Adrenal Glands
The adrenal glands are located above the kidneys, and are responsible for the production of various hormones of the body.
Anatomy
The adrenal gands are small (~4g) yellowish-coloured organs located above the kidney. They are located retroperitoneally.
The adrenal glands are divided into the cortex and the medulla.
Adrenal Cortex
The adrenal cortex produces steroid hormones, including
- aldosterone (zona glomerulosa)
- glucocorticoids (zona fasciculata)
- DHEA and other androgens (zona reticularis)
Aldosterone is primarily regulated by the renin-angiotensin II-aldosterone system, while cortisol and androgens are largely regulated by ACTH from the anterior pituitary.
<<PIC of STEROID HORMONES AND PRODUCTION>>
Adrenal Medulla
The adrenal medulla produces catecholamines.
Dopamine is the precursor of norepinephrine, a sympathetic neurotransmitter. The medulla is almost the exclusive site of the converting enzyme used to generate epinephrine, a key stress hormone.
Medullary secretions are about 85% epinephrine and 15% norepinephrine.
The medulla contains sympathetic ganglion cells and chromaffin cells, also known as pheochromocytes. These cells migrate from the neural crest during development, and it is possible some could be left behind along the aorta, the iliac arteries, and rarely in the bladder. These sites can also birth phaeochromocytomas.
Diseases and Conditions