Deck 7: Endocrine Physiology

Question 1

Use the graph below, which shows changes during the menstrual cycle, to answer the following Questions


-The increase shown at point $A$ is caused by the effect of

A) estrogen on the anterior pituitary
B) progesterone on the hypothalamus
C) follicle-stimulating hormone (FSH) on the ovary
D) luteinizing hormone (LH) on the anterior pituitary
E) prolactin on the ovary

Answer 1

progesterone on the hypothalamus

Question 2

Use the graph below, which shows changes during the menstrual cycle, to answer the following Questions


-Blood levels of which substance are described by curve $\mathrm{B}$ ?

A) Estradiol
B) Estriol
C) Progesterone
D) Follicle-stimulating hormone (FSH)
E) Luteinizing hormone (LH)

Answer 2

Progesterone

Question 3

Use the graph below, which shows changes during the menstrual cycle, to answer the following Questions


-The source of the increase in concentration indicated at point $\mathrm{C}$ is the

A) hypothalamus
B) anterior pituitary
C) corpus luteum
D) ovary
E) adrenal cortex

Answer 3

ovary

Question 4

Use the graph below, which shows changes during the menstrual cycle, to answer the following Questions


-The source of the increase in concentration at point $\mathrm{D}$ is the

A) ovary
B) adrenal cortex
C) corpus luteum
D) hypothalamus
E) anterior pituitary

Question 5

Use the graph below, which shows changes during the menstrual cycle, to answer the following Questions


-The cause of the sudden increase shown at point $\mathrm{E}$ is

A) negative feedback of progesterone on the hypothalamus
B) negative feedback of estrogen on the anterior pituitary
C) negative feedback of follicle-stimulating hormone (FSH) on the ovary
D) positive feedback of FSH on the ovary
E) positive feedback of estrogen on the anterior pituitary

Question 6

A 41-year-old woman has hypocalcemia, hyperphosphatemia, and decreased urinary phosphate excretion. Injection of parathyroid hormone (PTH) causes an increase in urinary cyclic adenosine monophosphate (cAMP). The most likely diagnosis is

A) primary hyperparathyroidism
B) vitamin $\mathrm{D}$ intoxication
C) vitamin D deficiency
D) hypoparathyroidism after thyroid surgery
E) pseudohypoparathyroidism

Question 7

Which of the following hormones acts on its target tissues by a steroid hormone mechanism of action?

A) Thyroid hormone
B) Parathyroid hormone (PTH)
C) Antidiuretic hormone (ADH) on the collecting duct
D) $\beta_{1}$ adrenergic agonists
E) Glucagon

Question 8

A 38-year-old man who has galactorrhea is found to have a prolactinoma. His physician treats him with bromocriptine, which eliminates the galactorrhea. The basis for the therapeutic action of bromocriptine is that it

A) antagonizes the action of prolactin on the breast
B) enhances the action of prolactin on the breast
C) inhibits prolactin release from the anterior pituitary
D) inhibits prolactin release from the hypothalamus
E) enhances the action of dopamine on the anterior pituitary

Question 9

Which of the following hormones originates in the anterior pituitary?

A) Dopamine
B) Growth hormone-releasing hormone (GHRH)
C) Somatostatin
D) Gonadotropin-releasing hormone (GnRH)
E) Thyroid-stimulating hormone (TSH)
F) Oxytocin
(G) Testosterone

Question 10

Which of the following functions of the Sertoli cells mediates negative feedback control of follicle-stimulating hormone (FSH) secretion?

A) Synthesis of inhibin
B) Synthesis of testosterone
C) Aromatization of testosterone
D) Maintenance of the blood-testes barrier

Question 11

Which of the following substances is derived from proopiomelanocortin (POMC)?

A) Adrenocorticotropic hormone (ACTH)
B) Follicle-stimulating hormone (FSH)
C) Melatonin
D) Cortisol
E) Dehydroepiandrosterone

Question 12

Which of the following inhibits the secretion of growth hormone by the anterior pituitary?

A) Sleep
B) Stress
C) Puberty
D) Somatomedins
E) Starvation
F) Hypoglycemia

Question 13

Selective destruction of the zona glomerulosa of the adrenal cortex would produce a deficiency of which hormone?

A) Aldosterone
B) Androstenedione
C) Cortisol
D) Dehydroepiandrosterone
E) Testosterone

Question 14

Which of the following explains the suppression of lactation during pregnancy?

A) Blood prolactin levels are too low for milk production to occur
B) Human placental lactogen levels are too low for milk production to occur
C) The fetal adrenal gland does not produce sufficient estriol
D) Blood levels of estrogen and progesterone are high
E) The maternal anterior pituitary is suppressed

Question 15

Which step in steroid hormone biosynthesis, if inhibited, blocks the production of all androgenic compounds but does not block the production of glucocorticoids?

A) Cholesterol $\rightarrow$ pregnenolone
B) Progesterone $\rightarrow$ 11-deoxycorticosterone
C) 17-Hydroxypregnenolone $\rightarrow$ dehydroepiandrosterone
D) Testosterone $\rightarrow$ estradiol
E) Testosterone $\rightarrow$ dihydrotestosterone

Question 16

A 46-year-old woman has hirsutism, hyperglycemia, obesity, muscle wasting, and increased circulating levels of adrenocorticotropic hormone (ACTH). The most likely cause of her symptoms is

A) primary adrenocortical insufficiency (Addison disease)
B) pheochromocytoma
C) primary overproduction of ACTH (Cushing disease)
D) treatment with exogenous glucocorticoids
E) hypophysectomy

Question 17

Which of the following decreases the conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol?

A) A diet low in $\mathrm{Ca}^{2+}$
B) Hypocalcemia
C) Hyperparathyroidism
D) Hypophosphatemia
E) Chronic renal failure

Question 18

Increased adrenocorticotropic hormone (ACTH) secretion would be expected in patients

A) with chronic adrenocortical insufficiency (Addison disease)
B) with primary adrenocortical hyperplasia
C) who are receiving glucocorticoid for immunosuppression after a renal transplant
D) with elevated levels of angiotensin II

Question 19

Which of the following would be expected in a patient with Graves disease?

A) Cold sensitivity
B) Weight gain
C) Decreased $\mathrm{O}_{2}$ consumption
D) Decreased cardiac output
E) Drooping eyelids
F) Atrophy of the thyroid gland
G) Increased thyroid-stimulating hormone (TSH) levels
H) Increased triiodothyronine $\left(\mathrm{T}_{3}\right)$ levels

Question 20

Blood levels of which of the following substances is decreased in Graves disease?

A) Triiodothyronine $\left(\mathrm{T}_{3}\right)$
B) Thyroxine $\left(\mathrm{T}_{4}\right)$
C) Diiodotyrosine (DIT)
D) Thyroid-stimulating hormone (TSH)
E) Iodide ( $\left.\mathrm{I}^{-}\right)$

Question 21

Which of the following hormones acts by an inositol 1,4,5-triphosphate ( $\left.\mathrm{IP}_{3}\right)-\mathrm{Ca}^{2+}$ mechanism of action?

A) 1,25-Dihydroxycholecalciferol
B) Progesterone
C) Insulin
D) Parathyroid hormone (PTH)
E) Gonadotropin-releasing hormone $(\mathrm{GnRH})$

Question 22

Which step in steroid hormone biosynthesis is stimulated by adrenocorticotropic hormone (ACTH)?

A) Cholesterol $\rightarrow$ pregnenolone
B) Progesterone $\rightarrow$ 11-deoxycorticosterone
C) 17-Hydroxypregnenolone $\rightarrow$ dehydroepiandrosterone
D) Testosterone $\rightarrow$ estradiol
E) Testosterone $\rightarrow$ dihydrotestosterone

Question 23

The source of estrogen during the second and third trimesters of pregnancy is the

A) corpus luteum
B) maternal ovaries
C) fetal ovaries
D) placenta
E) maternal ovaries and fetal adrenal gland
F) maternal adrenal gland and fetal liver
G) fetal adrenal gland, fetal liver, and placenta

Question 24

Which of the following causes increased aldosterone secretion?

A) Decreased blood volume
B) Administration of an inhibitor of angiotensin-converting enzyme (ACE)
C) Hyperosmolarity
D) Hypokalemia

Question 25

Secretion of oxytocin is increased by

A) milk ejection
B) dilation of the cervix
C) increased prolactin levels
D) increased extracellular fluid (ECF) volume
E) increased serum osmolarity

Question 26

A 61-year-old woman with hyperthyroidism is treated with propylthiouracil. The drug reduces the synthesis of thyroid hormones because it inhibits oxidation of

A) Triiodothyronine $\left(\mathrm{T}_{3}\right)$
B) Thyroxine $\left(\mathrm{T}_{4}\right)$
C) Diiodotyrosine (DIT)
D) Thyroid-stimulating hormone (TSH)
E) Iodide ( $\mathrm{I}^{-}$ )

Question 27

A 39-year-old man with untreated diabetes mellitus type I is brought to the emergency room. An injection of insulin would be expected to cause an increase in his

A) urine glucose concentration
B) blood glucose concentration
C) blood $\mathrm{K}^{+}$ concentration
D) blood $\mathrm{pH}$
E) breathing rate

Question 28

Which of the following results from the action of parathyroid hormone (PTH) on the renal tubule?

A) Inhibition of $1 \alpha$ -hydroxylase
B) Stimulation of $\mathrm{Ca}^{2+}$ reabsorption in the distal tubule
C) Stimulation of phosphate reabsorption in the proximal tubule
D) Interaction with receptors on the luminal membrane of the proximal tubular cells
E) Decreased urinary excretion of cyclic adenosine monophosphate (CAMP)

Question 29

Which step in steroid hormone biosynthesis occurs in the accessory sex target tissues of the male and is catalyzed by $5 \alpha$ -reductase?

A) Cholesterol $\rightarrow$ pregnenolone
B) Progesterone $\rightarrow$ 11-deoxycorticosterone
C) 17-Hydroxypregnenolone $\rightarrow$ dehydroepiandrosterone
D) Testosterone $\rightarrow$ estradiol
E) Testosterone $\rightarrow$ dihydrotestosterone

Question 30

Which of the following pancreatic secretions has a receptor with four subunits, two of which have tyrosine kinase activity?

A) Insulin
B) Glucagon
C) Somatostatin
D) Pancreatic lipase

Question 31

A 16-year-old, seemingly normal female is diagnosed with androgen insensitivity disorder. She has never had a menstrual cycle and is found to have a blind-ending vagina; no uterus, cervix, or ovaries; a $46 \mathrm{XY}$ genotype; and intra-abdominal testes. Her serum testosterone is elevated. Which of the following characteristics is caused by lack of androgen receptors?

A) $46 \mathrm{XY}$ genotype
B) Testes
C) Elevated serum testosterone
D) Lack of uterus and cervix
E) Lack of menstrual cycles