25: Stress and the adrenal glands

Question 1

What are the two main components of the adrenal gland?

Answer 1

Cortex (80%)

Medulla (20%)

Question 2

What are the zones of the adrenal gland?

Answer 2

• Capsule
• Glomerulosa
• Fasciculata
• Reticularis
• Medulla

Question 3

What is the main secretory product of the glomerulosa?

Answer 3

Aldosterone

Question 4

What is the main secretory product of fasciculata?

Answer 4

Cortisol

Question 5

What is the main secretory product of the reticularis?

Answer 5

Androgens

Question 6

What is the main secretory product of the medulla?

Answer 6

Epinephrine, Norepinephrine (also known as adrenaline)

Question 7

What is responsible for the rate limiting reaction of the synthesis of adrenal cortex hormone?

Answer 7

P450 side-chain-cleavage (P450scc)

Cholesterol –> P450scc –> Pregnenolone

Question 8

What zone do glucocorticoids come from and give example

Answer 8

From Zona Fasiculata

• Cortisol
• Corticosterone

Question 9

What zone do mineralcorticoids come from and give an example

Answer 9

Zona glomerulosa

Aldosterone

Question 10

What zone do sex steriod precursors come from, and give an example

Answer 10

From Zona reticularis

From androstenedione

Question 11

What are the roles of aldosterone? (5)

Answer 11

• Acts to maintain fluid volume
• Increases the reabsorption of sodium and water
• Increases secretion of potassium
• Aldosterone increases water retention and increases blood pressure
• Aldosterone binds mineralocorticoid receptors

Question 12

Describe cell signalling of aldosterone

Answer 12

slides

-need to refer this later as well

Question 13

What are direct methods that aldosterone release are controlled?

Answer 13

K+ flows into the adrenal gland, which creates the direct effect of allowing the secretion of aldosterone

Question 14

What is an indirect method of control of aldosterone release?

Answer 14

Indirectly from the heart, as it is able to control levels of atrial natiruetic hormone

Also indirect control by the kidney because the kidney also needs to have an indication of the fluid in the body so it would have feedback to the aldosterone secretion.

When ECF levels are decreased renin is produced by the juxtoglomerular cells in the kidney.

This the goes to activate angiotensin (which is released by the liver) to angiotensin I. Another converting enzyme from the lungs converts it to angiotensin II which goes to the adrenal gland.

(slides for picture)

Question 15

Describe the control of cortisol release

Answer 15

Cortisol releasing hormone cell

Corticotrope –> ACTH –> Adrenal cortex –> Glucocorticoids –>inhibits CRH

Question 16

What are two examples of glucocorticoids

Answer 16

• Corticosterone

- Cortisol -more common in humans

Question 17

Describe the control of cortisol release

Answer 17

Slides (diagram)

Question 18

Describe sympathetic controls of the adrenal medulla

Answer 18

Sympathetic nerve –> Acetylcholine (released from medulla) –> Epinephrine –> Acts on distant target cells

Sympathetic nerve —> Acetylcholine –> Sympathetic ganglion –> Norepinephrine –> Acts on target cells at point of release

Question 19

What are some cardiovascular effects of adrenaline

Answer 19

• Increase cardiac contractility (β1)
• Increase heart rate (β1)
• Dilate smooth muscle around arterioles (β2)
• Constrict other arterioles (α1)

Main effect: shunt blood to exercising muscles and the brain, and away from other tissues

Question 20

Describe the metabolic effects of adrenaline

Answer 20

Slides/diagram