Exam 2 (Lecture 8) - Adrenal Cortex and Cortisol

Question 1

Describe the structure of the adrenal gland. Name the layers of the adrenal cortex and hormones secreted by cells in each of the layers. Also, which hormones are secreted by the adrenal medulla?

Answer 1

1) Cortex (3 layers; outermost to innermost)
- zona glomerulosa = aldosterone (mineralocorticoid)
- zona fasciculata = cortisol/cortisone (glucocorticoids)
- zona reticularis = androstenedione, testosterone, estradiol (androgens)

2) Medulla
- epinephrine and norepinephrine (catecholamines)

Question 2

Which layers of the adrenal cortex are under ACTH control?

Answer 2

1) Zona fasciculata

2) Zona reticularis

Question 3

What is the precursor for the biosynthesis of hormones of adrenal cortex?

Answer 3

Cholesterol (they are all steroids)

Question 4

What are the effects of cortisol on the intermediary metabolism? Describe the relationship of this effect to effects of insulin, GH, catecholamines, and glucagon.

Answer 4

1) They are opposite the effects of insulin; acts permissively to mobilize fuel in times of need (potentiates effects of glucagon, epinephrine and GH); makes glucose available in plasma

Question 5

What are other major effects of cortisol?

Answer 5

1) Anterior pituitary = decreased ADH, TSH, and GH

2) Connective tissue = decreased collagen synthesis

3) GI tract = decreased mucosal barriers (increased chance of ulcers); decreased calcium absorption

4) Fetus = fetal cortisol prepares fetus organ systems for birth (eg stimulates production of lung surfactant)
- surge of fetal cortisol triggers parturition

5) Inflammatory and Immune System = decreased inflammatory and immune response; limits destruction of normal tissue during injury

6) Bone = decreased calcium deposition

Question 6

What is Cushing’s disease? In which domestic animals would you most likely encounter it? What are the most common treatments?

Answer 6

1) Pituitary-dependent hyperadrenocorticism (PDH)
- excessive ACTH secretion

2) Seen most commonly in dogs and older horses

3) Treatments:
- Horses: dopamine agonists and serotonin antagonists (suppress abnormal production of ACTH and other POMC derivatives in the pituitary)

  - Dogs: Mitotane (controlled destruction of cells in the adrenal cortex)
                Trilosane (blocks synthesis of cortisol)