The Adrenal Gland Flashcards
where are the adrenal glands situated
on the superior pole of the kidney in the retroperitoneal spacce
where does the left adrenal vein drain into
left renal vein
where does the right adrenal vein drain into
directly into the inferior vena cava
what kind of tissue makes up the adrenal medulla
modified sympathetic ganglion derived from neural crest tissue
what does the adrenal medulla secrete
catecholamines (epinephrine norepinephrine dopamine)
what kind of tissue makes up the adrenal cortex
adrenal cortex is a true endocrine gland derived from mesoderm
what are the 3 classes of steroid hormone that the adrenal cortex secretes
mineralcorticoids
glucocorticoids
sex steroids
what does the zona glomerulosa secrete
aldosterone (mineralcorticoid)
what does the zona fasiculata secrete
glucocorticoids
what does the zona reticularis secrete
sex hormones
what enzyme is needed to make aldosterone and cortisol
21-hydroxylase
what are considered the 2 min products of the adrenal cortex
cortisol and aldosterone
what is DHEA
a prehormone of testosterone and oestrogen
what is a common cause of congenital adrenal hyperplasia
defects in 21 hydroxylase
which hormone does cortisol have a negative feedback effect on
ACTH
what percentage of plasma cortisol is bound to a carrier protein
95%
what is the carrier protein that cortisol binds to
cortisol binding globulin
what kind of cells have receptors for glucocorticoid
all nucleated cells have cytoplasmic receptors for glucocorticoid
does cortisol or ACTH have longer half life
cortisol has a longer half life
when do cortisol and ACTH peak
6-9am
lowest level midnight
cortisol is essential to life why
- maintains blood glucose levels
- protects the brain from hypoglycaemia
- has a permissive action on glucagon
what is the actions of cortisol on glucose metabolism
- gluconeogensis-stimulates the formation of gluconeogenic enzymes in the liver
- proteolysis- to provide gluconeogenic substrates for the liver
- lipolysis-which increases [FFA] plasma creating an alternative fuel supply that allows [BG] to be protected
- decrease insulin sensitivity of tissues
excess cortisol is said to be ________
diabetogenic as in acts to oppose insulin
what effect does cortisol have on Ca2+ balance
decrease Ca2+ absorption from the gut
increases excreation at the kidney
increases bone resorption
what effect does cortisol have on mood
hypercortisolaemia is associated with depression and impaired cognitive function
what effect does cortisol have on epinephrine
permissive,
(particularly in vascular smooth muscle (alpha-receptor effect = vasoconstrictive therefore cushings disease is strongly associated with hypertension)
what effect does cortisol have on the immune system
suppression (inhibits the inflammatory response too)
what is the effect of increased aldosterone release
stimulates Na (and H2O) retention and K+ depletion at the kidneys
resulting in increased blood volume and pressure
what is the effect of decreased aldosterone secretion
leads to Na (and H2O) loss and increased [K+] plasma
resulting in decreased blood volume and decreased blood pressure
at which site in the kidneys does aldosterone act
acts on the distal tubule
what is Cushing’s disease
hypersecretion of cortisol
what are the most common causes of hypersecretion of cortisol
a tumour (adrenal cortex/pituitary)
iatrogenic
what is addisons disease
hyposecretion of ALL adrenal steroids due to autoimmune destruction of the adrenal cortex
what is a Pheochromocytoma
a rare neuroendocrine tumour, found in adrenal medulla which results in XS catecholamines
why do you have to be careful when withdrawing chronic glucocorticoid treatment
there is a risk of adrenal insufficency if withdraw too fast
what can be side effects of glucocorticoid therapy (increased cortisol)
- increased severity of infection (as cortisol suppresses the immune system)
- loss of percutaneous fat stores gives the appearance of thinning skin (as cortisol promotes lipolysis and protein catabolism)
