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Flashcards in Adrenal physiology Deck (14)
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1

What are the different layers of the adrenal cortex?

Zona glomerulosa - Mineralocortcoids, aldosterone, SALT
Zona fasciculata - Glucorticoids, cortisol, STRESS
Zona reticularis - androgens, SEX hormones

Medulla - ad

2

Corticosteroids

-Lipid soluble
-Bind to specific intracellular receptors
-Alter gene transcription directly or indirectly
-Exact action depends on structure, ability to bind to specific receptors (and recruit cofactors)

3

How does ACTH affect corticoids?

Adrenocorticotropic hormone binds to receptors on cell membrane, producing cAMP and the synthesis of corticosteroids

deficiency - adrenal shrinks
ACTH excess - grows

4

Glucocorticoids

-Zone fasciculata and retiularis
-STRESS
effects = increase glucose mobilisation, vascular tone, salt and water balance, dampens immune system

5

Describe the transport of Glucocorticoids in the body
-how does inflammation affect cortisol levels

90% bound to corticosteroid-binding globulin (CBG)
-5% bound to albumin
-5% free (these are the only ones that are available)

-inflammation lowers levels of CBG, so less is bound and there is a higher % of free cortisol

6

How is glucocorticoid synthesis regulated?

1. Stress, cytokines and diurnal rhythm affect the hypothalamus
2. Affects levels of Corticotropin-releasing hormone released
3. Affects pituitary levels and levels of Adrenocorticotropic hormone released
4. ACTH - stimulates cortisol release and synthesis
5. Affects adrenal to secrete glucocorticoids :)
6. Affect on tissue

7

What can cause stress?

"the sum of bodies responses to adverse stimuli"
-infection
-trauma
-haemorrhage
-medical illness
-psychological
-exercise/exhaustion

8

Mineralocorticoids

-Synthesised in zona glomerulosa (contains aldosterone synthase)
-Mainly aldosterone and DOC
-Critical to salt and water balance

9

Where does aldosterone affect?

-Affects distal tubule
-Increases Na+ resorption, more ENaC (epithelial sodium channel)
-Decreased excretion

10

What is the juxtaglomerular apparatus?

1. the macula densa, a part of the distal convoluted tubule of the same nephron (senses plasma pressure)
2. juxtaglomerular cells, which secrete renin
3. extraglomerular mesangial cells

-it lies next to (juxta) to the glomerulus

11

Describe the action of mineralocorticoids

-RAAS
-effects on pancreas
-sweat glands
-salivary glands
-colon

=increase sodium resorption

12

Adrenal androgens

-Weak androgens generated in adrenal gland
-Dehydroepiandrosterone (DHEA) is the most abudent adrenal steroid but very weak
-Androstenedione - more androgenic but much weaker than testosterone
-ostrogen
-testosterone

13

The adrenal medulla

-Autonomic system
-ACH transmitter
-Specialised ganglia - sympathetic
-Synthesises catecholamines (F & F)
-ADRENALINE AND NORADREALINE (v. low dopamine)

14

What is the effect of catecholamines

-F&F - from the adrenal medulla
-increased gluconeogensis in liver and muscle
-lipolysis in adipose tissue
-tachycardia and cardiac contractility
-redistribution of circulating volume