Adrenal function and disorders

Question 1

What are adrenal steroid hormones derived from and how

Answer 1

CHolesterol

-By sequential, enzymatically-mediated modification of the structure

Question 2

Where is cholesterol that is used to form adrenal steroid hormones derived from

Answer 2

Mainly Plasma LDL

Some from cell stores (synthesised from acetyl CoA)

Question 3

What is the rate limiting step in steroidogenesis

Answer 3

Transport of cholesterol from the outer to the inner mitochondrial membrane

Question 4

What is the first step in steroidogenesis and name the enzyme involved and its location

Answer 4

First enzyme is located in inner mitochondrial membrane

• There is initial side-chain cleavage of cholesterol.
• Cholesterol 20,22 desmolase turns cholesterol (C-27) into pregnenolone (C-21)

Question 5

In the adrenal gland, what does the zona glomerulosa mainly produce

Answer 5

Mineralocorticoids

Question 6

IN the adrenal gland, what does the zona fasiculata mainly produce

Answer 6

(Mainly) Glucocorticoids

and gonadocorticoids

Question 7

IN the adrenal gland, what does the zona reticularis mainly produce

Answer 7

Glucocorticoids and gonadocorticoids

Question 8

What are the zones in the adrenal gland going from the capsule end to the medullary end

Answer 8

Capsule- Zona glomerulosa

Zona fasciculata

Zona reticularis

Question 9

What does pregnenolone

Answer 9

It is a common precursor to the specific zones in the adrenal gland. There is zone specific steroid hormone synthesis and all areas produce different things but pregnenolone is used by all at first

Question 10

Where does each steroid go as it progresses along its biosynthetic pathway

Answer 10

Between 2 sub cellular compartments

Question 11

What is the action of mineralocorticoid activity

Answer 11

Na+ retention

Question 12

What is the action of glucocorticoid activity

Answer 12

Anti- inflammation

Question 13

What is is cortisol activity effective as

Answer 13

Equally asa mineralocorticoid and glucocorticoid

Question 14

What is aldosterone effective as

Answer 14

Mineralocorticoid

Question 15

What hormone regulates the endocrine axis only

Answer 15

Cortisol (ACTH and CRH release)

Question 16

What is the role of aldosterone and what is it

Answer 16

Mineralocorticoid

Principally act on DCT and collecting ducts of kidney to promote NA+ retention and so H20 retention and K+ elimination during formation of urine

Question 17

What is the secretion of aldosterone stimulated by

Answer 17

Increased plasma [K+] and renin angiotensin system ( largely independent of ACTH)

Question 18

What are androgens

Answer 18

DHEA/DHEAS and androstenedione

Question 19

How do androgen levels change with age

Answer 19

Starts at 6/7 yo. Peaks at 20-25 and decreases as person gets older

Question 20

How do androgens affect women and men

Answer 20

50% in women - contribute to axillary/pubic hair growth and libido

Negligible contribution in men

Question 21

What are androgens regulated by

Answer 21

ACtH but no feedback on CRH/ACTH

Question 22

What is the main glucocorticoid

Answer 22

Cortisol

Question 23

What happens when there is a stress stimulus

Answer 23

Activation of hypothalamus to release CRH

CRH acts on anterior pituitary which releases ACTH

This increases action of adrenal cortex to release cortisol

Question 24

when is the action of ADH stimulated

Answer 24

When the person is under stress such as when there is fluid deprivation

Question 25

How does ADH affect cortisol levels

Answer 25

Increases stimulation to anterior pituitary which increases ACTH levels and so this increases action of adrenal cortex and therefore cortisol

Question 26

How are steroid hormones transported in the circulation

Answer 26

Bound to plasma proteins

Question 27

What are the actions of cortisol

Answer 27

Metabolic effects Antiimflammatory/immunosuppressive effects Role in adaptation to stress

Question 28

what are the metabolic effects of cortisol

Answer 28

In muscle and adipose tissue (catabolic which means breakdown) IN liver- Stimulate glujconeogenesis and glycogen storage to elevate plasma glucose levels

Question 29

How does cortisol affect muscle

Answer 29

Decrease glucose uptake via insulin mediated GLUT4 Increase protein breakdown Decrease protein synthesis

Question 30

How does cortisol affect adipose tissue

Answer 30

Decrease glucose uptake (insulin mediated via GLUT4) Increase lipolysis Decrease lipogenesis

Question 31

What do the actions of cortisol on muscle and adipose tissue do to allow the liver to help with the actions of cortisol

Answer 31

Once cortisol has acted on adipose tissue and muscle, there are more free fatty acids and glycerol from adipose tissue and more amino acids from muscle which go to the liver and so there is increased gluconeogenesis and increased glycogen synthesis

Question 32

What does cortisol do to glycogen stores

Answer 32

Increases them. Does this by turning excess glucose into glycogen in case the stressful situation occurs again as it is a readily- accessible source of glucose

Question 33

How does cortisol have an anti-inflammatory/immunosuppressive effect

Answer 33

-It stimulates the production of Annexin1 which inhibits PLA2 (an enzyme that generates arachidonic acid which is the precursor for prostanoids and leukotrienes) - Decrease number and action of T lymphocytes - decrease production of cytokines - Stabilises lysosomes - Decrease NO production