Chapter 19: Mechanisms of Hormonal Regulation

Question 1

QUESTION: Which of the following is TRUE regarding thyroid hormone & thyroid-stimulating hormone (TSH)?

a.) TSH secretion is controlled by (+) feedback.
b.) TSH is secreted in excess when stimulated by T4.
c.) TSH secretion is regulated by thyrotropin-releasing hormone.
d.) Decreased anterior pituitary release of TSH stimulates thyroid hormone secretion.

Answer 1

C: TSH secretion is regulated by thyrotropin-releasing hormone primarily in the hypothalamus & by (-) feedback inhibition from thyroid hormones. Increased anterior pituitary release of TSH stimulates secretion of thyroid hormones. TSH is inhibited by thyroxine (T4).

Question 2

QUESTION: Insulin is secreted by the pancreas from which type of cell?

a.) F
b.) Beta
c.) Delta
d.) Alpha

Answer 2

B: Beta cells secrete preproinsulin, which is ultimately converted to insulin. F cells secrete pancreatic polypeptide. Delta cells secrete somatostatin. Alpha cells secrete glucagon.

Question 3

CASE STUDY: A 24 yr old mother visits her obstetrician’s office 1 week after delivering her baby. She is having trouble w/ breast-feeding & milk expression.
1.) For her milk expression, the obstetrician prescribes a nasal spray that will stimulate the posterior pituitary to release which one of the following hormones?

a.) Oxytocin
b.) Prolactin
c.) Calcitonin
d.) Incretin

Answer 3

A: Oxytocin is secreted in response to suckling & is responsible for the contraction of the uterus & milk ejection in lactating women. Prolactin functions to induce milk production during pregnancy & lactation. Calcitonin is secreted by the thyroid & acts to lower serum calcium levels by inhibiting bone resorption. The incretin hormones are secreted from the endocrine cells in the gastrointestinal tract & are active in controlling glucose levels.

Question 4

CASE STUDY: Following her appointment, as she is walking to her car, the mother becomes aware that someone is following her. Her body responds w/ a “fight or flight” response.

1.) The “fight or flight” response is regulated by the adrenal medulla’s secretion of which hormone?
a.) Cortisol
b.) Catecholamine
c.) Glucocorticoid
d.) Androgen

Answer 4

B: Cortisol is a glucocorticoid steroid hormone produced in the adrenal gland. It is active in the antistress & anti-inflammatory responses of the body & in the formation of glucose in the liver. The adrenal glands secrete the catecholamines-epinephrine & norepinephrine. They are responsible for the “fight or flight” response. Glucocorticoids are steroid hormones that play a role in the regulation of the metabolism of glucose & its synthesis. Androgens are steroid hormones that stimulate & control the development of male characteristics & may be converted to estrogens.

Question 5

MATCH THE FUNCTIONS: Match the altered function w/ the hormone.

• A Significant Change in Secretion of This Hormone
  1.) Antidiuretic hormone (ADH)
  2.) Parathyroid hormone (PTH)
  3.) Insulin
  4.) Gonadotropin-releasing hormone (GnRH)
  5.) Aldosterone
• Alters the Regulation of This Variable
  a.) Plasma calcium concentration
  b.) Blood glucose concentration
  c.) Body fluid osmolality
  d.) Extracellular fluid volume & plasma potassium concentration
  e.) Menstrual cycle regulation

Question 6

MATCH THE DEFINITIONS: Match the definitions on the right w/ the words on the left.

1.) Up-regulation
2.) Permissive effect
3.) Down-regulation
4.) 1st messenger
5.) 2nd messenger

a.) Chemical signal generated within a cell that mediates the action of a water-soluble hormone or other chemical
b.) Water-soluble hormone or other chemical that binds to receptors in plasma membranes
c.) Increased # or affinity of hormone receptors, often in response to low hormone concentration.
d.) Decreased # or affinity of hormone receptors, often in response to high hormone concentration.
e.) Hormone-induced change that facilitates the maximal response or functioning of a cell.

Question 7

CATEGORIZE THE HORMONES: Write the type of hormone beside each name. Choices: peptide, steroid, amine.

1.) Cortisol
2.) Insulin
3.) Thyroid hormones
4.) Adrenocorticotropic hormone (ACTH)
5.) Corticotropin-releasing hormone (CRH)
6.) Aldosterone
7.) Glucagon
8.) Growth hormone (GH)

Question 8

PICK THE CORRECT WORDS: Pick the correct word from the choices provided to complete these sentences.

1.) The hypothalamus is connected to a posterior pituitary by (portal blood vessels, a nerve tract) & to the anterior pituitary by (portal blood vessels, a nerve tract).
2.) Water-soluble hormones generally have a (short, long) half-life & circulate in (bound, free) forms.
3.) Low hormone concentrations usually cause cells to (down-regulate, up-regulate) receptors for that hormone, which (increases, decreases) cellular sensitivity to that hormone.
4.) Water-soluble hormones bind w/ (cell membrane, intracellular) receptors.
5.) Hormone receptors are (proteins, steroids, either proteins or steroids).
6.) (GH, ACTH) is an example of a somatotropic hormone.
7.) (Water, Lipid)-soluble hormones alter gene expression when the hormone-receptor complex binds to specific sites on (RNA, DNA) in the (nucleus, ribosomes).
8.) Secretion of cortisol increases when (ACTH, CRH) binds to receptors on cells in the adrenal (cortex, medulla).
9.) Many of the actions of growth hormone are mediated through the effects of (insulin-like growth factors, incretins, ghrelins), which also are known as (somatotropins, somatomedins, somatostatins).
10.) Catecholamines are released from the adrenal (cortex, medulla).
11.) The action of catecholamines (increases, decreases) blood glucose concentration as part of the (hypothalamic/pituitary/adrenal axis, fight-or-flight response).
12.) The net effect of insulin is to (increase, decrease) blood glucose concentration & (increase, decrease) synthesis of protein & fat.
13.) Cortisol acts to (increase, decrease) blood glucose concentration, (stimulate, inhibit) inflammation, & cause (only a few, numerous) other effects.
14.) A common mechanism of hormonal regulation is (+,-) feedback.

Question 9

DESCRIBE THE DIFFERENCES: Describe the difference between the items in each question.

1.) What is the difference between a direct effect & a permissive effect of a hormone?
2.) What is the difference between autocrine & paracrine action of a hormone?
3.) What is the difference between (-) & (+) feedback?

Question 10

COMPLETE THE SENTENCES: Write 1 word in each blank to complete these sentences.

1.) Steroid hormones are synthesized from ___________.
2.) ADH also is called arginine __________.
3.) In order for a hormone to act on a cell, the cell must have __________ for that hormone.
4.) Hormones that bind to receptors that activate adenylyl cyclase use ____________ as a 2nd messenger.
5.) Releasing hormones are produced by the ____________.
6.) An individual who has an iodine-deficient diet will have difficulty making enough __________ hormones.
7.) In the islets of Langerhans, alpha cells produce ___________, & beta cells produce insulin & ___________.
8.) Calcitonin is secreted by the ___________ gland & helps to regulate plasma ____________ concentration.
9.) The term somatopause indicates the decrease of ___________ hormone & insulin-like ____________ that occurs with aging.
10.) The neurohypophysis is the ____________ pituitary, & the adenohypophysis is the ______________ pituitary.

Question 11

TEACH PEOPLE ABOUT PHYSIOLOGY: Write your response to each situation in the space provided.

1.) A clinical research protocol includes drawing blood to measure insulin levels. “Our research subjects do not like blood draws,” says a research assistant. “Can we measure urine insulin instead?”
2.) “This drug information sheet says that sildenafil prolongs the action of cyclic GMP in blood vessel muscles,” says Mr. Lehrner. “I asked my doctor & he said cGMP is a 2nd messenger. What does ‘2nd messenger’ mean? Is that an abnormal thing?”
3.) Mr. Merryweather has a tumor that damaged his hypothalamus but not his pituitary gland. Among numerous other hormone problems, he is not secreting enough antidiuretic hormone (ADH). “I do not understand this,” says a nurse. “ADH comes from the pituitary & does not have a releasing hormone from the hypothalamus. How can a hypothalamic tumor cause lack of ADH?”
4.) “I understand why I need to take this antithyroid drug,” says Mr. Henderson, who has newly diagnosed hyperthyroidism. “It stops my thyroid gland from making any more thyroid hormones. But why does it take several weeks to have full effects? Don’t we make thyroid hormone every day?”
5.) A student is observing in an endocrine clinic. “Why do these laboratory slips have a place to request blood levels of carrier proteins for some hormones like thyroid but not for others like ADH & ACTH?”
6.) “Please help me make sense of the renin-angiotensin system,” says Mr. Phillipi. “If the kidney blood vessels sense low blood flow, they release renin into the blood, but how does that help fix the low blood flow? I want the details!”