Anatomy and Physiology of the Adrenal Glands, Animation

Adrenal Gland Overview and Cortex Structure00:00:03

The adrenal glands, located atop the kidneys, consist of an outer cortex and inner medulla. The cortex is divided into three layers: zona glomerulosa, zona fasciculata, and zona reticularis, each responsible for secreting specific steroid hormones.

Mineralocorticoids and Aldosterone00:00:30

The zona glomerulosa produces mineralocorticoids, primarily aldosterone. This hormone regulates sodium, potassium, and water balance, helping to maintain blood volume and blood pressure in response to the renin-angiotensin-aldosterone system or high potassium levels.

Glucocorticoids and Cortisol Regulation00:01:11

The zona fasciculata produces cortisol, the stress hormone, which increases blood glucose for energy, regulates metabolism, suppresses the immune system, and reduces inflammation. Cortisol release is regulated by the HPA axis via a negative feedback loop and circadian rhythms.

Adrenal Androgens00:03:06

The zona reticularis secretes DHEA, a weak androgen. While minor in males, adrenal androgens are a significant source of estrogen and testosterone in females, particularly post-menopause.

Adrenal Medulla and Fight or Flight00:03:40

The adrenal medulla acts as part of the sympathetic nervous system, containing chromaffin cells that release epinephrine and norepinephrine during acute stress. These hormones trigger the fight-or-flight response, redirecting blood flow and increasing energy output.