Adrenal Gland Physiology and Anatomy

Vocabulary flashcards detailing the anatomical zones, hormone production, and physiological regulation of the adrenal cortex and medulla.

Adrenal Gland

Organ located at the superior poles of the kidneys weighing approximately $4\,\text{grams}$.

Adrenal Cortex

The outer portion of the adrenal gland, constituting $80\%$ of its total structure.

Zona Glomerulosa

The outer thin layer ($15\%$) of the adrenal cortex responsible for producing mineralocorticoids like aldosterone.

Mineralocorticoid (Aldosterone)

A hormone that primarily affects electrolytes ($Na^+$ and $K^+$) in the extracellular fluid (ECF).

Regulation of Zona Glomerulosa

Directly regulated by Angiotensin II and Potassium.

Aldosterone Plasma Transport

$60\%$ binds to plasma proteins, while $40\%$ remains in free form; it has a half-life of $60\text{-}90\,\text{minutes}$.

Zona Fasciculata

The middle and widest zone ($75\%$) of the adrenal cortex that produces glucocorticoids and androgens.

Glucocorticoid (Cortisol)

Hormones that increase blood glucose concentration and affect protein and fat metabolism.

ACTH

The primary hormone responsible for regulating the zona fasciculata and the zona reticularis.

Cortisol Binding

$90\text{-}95\%$ binds to plasma proteins, specifically Cortisol-binding globulin (Transcortin) and Albumin, with a half-life of $20\,\text{minutes}$.

Zona Reticularis

The inner zone of the adrenal cortex that secretes androgens, estrogens, and glucocorticoids.

Androgens of Zona Reticularis

Includes Dehydroepiandrosterone and Androstenedione, which can cause masculinizing effects if in excess.

Adrenal Medulla

The innermost $20\%$ of the adrenal gland that secretes catecholamines.

Catecholamines

Hormones such as Epinephrine and Norepinephrine that increase heart rate, blood pressure, and metabolism.

Medullary Regulation

The secretion of hormones from the adrenal medulla is regulated by sympathetic stimulation.