14.5 Growth Hormones Growth is a complex process and requires the coordination of several hormones of which the main one is growth hormone. It is produced by the pituitary gland and acts on the liver, stimulating it to produce another hormone. It is this second hormone, which directly affects the growth of bone and muscle. Growth hormone also helps to control the body’s use of proteins, carbohydrates and fats. The lack of growth hormone can slow bodily development. 14.6 Adrenaline Adrenaline (BAN) or epinephrine (INN) is a hormone and a neurotransmitter. This hormone is produced by the adrenal glands, which lie at the tops of the kidneys. Normally a small amount of adrenaline is produced and this helps to maintain normal blood pressure. In situations of stress or excitement, however, a large amount of adrenaline is produced very quickly and this has a dramatic effect on the body. That is why adrenaline is sometimes called the ‘emergency hormone’. It prepares the body for a fight or flight response. In stressful situations, your body produces adrenaline and prepares itself for a physical response. Functions of Adrenaline: • raises blood sugar levels by stimulating the liver to change glycogen into glucose • causes fatty tissue to release fat into the blood • increases the heart rate • increases blood flow to the muscles • reduces blood flow to the skin and the intestines • widens the bronchioles • dilates the pupils All of this means the body is ready for action. Unfortunately, in today’s world, people suffer from stress and produce adrenaline in situations where no physical activity is required. A certain amount of stress is good and keeps our bodies working properly but repeated and prolonged episodes of stress can cause health problems such as sleepless nights, high blood pressure, and digestive problems. Epinephrine is used as a drug in cardiac arrest and other cardiac disrhythmias, as a vasoconstrictor in anaphylactic shock and sepsis, and as a bronchodilator in acute bronchial asthma. Allergy patients undergoing immunotherapy can get an epinephrine rinse before their allergen extract is administered. 14.7 ADH (Anti-Diuretic Hormone) The amount of water in the blood must be kept more or less the same all the time so there has to be a balance between the amount of water taken in the diet and the amount lost by the body in sweating, evaporation, faeces, and urine. This is achieved by the action of the hormone ADH (Anti-Diuretic Hormone). The hypothalamus detects whether there is or not enough water in the blood. Then it sends a message to the pituitary gland, which releases ADH. The kidneys save more water, so that the urine becomes less in volume and more concentrated. The level of water in the blood can then begin to rise as water is ingested and produced by the process of respiration. If there is too high a level of water in the blood, production of ADH will stop. The kidneys will not save as much water and the urine becomes dilute and of greater volume. The level of water in the blood then begins to fall towards the ideal level. 14.8 Endorphin Endorphins are endogenous opiod biochemical compounds. They are peptides produced by the pituitary gland and the hypothalamus in vertebrates, and they resemble the opiates in their abilities
/ 98
Ukázka elektronické knihy, UID: KOS522265
to produce analgesia and a sense of well-being. In other words, they work as “natural pain killers”. Endorphins regulate feelings of pain and hunger and are connected to the production of sex hormones. According to some reports, laughter releases endorphins in the brain. So besides widening the blood vessels, suppressing the production of stress hormones and raising antibody levels in the blood, laughing would thus also have an analgesic effect. Another widely publicised situation of endorphin production is the so-called runner’s high, which is said to occur during strenuous exercise that activates endorphin production. Ultraviolet light may also stimulate the release of endorphins.
hypothalamus
Neurosecretory cells produce AHD and oxytocin.
Neurosecretory cells produce releasing and release-inhibiting hormones. These hormones are sekreted into a portal systems.
These hormones move down axons to axon ending. portal system
When appropriate, ADH and oxytocin are secreted from axon endings into the bloodstream.
Each type of hypothalamic hormone either stimulates or inhibits production and secretion of an anterior pituitary hormone. The anterior pituitary secretes its hormones into the bloodstream.
posterior pituitary
anterior pituitary
antidiuretic hormone ADH
gonadotropins FSH and LH
kidney tubules
ovaries, tested
growth hormone GH
oxytocin oxytocin
prolactin PRL thyroid stimulating hormone THS
smooth muscle in uterus
andrenocorticotropin ACTH
mammary glands
mammary glands thyroid
bones, tissuues
adrenal cortex
Figure 14.1 Hypothalamus and the pituitary.
Exercises 1. Text comprehension. 1. What is the function of hormones (in general)? 2. Describe the effects of endorphins. 3. Characterise diabetes mellitus (types 1 and 2). 4. Describe the modes of administration of insulin.
/ 99
Ukázka elektronické knihy, UID: KOS522265
5. What are the function and the effects of adrenalin? 6. Explain what FSH means and describe its function. 7. What is IVF? 8. Describe the function of ADH. 2. True or false? Correct the statements and justify your answers. 1. The best known hormones are produced by bone marrow. 2. Endorphins regulate the feeling of cold and heat. 3. Insulin is produced in the Islets of Langerhans in the pancreas. 4. Epinephrine is an important constituent of oral contraceptives. 5. Patients with Type 1 diabetes mellitus occasionally require insulin administration. 6. Insulin can be taken orally. 7. When released into the bloodstream, adrenaline depresses physiological functions of the organism. 8. LH is one of the hormones responsible for bodily changes during puberty. 3. Complete the text with suitable expressions. available ovulation reach
contains reversible remain
accept common menstrual
fertility unwanted known
been taken
Oral contraceptives are contraceptives which are 1. ……… orally and inhibit the body’s 2. ……… by chemical means. Female oral contraceptives have 3. ……… on the market since the early 1960s. Male oral contraceptives 4. ……… a subject of research and development, and are not 5. ……… widely (if at all) to the public. Female oral contraceptives, colloquially 6. ……… as the Pill, are the most 7. ……… form of pharmaceutical contraception, the prevention of 8. ……… pregnancy. They consist of a pill that women take daily and that 9. ……… doses of synthetic hormones (estrogen and progesterone); the doses are adjusted in synchrony with the 10. ……… cycle. Mechanism of action. The Pill works by preventing 11. ………, as well as making the uterus less likely to 12. ……… implantation of an embryo if one is created, and thickens the mucus in the cervix making it more difficult for sperm to 13. ……… any egg. Taken correctly, it is the single most reliable form of 14. ……… contraception, with less than one in 100 women using the pill becoming pregnant in a year of continuous use. 4. Match the couples. 1. runner’s 2. oral 3. analgesic 4. gastrointestinal 5. chemical 6. endocrine 7. reproductive 8. heart 9. anaphylactic 10. insulin
a) glands b) cycle c) shock d) rate e) pump f) effect g) messenger h) contraceptives i) tract j) high
/ 100
Ukázka elektronické knihy