The Adrenal Gland Flashcards
where are the adrenal glands situated
the adrenal glands are situated on the superior pole of the kidney in the retroperitoneal space
how are the kidneys peritonised
retroperitoneal
where does the left adrenal vein drain into
the left renal vein
where does the right renal vein drain into
directly into the inferior vena cava
describe the adrenal medulla gland
it is a modified sympathetic ganglion
what does the adrenal medulla secrete
catecholamines mainly:
epinephrine
norepinephrine
dopamine
describe the adrenal cortex
it is a true endocrine gland derived from mesoderm
what 3 classes of hormones does the adrenal cortex secrete
Mineralocorticoids (e.g aldosterone)
Glucocorticoids (e.g cortisol)
sex steroids (e.g testosterone)
what is the role of aldosterone
involved in the regulation of Na+ and K+
what is the role of cortisol
involved in maintaining plasma glucose
aldosterone and cortisol are essential for survival true or false
true
what hormone does the zona glomerulosa of the cortex produce
aldosterone
what hormones does the zona fasciculata of the cortex produce
glucocorticoids
what hormones does the zona reticularis of the cortex produce
sex hormones
what are the main products of the adrenal cortex
cortisol and aldosterone
what is DHEA
a pre-hormone of testosterone and oestrogen (marked decline with age)
defects in 21-hydroxylase is a common cause of what
congenital adrenal hyperplasia
what does congenital adrenal hyperplasia result in
deficiency of aldosterone and cortisol and associated physiological dysfunction of salt and glucose balance
where is ACTH secreted from
anterior pituitary gland
why does a deficit in the 21-hydroxylase cause adrenal hyperplasia
Lack of 21-hydroxylase inhibits synthesis of cortisol.
This removes the negative feedback on ACTH and CRH release.
Increased ACTH secretion is responsible for enlargement of adrenal glands.
Negative feedback of ACTH on CRH synthesis remains.
95% of cortisol is bound to a carrier protein, what is it called
cortisol binding globulin
all nucleated cells have cytoplasmic glucocorticoid receptors true or false
true
to diffuse into the target cell what state does a hormone have to be in
it has to be unbound
where would you find steroid hormone receptors in a cell
in the cytoplasm or nucleus
what implications does loss of cortisol have
loss of cortisol means animals cannot properly deal with stress particulary in terms of maintaing blood glucose
what protection does cortisol serve to the brain
Cortisol as a glucocorticoid is crucial in helping to protect the brain from hypoglycaemia.
what hormone does cortisol have a permissive action on
it has a permissive action on glugacon which is vital
what action does cortisol have on gluconeogenesis
Cortisol stimulates formation of gluconeogenic enzymes in the liver thus enhancing gluconeogenesis and glucose production. This is aided by cortisol’s action on muscle
what action does cortisol have on proteolysis
cortisol stimulates the breakdown of muscle protein to provide gluconeogenic substrates for the liver.
what action does cortisol have on lipolysis
cortisol stimulates lipolysis in adipose tissue which increases [FFA] plasma creating an alternative fuel supply that allows [BG] to be protected while also creating a substrate (glycerol) for gluconeogenesis
what action does cortisol have in relation to insulin sensitivity
decreases insulin sensitivity of muscles and adipose tissue
what effect does cortisol have on Ca2+ balance
decreases absorption of Ca2+ from the gut
increases excretion of Ca2+ from the kidney resulting in a net Ca2+ loss
increases bone resorption-osteoporosis
what effect does cortisol have on mood
depression and impaired cognitive function are strongly associated with hypercortisolaemia.
what are cortisols permissive effects on norepinephrine
effects vascular smooth muscle (a-receptor effect = vasoconstrictive)
Cushings disease-associated with HT
low levels of cortisol- hypotension
what effect does cortisol have on the immune system
Cortisol reduces the circulating lymphocyte count, reduces antibody formation and inhibits the inflammatory response
what are side effects of glucocorticoid therapy
increased severity/frequency of infection
muscle wastage
loss of percutaneous fat stores
what type of hormone is aldosterone
mineralocorticoid
where does aldosterone act
distal tubule of the kidney to determine the levels of minerals reabsorbed/ secreted
what is the function of aldosterone
Aldosterone increases the reabsorption of Na+ ions and promotes the secretion of K+ ions.
what controls the secretion of aldosterone
secretion of aldosterone by the adrenal cortex is primarily controlled by a complex reflex pathway originating in the kidney, the renin-angiotensin-aldosterone system (RAAS)
what does increased aldosterone release stimulate
stimulates Na+ (and H2O) retention and K+ depletion, resulting increased blood volume and increased blood pressure
what does decreased aldosterone stimulate
Decreased aldosterone leads to Na+ (and H2O) loss and increase[K+]plasma, resulting in diminished blood volume and decreased blood pressure.
aldosterone, like cortisol, is essential for life true or false
true!
what is Cushings Disease
hypersecretion of corisol
what is Addisons disease
Hyposecretion of all adrenal steroid hormones
Due to autoimmune destruction of adrenal cortex
the adrenal medulla is not true endocrine tissue what is it
modified sympathetic ganglion (similar to the posterior pituitary)
what is a pheochromocytoma
a rare neuroendocrine tumour found in adrenal medulla
what does a pheochromocytoma result in
results in XS catecholamines (see slide)
