HPA axis

Question 1

What does HPA do?

Answer 1

Stress response

Pituitary - kidneys - adrenal gland

Question 2

What happens when you’re stressed?

Answer 2

Hypothalamus releases CRH
Pituitary releases ACTH
ACTH stimulates release of cortisol from cortex
Mobilises energy from glucose

Question 3

What is the Adenohypophysis?

Answer 3

Anterior pituitary

Question 4

What is the neurohypophysis?

Answer 4

Posterior pituitary

Question 5

What is produced by posterior pituitary?

Answer 5

ADH and oxytocin

Question 6

What does the portal vein do?

Answer 6

Takes hormones to pituitary

Question 7

Where is cortisol released?

Answer 7

Adrenaline;s

Question 8

Where is CRH released?

Answer 8

Hypothalamus

Question 9

What does cortisol do in stress?

Answer 9

Increases gluconeogenesis - increases BP and glucose for fight/flight
Inhibits CRH and ACTH release

Question 10

What does zona glomerulosa do?

Answer 10

Aldosterone production, increased sodium reabsorption, increased potassium excretion

Question 11

What does zona fasciculata do?

Answer 11

Cortisol production, increased gluconeogenesis, increased BP

Question 12

What does zona reticular do?

Answer 12

Androgens to be converted to sex hormones

Question 13

What does medulla do?

Answer 13

Adrenaline/noradrenaline

Fight or flight

Question 14

What does cortisol do?

Answer 14

Steroid
Gluconeogenesis
Immunosuppression
Anti-inflammatory effects

Question 15

What is Addison’s disease?

Answer 15

Primary adrenal failure - complete lack of cortisol and mineralocorticoids
Main cause is TB

Question 16

What is an Addisonian crisis?

Answer 16

Medical emergency, body shutdown, low BP and salt, hypoglycaemic

Question 17

How are pituitary and adrenal failure linked?

Answer 17

If pituitary can’t make ACTH then adrenals won’t make cortisol

Question 18

Sodium, potassium, cortisol and ACTH in Addison’s

Answer 18

Low sodium, high potassium, low cortisol, high ACTH

Question 19

Why does Addison’s lead to hyperpigmentation?

Answer 19

Metabolite from converting POMC to ACTh is melanocyte stimulating hormone

Question 20

How to investigate Addison’s further

Answer 20

Give synthetic ACTH - in primary failure it will have no impact on cortisol b

Question 21

How to treat Addison’s

Answer 21

Hydrocortisone IV

Question 22

What causes Cushing’s disease?

Answer 22

Excess cortisol

Overstimulation of adrenals by ACTH or overproduction of cortisol from adrenals

Question 23

What does iatrogenic mean?

Answer 23

We have caused the problem

Question 24

How are Cushing’s disease and Cushing’s syndrome connected?

Answer 24

Cushing’s disease - pituitary tumour - increased cortisol

Question 25

Symptoms of Cushing’s disease

Answer 25

Hypertension, hyperglycaemia, moon face, buffalo hump, easy bruising, obesity, hypokalaemia

Question 26

Why does Cushing’s lead to weight gain?

Answer 26

Cortisol = more gluconeogenesis = hyperglycaemia = weight gain

Question 27

Main cause of Cushing’s

Answer 27

Pituitary tumour producing ACTH

Question 28

Differences between primary and secondary cause

Answer 28

Primary is ACTH independent

Secondary is ACTH dependent

Question 29

How to test for primary or secondary cause

Answer 29

Dexamethasone has no impact on primary
CRH test
Cortisol levels rise in secondary