adrenal gland Flashcards by Abbie McGuire

position of adrenals?

lies on superior pole of kidney in retroperitoneal space

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weight go each adrenal?

~4g

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2 parts of adrenal gland?

adrenal cortex

adrenal medulla

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% of medulla v.s. cortex

medulla - 25%

cortex - 75%

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adrenal medulla - what is it?

a modified sympathetic ganglion - i.e. neuroendocrine gland

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where does adrenal medulla secrete hormones?

postganglionic cell

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which hormones are secreted from adrenal medulla?

epinephrine mainly, also norepinephrine and dopamine

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how is the adrenal cortex ascribed and what does it secrete?

true endocrine gland -

secretes - mineralocorticosteroids, glucocorticosteroids, sex steroids

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examples of -
1 - mineralocorticoids
2 - glucocorticoids
3 - sex steroids

1 - aldosterone
2 - cortisol
3 - testosterone

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describe layers of adrenal gland from the outside in

OUTSIDE - 
capsule
zone glomerulosa (CORTEX)
zone fasciculata (CORTEX)
zone reticularis (CORTEX)
medulla 
INSIDE

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which hormones are produced from the three layers of the adrenal cortex?

zone glomerulosa - aldosterone
zone fasciculata - glucocorticoids
zone reticularis - sex hormones

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common cause of congenital adrenal hyperplasia?

defects in 21-hydroxylase

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result of congenital adrenal hyperplasia?

deficiency in aldosterone and cortisol, associated with disruption of salt and GLC

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Why does a deficit in 21-hydroxylase cause adrenal hyperplasia?

lack inhibits synthesis of cortisol

> removes -ve feedback on ACTH and CRH release
> increased ACTH secretion
> enlargement of adrenal glands
> -ve feedback on ACTH on CRH synthesis remains
> sick babies

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how much cortisol is bound to a carrier protein?

~95%

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what is this carrier protein?

CBG - cortisol binging globulin

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what does cortisol do?

influence GLC metabolism

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where are steroid hormone receptors found in the cell?

cytoplasm, membrane or nucleus

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peak plasma cortisol conc vs lowest?

peak - ~6-9am

lowest - ~midnight

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what are fluctuations of cortisol conc during the day related to?

stress and other related stimuli

an effect of loss of cortisol in animals?

inability to deal with stress, especially maintaining BG levels
also inability to maintain ECF volume

another crucial role of cortisol?

protecting the brain from hypoglycaemia - due to permissive action on glucagon - i.e. they work together

4 actions of cortisol on GLC metabolism?

glucocorticoid action

gluconeogenesis
proteolysis
lipolysis
decrease in insulin sensitivity

how would you describe the role of cortisol re insulin?

it opposes the action of insulin -

excess cortisol is diabetogenic

4 further actions of cortisol? (non-glucocorticoid action)

-ve effect on Ca2+ depression and cognitive impairment permissive effects on norepinephrine suppression of immune system

what is the condition presenting as hypercortisolaemia and what is its effect on BP?

Cushing's Disease - | associated with hypertension

association of hypocortisolaemia and BP?

associated with hypotension

3 side effects of glucocorticoid therapy?

muscle wastage increased severity amp frequency of infection thinning of and fragile skin

risk related to withdrawing chronic glucocorticoid treatment too quickly?

atrophy of adrenal gland resulting in ADRENAL INSUFFICIENCY

function of aldosterone?

acts on the distal tubule of the kidney to determine the levels of minerals reabsorbed/excreted

type of hormone - aldosterone?

mineralocorticoid

which pathway controls the secretion of aldosterone?

RAAS - renin-angiotensin-aldosterone system

effects of increased aldosterone?

stimulates Na+ (and H2O) retention and K+ depletion, resulting increased blood volume and increased blood pressure

effects of decreased aldosterone?

Na+ (and H2O) loss and increases [K+]plasma, resulting in diminished blood volume and decreased blood pressure.

hypersecretion of cortisol, causing Cushing's, is due to what?

tumour in adrenal cortex (1y hypercortisolism) OR... tumour in pituitary gland (2y hypercortisolism)

1y hypercortisolism - result?

cushings SYNDROME

2y hypercortisolism - result?

cushings DISEASE

iatrogenic hypercortisolism?

therapeutic administration of cortisol errors

hyposecretion is less common - what is the result?

Addison's disease

what is Addison's a result of?

Hyposecretion of all adrenal steroid hormones due to autoimmune destruction of adrenal cortex

presentation of Cushing's disease?

wasting of extremities and limbs, redistribution of fat to face (moon face) and trunk

which hormones are secreted as a result of stress?

CRH | ACTH

alcohols effect on CRH and ACTH?

it increases the secretion of these hormones

what is the result of an increase of ACTH and CRH?

elevation of cortisol - >suppressing immune system - >increases vulnerability to infection

how are hormones released by the postganglionic fibres in the adrenal medulla?

directly into blood - bc they do not have axons

tumour of the adrenal medulla and its effect?

Pheochromocytoma - results in excess catecholamines

result of excess catecholamines?

increase in HR - >increase in CO - >sig. increases BP

how is Pheochromocytoma described due to its effect on GLC metabolism?

diabetogenic

treatment for Pheochromocytoma?

surgery