Adrenal Gland Flashcards
Where are the adrenal glands located?
On the superior pole of the kidney
How are the suprarenal glands peritonised?
Retroperitoneal
Where does the left adrenal vein drain?
Into the left renal vein
Where does the right renal vein drain?
Directly into the IVC
What are the 2 parts of the adrenal gland?
Adrenal medulla
Adrenal Cortex
What % of the adrenal gland is the medulla and cortex?
Cortex - 75%
Medulla - 25%
Which part of the adrenal gland is the true endocrine portion?
Cortex
Where is the adrenal medulla derived from?
Neural crest tissue
What are the 3 classes of steroids secreted by the adrenal cortex?
Mineralocorticoids
Glucocorticoids
Sex steroids
Which sex hormones do males and females circulate?
All 3 of them
But men secrete more testosterone
And females secrete more progesterone and oestrogen
Which hormones does the medulla secrete?
Catceholamines:
Mainly epinephrine
Noriepinephrine and dopamine
What are the 3 layers of the cortex?
Zona glomerulosa
Zona Fasciculata
Zona Reticularis
What does the zona glomerulosa produce?
Aldosterone
What does the zona fasciculata produce?
Glucocorticoids
What does the zona reticularis produce?
Sex hormones
What type of horomones does the adrenal gland produce (peptide, steroid ect)?
Steroid hormones
What are the main products of the adrenal cortex?
Cortisol
Aldosterone
What is DHEA?
A pre-hormone of testosterone and oestrogen
What is a defect in 21-hydroxylase a common cause for?
Congenital adrenal hyperplasia resulting in deficiency of aldosterone and cortisol
How does lack of 21-hydroxylase cause enlargement of the adrenal glands?
Lack of 21-deydroxylase inhibits the synthesis of cortisol
Removes negative feedback on ACTH and CRH release
This increases ACTH and is reposnsible for the enlargement of the adrenal glands
What controls the release of ACTH from the anterior PG?
CRH from the hypothalamus
What controls the release of cortisol from the adrenal cortex?
ACTH from the anterior PG
What happens to the negative feedback loop of ACTH on CRH in 21-hydroxylase?
It remains
What class of hormone is cortisol?
Glucocorticoid
How does cortisol travel in the blood?
Bound to carrier proteins
Which cells have cytoplasmic glucocorticoid receptors?
All nucleated cells
Which cells in the body can repsond to glucocorticoid hormones?
All cells
Why is cortisol bound to a carrier protein?
Because it is a steroid hormone - meaning it it hydrophobic
Able to travel in the plasma bound to a carrier protein
Can bound cortisol diffuse into the target cell?
No only unbound hormone can diffuse
What is cortisol crucial for?
Helping to protect the brain from hypoglycaemia
What is the effect of cortisol on gluconeogeneis?
Stimulates the formation of gluconeogenic enzymes in the liver thus enhanching gluconeogeneis and glucose production
What is the effect of cortisol on proteolysis?
Stimualtes the breakdown of muscle proteins to provide gluconeogenic substrates for the liver
What is the effect of cortisol on lipolysis?
Stimulates lipolysis in adipose tissue releasing free FA creating an alternative fuel source
What is the effect of cortisol on insulin sensitivity?
Decreases insulin sensitivty of muscle and fat tissue
How does cortisol act on insulin?
Acts to oppose it
Why is excess cortisol diabetogenic?
Because it acts to oppose inuslin
What is the effect of cortisol on Ca2+?
Has a negative effect
decrease absorption from gut,
increases excretion at kidney resulting in net Ca2+ loss. Also increase bone resorption - osteoporosis
How does cortisol affect mood and behaviour?
Causes depression and impaired cognitiion when too high
How does cortisol affect the immune system?
Reduces cirulatory lymphocytes count, reduces antibody formation and inhibits inflammatory response
What class of hormone is aldosterone?
Mineralocorticoid
What is the effect of aldosterone?
Increases reabsorption of Na+ and promotes excretion of K+
What controls the release of aldosterone?
The RAAS system
What is the effect of increases aldosterone?
Release stimulates Na+ retention and K+ depletion
Resulting in increase blood volume and increased BP
What is the effect of decreased aldosterone?
Leads to Na+ loss and increase K+ retenton
Resulting in diminished blood volume and decrease blood BP
What is the most common cause of hypersecretion of cortisol?
Cushing’s Disease/sydrome
What is hypersecretion of cortisol most commonly due to?
A tumor in the adrenal cortex
What is the difference between Cushing’s disease and syndrome?
Syndrome - when the problem is in the adrenal cortex
Syndrome - when the problem is in the pituitary gland
Which is more common cortisol hyper or hyposecretion?
Hyper
What is the most common cause of cortisol hypersecretion?
Addison’s
Do post ganglionic fibres in the adrenal medulla have axons?
No they release adrenaline directly into the blood
What is phechromocytoma>
Rare endocrine tumour found in the adrenal medulla
What can happen iwhen glucocorticoid treatment is withdrawn too fast?
Adrenal insufficiency can occur
What do mineralocorticoids regulate?
salt and mineral balance and blood volume
What do glucocorticoids influence?
Metabolism rates of protein, fats and glucose
Where does aldosterone act on?
The kidneys
