Endocrine SystemЁЯШн (from test yourself answers)
What is a hormone
. Hormones are chemical messengers produced by endocrine glands and are secreted directly into blood vessels.
Does ADH help promote or prevent the loss of large amounts of water in the urine? What effect would the inhibition of ADH release have on the body?
. It helps prevent the loss of large quantities of water in the urine. Inhibition of ADH would cause more water to flow out of the body in the urine.
Why are patients with kidney failure often anemic?
. Kidney failure patients are often anemic because of their deficiency of erythropoietin produced by the failing kidney, which normally stimulates red bone marrow to increase production of oxygen-carrying red blood cells.
Which chemical hormones groups bind to receptors on the target cells membrane? In the cytoplasm or nucleus
. Peptide hormones and monoamine catecholamine hormones bind to receptors on the target cell membrane. Steroid hormones and monoamine thyroid hormones bind to receptors in the cytoplasm or nucleus.
What hormone plays an important role in helping an animal maintain its body temperature under cold environmental conditions? How does it produce its effects?
. Thyroid hormone. It does this through its calorigenic effect. The production of thyroid hormone increases with exposure to cold temperatures. This response increases the body's metabolic rate, which generates more heat. It also causes nutrients to be burned at a faster rate; so to prevent significant loss of body weight, animals housed outdoors in cold temperatures need to be fed more calories than those kept in warmer temperatures.
What is a hormone target
A cell that has receptors for a particular hormone is referred to as a target of that hormone.
How does the negative feedback system control the secretion of many hormones
A gland produces its hormone as a result of stimulation by another hormone. When the level of hormone from the first gland drops below needed levels, the second gland, the stimulating gland, produces more stimulating hormone, which stimulates the first gland to produce more of its hormone. The rising level of hormone from the first gland in the bloodstream eventually reaches the level required in the body. Once that level is reached, the production of stimulating hormone by the second gland is turned down. This reduces the stimulation of the first gland, causing it to produce less hormone. When the level of hormone from the first gland drops below what the body needs again, the second gland (stimulating gland) turns its production of hormone back up, which turns the production of hormone from the first gland back up, and the process continues.
Though what mechanism does the hypothalamus control the production or release of hormones from the pituitary gland? How do its effects on the anterior and posterior portions of the pituitary differ
A system of tiny blood vessels called a portal system links the hypothalamus with the anterior portion of the pituitary gland. Modified neurons in the hypothalamus secrete hormones into these portal blood vessels. The hormones travel the short distance down to the anterior pituitary and regulate much of its function. These hypothalamic hormones, called releasing and inhibiting factors, are each specific for a particular anterior pituitary hormone. As their names imply, a releasing factor causes the anterior pituitary to produce and release a particular hormone, and an inhibiting factor has the opposite effect of inhibiting the production and release of a hormone. Because some anterior pituitary hormones influence all of the body's cells, the hypothalamus indirectly affects the whole body by regulating anterior pituitary gland functions. The effect of the hypothalamus on the posterior part of the pituitary gland is more direct. Modified neurons in the hypothalamus produce two hormones, antidiuretic hormone and oxytocin, that are transported down nerve fibers to the posterior pituitary gland, where they are stored. They are then released into the bloodstream by nerve impulses from the hypothalamus.
How do the clinical signs of hypothyroidism and hyperthyroidism relate to the normal functions of thyroid hormone?
Because thyroid hormone influences the functioning of all cells, organs, and systems, hypothyroidism affects the whole body. Clinical signs relate primarily to a slowing of the body's metabolism and include alopecia (hair loss, usually bilaterally symmetrical), dry skin, lethargy, reluctance to exercise, and weight gain without any increase in appetite. An affected animal often seeks out sources of heat because deficient thyroid hormone levels cause the animal to have difficulty maintaining its body temperature. Most cases of hypothyroidism occur in middle-age animals, but if it occurs in a young animal, dwarfism (impaired growth) and impaired mental development occur along with the other common signs. Hyperthyroidism is most commonly seen in cats, although it is seen occasionally in dogs. Excessive amounts of thyroid hormone speed up cellular metabolism all over the body. This results in signs such as nervousness, excitability, weight loss, increased appetite, tachycardia (abnormally fast heart rate), vomiting, diarrhea, polyuria (excessive urine production), and polydipsia (excessive thirst).
In what ways are the functions and characteristics of the endocrine system similar to those of the nervous system? In what ways are they different
Both systems regulate body functions to maintain homeostasis. The endocrine system's reaction to stimuli is slow, whereas the reaction of the nervous system to stimuli is fast. The endocrine system's duration of effects is long, whereas the duration of effects of the nervous system is short. The target tissues for the endocrine system are virtually all body cells and tissues, whereas the target tissues for the nervous system are muscle and glandular tissues. The chemical messengers of the endocrine system are hormones, whereas the chemical messengers of the nervous system are neurotransmitters. The messenger-producing cells of the endocrine gland are cells or modified neurons, whereas the messenger-producing cells of the nervous system are neurons. The distance from chemical message production to the target for the endocrine system is long (via the bloodstream), whereas this distance for the nervous system is short (across the synaptic space).
How do endocrine glands differ from exocrine glands
Endocrine glands secrete tiny amounts of hormones directly into the bloodstream and not through ducts. This feature differentiates them from exocrine glands, which secrete their products onto epithelial surfaces through tiny tubes called ducts.
How do the basic anabolic steroid drugs related to
Estrogens are responsible for the physical and behavioral changes that prepare the female for breeding and pregnancy and signal the male that the time for breeding is approaching. Progesterone, the primary progestin, helps prepare the uterus to receive the fertilized ovum and is necessary for pregnancy to be maintained once the fertilized ovum implants in the uterus.
What three groups of hormones are produced in the adernal cortex? What are their effects
Glucocorticoid hormones, mineralocorticoid hormones, and sex hormones. Glucocorticoids have a general hyperglycemic effect: that is, they cause the blood glucose level to rise. Mineralocorticoid hormones regulate the levels of some important electrolytes (mineral salts) in the body. The principal mineralocorticoid hormone aldosterone affects the levels of sodium, potassium, and hydrogen ions in the body. Aldosterone's target is the kidney, where it causes sodium ions to be reabsorbed from the urine back into the bloodstream in exchange for potassium and hydrogen ions. Aldosterone also affects water levels in the body, in that water accompanies sodium back into the bloodstream when sodium ions are reabsorbed. The amounts of sex hormones are very small, and their effects are usually minimal.
Other than promoting growth in young animals, what are some of other effects of GH?
Growth hormone (GH) helps regulate the metabolism of proteins, carbohydrates, and lipids in all of the body's cells. The effect of GH on protein metabolism is to encourage the anabolism, or synthesis, of proteins by body cells. The effects of GH on carbohydrate and lipid metabolism are linked. GH causes the mobilization (release) of lipids from storage in adipose (fat) tissue and their catabolism (breakdown) in body cells for energy production. At the same time, it discourages the cells from using carbohydrates, principally glucose, as energy sources. Because glucose is such an important energy source for the body's cells, a balance between GH and insulin is important to maintain homeostasis of glucose levels in the blood.
Which four hormones have hyperglycemic effects in the body? What is the only hormone that acts to lower the blood glucose level?
Growth hormone, thyroid hormone, glucocorticoid hormones, and glucagon all serve to increase the level of glucose in the blood. Insulin acts to lower the blood glucose level.
Why do hormonelike drugs generally have a high potential for undesirable side effects?
Hormonelike drugs have a high potential for undesirable side effects because the production and effects of natural hormones are so interrelated, so the therapeutic use of hormones and hormonelike drugs can produce some potent and widespread problems. Also, the amounts of hormones used therapeutically are usually very large compared with the normal physiologic hormone levels in the body; therefore, the potential for undesired side effects increases accordingly. If these drugs are not discontinued gradually, serious side effects can occur.
What stimulates the continued release of prolactin during lacation
Once lactation begins, prolactin production and release by the anterior pituitary gland continue as long as the teat or nipple continues to be stimulated by nursing or milking.
What two hormones play important roles in maintaining homeostasis of blood calcium levels in the body? Which one prevents hypercalcemia? Which prevents hypocalcemia
Parathyroid hormone (PTH), also called parathormone, and calcitonin. PTH helps prevent hypocalcemia, and calcitonin helps prevent hypercalcemia.
What are the three main chemical groups of hormones
Peptide hormones, steroid hormones, and monoamine hormones
Why are progtaglandins referred to as tissue hormones
Prostaglandins are sometimes called tissue hormones because they travel only a short distance from where they are produced as opposed to hormones, whose effects occur at a longer distance from where they are produced.
How does relaxin help prepare a pregnant animal for parturition?
Relaxin causes ligaments between the bones surrounding the birth canal to soften and relax, facilitating the passage of the newborn during parturition.
Which hormone are anabolic steroid drugs related to
Testosterone
Why is the pituitary gland referred to as the master endocrine gland
The pituitary gland is often called the master endocrine gland because many of its hormones direct the activity of other endocrine glands.
How are the hormones of the adrenal medulla involved in the flight-or fight response
These effects of the fight-or-flight response are produced partly by direct sympathetic nerve stimulation of target tissues and partly by the epinephrine and norepinephrine released into the bloodstream by the adrenal medulla. The adrenal medullary hormones circulate around the body, helping to produce the whole-body fight-or-flight effect. After the threat has passed, it takes the body a while to come down from its excited state. This delay results from the epinephrine and norepinephrine circulating in the bloodstream. It takes some time for them to be metabolized and removed from circulation.
When milking a cow by hand, why does it take a minute or two of teat stimulation before milk starts to flow freely?
This is how long it takes for the sensory stimulation to reach the brain and signal the hypothalamus to release oxytocin from the posterior pituitary and for the oxytocin to reach the mammary gland via blood circulation.
How do the actions of gastrin on the stomach differ from those of secretin and cholesystoknin
When released by stomach cells, gastrin stimulates gastric (stomach) glands to secrete hydrochloric acid and digestive enzymes, and it encourages muscular contractions of the stomach wall. Secretin and cholecystokinin are produced in the small intestine. Secretin stimulates the pancreas to secrete fluid rich in sodium bicarbonate into the duodenum to neutralize the acidic chyme from the stomach. Cholecystokinin stimulates the release of digestive enzymes from the pancreas into the duodenum. Both secretin and cholecystokinin also act on the stomach to inhibit gastric gland secretions and stomach motility. This slows the movement of chyme into the small intestine. They also stimulate the gallbladder of the liver to contract, sending bile down into the small intestine to aid the digestion and absorption of fats and fat-soluble vitamins.
Do FSH ans LH play important roles in male animals? If so, what are they
Yes. In the male, FSH has an effect similar to one of its effects in the female. It stimulates spermatogenesis, the development of male reproductive cells (the spermatozoa) in the seminiferous tubules of the testes. In the male, LH stimulates cells in the testes called interstitial cells to develop and produce the male sex hormone testosterone. Therefore, LH is sometimes called interstitial cell-stimulating hormone (ICSH) in the male.