Chapter 18 Check points
Why do levels of HH-RH and CRH rise during the resistance phase of general adaptation syndrome?
During the resistance phase of the general adaptation syndrome, there is a high demand for glucose, especially by the nervous system. the hormones GH_RH and CRH increase the levels of GH and ACTH, respectively
Identify a hormone released by adipose tissue.
leptin is a hormone released by adipose tissue.
List three possible functions of melatonin.
melatonin inhibits reproductive functions, protects against free radical damage, and influences circadian rhythms.
A blood sample contains elevated levels of somatomedins. Which pituitary hormone would you also expect to be elevated?
somatomedins mediate the action of growth hormone. elevated levels of growth hormone typically accompany elevated levels of somatomedins.
Discuss the general role of the endocrine system in the functioning of other body systems.
the endocrine system adjusts metabolic rates and substrate utilization, and regulations growth and development, in all other body systems.
Identify four mechanisms of intercellular communication.
the four mechanisms of intercellular communication are direct, paracrine, endocrine, and synaptic.
Identify the hormone secreted by the parathyroid glands.
the hormone secreted by the parathyroid glands in parathyroid hormone.
Describe the location of the parathyroid glands.
the parathyroid glands are embedded in the posterior surfaces of the lateral lobes of the thyroid gland.
The removal of the parathyroid glands would result in a decrease in the blood concentration of which important mineral?
the removal of the parathyroid glands would result in a decrease in the blood concentration of calcium ions. increasing the amounts of vitamin D and calcium in the diet could counteract the effects.
List the three zones of the adrenal cortex.
the three zones of the adrenal cortex from superficial to deep are the zona glomerulosa, zona fasciculata, zona reticularis.
Identify the two lobes of the pituitary gland.
the two lobes of the pituitary gland are the anterior lobe and the posterior lobe.
Identify the two regions of the adrenal gland, and cite the hormones secreted by each.
the two regions of the adrenal gland are the cortex and medulla. the cortex secretes mineralocorticoids(primarily aldosterone), glucocorticoids(mainly cortisol, hydrocortisone, and corticosterone), and androgens; the medulla secretes epinephrine and norepinephrine.
Insulin lowers blood glucose levels, and glucagon causes glucose levels to rise. What is this type of hormonal interaction called?
the type of hormonal interaction in which two hormones have opposite effects on their target tissues is called antagonism.
Identify the hormones of the thyroid gland.
thyroxine, triiodothyronine, and calcitonin are hormones associated with the thyroid gland.
Identify two hormones secreted by the kidneys.
two hormones secreted by the kidneys are erythropoietin and calcitriol.
Identify the types of cells in the pancreatic islets and the hormones produced by each.
The cells of the pancreatic islets(and their hormones) are alpha cells(glucagon), beta cells(insulin), delta cells(GH-IH), and F cells(pancreatic polypeptide).
What primary factor determines each cell's hormonal sensitivities?
a cell's hormonal sensitivities are determined by the presence or absence of the receptor complex needed to bind a given hormone.
Define hormone. a hormone is a chemical messenger that is secreted by one cell and travel through the bloodstream to affect the activities of cells in other parts of the body.
a hormone is a chemical messenger that is secreted by one cell and travel through the bloodstream to affect the activities of cells in other parts of the body.
The lack of which hormones would inhibit skeletal formation?
a lack of GH, thyroid hormone, PTH, and the gonadal hormones would inhibit the formation and development of the skeletal system.
How would the presence of a substance that inhibits the enzyme adenylate cyclase affects the activity of a hormone that produces its cellular effects by way of the second messenger cAMP?
a substance that inhibits adenylate cyclase, the enzyme that converts ATP to cAMP, would block the action of any hormone that requires cAMP as a second messenger.
What signs and symptoms would you expect to see in an individual whose diet lacks iodine?
an individual whose diet lacks iodine would be unable to form the thyroid hormones thyroxine and triiodothyronine. as a result, you would expect to see signs and symptoms associated with their deficiency: decreased metabolic rate, decreased body temperature, a poor response to physiological stress, and an increase in the size of thyroid gland(goiter).
Why does a person with type 1 or type 2 diabetes urinate frequently and have increased thirst?
an individual with type 1 or type 2 diabetes has such high blood glucose; some glucose is lost in urine. because the urine contains high concentrations of glucose, less water can be reclaimed by osmosis, so the volume of urine production increases. the water losses reduce blood volume and elevated blood osmotic pressure, promoting thirst and triggering the secretion of ADH.
What effect would elevated circulating levels of cortisol, a steroid hormone from the adrenal cortex, have on the pituitary secretion of ACTH?
elevated circulating levels of cortisol inhibit the endocrine cells that control the release of ACTH from the pituitary gland, so ACTH levels would decrease. this is an example of a negative feedback mechanism.
Discuss the functional relationship between the endocrine system and the muscular system.
hormones of the endocrine system adjust muscle metabolism, energy production, and growth; hormones also regulate calcium and phosphate levels, which are critical to normal muscle functioning. for their part, skeletal muscles protect some endocrine organs.
If a person were dehydrated, how would the amount of ADH released by the posterior lobe change?
in dehydration, blood osmotic concentration is increased, which would stimulate the posterior lobe of the pituitary gland to release more ADH.
Increased amounts of light would inhibit the production of which hormone?
increased amounts of light would inhibit the production(and release) of melatonin from the pineal gland, which receives neural input from the optic tracts. melatonin secretion is influenced by light-dark cycles.
What effect would increased levels of glucagon have on the amount of glycogen stored in the liver?
increased levels of glucagon stimulate the conversion of glycogen to glucose in the liver, which would in turn reduce the amount of glycogen in the liver.
When a person's thyroid gland is removed, signs of decreased thyroid hormone concentration do not appear until about one week later. Why?
most of the body's reserves of the thyroid hormones, thyroxine and T4 , are bound to blood-borne proteins called thyroid-binding globulins. because these compounds represent such a large reservoir of thyroxine and T4, it takes several days after removal of the thyroid gland for blood levels of thyroxine and T4 to decline.
How would you distinguish between a neural response and an endocrine response on the basis of response time and duration? neural responses occur within fractions of a second and are of short duration. conversely, endocrine responses are slow to appear but last for minutes to days.
neural responses occur within fractions of a second and are of short duration. conversely, endocrine responses are slow to appear but last for minutes to days.
Describe the action of renin in the bloodstream.
once released into the the bloodstream, renin functions as an enzyme, catalyzing the conversion of angiotensinogen to angiotensin I.
What effect would elevated cortisol levels have on blood glucose levels?
one function of cortisol is to decrease the cellular use of glucose while increasing both the available glucose(by promoting the breakdown of glycogen) and the conversion of amino acids to carbohydrates. therefore, the net result of elevated cortisol levels would be an elevation of blood glucose.
Describe paracrine communication. paracrien communication is the use of chemical messengers to transfer information from cell to cell within a single tissue.
paracrien communication is the use of chemical messengers to transfer information from cell to cell within a single tissue.
Identify the hormone-secreting cells of the pineal gland.
pinealocytes are the special secretory cells in the pineal gland.
