Adrenocortical Function and Dysfunction Flashcards
(27 cards)
What is the embryological origin of the adrenal medulla?
Modified sympathetic ganglion (catecholamines/neurohormones)
What is the embryological origin of the adrenal cortex?
Endocrine
What are the functions mediated by CRH?
inflammation and immune responses; inhibition of appetite; signals onset of labour from placenta; linked to mood
What is pro-opiomelanocortin (POMC)?
large protein that yields several bioactive peptides: ACTH (a. pit), beta-endorphin (a. pit), alpha-melanocyte-stimulating hormone (systemic ACTH)
What is the function of beta-endorphin?
blocks pain perception
What is the function of alpha-MSH?
decrease food intake, increase skin melanin
What are melanocortins?
MSH hormones and ACTH
What are the functions of cortisol?
essential; coping with long term stress; protects against hypoglycaemia by increasing catabolism of energy; permissive for glucagon and catecholamine actions
What are the effects of long-term cortisol use?
inhibition of ACTH secretion and atrophy of cortisol-secreting cells - tf need to taper doses on and off so body can physiologically adapt
A primary adrenal cortex disorder would be the result of
an adrenal cortex defect (primary = defect of the gland)
A secondary adrenal cortex disorder would be a result of
defect of the hypothalamus or anterior pituitary
What are the catecholamines?
Epinephrine (adrenal medulla only), norepinephrine, dopamine
Why is epinephrine only made in the adrenal medulla?
phenylethanolamine-N-methyltransferase (PMNT) that converts norepinephrine to epinephrine is only found here
What is the physiological result of hyperaldosteronism?
hypernatremia, hypokalemia, hypertension
Cushing’s syndrome is what type of hypercortisolism?
Primary - adrenal cortex tumours secreting cortisol (ACTH independent)
Cushing’s disease is what type of hypercortisolism?
Secondary - pituitary tumour secreting ACTH (ACTH-dependent)
What is the most common cause of hypercortisolism?
Iatrogenic from prescription cortisol therapy
What is adrenogenital syndrome?
Excess androgen and estrogen production due to lack of enzyme in the cortisol steroidogenic pathway shunting away from cortisol production towards sex hormones
What is the effect of adrenogenital syndrome?
Inappropriate masculinisation (or early) of all but adult males
What causes hyperglycaemia in Cushing’s syndrome?
Excess gluconeogenesis and glycogenolysis
Decreased production of aldosterone (Addison’s, hypocortisolism) causes
K+ retention (cardiac arrhythmia) and Na+ and water depletion (hypotension)
What causes salt and water retention in Cushing’s syndrome?
excess cortisol crossing over to react with mineralocorticoid receptors
Secondary adrenal hyposecretion is caused by
abnormal hypothalamus or pituitary function causing decreased ACTH and cortisol production (aldosterone is normal)
PMNT
phenylethanolamine-N-methyltransferase; converts norepinephrine to epinephrine in the adrenal medulla
