The Adrenal Gland Flashcards
How much do the adrenal glands weight?
4g each
Where does the left adrenal gland drain?
Into the left renal vein or left inferior phrenic vein
Where does the right adrenal gland drain?
Into the IVC
Proportionally, how much of the adrenal glands is medulla and how much is cortex?
Cortex - 75%
Medulla - 25%
The adrenal medulla secretes what?
Catecholamines:
Epinephrine
Norepinephrine
Dopamine
The adrenal medulla is derived from what?
Modified sympathetic ganglion derived from neural crest tissue
The adrenal cortex is derived from what?
Mesoderm
The adrenal cortex secretes what?
Mineralocorticoids
Glucocorticoids
Sex steroids
What is the role of mineralocorticoids? Give an example
Aldosterone
Regulation of Na+ and K+
What is the role of glucoocorticoids? Give an example
Cortisol
Regulation of plasma glucose
What is the arrangement of the adrenal cortex?
3 layers:
Zona glomerulosa
Zona fasciculata
Zona reticularis
Steroid hormones are derived from what?
Cholesterol
What is DHEA?
Pre-hormone of testosterone and estrogen
What are the main products of the adrenal cortex?
Cortisol
Aldosterone
How does DHEA change in life?
Declines with age
What is the common cause of congenital adrenal hyperplasia?
Defects in 21-hydroxylase
What do defects in 21-hydroxylase cause?
Deficiency in aldosterone and cortisol
Disruption of salt and glucose
Accumulation of steroid precursors
Accumulation of steroid precursors causes what?
Excessive adrenal androgen production
Cortisol causes feedback inhibition on which hormones?
CRH
ACTH
Hypothalamic secretion of CRH stimulates what?
ACTH release from the anterior pituitary
Anterior pituitary ACTH secretion stimulates what?
Cortisol secretion from the adrenal cortex
21-hydroxylase is necessary for what?
Conversion of progesterone to Cortisol and Aldosterone
Why does 21-hydroxylase cause adrenal hyperplasia?
- Inhibited cortisol synthesis
- Loss of -ve feedback on ACTH and CRH
- Increased ACTH secretion
- Enlargement of adrenal glands
- (CRH synthesis remains)
- Huge excess of sex steroids
What is the negative feedback effect of ACTH?
Inhibition of CRH synthesis
What type of hormone is cortisol?
Glucocorticoid hormone
All nucleated cells have what receptors?
Cytoplasmic glucocorticoid receptors
What % of plasma cortisol is bound? What is it bound to?
95%
Cortisol binding globulin
How does cortisol alter gene expression?
Hormone receptor complex migrates to nucleus
Binds to DNA via hormone-response element
What is the pattern of cortisol release?
Circadian rhythm
Preceded by ACTH release
Cortisol burst longer (longer 1/2 life)
When does cortisol peak?
6-9am
When is cortisol lowest?
Midnight
Fluctuations of cortisol levels are related to what?
Stress