The Adrenal Gland Flashcards
Where are the adrenal glands located and how much do they weigh?
On each pole of the kidney and 4g
Where does the left adrenal vein drain into?
The right renal vein
Where does the right adrenal vein drain into?
Directly into the IVC
What are the 2 sections of the adrenal gland and what are their contributing proportions?
The adrenal medulla makes up 25% and the adrenal cortex - 75%
From where is the adrenal medulla derived?
The neural crest tissue
What is the function of the medulla?
Secretion of catecholamines - epinephrine, norepinephrine and dopamine
What 3 classes of steroid hormones does the cortex secrete? Give and example of each
Mineralocorticoids - aldosterone
Glucocorticoids - cortisol
Sex steroids - testosterone
Which zone produces mineralocorticoids?
Zona glomerulosa
What does bona fasciculata secrete?
Glucocorticoids?
What zone secretes the sex hormones?
Zona reticularis
What are all steroid hormones derived from?
Cholesterol
What is DHEA?
A pre-hormone of testosterone and oestrogen
What enzyme is vital in the production pathway of cortisol and aldosterone?
21-hydroxylase
A defect in the enzyme 21-hydroxylase will lead to?
Congenital adrenal hyperplasia resulting in the deficiency of aldosterone and cortisol - associated glucose and sodium imbalance
What pathway causes adrenal hyperplasia in 21-hydroxylase deficiency?
Lack of the enzyme inhibits the synthesis of cortisol, this results in the loss of the negative feedback on the ACTH and CRH, leading to increased secretion of ACTH and enlargement of the glands
What is cortisol
A glucocorticoid hormone that influences glucose metabolism
What percentage is bound to its carrier protein?
95%
What is the carrier protein for cortisol?
Albumin
Why do all cells with the exception of RBC’s respond to glucocorticoids?
Because all nucleated cells have a cytoplasmic glucocorticoid receptor
How does the binding of the glucocorticoid bring about an effect within the cell?
The receptor complex migrates to the uncles and causes transcription or translation of certain genes
What is the release of cortisol driven by?
The release of ATCH
Which half life is longer cortisol or ACTH?
Cortisol - so it persists in the plasma longer
When is the biggest release of cortisol? And why?
Between 6 and 8am because this is jus before we get up - very physiologically stressful - have to oppose the forces of gravity and get the CVD demand etc
What other stimuli causes the release of cortisol?
Any stressful stimulation
