Adrenocortical Function and Dysfunction Flashcards
What are the 2 glands that make up the adrenal and what makes them different?
the adrenal medulla is a modified sympathetic ganglion that secretes catecholamines and the adrenal cortex is a true endocrine gland that secretes steroids
What are the layers of the adrenal cortex from out to in?
zona glomerulosa, zona fasciculata, zona reticularis
Where are the sex hormones made in the adrenal cortex?
in the zona reticularis (and also fasciculata)
Where are the glucocorticoids made in the adrenal cortex?
in the zona fasciculata (and also the zona reticularis)
Where are the mineralocorticoids made in the adrenal cortex?
in the zona glomerulosa
What other effect does ACTH have on the adrenal gland apart from glucocorticoid release?
tropic to zona reticularis and zona fasciculata
Why does excessive cortisol cause high blood pressure?
because the chemical structure of cortisol and aldosterone is similar and so cortisol can act on the aldosterone receptor to cause the same effects as aldosterone
What does inhibition of the enzyme aromatase cause?
more male sex steroids than female sex steroids
What enzyme creates glucocorticoids?
hydroxylase
Which protein must be cleaved to create ACTH?
POMC
Which POMC fragment is responsible for blocking pain perception?
beta endorphin
What is the action of ACTH in non-pituitary tissues?
it is cleaved into alpha-MSH which is responsible for melanin synthesis, immune response and decreasing food intake
Which hormones is cortisol permissive for?
glucagon and catecholamines
What time of day is plasma cortisol the highest?
usually the morning
How does cortisol effect calcium balance?
decreases absorption, increases excretion and increases bone breakdown
Is cortisol made on demand or stored?
made on demand
What is the half life of cortisol?
60-90 minutes
What enhances the release of cortisol?
stress
What are the symptoms of hyperaldosteronism?
hypernatremia, hypokalemia, hypertension
What are the causes of Cushing’s syndrome?
adrenal tumour, pituitary tumour and iatrogenic hypercortisolism
What causes adrenogenital syndrome (excess androgen and oestrogen)?
lack of enzyme in cortisol pathway
What are the symptoms of Cushing’s syndrome?
hyperglycaemia, muscle wasting, fat deposition in face, neck and stomach, hypertension, osteoporosis, mood elevation and depression, problems with learning and memory
What is Addison’s disease and what are the symptoms?
autoimmune destruction of the adrenal cortex - causes cardiac arrhythmias, hypotension and hypoglycaemia
What is the impact of a pituitary or hypothalamic pathology on aldosterone?
no impact - aldosterone will be normal but cortisol will be low
Why is adrenaline only produced in the adrenal medulla?
because this is the only site with the enzyme PMNT required for adrenaline synthesis
What are the actions of adrenaline?
increase heart rate and contractility, increase TPR, increase BP, increase glucose and free fatty acids to increase basal metabolic rate, increase arousal and alertness
What are the symptoms of hypersecretion of the adrenal medulla?
hypertension - deadly
