Adrenal Gland Physiology

Question 1

The cortex is divided into four zones: _____________.

Answer 1

zona glomerulosa (outermost), zona fasciculata, zona reticularis, and medulla (innermost)

Question 2

The mineralocorticoids are produced by which layer of the adrenal cortex?

Answer 2

Zone glomerulosa (outmost)

Question 3

The glucocorticoids are produced by which layer of the adrenal cortex?

Answer 3

Zona fasciculata (second-most superficial)

Question 4

The sex hormones are produced by which layer of the adrenal cortex?

Answer 4

Zona reticularis (third from the surface)

Question 5

Epinephrine is made by the _____________.

Answer 5

adrenal medulla

Question 6

Trace the adrenal chemical pathway.

Answer 6

Cholesterol
Pregnenolone (which gets converted to aldosterone)
17-OH pregnenolone (which gets converted to cortisol)
Dehydroepiandrosterone (which gets converted to sex steroids)

Question 7

More than 90% of cortisol circulates _____________.

Answer 7

bound to cortisol-binding globulin (CBG)

Question 8

Cortisol receptors are ______________.

Answer 8

Hsp90, which are cytosolic

Question 9

What metabolic effects does cortisol have?

Answer 9

Increases gluconeogenesis
Increases glycogenolysis
Increases hormone-sensitive lipase, leading to release of FFAs
Centripetal redistribution of fat
Protein breakdown

Question 10

What hematologic effects does the hormone secreted by the zona fasciculata have?

Answer 10

It (cortisol) increases RBC production, so excess cortisol can lead to polycythemia and deficient cortisol can lead to anemia.

Question 11

Increased cortisol leads to _____________ collagen synthesis.

Answer 11

decreased (by inhibited fibroblast proliferation)

Question 12

Why does Cushing’s syndrome lead to osteoporosis?

Answer 12

Cortisol is a vitamin D antagonist.

Question 13

By what ways does cortisol inhibit the immune system?

Answer 13

• By inhibiting phospholipase A2, cortisol counteracts inflammation and vasodilation. Without vasodilation, leukocytes cannot get to infected tissues.
• By inhibiting fibroblast proliferation, infections are less containable.
• Cortisol also prevents T-cell proliferation.

Question 14

Cortisol inhibits the secretion of ____________.

Answer 14

CRH

Question 15

ACTH is derived from _______________.

Answer 15

proopiomelanocortin (POMC)

Question 16

The key regulator of ACTH is ___________.

Answer 16

cortisol

Question 17

Addison’s disease results from _____________.

Answer 17

primary adrenal insufficiency

Question 18

What lab findings are suggestive of Addison’s?

Answer 18

Decreased cortisol and aldosterone

Increased ACTH

Question 19

Secondary hypocortisolemia results from ____________. What lab findings are suggestive of this?

Answer 19

failure of the pituitary to secrete ACTH.

Decreased cortisol and ACTH

Question 20

Primary Cushing’s (also called Cushing’s syndrome) will present with what lab findings?

Answer 20

Increased cortisol and decreased ACTH

Question 21

Pituitary Cushing’s (also called secondary Cushing’s or Cushing’s disease) leads to what lab findings?

Answer 21

Increased cortisol and ACTH

Question 22

The adrenal medullary cells are also called ____________.

Answer 22

chromaffin cells

Question 23

Which nerve stimulates adrenal release of epinephrine?

Answer 23

The splanchnic nerve

Question 24

One of the key inhibitors of hormone-sensitive lipase is ____________.

Answer 24

insulin

Question 25

Alpha-adrenergic receptors outnumber beta-adrenergic receptors on pancreatic __________ cells.

Answer 25

beta; hence, epinephrine tends to inhibit insulin release

Question 26

Adrenal cholesterol is mainly attained by _______________.

Answer 26

LDL circulation

Question 27

The zona glomerulosa lacks the enzyme ___________, so all the pregnenolone gets converted to aldosterone.

Answer 27

17-alpha-hydroxylase

Question 28

The zona fasciculata contains the enzyme ____________, which is necessary for corticosteroid synthesis.

Answer 28

11-beta-hydroxylase

Question 29

What happens in the most common adrenal enzyme defect?

Answer 29

21-hydroxylase deficiency leads to absent aldosterone and cortisol and increased testosterone

Question 30

Testosterone and ____________ have similar effects, but testosterone is just much more potent. In females, however, _______________ is the major androgen.

Answer 30

adrenal androgen (x2)

Question 31

Two things must be replaced in primary adrenal insufficiency: ____________________.

Answer 31

glucocorticoids and mineralocorticoids

Question 32

Explain the pathogenesis of congenital adrenal hyperplasia.

Answer 32

Congenital absence of 21-hydroxylase and 11-beta-hydroxylase leads to decreased production of cortisol and aldosterone. ACTH increases as a result of low cortisol levels, leading to adrenal hyperplasia. All of the increased pregnenolone gets converted to testosterone which, in females, leads to virilization of the genitals. The main distinction between these two is that in 11-beta-hydroxylase deficiency an intermediate (11-deoxycorticosterone) is produced that can act to increase BP and decrease [K+].