Adrenal Gland Flashcards
(13 cards)
Adrenal glands
Also called the suprarenal glands - one of which lies superior to each kidney in the retroperitoneal space. They have a flattened pyramidal shape. Consists of two distinct regions called the adrenal cortex (biggest) and the adrenal medulla.
Adrenal cortex
The adrenal cortex produces steroid hormones that are essential for life. Loss of this can cause dehydration and electrolyte imbalances.
Adrenal medulla
produces three catecholamine hormones
- norepinephrine
- epinephrine
- small amount of dopamine
Adrenal cortex zones -3
- Zona glomerulosa - consists of cells that are tightly packed and arranged in spherical clusters and arched columns, secrete hormones called mineralocorticoids which affect mineral homeostasis.
- Zona fasciculata - the middle zone, the widest of the three and consist of cells arranged in long, straight columns. Secrete mainly glucocorticoids primarily cortisol - affect glucose homeostasis.
- Zona reticularis - the inner zone, are arranged in branching cords. synthesize small amounts of weak androgens which are steroid hormones that have masculinizing effects.
Mineralocorticoids
Aldosterone = the major mineralocorticoid which regulates homeostasis of two mineral ions. Both sodium ion and potassium ion. & helps to adjust blood pressure and blood volume. Controlled secretion by the renin-angiotensin-aldosterone pathway.
Glucocorticoids
regulate metabolism and resistance to stress. (cortisol and cortisone) Cortisol is the most abundant at 95%.
What are the effects of Glucocorticoids?
- Protein breakdown
- Glucose formation
- Lipolysis
- Resistance to stress
- Anti-inflammatory effects
- Depression of immune responses.
Gluconeogenesis
When liver cells may convert certain amino acids or lactic acids to glucose which neurons and other cells can use for ATP production.
Lipolysis
The breakdown of triglycerides and release of fatty acids from adipose tissue into the blood.
What controls Glucocorticoid Secretion?
This occurs with a negative feedback system. Low levels of cortisol and the secretion of CRH (Corticotropin-releasing hormone) promotes the release of ACTH from the anterior pituitary which flows in the blood to the adrenal cortex.
Adrenal Medulla
A modified sympathetic ganglion of the ANS. Cells lack axons and form in large clumps around blood vessels. Secrete hormones by hormone producing cells called chromaffin cells and are innervated by sympathetic preganglionic neurons of the ANS.
What hormones are synthesized by the adrenal medulla?
- epinephrine (adrenaline) 80%
- norepinephrine (noradrenaline) 20%
Control of secretion of epinephrine and norepinephrine?
in stressful situations or during exercise, impulse from the hypothalamus stimulate sympathetic preganglionic neurons which stimulate the chromaffin cells to secrete these hormones. Increase fight or flight.
