Adrenal Gland and Adrenal Hormones Flashcards
Aldstere governs extracellular volume due to its action on what
Na retention/absorption by the kidney
What’s another name for Arginine vasopressin (AVP)
antidiuretic hormone (ADH)
what does antidiuretic hormone do and why
regulates osmolality
its effect on free water balance
indirectly affects Na concentration
how is aldosterone synthesised
in the adrenal cortex from cholesterol
what are the only cells that contain aldoesterone synthase
glomerulosa cells
how is secretion of aldosterone limited
by the adrenal ->
controls the rate at which glomerulosa cells synthesise the hormne
what stimulates the production of aldoesterone in the glomerulosa cell
ACTH
extracellular K+, Na+
ANG II - peptide hormone
what is the major action of aldosterone
stimulate secretion of the kidney to reabsorb Na+ and water to enhance K+ secretion
Increases blood pressure
what is the major action of aldosterone
stimulate secretion of the kidney to reabsorb Na+ and water to enhance K+ secretion
where does aldosterone exert its affects
kidney
colon
salivary glands
sweat glands
where are mineralocorticoid receptors located
myocardium
liver
brain
other tissues…
how does aldosterone work
(like all other steroid hormones)
modulating gene transcription after binding to the MR
Aldosterone regulates what and occurs where
small fraction of Na+ reabsorption
large change in water reabsorption
distal tubule and collecting duct
Most Na+ reabsoprtion by aldosterone occurs where
proximal tubule by
aldosterone independant mechanisms
loss of aldosterone mediated Na+ reabsorption can result in what
electrolyte abnormalities
hyperkalaemia and hypotension
excess aldosterone causes what
hypokalaemia
hypertension
In target cells of renal tubule, aldosterone increases activity of what involved in Na+ transport
transcription of the Na-K pump
expression of apical Na+ channels and an Na/K/Cl transporter -> increasing reabsorption and K+ secretion
Na and water levels feedback through what
RAAS
where is Angiotensin I converted into Angiotensin II
the lungs
how is angiotensin I converted to angiotensin II
ACE angiotensin converting enzyme
kidneys release renin
adrenal cortex is developed from what cells and produces what
mesodermal cells into steroidogenic cells
->that produce mineralocorticoids, glucocorticoids, and adrenal androgens
cortisol induces expression of what
(PNMT) in chromaffin cells
why don’t chromaffin cells develop into postganglionic sympathetic neurons
the cells of the adrenal medulla are exposed to high local concentrations of cortisol -> inhibits neuronal differenciation
where are adrenomedullary catecholamines secreted
into the blood and act as hormones
adrenal cortex is a true ________ gland
endocrine
adrenal medulla is a modified ______ ganglion
sympathetic
the chromaffin cell is a modified _________ _________ neuron
postganglionic sympathetic
Adrenaline is a ________ that enters the blood
neurohormone
Chromaffin granules store what
adrenaline and noradrenaline
about 80% of the cells that the adrenal medulla secrtes is _______
about 20% is ________
adrenaline
noradrenaline
secretion of adrenaline and noradrenaline from adrenal medulla is regulated by _______
in response to what
descending sympathetic signals
various forms of stress
->hypoglycaemia
the primary autonomic centers that initiate sympathetic responses reside where
in the hypothalamus and brainstem
the chemical signal for catecholamine secretion from the adrenal medulla is _______
acetylcholine
where is acetylcholine secreted from
preganglionic sympathetic neurons
where does acetylcholine bind to
nicotinic receptors on chromafin cells
Acetylcholine increases the activity of what
rate limiting enzyme
tyrosine hydroxylase
dopamine beta-hydroxylase
stimulates excocytosis of the chromaffin granules
cortisol regulates ________ production by adequate expression of the ________ in chromaffin cells
adrenaline
PNMT gene
What are the two enzymes involved in the degradation of catecholamines
monoamine oxidase
catechol -O-methyltransferase
the alpha and beta3 receptor respond better to _______ than _________
noradrenaline
adrenaline
what are adrenaline and noradrenaline examples of
catecholamines
epinephrine evokes what
vasodilation and vasoconstriction
what is the adrenal medulla directly innervated by
autonomic nervous system
because the adrenal medulla is directly innervated by _______ responses are _______
ANS
very rapid
adrenomedullary responses can precede onset of actual stress meaning responses can be
anticipated
increased blood flow to the muscles prepares for what?
flight
in flight adrenaline and noradrenaline (beta1) act on the heart to incraese the rate and strength of
contraction
adrenaline and noradrenaline act on the heart t induce ________ in flight
vasoconstriction of the veins
synthesis of glucose is initiated by
adrenaline
what is pheochromocytoma
an uncommon tumor caused by hyperplasia if adrenal medulla or other chromaffin tissue
list symptoms of pheochromocytoma
Sudden outburst of hypertension,
headaches,
episodes of sweating,
anxiousness,
tremor and
glucose intolerance
