16 The Endocrine System

directly onto their target cell into the cerebrospinal fluid A major difference between neurotransmitters and hormones is that hormones are secreted ____________. directly onto their target cell into the cerebrospinal fluid into ducts into the blood Answer: d. into the blood

A major determinant of a hormone’s mechanism of action is __________. whether the hormonal molecule is hydrophobic or hydrophilic its size whether it is rapid acting or slow acting if it activates gene activity or not Answer: a. whether the hormonal molecule is hydrophobic or hydrophilic

Receptors for steroid hormones are commonly located _________. inside the target cell on the plasma membrane of the target cell in the blood plasma in the extracellular fluid Answer: a. inside the target cell

direct gene activation a second messenger endocytosis Interaction with a membrane-bound receptor will transduce the hormonal message via __________. depolarization direct gene activation a second messenger endocytosis Answer: c. a second messenger

immediate cessation of cell response to the hormone Treatment of a hormone’s target cell with a phosphodiesterase inhibitor will result in ________. immediate cessation of cell response to the hormone prolonged activity of the cell inability of the hormone to bind to its receptor irreversible binding of the hormone to its receptor Answer: b. prolonged activity of the cell

they are not important signal molecules. Second messenger–activating hormones circulate in minute quantities because: they are not important signal molecules. small concentrations of hormone can activate many intracellular signals via amplification. they are continuously released from the gland. neurotransmitters also bind to hormone receptors. Answer: b. small concentrations of hormone can activate many intracellular signals via amplification.

Which of the following molecules act as second messengers? cAMP Ca2+ Inositol triphosphate All of the above Answer: d. All of the above

the steroid hormone may direct the synthesis of the protein. It’s possible for a steroid hormone and a protein hormone to affect the same intracellular protein because: the steroid hormone may direct the synthesis of the protein. the protein hormone may activate the protein. the protein hormone may direct the synthesis of the protein. of all of the above. Answer: d. all of the above

In order for a hormone to activate a target cell, the target cell must possess _______. a receptor a second messenger the hormone a chaperone Answer: a. a receptor

The most common form of endocrine malfunction is __________. failure of the gland to produce the hormone insensitivity of the target cell to the hormone overproduction of the hormone by the gland All of the above are common disorders. Answer: d. All of the above are common disorders.

When the pancreas releases insulin in direct response to blood glucose, this is an example of ________ stimulation. humoral neural hormonal negative feedback Answer: a. humoral

When an infant suckles at his mother’s breast, the mother’s neurohypophysis releases oxytocin. This is an example of __________ stimulation. humoral neural hormonal negative feedback Answer: b. neural

When the ovaries secrete estrogen in response to the hormone GnRH, this is an example of __________ stimulation. humoral neural hormonal negative feedback Answer: c. hormonal

Blood levels of hormone are kept within very narrow ranges by _________ mechanisms. humoral neural hormonal negative feedback Answer: d. negative feedback

Hormones secreted into the hypophyseal portal system are delivered directly to the ________. neurohypophysis adenohypophysis median eminence infundibulum Answer: b. adenohypophysis

The long bone growth-promoting effects of growth hormone are mediated by __________. somatostatin somatotrophs somatomedins insulin Answer: c. somatomedins

adrenal cortex; gonads thyroid; mammary glands gonads; adrenal cortex Secretions from the corticotrophs activate cells of the _______, while secretions from the gonadotrophs affect cells of the ________. adrenal cortex; gonads thyroid; mammary glands gonads; adrenal cortex mammary glands; gonads Answer: a. adrenal cortex; gonads

hyposecretion of oxytocin hypersecretion of oxytocin A patient is displaying high volumes of urine output and severe dehydration. The most likely cause is _________. hyposecretion of oxytocin hypersecretion of oxytocin hyposecretion of ADH hypersecretion of ADH Answer: c. hyposecretion of ADH

Common secretion(s) of the thyroid gland is (are) _________. calcitonin triiodothyronine thyroxine all of the above Answer: d. all of the above

hypersecretion of calcitonin A patient is losing weight rapidly, sweating profusely, and is always anxious. The patient may be suffering from _______. hypothyroidism cretinism hyperthyroidism hypersecretion of calcitonin Answer: c. hyperthyroidism

Occasionally, a female patient will experience hirsutism, or excessive facial hair growth. However, blood tests reveal that her levels of testosterone are normal for a female. Another cause could be hypersecretion of: catecholamines. mineralocorticoids. glucocorticoids. gonadocorticoids. Answer: d. gonadocorticoids.

Thyroid hormones; calmodulin Calcitonin; PTH Two hormones govern calcium regulation. ________ acts to elevate blood calcium levels, whereas ________ lowers blood calcium levels. PTH; calcitonin Thyroid hormones; calmodulin Calcitonin; PTH Calcitonin; thyroid hormone Answer: a. PTH; calcitonin

__________ is the adrenal hormone responsible for maintaining appropriate blood sodium levels. Cortisol DHEA Aldosterone Epinephrine Answer: c. Aldosterone

_________ trigger(s) secretion of aldosterone. Increased K+ Angiotensin II ANP Both a and b Answer: d. Both a and b

During times of stress, elevated levels of _______ often occur, which explains why we get a cold during final exam time. cortisol aldosterone ACTH androgens Answer: a. cortisol

Along with the sympathetic nervous system, the _________ is the other primary mediator of acute stress. adrenal medulla adrenal cortex zona glomerulosa zona reticularis Answer: a. adrenal medulla

The secretion of ________ helps regulate our circadian rhythms. estrogen testosterone thyroid hormones melatonin Answer: d. melatonin

The thymus secretes the hormone(s) ______________. thymopoietin thymosin thymic factor all of the above Answer: d. all of the above

Which of the following structures produces a hormone responsible for stimulating red blood cell production? Stomach Heart Kidney Skin Answer: c. Kidney

Which of the following structures produces a precursor to hormonal vitamin D, important for Ca2+ regulation? Stomach Heart Kidney Skin Answer: d. Skin