Adrenal hormones

Question 1

Parts of the adrenal gland and what they make

Answer 1

Cortex: Zona glomerulosa (aldosterone (mineralcorticoid)), zona fasciculata (glucocorticoids: cortisol), zona reticularis (androgens); and medulla: epi and norepi

Question 2

Name some steroid hormones and talk about their effects

Answer 2

Aldosterone, cortisol, progesterone, testosterone, estrogen, (vitamin D). All derived from cholesterol. Very complex, varied response due to DNA binding site variance. Dysfunction is often related to enzyme defects in synthesis

Question 3

Synthesis of steroid hormones map

Answer 3

Chart. Important enzymes are 21-hydroxylase (needed for cortisol and aldosterone) and aromatase (needed to convert testosterone to estrogen)

Question 4

What is the main defect in Congenital adrenal hyperplasia

Answer 4

21-hydroxylase - so cortisol and aldosterone low

Question 5

What causes release of CRH, which then releases ACTH?

Answer 5

Physical/emotional stress, hypoglycemia, cold, pain.

Question 6

What are symptoms of adrenal insufficiency?

Answer 6

Low aldosterone, high K, crave salt. 1˚: adrenal dysfunction. 2˚ and 3˚: hypothalamus or pituitary dysfunction.

Question 7

Regulation of crystal secretion

Answer 7

CRH - ACTH - cortisol. Pulsatile release - key for function; Otherwise the receptors would down regulate. Highest from 6-10am and lowest at midnight. Goes up within 40 minutes of ACTH release.

Question 8

4th part of pituitary that releases hormone!

Answer 8

pars tuberalis. releases glycosylated TSH. Affected by sunlight, induces seasonal behaviour (ie hibernating, migration). Affects our cortisol etc.

Question 9

Cortisol transport

Answer 9

Most bound to cortisol binding globin. Some to albumin, very little free.

Question 10

Functions of cortisol (list)

Answer 10

Glucose metabolism. Catabolic effects. Affects Minerals, Immune system, Cardiovascular system, CNS

Question 11

Function of cortisol on glucose metabolism

Answer 11

gluconeogenesis and glycogen storage in liver; decreases muscle glucose utilization; increases blood glucose, thus making glucose available for insulin insensitive tissues (tissues that don’t require insulin for glucose uptake: brain, heart, kidney, red blood cells).

Question 12

Catabolic Function of cortisol

Answer 12

stimulates breakdown of proteins to amino acids, stimulates lipolysis

Question 13

Function of cortisol on minerals

Answer 13

electrolyte/H2O balance (high cortisol has an effect on mineralocorticoid receptors: salt and water retention); antagonizes actions of Vitamin D and impairs calcium absorption

Question 14

Function of cortisol on immune system

Answer 14

immunosuppression (lower lymphocyte infiltration, lower lymphocyte numbers, suppress cell-mediated hypersensitivity, impairs phagocytes). decreases inflammation. Used in transplants, arthritis, etc.

Question 15

Function of cortisol on cardiovascular system

Answer 15

(not major). maintains integrity of CV system (lower permeability of capillary endothelium, inotropic action on myocardium, facilitates vasoconstriction). Used in ICU so you don’t get edema, ie in lungs.

Question 16

Function of cortisol on CNS

Answer 16

(euphoria, reduces seizure threshold, can produce psychotic responses in high doses)

Question 17

How does pigmentation relate to cortisol?

Answer 17

ACTH is made from same pro hormone as MSH, so if adrenal is not producing enough cortisol, ACTH goes up and with it MSH.

Question 18

What lowers cortisol?

Answer 18

Omega 3 fatty acids, Music (depends on music!), Massage therapy, Laughing, and the experience of humour, Crying, Vitamin C blunts cortisol release in response to mental and physical stressors, regular dancing to Argentinian tango, sexual intercourse, black tea may hasten recovery from high cortisol states

Question 19

What increases cortisol levels?

Answer 19

Caffeine, Sleep deprivation, Intense or prolonged physical exercise, Hypoestrogenism, Melatonin supplementation, Burnout, Anorexia nervosa, Severe trauma or stressful events, Stimulation of the serotonin receptor gene 5-HT2C, Oral contraceptive pills can in young women who perform whole-body-resistance exercise training (may cause a reduction in the ability to gain muscle mass by weight training), Subcutaneous adipose tissue regenerates cortisol from cortisone, Commuting increases cortisol levels relative to length of trip

Question 20

General Function of aldosterone

Answer 20

Increase Na reabsorption, which leads to increase water retention, and K excretion

Question 21

How does aldosterone increase Na reabsorption?

Answer 21

it stimulates transcription Na/K ATPase, leading to more sodium pumps in nephron. also stimulates expression of a Na channel which facilitates uptake of sodium from tubular lumen. Has effects on sweat glands, salivary glands and the colon (bascially same as distal tubule of kidney)

Question 22

Membrane binding sites for aldosterone?

Answer 22

Exist in heart and blood vessels to help increase BP

Question 23

Pathway leading to aldosterone release

Answer 23

Lower blood flow to kidneys (ie lower volume), kidney releases renin, which cleaves angiotensiogen to angiotensin I, ACE cleaves this to angiotensin II, which then acts on adrenal to release aldosterone.

Question 24

Control of aldosterone secretion?

Answer 24

Release. Major: increased K (direct effect on adrenal), Angiotensin II (via renin etc). Minor: ACTH, low Na. Inhibit aldosterone: high Na, low K, atrial natriuretic peptide

Question 25

Catecholamine biosynthesis

Answer 25

Derived from tyrosine: Tyr - DOPA - dopamine - norepi - epi. rate-limiting step is tyrosine hydroxylase (1st enzyme). DOPA and dopamine feed back in the adrenal and neurons to down-regulate tyrosine hydroxylase activity. symathetic nerves from the splanchnic bed can trigger catecholamine release

Question 26

Effects of catecholamines

Answer 26

Heart: increase HR, BP, conduction, increase flow from viscera to heart, brain, muscle. Smooth muscle: pupil and bronchodilation, decreased gut motility. Metabolic: glycogenolysis, gluconeogenesis, lipolysis (lead to hyperglycemia)

Question 27

What are the metabolites of epi and norepi?

Answer 27

Metanephrin and normetanephrin. Very stable metabolites, measured in urine.

Question 28

Adrenal androgens

Answer 28

Not important in males. Excess in females can lead to hirsuitism or abnormal menses. DHEA and DHEA-S. Ying-yang or inversely proportional with cortisol.