the adrenal glands

Question 1

where are the adrenal glands?

Answer 1

above(superior to) the kidneys (ad renal)

Question 2

describe the vasculature of the adrenal glands

Answer 2

Left adrenal vein drains into renal vein. Right adrenal vein drains into IVC. Both adrenals have many arteries but only one vein

Question 3

what are the sections of the adrenal glands (from outside to inside)?

Answer 3

zona glomerulosa- part of adrenal cortex
zona fasciculata- part of adrenal cortex
zona reticularis- part of adrenal cortex
adrenal medulla

Question 4

what hormones does the adrenal medulla produce?

Answer 4

catecholamines
noradrenaline/ norepinephrine
adrenaline/ epinephrine
dopamine

Question 5

what hormones does the adrenal cortex produce?

Answer 5

corticosteroids
Mineralocorticoids (Aldosterone)
Glucocorticoids (Cortisol)
Sex steroids (Androgens, oestrogens)

Question 6

what part of the adrenal cortex produces aldosterone?

Answer 6

zona glomerulosa

Question 7

what part of the adrenal cortex produces cortisol and sex steroids?

Answer 7

zona fasciculata and zona reticularis

Question 8

what is a steroid?

Answer 8

a hormone originating from cholesterol

Question 9

how many carbons does cholesterol have?

Answer 9

27

Question 10

what carbon does the cholesterol side chain start at?

Answer 10

carbon 20 (stems off carbon 17)

Question 11

what enzyme converts cholesterol to pregnenolone?

Answer 11

side chain cleavage enzyme

Question 12

what enzyme converts pregnenolone to progesterone?

Answer 12

3 beta hydroxy steroid dehydrogenase

Question 13

what enzyme converts progesterone to 11 deoxycorticosterone?(aldosterone production)

Answer 13

21 hydroxylase

Question 14

what enzyme converts 11 deoxycorticosterone to corticosterone?(aldosterone production)

Answer 14

11 hydroxylase

Question 15

what enzyme converts corticosterone to aldosterone?

Answer 15

18 hydroxylase

Question 16

what enzyme converts progesterone to 17-hydroxyprogesterone?(cortisol production)

Answer 16

17 hydroxylase

Question 17

what enzyme converts 17-hydroxyprogesterone to 11 deoxy-cortisol?(cortisol production)

Answer 17

21 hydroxylase

Question 18

what enzyme converts 11 deoxy-cortisol into cortisol?

Answer 18

11 hydroxylase

Question 19

what is the net effect of aldosterone?

Answer 19

conserve body sodium by stimulating its reabsorption

Question 20

what is aldosterone’s mechanism of action?

Answer 20

Stimulates Na+ reabsorption in distal convoluted tubule and cortical collecting duct in kidney (and in sweat glands, gastric glands, colon)
Stimulates K+ and H+ secretion, also in distal convoluted tubule and cortical collecting duct
Increased sodium reabsorption water reabsorption,
raising blood volume

Question 21

outline how aldosterone is regulated

Answer 21

renin is produced
this turns angiotensinogen into angiotensin I
ACE then turns this into angiotensin II which has effects like vasoconstriction
this also increases aldosterone production

Question 22

how is renin released?

Answer 22

when blood pressure falls in kidney
Decreased renal perfusion pressure (normally associated with decreased arterial BP)

Increased renal sympathetic activity (direct to JGA(juxtaglomerular apparatus) cells)

Decreased Na+ load to top of loop of Henle (macula densa cells)

Question 23

what enzymes does angiotensin II effect?

Answer 23

Activation of the following enzymes
Side Chain Cleavage
3 Hydroxysteroid dehydrogenase
21 hydroxylase
11 hydroxylase
18 hydroxylase

Question 24

what are the effects of cortisol?

Answer 24

peripheral protein catabolism
hepatic gluconeogenesis
increased blood glucose concentration
fat metabolism (lipolysis in adipose tissue)
enhanced effects of glucagon and catecholamines
excretion of water load
increased vascular permeability

Question 25

how is cortisol production regulated?

Answer 25

through ACTH | and negative feedback(cortisol causes hypothalamus and anterior pituitary to reduce ACTH)

Question 26

what enzymes does ACTH act on in the adrenal glands?

Answer 26

``` Side Chain Cleavage 3 Hydroxysteroid dehydrogenase 21 hydroxylase 11 hydroxylase 17 hydroxylase ```

Question 27

what happens to cortisol levels during the day?

Answer 27

fluctuates lowest at midnight highest at 8:30 regulates time of day (circadian rhythm) (ACTH levels rise before)

Question 28

what is addison's disease?

Answer 28

Primary adrenal failure Autoimmune disease where the immune system decides to destroy the adrenal cortex (UK) Tuberculosis of the adrenal glands (commonest cause worldwide) large amounts of ACTH and MSH

Question 29

what are the symptoms of addison's disease?

Answer 29

``` hyperpigmentation vitiligo low blood pressure weight loss weakness nausea diarrhoea vomiting constipation abdominal pain ```

Question 30

what are the signs of an adrenal crisis?

Answer 30

``` fever syncope convulsions hypoglycaemia hyponatremia severe vomiting and diarrhoea ```

Question 31

what causes the tan in addison's disease?

Answer 31

pro-opio-melanocortin(POMC) is a precursor to ACTH so if lots of ACTH is being made lots of POMC is made the other product of POMC breakdown is MSH which causes a tan

Question 32

how do you treat an addisonian crisis?

Answer 32

saline dextrose hydrocortisone (or another glucocorticoid

Question 33

what is cushing's syndrome?

Answer 33

large amounts of cortisol

Question 34

what could cause cushing's syndrome?

Answer 34

Taking steroids by mouth (common) pituitary dependent Cushing’s disease (pituitary adenoma) Ectopic ACTH (lung cancer) adrenal adenoma or carcinoma

Question 35

what are the symptoms of cushing's syndrome?

Answer 35

``` Thin skin Proximal myopathy Centripetal obesity (lemon on sticks) Diabetes, hypertension and osteoporosis Immunosuppression (reactivation of TB) Moon face Striae emotional disturbances etc ```

Question 36

what amino acid is the precursor to adrenaline and noradrenaline?

Answer 36

tyrosine

Question 37

how are the catecholamines stored?

Answer 37

in cytoplasmic granules

Question 38

what causes the catecholamines to be released?

Answer 38

released in response to ACh from preganglionic sympathetic neurones

Question 39

what is the role of catecholamines?

Answer 39

fight or flight | e.g. tachycardia, sweating, increased blood glucose, alertness, vasoconstriction

Question 40

how are catecholamines transported in blood?

Answer 40

bound to albumin

Question 41

what enzymes degrade the catecholamines?

Answer 41

Degraded by two hepatic enzymes: monoamine oxidase & catechol-O-methyl transferase