The Adrenal Gland Flashcards
vertebral level of adrenals
t12
difference between venous drainage of adrenals
left –> left renal vein
right –> IVC
3 types of hormone secreted by adrenal cortex
mineralocorticoids
glucocorticoids
sex hormones
3 layers of cortex and what they secrete
zona glomerulosa - mineralocorticoids
zona fasciculata - glucocorticoids
zona reticularis - sex hormones
which of the cortex layers is most external
zona glomerulosa
what type of hormones are those secreted by adrenal cortex
steroid (dervied from cholesterol)
what hormones are secreted by the adrenal medulla
epinephrine, norepinephrine and dopamine
what type of hormones are secreted by the adrenal medulla
amine –> tyrosine –> catecholamines
where is cortisol secreted from
adrenal cortex –> zona fasciculata
DHEA is a pre-hormone of what two sex hormones
testosterone and oestrogen
defects in what enzyme causes adrenal hyperplasia and cortisol and aldosterone deficiency
21-hydroxylase
what would consequences of 21-hydroxylase deficiency be
inability to regulate blood pressure, unable to cope with bodily stresses and genital ambiguity at birth
why is there an excess of sex hormones in 21-hydroxylase deficiency
because cortisol and aldosterone cannot be produced but there is an excess of adrenal stimulation by ACTH so activity gets shunted to producing sex hormones
why is ACTH in greater excess than CRH in 21-hydroxylase deficiency
because there is no feedback inhibtion on ACTH from cortisol but there is feeback inhibition on CRH from ACTH
how is cortisol transported in blood
95% is bound to carrier protein
process of steroid hormone cell response
lipophillic so passes through membrane –> cytoplasmic/nucleic receptors –> formed complex binds to DNA –> genes altered/expressed –> response produced through proteins
when are cortisol levels highest and why
between 6-9am, need cortisol to deal with oncoming stresses at the start of the day
what glucose counter-regulatory hormone is cortisol permissive to
glucagon
can glucagon respond to hypoglycaemia alone
no it need the other ones to help and for their permissive effects
actions of cortisol on metabolism
gluconeogensis, proteolysis, lipolysis and decreased insulin sensitivity
how does proteolysis and lipolysis help the brain
give other bodily tissues a source of energy so that glucose can be spared for brain
what tissues does cortisol reduced insulin sensitivity in
muscle and fat
action of cortisol on Ca2+ absorption
decreases its absoprtion in gut while increasing its resorption in bone
action of cortisol on norepinephrine
permissive: especially in vascular smooth muscle (i.e. aids vasocontriction)
what effect would low cortisol have on blood pressure
low cortisol –> reduced permissive effect on norepinephrine –> less vasocontriction –> hypotension
effect of cortisol on mood
low mood and impaired cognition
what does cortisol do to the immune system
it suppresses it, clinically useful in autoimmune?
what is cushings disease
over secretion of cortisol resulting in peripheral protein and fat breakdown with central (trunk and face) getting bigger
what two levels of cortisol pathway most commonly cause cushings
an overactive pituitary gland (2nd degree) and overactive adrenal cortex (1st degree)
what is hyposecretion of cortisol called
addison’s disease
what hormones are undersecreted in addison’s
all adrenal steroid hormones (from cortex)
what triggers CRH and ACTH release
stress
what embryological structure does the adrenal medulla form from
the neural crest tissue
what embryological structure does the adrenal cortex form from
the mesoderm
true/false the postganglionic cells in adrenal medulla have no axons
true - they release their neurohormones directly into the bloodstream
pheochromocytoma?
rare tumour of adrenal medulla and causes excess catecholamine secretion –> diabetogenic and increase BP
what is a consequence of withdrawing long term glucocorticoids
inducing adrenal insufficiency (enhanced negative feedback of supplement cortisol on ACTH causes adrenal atrophy, so withdrawal will leave an adrenal not up to job, so do slow and give it tie to grow from ACTH stimulation)
