. Even polysaccharides can be easily broken apart. Proteins, on the other hand, require the body to expend much more energy to unwind and break down their component amino acids, which only then can be absorbed by the body. The same is true of lipids.

Answers to Review Questions (p. 54) 1. Element: A substance that cannot be broken down into two or more different substances. Compound: A substance that can be broken down or decomposed into the elements within it. Atom: The smallest particle of an element that retains the properties of that element. Molecule: Two or more atoms sharing electrons to form a chemical bond. 2. In the nineteenth century, Dalton conceived of atoms as solid and indivisible particles. Today we know that atoms are divisible into smaller subatomic particles, some of which exist in a cloud around a dense central core called a nucleus. 3. Protons: Positively charged particles found in the nucleus. Neutrons: Neutral particles found in the nucleus. Electrons: Negatively charged particles that move around the nucleus in a cloud or field. 4. Atoms are not electrically charged particles, because they have an equal number of positively charged protons and negatively charged electrons, which neutralize each other. 5. About 96% of the body’s weight is made up of oxygen, carbon, hydrogen, and nitrogen. 6. Atomic number: The number of protons in an atom’s nucleus. Mass number: The mass of the atom, which equals the number of protons plus the number of neutrons in the nucleus. 7. An atom can be listed as chemically inert and unable to react with another atom if the outermost electron shell has eight electrons. 8. An isotope is an atom that contains the same number of protons as other atoms of the same element but a different number of neutrons. The text includes examples of deuterium, tritium, and carbon-14. 9. Radioactivity is the emission of radiation from the atom’s nucleus. 10. When an atom is radioactive, it changes the chemical identity of the element. Chemical activity may change how two or more atoms are joined, but the chemical identity remains the same. 11. Alpha particles: Particles consisting of two protons and two neutrons. Beta particles: Electrons formed in the nucleus of an atom by neutrons breaking down to a proton and an electron. Gamma rays: A form of electromagnetic radiation.

Anatomy and Physiology, 9th ed. Patton

___________________________________________________________ Chapter 3 | Chemical Basis of Life

12. If an atom emits an alpha particle, it is transformed into the element with two fewer protons; it also has two fewer neutrons. If it emits a beta particle, it is transformed into an element with one more proton, and it has one fewer neutron. 13. A chemical reaction is an interaction between two or more atoms as a result of activity of electrons in their outermost shell. 14. In a synthesis reaction, two or more substances are combined to form a different, more complex substance. In a decomposition reaction, a complex substance is broken down into two or more simpler substances. In an exchange reaction, two different reactants exchange components and form two new products. 15. An inorganic compound is a compound that usually does not contain carbon but never contains C-C or C-H bonds. 16. Water is said to be polar because the molecule has a partial positive side and a partial negative side. The four functions of water that are crucial to survival are its strong polarity, its high specific heat, its high heat of vaporization, and the cohesion of the molecules. 17. Electrolytes are inorganic, charged particles that form when substances dissociate. An example would be NaCl dissociating into Na+ and Cl−. Any ionic compound that is water soluble would be an example. 18. A cation is a positive ion. (Any positive ion can be used as an example.) An anion is a negative ion. (Any anion can be used as an example.) An ion is a charged atom or molecule. (Any charged particle can be used as an example.) 19. Acid: A substance that will release a hydrogen ion when in solution. Base: A substance that shifts the H+/OH− balance in favor of OH− by increasing the number of OH− ions or decreasing the number of H+ ions. Salt: A substance that results from a reaction between an acid and a base. Buffer: A substance that minimizes changes in the concentration of the H + and OH− ions. It maintains a constancy of pH. 20. A pH of less than 7.0 indicates the solution is an acid. The lower the value, the greater the hydrogen ion concentration. A pH of more than 7.0 indicates the solution is a base. The higher the value, the greater the concentration of the hydroxide ion. Each change of 1 unit on the pH scale represents a tenfold difference in the ion concentration. 21. Catabolism consists of chemical reactions that break down relatively complex compounds into simpler ones. The function of catabolism is to release energy. 22. Catabolism breaks down large molecules that release energy. Anabolism builds large molecules from smaller molecules and requires energy. Metabolism encompasses all the reactions in the body—that is, the sum of anabolism and catabolism.

Answers to Critical Thinking Questions (p. 54) 1. Biochemists would have an interest in living organisms and life processes, such as growth, muscle contraction, transmission of nerve impulses, homeostatic processes, and control mechanisms. 2. Helium has two electrons in its outer shell. Hydrogen has only one electron in its outer shell. Because helium’s outer shell is filled, helium is unreactive. Hydrogen, however, has an incomplete outer shell and is very reactive. 3. In a single covalent bond, two electrons (one pair) are shared between two atoms. In a double covalent bond, four electrons (two pairs) are shared between two atoms. In an ionic bond, electrons are transferred from one atom to another, and the bond is formed by the attraction of opposite electrical charges. 4. In an adult with a body weight of 170 pounds, about 119 pounds would be water (170  0.70 = 119).

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

4 Biomolecules ANSWER KEYS

Answers to Quick Check Questions 1. The four major groups of organic substances are proteins, carbohydrates, lipids, and nucleic acids. 2. Glucose is the most important monosaccharide in terms of body function. 3. Disaccharides and polysaccharides are carbohydrate compounds, or polymers, made of two or more simple sugars that are bonded together through a synthesis reaction. Monomers of glucose are joined together in a synthesis reaction that also involves the removal of water. 4. Fatty acids and glycerol are the building blocks of a triglyceride. 5. Phospholipids are fat compounds similar to triglycerides. They are modified, however, in that one of the three fatty acids attached to glycerol in a triglyceride is replaced in a phospholipid by another type of chemical structure containing phosphorus and nitrogen. Phospholipids form the backbone of the plasma membrane. 6. Cholesterol is the important steroid that stabilizes cellular structure. 7. Nitrogen is present in all proteins but not in carbohydrates. 8. Amino acids are the building blocks of proteins. An amino acid consists of a carbon atom to which are bonded an amino group, a carboxyl group, a hydrogen atom, and a side chain, or group of elements designated by the letter R. 9. The four levels of protein structure are as follows: primary refers to the number, kind, and sequence of amino acids that make up the polypeptide chain; secondary are polypeptide chains that are coiled or bent into pleated sheets; tertiary is a polypeptide chain that undergoes contortions and twisting to form a globular shape; and quaternary is protein that contains clusters of more than one polypeptide chain, all linked together into one giant molecule. 10. DNA and RNA are both important nucleic acids. 11. Nucleotides are small molecules of phosphates, sugar, and nitrogen bases that make up nucleic acids. 12. Base pair: Each nitrogen base in one chain of the DNA molecule is joined to a nitrogen base in the other chain by means of hydrogen bonds. 13. Besides joining together to form nucleic acids, nucleotides play a role in adenosine triphosphate (ATP) structure and energy-transferring molecule (nicotinic adenine dinucleotide [NAD +] and flavin adenine dinucleotide [FAD]) structure. They are also used as a signal inside the cell.

Answers to Case Study Questions (p. 72) 1. c: A high total cholesterol value is associated with a high risk of atherosclerosis. In particular, if that total cholesterol value includes a high blood concentration of low-density lipoprotein, an individual increases his/her risk for this and other coronary diseases. 2. d: High blood concentrations of high-density lipoproteins (HDLs) have been associated with a low risk of developing atherosclerosis and its many possible complications. HDL molecules are attracted to HDL receptors embedded in plasma membranes. Once they bind to their receptors, the cell is stimulated to release some of its cholesterol from storage. The released cholesterol migrates to the plasma membrane, where it may attach to the HDL molecule and then transported to the liver for excretion in bile. 3. a: Cholesterol is found only in foods of animal origin. It is particularly high in liver and the yolk of eggs.

Anatomy and Physiology, 9th ed. Patton

Chapter 4 | Biomolecules __________________________________________________________________

Answers to Review Questions (p. 74) 1. The building blocks of proteins are amino acids. The building blocks of carbohydrates are monosaccharides. The building blocks of triglycerides are fatty acids and glycerol. The building blocks of DNA are nucleotides. 2. The binding site is the location on an enzyme with a unique shape that joins with a substrate. The binding site is the location on the enzyme where the reaction that the enzyme catalyzes takes place. 3. Proteins can perform some of the following functions: provide structure, catalyze chemical reactions (enzymes), transport substances in the blood (albumins), communicate information to cells (hormones), act as receptors (membrane binding sites), defend the body against harmful agents (immunoglobulins), and provide energy (protein catabolism). 4. Lipids are insoluble in water, contain nitrogen, and include prostaglandins and phospholipids. 5. Nucleotides are composed of a phosphate group; a pentose, or five-carbon, sugar; and a nitrogen base. 6. The pentose sugar deoxyribose is present in deoxyribonucleotide. 7. The DNA molecule is the largest molecule in the body. It is a polymer composed of many nucleotides. Two chains of nucleotides make up a single DNA molecule. The chains coil around each other to form a double helix. 8. Thymine is always paired with adenine, and guanine is always paired with cytosine in the DNA molecule. 9. The function of DNA is to act as the molecule of heredity—to pass the traits of one generation on to the next generation.

Answers to Critical Thinking Questions (p. 44) 1. Enzymes specifically catalyze one specific reaction (lock-and-key model). If amylase is altered in any way, it would not catalyze the starch, and it would not be broken down into a simpler, less complex molecule. 2. Amino acids are like letters of the alphabet. Just as the combinations of individual letters form words, different amino acid combinations form the many different protein chains. 3. ATP supplies the cells with energy by breaking the high-energy bonds between the second and third phosphate and releasing the energy from that bond. The outline should contain a representation of the ATPADP cycle.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

5 Cell Structure ANSWER KEYS

Answers to Quick Check Questions 1. Schleiden and Schwann proposed the cell theory. 2. The answer may include one of the following examples: • Nerve cells have threadlike extensions over a meter in length. This structure allows the nerve cell to transmit nervous impulses from one area of the body to another. • Muscle cells are specialized to contract or shorten. • Red blood cells contain hemoglobin, which attracts oxygen. • Gland cells release a secretion to the outside of the cell. • Immune cells have outer membranes that allow them to engulf other cells. 3. Plasma membrane, cytoplasm, and the nucleus are the three main components of a typical cell. 4. The plasma membrane (1) serves as the boundary of the cell, maintaining its integrity; (2) it controls what goes in and out of the cell and (3) contains proteins and carbohydrate chains that serve as identifying markers and receptor molecules. 5. Organelles are “little organs” that are located within the cytoplasm. There are several types, each with a specific function for cell metabolism. 6. Answers will vary. Some examples of organelles and their functions include the following: Golgi apparatus, synthesizes carbohydrate; lysosome, cell’s “digestive system;” mitochondria, catabolism; ribosome, cell’s “protein factory;” and nucleus, houses genetic code. 7. The membranous organelles are the organelles that are specialized sacs or canals made of cell membrane. The nonmembranous organelles are not made of membrane but are made of microscopic filaments or other nonmembranous materials. 8. Microfilaments are the smallest cell fibers; are made of thin, twisted strands of protein molecules; and usually form bundles that lie parallel to the long axis of the cell. They are found in muscle cells. Intermediate fibers are twisted protein strands that are slightly thicker than microfilaments. They are thought to form much of the supporting framework in many types of cells. Microtubules are the thickest of the cell fibers. They are tiny, hollow tubes made of protein subunits arranged in a spiral fashion. Microtubules often move things around in the cell or even cause movement of the entire cell. 9. The centrosome plays an important role during cell division, when a special “spindle” of microtubules is constructed for the purpose of moving chromosomes around the cell. 10. Desmosomes are the small “spot welds” that hold adjacent cells together. Gap junctions are formed when membrane channels of adjacent plasma membranes adhere to each other. Tight junctions occur in cells that are joined by “collars” of tightly fused membrane.

Answers to Case Study Questions (p. 94) 1. d: Hydrophilic molecules (represented by people in this case) can pass through channel proteins, which act as gates within the cell membrane “fence.” They cannot, however, pass through the phospholipid bilayer. Some proteins are transmembranous, meaning they stretch across the inside of the cell from one side to the other. And cholesterol is part of the cell membrane, but it does not function as a passageway. Its main function is membrane stability. 2. b: Two organelles may look similar when a cell model is first examined. The endoplasmic reticulum truly is an interconnected “maze” of tubes. Reticulum means “network.” The other organelle that looks mazelike, the Golgi apparatus, is not connected. Rather, it is a series of closed-ended tubes, like a stack of curved pancakes.

Anatomy and Physiology, 9th ed. Patton

Chapter 5 | Cell Structure __________________________________________________________________

3. c: Ribosomes may be found floating free in the cytoplasm, but many of them are attached to the rough endoplasmic reticulum where they make proteins that are then transported through the network of canals. 4. a: Microtubules are the thickest of the cytoskeleton, made up of hollow tubes, like pipes. Microfilaments are the thinnest fiber, whereas intermediate filaments (as their name implies) are in between the two in size.

Answers to Review Questions (p. 97) 1. The range of human cell diameters is from 7.5 to 300 m. 2. The three main cell structures are the plasma membrane, the cytoplasm (with organelles), and the nucleus. 3. The plasma membrane is the outer boundary of the cell. It is a thin sheet, about 75 Å thick. The molecular structure includes lipids (such as, phospholipids and cholesterol) and proteins. 4. The communication function depends on membrane receptor proteins, which can respond to hormones or other regulatory chemicals, thereby triggering changes in cell functioning. The transport function depends on membrane proteins, which act as gates to let material in. The protein gates are selective. The identification function depends on glycoproteins, which identify the cell as “self.” 5. Endoplasmic reticulum: This consists of membranous-walled canals and flat, curving sacs arranged in parallel rows. If ribosomes are attached to their walls, they are called rough endoplasmic reticulum. If no ribosomes are attached, they are called smooth endoplasmic reticulum. The rough endoplasmic reticulum functions in both protein synthesis and intracellular transport of molecules. The smooth endoplasmic reticulum functions in the synthesis of membrane for use throughout the cell. Ribosomes: These are non-membranous structures made of two parts: a large and small subunit composed of RNA and protein. The function of ribosomes is protein synthesis. Golgi apparatus: This is a membranous organelle consisting of tiny sacs (cisternae) stacked on one another and located near the nucleus. Its function is the processing and packaging of protein for export from the cell. Mitochondria: This is a sausage-shaped structure with an inner and outer membrane. The inner membrane has many folds called cristae. The mitochondria provide the cells with most of their energy. Lysosomes: These are saclike structures that contain digestive enzymes. The function of lysosomes is to digest molecules or bacteria that are in the cell. Proteasomes: These are cell structures that break down proteins. Peroxisomes: These are small saclike structures containing peroxidase and catalase. Their function is to detoxify harmful chemicals in the cell. Cytoskeleton: This is a name given to the rodlike structure of various sizes. The smallest are called microfilaments. The next larger fibers are called intermediate filaments, and the largest fibers are called microtubules. Their function is to form a three-dimensional lattice structure in the cell. The microtubules are also important in movement within the cell. Cell fibers: These are intricate arrangements of fibers that form a three-dimensional lattice within the cell. They appear to support parts of the cell formerly thought to float free in the cytoplasm—the endoplasmic reticulum, mitochondria, and “free” ribosomes. Centrosome: This is composed of a cylinder made up of nine bundles of microtubules with three tubules in each bundle. There are two such structures at right angles to each other. Their function is to move chromosomes to the proper part of the cell during cell division. Centrioles: These are a pair of cylindrical structures located near the nucleus. They play a role in cell division. Cell extensions: These are special projections of cytoskeleton. There are three types: microvilli, cilia, and flagella. The microvilli are small fingerlike projections of the cell that allow for increased surface area for absorption. Cilia are short hairlike microtubule projections from the cell. Cilia function to move material in a particular direction. The flagella have a long microtubule structure that provides mobility of the sperm cell. 6. Desmosomes are analogous to spot welds that hold adjacent cells together. This allows cells to be held in place tightly. Gap junctions are formed when channels of adjacent cells adhere to each other. This provides tunnels from one cell to the next and also fuses two plasma membranes together. Tight junctions occur when cells are joined by collars of membranes tightly fused with neighboring cells. This prevents molecules from moving through sheets of cells.

Anatomy and Physiology, 9th ed. Patton

__________________________________________________________________ Chapter 5 | Cell Structure

7. The nucleus holds the DNA, which is the molecule responsible for directing the production of proteins in the cell. The nucleoli functions to synthesize ribosomal RNA. 8. Light microscopy: This is used to look directly at the specimen. Stains can be used to differentiate cells. Transmission electron microscopy: Using a thinly sliced specimen, this provides greater magnification with sharper images. All images are in black and white. Scanning electron microscopy: The images are greatly magnified, but one can see only surface structures. All images are in black and white.

Answers to Critical Thinking Questions (p. 97) 1. Students should describe the nerve cell and explain how its processes (dendrites and axons) allow it to receive and send nerve impulses. The muscle cell’s elongated shape allows it to contract or shorten. 2. Ribosomes are structures that form polypeptides, which are released into the endoplasmic reticulum (ER) for processing into proteins. Vesicles move the processed proteins from the ER to Golgi apparatus for final steps of processing. Vesicles move the finished proteins to the plasma membrane where the vesicle membrane fuses with the plasma membrane—thus releasing the proteins by exocytosis.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

6 Cell Function ANSWER KEYS

Answers to Quick Check Questions 1. Diffusion, dialysis, osmosis, filtration, and facilitated diffusion—not all of these transport processes require cell energy to move substances across the membrane. They differ in how the substances move across the membrane. Dialysis is a form of diffusion in which the selectively permeable nature of the membrane causes the separation of smaller solute particles from larger solute particles. Osmosis is the diffusion of water across a semipermeable membrane. Filtration differs in that it moves substances across a membrane by the force of hydrostatic pressure. Facilitated diffusion uses carrier molecules that attract a solute, change its shape, and then release it to the other side of the membrane. 2. Osmotic pressure develops in the cell that originally had the higher concentration of impermanent solute. Osmotic pressure arises from the tendency of a pure solvent to move through a semipermeable membrane and into a solution containing a solute to which the membrane is impermeable. 3. The three active processes that transport substances across a cell membrane are sodium-potassium pump, endocytosis, and exocytosis. The sodium-potassium pump operates in the plasma membrane by actively transporting sodium ions and potassium ions but in opposite directions. In endocytosis, the plasma membrane “traps” some extracellular material and brings it into the cell. Exocytosis is the process by which large molecules, notably proteins, can leave the cell even though they are too large to move out through the plasma membrane. All of these processes require cell energy. 4. Enzymes are proteins and have the chemical properties of proteins. They are usually tertiary or quaternary proteins of complex shape. Enzymes often contain a nonprotein part called a cofactor. An important structural attribute of enzymes is the active site. The active site is the portion of the enzyme molecule that chemically “fits” the substrate molecule(s). This structure allows the enzymes to bind substrates together or unbind components of a substrate. 5. An allosteric effector is a molecule or other agent that alters enzyme function by changing its shape. Examples include certain antibiotic drugs, changes in pH, or changes in temperature. 6. Glycolysis, citric acid cycle, and the electron transport system are the three catabolic pathways that together make up the process of cellular respiration. 7. The aerobic pathway extracts more energy. 8. Energy must be transferred to adenosine triphosphate (ATP) before it can be used by most cell processes. 9. Glycolysis is a catabolic pathway that begins with glucose and ends with two molecules of pyruvic acid. Two ATP molecules and nicotinamide adenine dinucleotide (NADH) are generated in this pathway. The citric acid cycle converts pyruvic acid to acetyl coenzyme A and moves into a sequence of reactions that generate ATP, NADH, FADH2, and carbon dioxide. The electron transport system uses the NADH and FADH 2 to transfer energized electrons to a set of special molecules embedded in the cristae of the inner mitochondrial membrane. Additional ATP molecules are formed along with molecules of water.

Answers to Case Study Questions (p. 117) 1. b: Just as some molecules need a facilitator (either a channel or carrier) to allow them to enter a cell, the subway car doors acted as a channel through which the people could move into the train. The people were moving from a high concentration to a low concentration, so their movement was passive. 2. d: Because sodium is moving from low concentration to high concentration, the movement requires energy. This example would be a form of active transport. Sodium molecules are small enough to be transported across the cell membrane by a protein pump.

Anatomy and Physiology, 9th ed. Patton

Chapter 6 | Cell Function ___________________________________________________________________

3. b: The input of water (with no solutes) into Tobie’s system would make his blood more dilute (i.e., more water increase than solute increase). That would make the fluid part of his blood hypotonic (hypo = low), a potentially dangerous situation (see Figure 6-5).

Answers to Review Questions (p. 119) 1. Diffusion is the natural tendency of small particles to spread out evenly within any given space. Dialysis is a form of diffusion in which a selectively permeable membrane causes the separation of small solute particles from larger ones. Facilitated diffusion occurs when movement of molecules is facilitated or made more efficient by the action of carrier mechanisms in a cell membrane. Osmosis is the diffusion of water through a selectively permeable membrane. Filtration is the passing of water and permeable solutes through a membrane by the force of hydrostatic pressure. 2. A concentration gradient is a measurable difference in concentration from one area to another. Because molecules spread from a high concentration to a low concentration, they spread down a concentration gradient. 3. A membrane channel is a pore in the cell membrane through which specific ions or other small water-soluble molecules can pass. The text specifically names sodium and chloride channels. 4. Isotonic means that two solutions have the same potential osmotic pressure because they have the same concentration of impermeable solutes. Hypotonic means that a solution has a lower concentration of impermeable solutes and a higher concentration of water than does a reference solution. Hypertonic means that a solution has a higher concentration of impermeable solute and a lower concentration of water than does a reference solution. 5. Osmotic pressure develops in the solution that originally has the higher concentration of impermeable solute. 6. Active transport is a carrier-mediated process that uses cellular energy to move molecules “uphill;” that is, from an area of lower concentration to an area of higher concentration. 7. The sodium-potassium pump operates in the plasma membrane. It actively transports sodium ions out of the cell and potassium ions into the cell. 8. In endocytosis, the plasma membrane receptors bind to a specific molecule in the intracellular fluid, causing a portion of the plasma membrane to be pulled inward by the cytoskeleton. This forms a small pocket around the material. The edges of the pocket fuse, forming a vesicle in the cell. In exocytosis, the material to leave the cell is enclosed by a membranous vesicle and is moved to the plasma membrane by the cytoskeleton. The vesicle then fuses to the plasma membrane, which releases the material outside the cell. 9. Oxidation-reduction enzymes allow energy release for the cells. Hydrolyzing enzymes are digestive enzymes that break down molecules. Phosphorylating enzymes add or remove phosphate groups. Carboxylases add or remove carbon dioxide. Mutases or isomerases rearrange atoms in a molecule. Hydrases add water to molecules but do not break them down. 10. Answers should include three of the following principles: • Enzymes are specific in their action; they act on only one substance. • Various physical and chemical agents activate or inhibit the enzyme by changing its shape. These include allosteric effectors, pH, and temperature. • Enzymes are able to catalyze a reaction in both directions. • Enzymes are not used up by the reaction, but they are continually wearing out and need continual synthesis. • Many enzymes are synthesized as inactive proenzymes.

Anatomy and Physiology, 9th ed. Patton

__________________________________________________________________ Chapter 6 | Cell Function

11. Metabolism is the complete set of chemical reactions in the living organism. Catabolism is the breaking down of large molecules into smaller molecules to release energy. Anabolism is the building up of large molecules from smaller ones, which requires energy. 12. Glycolysis releases a small portion of the energy in glucose. This occurs in the cytosol and releases adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH). The end product is pyruvic acid. This process can occur without oxygen. Citric acid cycle uses the pyruvic acid from glycolysis and converts it into acetyl coenzyme A (CoA). The cycle occurs in the mitochondria. The acetyl CoA enters the cycle and is broken down, releasing carbon dioxide, ATP, NADH, and a reduced form of flavin adenine dinucleotide (FADH 2). The electron transport system uses energized electrons, which are carried by the NADH and FADH 2 to electron-acceptors in the mitochondria. The electrons are passed along a chain of electron-accepting molecules. Their energy is used to pump hydrogen ions between the spaces of the mitochondrial membranes. When they flow back, the energy they provide is used to form ATP. The hydrogen eventually joins with oxygen to form water.

Answers to Critical Thinking Questions (p. 119) 1. Dialysis is the diffusion of small solute particles, but not large particles, through a selectively permeable membrane that separates the larger from smaller solutes. It is a passive transport process. Phagocytosis is the process of moving large particles or bacteria into the cell by trapping them in a section of plasma membrane that pinches off to form an intracellular vesicle. It is an active transport process. 2. Because potential osmotic pressure is a prediction rather than a measurement of what has already developed, actual osmotic pressure is more easily measured. 3. Because osmotic pressure is based on the number of particles, it is important to determine how many particles are being added to the solvent. If the solvent is a nonelectrolyte (such as, sugar), 1 mole of sugar will produce 1 mole of particles. If it is an electrolyte (such as, NaCl), 1 mole of NaCl will produce 2 moles of particles—1 mole of each ion. If the solution is not isotonic, the cells may burst (if solution is hypotonic) or shrink in size (if solution is hypertonic). 4. The engulfing of bacteria is phagocytosis, which is the endocytosis of solid material. The engulfing of the dissolved proteins is pinocytosis, which is the endocytosis of liquid material. 5. The shape of the enzyme determines what substrate the enzyme fits and, hence, the chemical reaction that it catalyzes. The allosteric effector can inhibit the enzyme by changing its shape so that it no longer fits the substrate. Conversely, the allosteric effector can activate the enzyme by changing its shape so that it does fit the substrate. 6. Aerobic (oxygen-requiring) respiration is a catabolic process that produces the maximum amount of energy available from each glucose molecule. Anaerobic respiration is a catabolic process that does not require the immediate use of oxygen. Besides its ability to produce ATP without oxygen, anaerobic respiration has the advantage of being rapid. Cells having difficulty getting oxygen may rely on anaerobic respiration to resynthesize their ATP molecules. 7. Mitochondria are necessary so that enough energy can be released to keep the cell functioning. Cells that are active (e.g., skeletal muscle cells) require more mitochondria to keep up with the energy demands.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

7 Cell Growth and Development ANSWER KEYS Answers to Quick Check Questions 1. The sequence of nitrogen base pairs is a code or blueprint that controls the activity of each cell and the genome of the individual. 2. Transcription occurs in the nucleus. Editing (splicing) also occurs in the nucleus. Translation occurs in the ribosomes (cytoplasm). 3. Transfer RNA determines the sequence. 4. Cell growth and reproduction are the two major phases of the cell life cycle. Mitosis occurs during cell reproduction. 5. Protein synthesis and an increase in size of the membranous organelles and plasma membrane cause the cytoplasm to grow. 6. Mitosis (mitotic cell division) is a process of organizing and distributing nuclear DNA during cell division. It results in two gametes, each with the identical number of chromosomes as the parent cell. Meiosis (meiotic cell division) occurs only in primitive sex cells. It results in four gametes, each having half of the number of chromosomes of the parent cell.

Answers to Case Study Questions (p. 134) 1. a: If the body loses its ability to control mitosis normally, abnormal hyperplasia may occur. The new mass of cells thus formed is a tumor or a neoplasm. Neoplasms may be relatively harmless growths, which are called benign. 2. b: Apoptosis is a type of programmed cell death in which organized biochemical steps within the body lead to fragmentation of the cell and removal of the pieces by phagocytic cells. Apoptosis occurs frequently in the cells of your body when cells are no longer needed or when they have certain malfunctions that could lead to cancer or some other potential problem. 3. c: Anaplasia is a condition in which cells fail to differentiate into a specialized cell type. Cells in malignant neoplasms often exhibit this characteristic.

Answers to Review Questions (p. 136) 1. DNA is one of the largest molecules in the body. It has the shape of a twisted ladder, a double helix. 2. DNA is located in the nucleus of the cell. 3. Protein synthesis begins with the DNA molecule opening up and attracting a messenger ribonucleic acid (mRNA) molecule. The mRNA separates from the DNA and moves out of the nucleus and to a ribosome. The ribosome “reads” the mRNA and attracts a specific transfer RNA (tRNA) molecule with a nucleotide sequence opposite to that of the mRNA. The tRNA is carrying with it a specific amino acid, which is added to the growing protein. This process repeats with more tRNA molecules bringing specific amino acids until the complete protein is formed. 4. Additional material is added as a cell grows by way of protein synthesis, the synthesis of more organelles and plasma membrane, and the replication of more mitochondria. This increases the amount of cytoplasm and, therefore, the size of the cell. 5. The DNA molecule “unzips” to expose the nucleotide bases, and through the mechanism of obligatory base pairing, new nucleotides pair with either side of the DNA molecule, forming a new half to each of the original strands of DNA. This process is catalyzed by DNA polymerase. After all the bases have been paired, two new DNA molecules have been formed. This process occurs in the synthesis, or S, phase of the cell cycle. 6. Mitosis is the process of organizing and distributing nuclear DNA during cell division.

Anatomy and Physiology, 9th ed. Patton

Chapter 7 | Cell Growth and Development _____________________________________________________

7. Prophase: Chromosomes shorten and thicken, centrioles move to opposite poles of the cell, and spindle fibers appear and begin to orient between opposing poles. The nuclear membrane and the nucleolus disappear. Metaphase: Chromosomes align across the equator of spindle fibers. Each pair of chromatids is attached to a spindle fiber at its centromere. Anaphase: Each centromere splits, detaching the chromosomes. Each chromosome moves to an opposite pole. Telophase: Chromosomes uncoil, the nuclear membrane and nucleolus reappear, and the spindle fibers disappear. 8. Meiosis is the process of nuclear division that produces gametes with half the usual number of chromosomes. The two stages are meiosis I and meiosis II. In meiosis I, the DNA replication occurs before division. The number of chromosomes is halved, but the chromatid pairs remain together. In meiosis II, the DNA is not replicated and the chromatids split apart, providing the haploid number of chromosomes to each of the new cells. 9. The reduction from diploid to haploid number takes place in meiosis II. 10. A normal example of hyperplasia occurs in the milk-producing glands in the female breast during pregnancy. Abnormal hyperplasia can occur when the body loses control over mitosis and a tumor forms.

Answers to Critical Thinking Questions (p. 136) 1. The loss of ribosomes would not affect transcription; this process occurs in the nucleus. However, the loss of ribosomes would have a great impact on translation, because it is at the ribosome where translation, the building of the protein molecule, occurs. 2. The nitrogen bases are like letters of the alphabet. The sequence of these bases forms a code, much like forming words in a text. These coded sequences of nucleotides dictate the genetic structure of the individual and the metabolic function of the individual’s cells. 3. The process of protein synthesis is responsible for the production of enzymes for the cell. Enzymes regulate all the anabolic and catabolic reactions in the cell. Without a sufficient number of the correct enzymes, the cell would not stay alive. 4. Atrophy caused the change in the muscles of the limb. When muscles are out of use, the muscle cells decrease in size. 5. Hypertrophy refers to an increase in cell size. Hyperplasia refers to cells increasing their rate of reproduction. 6. This question can be answered in a variety of ways. The correct answer should include the role of the nucleus in the formation of the cytoplasm, the directions for protein synthesis for making enzymes and new organelles, the regulation of anabolic and catabolic reactions, and the role of DNA in mitosis and genetic continuity.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

8 Introduction to Tissues ANSWER KEYS Answers to Quick Check Questions 1. The four basic tissue types are epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Epithelial tissue covers and protects the body surfaces, lines body cavities, specializes in moving substances into and out of the blood, and forms many glands. Connective tissue is specialized to support the body and its parts, to connect and hold them together, to transport substances through the body, and to protect it from foreign invaders. Muscle tissue produces movement. Nervous tissue specializes in communication between various parts of the body and the integration of their activities. 2. A primary germ layer is an orderly arrangement of cells that develop within 2 weeks after the blastocyst has implanted itself in the uterus. 3. ECM is the extracellular matrix. ECM is made up mostly of proteins, proteoglycans, and water. 4. Elastic fibers are flexible and not very strong, but they are also stretchy and rebound after stretching. Collagenous fibers, on the other hand, are not stretchy, but they are very strong when pulled by movement of surrounding tissues. 5. Epithelial and connective tissues have the greatest capacity to regenerate after an injury. 6. Damaged muscle is sometimes replaced with fibrous connective tissue instead of muscle tissue. This results in the muscle losing some or all of its ability to function. 7. Cutaneous, serous, and mucous and connective are the four principal types of body membranes. Cutaneous, serous, and mucous are epithelial membranes. 8. Mucus is a watery secretion that contains a mixture of mucins, which are a group of about two dozen different proteoglycans. Mucus coats and protects the underlying cells of the mucous membrane. It also acts as a lubricant for food as it moves along the digestive tract and serves as a sticky trap for contaminants in the respiratory tract.

Answers to Case Study Questions (p. 152) 1. c: Muscle and nerve tissue have limited capacity to regenerate. Damaged muscle is sometimes replaced with fibrous connective tissue instead of muscle. When this happens, the muscle loses some or all of its ability to function. Neurons can sometimes regenerate but very slowly and only if certain neuroglia are present to “pave the way.” 2. a: The skin is also known as the cutaneous membrane, composed of stratified squamous epithelium and underlying connective tissue. The superficial layer of the cutaneous membrane is the epidermis. Mucous membranes are found lining cavities open to the outside (e.g., the mouth, nose, and urinary tract). Serous membranes line cavities that are closed (e.g., thoracic cavity). 3. b: A material called the basement membrane exists between epithelial and connective tissues. It is composed of secretions from both the epithelial and the connective cells. 4. c: When a break in the connective tissue occurs, collagen fibers usually form a dense fibrous mass (scar). An atypical and unusually thick scar may develop in the lower layer of the skin (keloid).

Answers to Review Questions (p. 154) 1. Tissue is defined as a group of similar cells that perform a common function. The four principal tissue types are epithelial tissue, connective tissue, nervous tissue, and muscle tissue. 2. The three germ layers are the endoderm, mesoderm, and ectoderm. These germ layers are a result of cells moving and regrouping within the early embryo. The function of these layers is to differentiate to form specific tissues (histogenesis).

Anatomy and Physiology, 9th ed. Patton

Chapter 8 | Introduction to Tissues ___________________________________________________________

3. Muscle has a limited capacity to regenerate itself, and damaged muscle is often replaced by connective tissue. Nervous tissue also has a limited capacity to regenerate itself. Nerves outside the central nervous system can regenerate slowly and only if certain neuroglia cells can pave the way. Normal brain and spinal cord neurons do not grow back when injured. 4. Epithelial tissue and connective tissue are the major categories of body membranes. Some examples of epithelial tissue membranes are cutaneous, serous, and mucous. An example of connective tissue membrane is synovial. 5. Neoplasm (new matter) or tumor refers to any abnormal growth of cells. Neoplasm is often classified as benign (does not spread to other tissues) or malignant (tends to spread to other regions of the body).

Answers to Critical Thinking Questions (p. 154) 1. The skeletal and muscular systems arise from the mesoderm. The earliest time in development when only these tissue types would be affected is during or shortly after gastrulation. 2. A proper amount of fat in the body is necessary. Fat is used to protect various body organs, such as the kidneys. It acts as an insulator to help maintain body temperature and acts as a source of stored energy for the body. Too little fat affects the athlete’s health by compromising these functions. 3. The student should construct a flowchart or diagram on tissue healing that includes the following: All answers should include the fact that an injury is followed by phagocytotic cells removing dead or injured cells and an attempt at regeneration. If the tissue is epithelial or connective and if the injury is small, it will heal completely. If the injury is deep or large, it may leave a scar. A larger scar called a keloid may form. Muscle tissue has a limited ability to heal itself and is often replaced by connective tissue. Nervous tissue has the most limited ability to heal itself. Neurons outside the central nervous system may heal, but cells in the central nervous system usually do not heal. 4. The skin will probably heal faster and more completely. It is made up of epithelial tissue, which heals faster and more completely than muscle tissue. 5. The fluid is synovial fluid. It is produced by the synovial membrane surrounding the joint; its function is to reduce the friction between bones in movable joints.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

9 Tissue Types ANSWER KEYS

Answers to Quick Check Questions 1. The answer may include any three of the following: protection, sensory functions, secretion, absorption, and excretion. 2. Squamous, cuboidal, and columnar are the three basic shapes of epithelial cells. 3. Simple squamous epithelium tissue consists of only one layer of flat, scalelike cells. Stratified epithelium tissue is characterized by multiple layers of cells. 4. Exocrine glands discharge their secretion products into ducts. 5. The three kinds of fibers that may be present in a connective tissue ECM are collagenous fibers, reticular fibers, and elastic fibers. Collagenous fibers are white fibers made up of collagen and often occur in bundles. Reticular fibers are made up of a specialized type of collagen called reticulin. Elastic fibers are made up of a protein called elastin. 6. The four types of fibrous connective tissue are loose, adipose, reticular connective, and dense connective. Loose connective tissue is stretchable and one of the most widely distributed of all tissues. The matrix is a soft, thick gel. It contains many fibroblasts and macrophages. Adipose connective tissue contains predominantly fat cells and many fewer fibroblasts, macrophages, and mast cells. Reticular connective tissue is a dense, net-like tissue with branching reticulin fibers with reticular cells. It filters injurious substances out of blood and lymph. Dense connective tissue has fibers packed densely into a matrix that contains relatively few fibroblast cells. It is designated regular or irregular. 7. The inorganic (bone salt) portion of bone makes it hard. 8. Blood tissue exists in a liquid state. 9. The two types of involuntary muscle are smooth and cardiac. Smooth muscle is found in the walls of the viscera. Cardiac muscle makes up the wall of the heart. 10. The two principal types of cell in nervous tissue are neurons and neuroglia. Neurons are conducting units of the nervous system. The function of neuroglia is connecting and supporting cells.

Answers to Case Study Questions (p. 174) 1. c: Adipose tissue contains mainly fat cells (adipocytes) and many fewer fibroblasts, macrophages, and mast cells. Each adipocyte typically has one large vesicle filled with stored triglycerides. This fat cell is so large that it pushes the cytoplasm of the cell outward toward the plasma membrane as it stores more and more fat. 2. b: This tissue sample of dense fibrous tissue predominantly characterized by bundles of collagenous fibers is found in structures that anchor muscle to bone, such as tendons. Tendons provide great strength because of the arrangement of collagen fibers. 3. a: This calcified tissue sample is cancellous (spongy) bone. The thin beams (trabeculae) form a framework that supports a softer tissue (red bone marrow). The lattice of trabeculae also give internal support to the bone—much as the crisscrossing pattern of the roof trusses of a building help support the weight of the roof. 4. b: This tissue sample is hyaline cartilage. Hyaline cartilage takes its name from the Greek word hyalos or “glass.” The name is appropriate because the low amount of collagen in the matrix gives hyaline cartilage a shiny and translucent appearance. This is the most prevalent type of cartilage and is found covering the ends of bones that articulate at joints. The external ear is composed of elastic cartilage.

Anatomy and Physiology, 9th ed. Patton

Chaper 9 | Tissue Types ___________________________________________________________________

Answers to Review Questions (p. 178) 1. The five most important functions of epithelial tissue are protection, sensory function, secretion, absorption, and excretion. 2. None. The epithelial tissues have no blood vessels. 3. Epithelial cells are classified based on cell shape into four categories: squamous, cuboidal, columnar, and pseudostratified columnar. Squamous cells are flat and platelike. Cuboidal cells are cube shaped. Columnar epithelial cells are higher than they are wide and appear narrow and cylindrical. Pseudostratified columnar cells are oddly shaped columnar cells. Although each cell touches the basement membrane, the tops of the cells do not fully extend to the surface of the membrane. 4. Arrangement of epithelial cells in a single layer is called simple epithelium. If the epithelial cells are layered one on another, the tissue is called stratified epithelium. If the epithelial cells are layered in a relaxed state but can form a single layer when stretched, the tissue is called transitional epithelium. 5. Simple squamous epithelium: Examples include alveoli; the lining of blood and lymph vessels; and the surfaces of pleura, pericardium, and peritoneum. Simple cuboidal epithelium: Examples include glands and their ducts and tubules and ducts of the kidney. Simple columnar epithelium: Examples include the cells that line the stomach, intestine, uterus, uterine tubules, and parts of the respiratory tract. Pseudostratified columnar epithelium: Examples include air passages of the respiratory system and certain parts of the male reproductive system, such as the urethra. Stratified squamous (keratinized) epithelium: An example is the skin. Stratified squamous (nonkeratinized) epithelium: Examples include the lining of the vagina, mouth, and esophagus. Stratified cuboidal epithelium: Examples include sweat gland ducts, the pharynx, and parts of the epiglottis. Stratified transitional epithelium: An example is the wall of the urinary bladder. 6. Glandular epithelium is specialized for secretory activity. Glandular epithelial cells may function singly as unicellular glands or in groups or clusters of solid cords or follicles as in multicellular glands. If the glands empty into ducts, they are exocrine glands. If they empty into the blood, they are endocrine glands. 7. Exocrine glands can be classified by their structure using the shape and complexity of their ducts. They can be tubular or alveolar (saclike); they can have one duct leading out of a simple gland or more than one duct leading out of a complex gland. Examples of tubular simple glands are intestinal glands, sweat glands, and gastric glands. Examples of alveolar simple glands are sebaceous glands. Mammary glands can be either tubular compound glands or alveolar compound glands. Salivary glands can be either tubular or alveolar compound glands. 8. Loose fibrous connective tissue has a matrix of soft viscous gel because it contains hyaluronic acid. The matrix also contains collagen and elastic fibers, which allow it to stretch. 9. Dense fibrous connective tissue consists mainly of fibers packed densely in the matrix. In dense (irregular) fibrous tissue, the fibers intertwine in irregular, swirling arrangements. Dense (regular) fibrous tissue contains fibers that are arranged in regular, parallel rows. One form of dense (regular) fibrous tissue is predominantly bundles of collagenous fibers (collagenous dense [regular] fibrous tissue). Another form of dense (regular) fibrous tissue contains mostly elastin fibers (elastic dense [regular] fibrous tissue). 10. Bone on the microscopic level is organized into osteons or Haversian systems. Bone cells are located in small spaces called lacunae. They are arranged in concentric layers of bone matrix called lamellae. Small canals called canaliculi connect each lacuna and bone cell with the nutrient blood vessels found in the central Haversian canal. Like bone cells, cartilage cells (chondrocytes) are found in lacunae. Cartilage is avascular, and blood must move through the cartilage by diffusion. 11. The three major types of cartilage tissue are hyaline, fibrocartilage, and elastic. Hyaline cartilage is shiny and translucent. It is found in support rings of the respiratory tubes and covering the ends of bones. Fibrocartilage is a durable cartilage with a rigid matrix filled with strong white fibers. It serves as shock absorbers between

Anatomy and Physiology, 9th ed. Patton

__________________________________________________________________ Chapter 9 | Tissue Types

vertebrae and in the knee joint. Elastic cartilage has a large number of fine elastic fibers that give it strength and flexibility. This is found in the external ear and the larynx. 12. Blood is composed of plasma and blood cells. The blood cells are erythrocytes, leukocytes, and thrombocytes. The erythrocytes transport respiratory gases. The leukocytes destroy harmful microorganisms, and thrombocytes assist in blood clot formation. The plasma transports nutrients and waste products, regulates the pH of body fluids, and helps maintain body temperature. 13. The three major types of muscle tissue are skeletal muscle tissue, smooth muscle tissue, and cardiac muscle tissue. 14. The two basic types of cells in the nervous system are the neurons, which are the conducting cells, and neuroglia cells, which are support cells.

Answers to Critical Thinking Questions (p. 136) 1. Epithelial tissues have limited amounts of intercellular material. They can form continuous sheets of tightly packed cells. Epithelial cells in the skin and in mucous and serous membranes are attached firmly to the connective tissue under them by forming a basement membrane. The cells in an epithelial sheet are held together by desmosomes, or tight junctions. The secretory function is accomplished by epithelial cells grouped in solid cords of specialized follicles. 2. Oil production does the most damage. It comes from holocrine glands; the cells rupture to release the oil from the gland, killing the cell that produced it. 3. Connective tissue contains one or more of the following fibers: collagenous fibers, which are tough and strong; reticular fibers, which are delicate; or elastic fibers, which are extensible and elastic. Fibrous tissues (such as, areolar, adipose reticular, and dense fibrous) have extracellular fibers as their predominant feature. The type and arrangement of these fibers are what distinguishes one type of tissue from another. 4. Calcium and other inorganic material are responsible for about 66% of the extracellular matrix of bone tissue. Insufficient amounts of calcium would compromise normal growth and weaken the bone and thus make it susceptible to injury and disease. To ensure normal development of bone, calcium is a necessary part of an individual’s diet. 5. A tendon is made up of collagen fibers. This gives density and flexibility with great tensile strength but no elasticity. Ligaments are made up of predominantly elastic fibers, which give the ligaments less strength but more elasticity. Because of this structural difference, the ligament is not able to function as a tendon.

Anatomy and Physiology, 9th ed. Patton

Instructor’s Resource Material for

10 Skin

ANSWER KEYS Answers to Quick Check Questions 1. Epidermis and dermis are the primary skin layers. Epithelium dominates the epidermal layer, and connective tissue dominates the dermis. 2. Most of the body surface is covered by thin skin. Skin covering the palms of the hands, soles of the feet, and other body areas subject to friction is classified as thick skin. In thin skin, the number of cell layers in each epidermal stratum is less than that in thick skin. Raised parallel ridges are not present in the dermis of thin skin. 3. Keratinocytes and melanocytes are the two main cell types in the epidermis. 4. Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale are the five layers of the epidermis. 5. The dermal-epidermal junction separates the dermis and epidermis. 6. The dermal papillae form the bumps that produce ridges. 7. The dermis layer is vascular. 8. The hypodermis forms a connection between the skin and the underlying structures of the body. 9. Metabolism of foods is the source of body heat. Muscles and glands produce more heat than any other tissues. 10. The answer should be any three out of the following: evaporation, radiation, conduction, and convection. 11. Varying amounts of melanin determine hair color. 12. The seven functions of the skin are: (1) protection, (2) sensation, (3) growth, (4) synthesis of important chemicals and hormones, (5) excretion, (6) temperature regulation, and (7) immunity. 13. The surface film is produced by the mixing of residue and secretions from sweat and sebaceous glands, with the epithelial cells constantly being cast off from the epidermis. 14. Hair, nails, and skin glands are the appendages of the skin. 15. The two types of sweat glands are eccrine and apocrine. Eccrine are the most numerous and widespread of the sweat glands in the body. They are small and function throughout life to produce perspiration rich in salts, ammonia, uric acid, urea, and other wastes. Apocrine glands are located deep in the subcutaneous layer. They are much larger than eccrine glands and are connected with hair follicles. Apocrine glands enlarge and begin to function at puberty, producing a more viscous and colored secretion. 16. Sebum (1) keeps the hair supple and (2) keeps the skin soft and pliant. 17. Surface film of the skin is produced by the mixing of residue and secretions from sweat and sebaceous glands with epithelial cells.

Answers to Case Study Questions (p. 204) 1. a: The epidermis is composed of only epithelial tissue. Epithelial tissue is avascular (meaning it has no blood vessels). The dermis has many blood vessels. If Aidan's finger is not bleeding, then the splinter could not have penetrated down to the dermis. So, the correct answer must be “a. Epidermis only.” In case you were still considering “d. Stratum basale only,” look again at the layers in the epidermis. The stratum basale is the deepest layer (farthest from the surface); so, the splinter would have to pass through the upper layers first. 2. d: The skin on the palms (and fingertips) is thick skin, whereas the skin on the arm is thin skin. Only the thick skin contains the stratum lucidum layer. All of the other layers listed are found in both thick and thin skin.

Anatomy and Physiology, 9th ed. Patton

Chapter 10 | Skin _________________________________________________________________________

3. c: Epidermal dendritic cells (Langerhans cells) are the “first responders” that identify a protein on an invading organism and show that protein to other immune system cells. By showing the immune cells the invader’s protein, the dendritic cells are saying, “This is your target!” which is sort of like giving a bloodhound a scent.

Answers to Review Questions (p. 208) 1. The skin has several functions: Protection: The skin protects the body from microorganisms, harmful chemicals, and mechanical injuries. It protects the body from dehydration and from ultraviolet light by forming melanin. Sensation: The skin can respond to pain, heat, cold, pressure, and touch. Movement and growth without injury: The skin is supple and elastic so that the body can move and grow without injury. Vitamin D production: The skin allows a precursor substance to be converted to vitamin D on exposure to ultraviolet light. Excretion: The skin excretes water, urea, ammonia, and uric acid. Immunity: Specialized cells that attach to and destroy microorganisms are found in the skin. Also, Langerhans cells function with T cells to trigger immune reactions. Temperature regulation: Production of sweat and regulation of blood flow to and away from the skin surface helps regulate body temperature. 2. The cell types found in the epidermis are keratinocytes, melanocytes, Langerhans cells, and helper T cells. 3. Stratum corneum: This is the outermost layer composed of a thin sheet of squamous cells that are dead and continuously being replaced. The cytoplasm in these cells has been replaced by keratin. The cells are water repellent and chemical resistant. They are held together by desmosomes. Stratum lucidum: The keratinocytes are tightly packed together in this layer. Nuclei are absent, and the cells are filled with a soft gel-like substance called eleidin, which will be transformed into keratin. Stratum granulosum: Keratinization begins here. Cells are arranged into sheets, two to four layers deep, and filled with intensely staining granules called keratohyalin. This is necessary for keratin formation. Cells in this layer have begun to degenerate as a result of lysosomal enzymes. Nuclei are missing or degenerate. Stratum spinosum: This is composed of 8 to 15 layers of irregularly-shaped cells with very prominent intercellular bridges or desmosomes. Microscopically, the desmosomes give the layer a spiny appearance. Cells are rich in RNA to initiate protein synthesis. Stratum basale: This is a single layer of columnar cells. Only the deepest cell layer undergoes mitosis. Because of this, the cells push up through the other layers. 4. The stratum corneum is sometimes called the barrier area. 5. There are a number of correct answers, but they all should include the following: The cells of the stratum basale continue to go through mitosis at the same rate that the cells are shed from the surface of the skin. Injury stimulates an increased rate of mitosis, and continued abrasion will form a thickening of the stratum corneum called a callus. 6. Keratin is a protective, water-repellent protein in skin cells in the stratum corneum. Cells in the stratum granulosum contain keratohyalin, which is necessary for the formation of keratin. The cells in the stratum lucidum contain eleidin, which will eventually become keratin. 7. The dermis of the skin contains blood vessels. 8. A blister is the result of injury to the epidermis or the dermoepidermal junction. This can damage the desmosomes, which hold the skin cells together. Blisters can form following burns, friction injuries, exposure to irritants, or accumulation of toxic products after cell injury or death. Typically, these break disulfide linkages or hydrogen bonds, which are the links in the desmosomes. This is an example of the relationship between the skin’s structure and function. 9. The two layers of the dermis are the papillary layer and the reticular layer. The reticular layer makes the skin stretchable and able to rebound. 10. The arrector pili muscles are small bundles of involuntary muscles attached to each hair follicle. Contraction of these muscles makes the hair stand on end. The skin around them rises in what is called “goose pimples.”

Anatomy and Physiology, 9th ed. Patton

________________________________________________________________________ Chapter 10 | Skin

11. The appendages of the skin are nails, hair, and skin glands. 12. Hair papilla: Contains the blood capillaries, which nourish the germinal matrix of the hair. Germinal matrix: A cup-shaped cluster of cells that forms in the stratum germinativum, which is the follicle’s innermost layer at the bottom. Hair root: The part of the hair that remains hidden in the follicle. Hair shaft: The visible part of the hair. Follicle: The small tube of epidermal cells that spreads down into the dermis. It forms two layers: the outer dermal root sheath and the epithelial root sheath. 13. The three primary types of skin glands are sweat glands, sebaceous glands, and ceruminous glands. 14. Eccrine glands are small and distributed over almost the entire body surface. They are simple coiled, tubular type of glands that produce a transparent watery liquid rich in salts, ammonia, uric acid, and urea. They play an important role in regulating body temperature. Apocrine glands are found in the axilla, in the areola of the breast, and around the anus. They are larger than the eccrine glands and are connected to hair follicles. They are simple branched tubular glands that enlarge and begin functioning at puberty. They produce a more viscous and colored secretion than do the eccrine glands. In females, apocrine glands show cyclic changes linked to the menstrual cycle. 15. The skin surface film has a variety of functions, including antibacterial and antifungal activity. It provides lubrication and hydration of the skin surface, acts as a buffer for skin irritants, and provides a block to toxic agents. 16. The “rule of nines” divides the total body surface into 11 areas of 9% (or multiples of 9%). The front and back of the trunk are 18% each. The front and back of each leg are 9% each. Each arm is 9%, and the head is 9%. The perineum makes up the additional 1%. By determining the parts of the body involved in the burn, one can make a rough estimate as to the percentage of body surface involved. 17. First-degree burns cause minor discomfort and reddening of the skin. Skin may peel, but tissue destruction is minimal and there are no blisters. Second-degree burns injure the upper layer of the dermis, which may include the sweat glands, sebaceous glands, and hair follicles. Tissue death is not complete. Blisters, severe pain, swelling, and edema characterize this type of burn. Scarring is common. Third-degree burns destroy both epidermis and dermis. Tissue death extends below hair follicles and sweat glands and may involve muscle or bone. Third-degree burns are insensitive to pain immediately after the injury; scarring is serious.

Answers to Critical Thinking Questions (p. 208) 1. The hair follicle, nail, sweat glands, and oil glands are part of the integumentary system only. The stratum corneum and the stratum basale are part of both the integumentary system and the integument. The skin is the integument. The skin and its appendages make up the integumentary system. 2. In thick skin, all layers of skin are present and each is several layers thick. In thin skin, the layers are less thick and one or more layers may be absent entirely. The thickness of the hypodermis depends on the amount of fat in this layer. 3. The dermoepidermal junction (DEJ) is the attachment point of the epidermis to the dermis. It has a basement membrane, special fibrous elements, and a polysaccharide gel. This allows it to hold the two parts of the skin together. 4. To leave as small a scar as possible, the incision should be made parallel to the Langer cleavage lines. These lines are different from the front and rear of the thigh; so, the incision should be made at a different angle. 5. This might hamper the skin’s ability to produce vitamin D. This function can occur only when the skin is exposed to ultraviolet (UV) light, which as a rule would be sunlight. 6. Light-skinned individuals are more likely to sunburn easily. It has been recently theorized that blistering sunburns may trigger the development of malignant melanoma.

Anatomy and Physiology, 9th ed. Patton

Chapter 10 | Skin _________________________________________________________________________

7. During a period of increased body temperature, the brain signals the sweat glands within the layer of skin to secrete sweat. The evaporation of sweat cools the body and is essential in keeping the body temperature in balance. To avoid dehydration, it is important to increase fluid consumption before, during, and after any type of exercise.

Anatomy and Physiology, 9th ed. Patton