The Adrenal Gland

Question 1

What is the adrenal medulla?

Answer 1

A modified sympathetic ganglion derived from neural crest tissue

Question 2

What does the adrenal medulla secrete?

Answer 2

Catecholamines - epinephrine, noradrenaline, dopamine

Question 3

What is the adrenal cortex?

Answer 3

A true endocrine gland from the mesoderm

Question 4

What does the adrenal cortex secrete?

Answer 4

1. Mineralocorticoids
2. Glucocorticoids
3. Sex Steroids

Question 5

What are the two main products of the adrenal cortex?

Answer 5

Cortisol and Aldesterone

Question 6

What is DHEA?

Answer 6

A pre-hormone of testosterone and oestrogen

Question 7

What do defects in 21-hydroxylase cause?

Answer 7

congenital adrenal hyperplasia (aldosterone and cortisol and is associated with a disruption of salt and glucose balance)

Ambiguous genitalia

Question 8

Why does a deficit in 21-hydroxylase cause adrenal hyperplasia?

Answer 8

1. Lack of 21-hydroxylase inhibits synthesis of cortisol
2. This removes the negative feedback ACTH and CRH release
3. Increased ACTH secretion is responsible for enlargement of adrenal glands
4. Negative feedback of ACTH on CRH synthesis remains

Question 9

What is cortisol ?

Answer 9

A glucocorticoid hormone which influences glucose metabolism

Question 10

What is cortisol bound to?

Answer 10

CBG

Question 11

When is cortisol released?

Answer 11

Burst at 6-9am

Lowest level - midnight

Question 12

What are cortisol levels linked to?

Answer 12

Stress

Question 13

What occurs if the adrenal glands are removed?

Answer 13

Animals cannot deal with stress as it cannot deal with hypoglycaemia = no maintenance of ECF

Question 14

How does cortisol affect gluconeogenesis?

Answer 14

Cortisol stimulates formation of gluconeogenic enzymes in the liver, thus enhancing gluconeogenesis and glucose production.

Question 15

How does cortisol affect proteolysis?

Answer 15

Cortisol stimulates the breakdown of muscle protein to provide gluconeogenic substrates for liver

Question 16

How does cortisol affect lipolysis?

Answer 16

Cortisol stimulates lipolysis in adipose tissue which increases plasma [FFA] creating an alternative fuel supply that allows [BG] to be protected whilst also creating a substrate for glucoeogenesis

Question 17

What affect does cortisol have on calcium balance?

Answer 17

Decrease absorption from gut, increases excretion at kidney resulting in net Ca2+ loss. Also increases bone resorption

Question 18

How does cortisol affect mood and cognition?

Answer 18

Too much causes depression and impaired cognitive function

Question 19

How does cortisol affect norepinephrine?

Answer 19

Has a permissive effect. Too much causes cushings, too little causes hypotension

Question 20

How does cortisol affect the immune system?

Answer 20

Reduces lymphocyte count, reduces antibody formation, inhibits inflammatory response

Question 21

What is aldosterone?

Answer 21

A mineralcortocoid which acts on the distal tubule of the kidney to determine the levels of minerals reabsorbed/excreted

Question 22

What pathway controls aldosterone secretion?

Answer 22

Renin-Angiotensin-Aldosterone System (RAAS)

Question 23

What occurs when aldosterone levels are increased?

Answer 23

Na+ is released, H2O is retained, K+ is depleted and blood volume & blood pressure is increased

Question 24

What occurs when aldosterone levels are decreased?

Answer 24

Leads to Na+ and H2O loss, increased K+ within plasma, diminised blood volume and blood pressure

Question 25

What occurs in hypersecretion of cortisol?

Answer 25

Cushings disease

Question 26

What occurs in hyposecretion of cortisol?

Answer 26

Addisons

Question 27

When is CRH and ACRH release promoted?

Answer 27

During periods of stress