anatomy 20.6

Location of adrenal glands

On the superior surface of each kidney.

Another name for adrenal glands

Suprarenal glands.

Shape of adrenal glands

Pyramid-shaped.

What surrounds adrenal glands?

They are embedded in fat and fascia, minimizing movement and contributing to the surrounding capsule.

Arteries supplying adrenal glands

Multiple suprarenal arteries branching from the inferior phrenic arteries, aorta, and renal arteries.

Venous drainage entry from adrenal glands

The suprarenal veins.

Major regions of adrenal gland

The outer adrenal cortex and inner adrenal medulla.

What does the adrenal cortex produce?

Steroid hormones, collectively called corticosteroids, including mineralocorticoids, glucocorticoids, and gonadocorticoids.

Hormones produced by adrenal medulla

Epinephrine and norepinephrine.

Embryonic origin of adrenal cortex

Intermediate mesoderm.

Embryonic origin of adrenal medulla

Neural crest cells.

Stimulus for adrenal cortex

Primarily by ACTH from the anterior pituitary.

Stimulus for adrenal medulla

By preganglionic axons from the sympathetic division of the autonomic nervous system.

Why does adrenal cortex appear yellow?

Because of the stored lipids in its cells.

Different steroid hormones synthesized by adrenal cortex

More than 25 different steroid hormones.

Collective name for steroid hormones from adrenal cortex

Corticosteroids.

Importance of corticosteroids for survival

They perform essential functions in regulating electrolytes, metabolism, blood glucose, energy use, and other body processes.

Outcome if adrenal glands are damaged or removed

The person requires corticosteroid supplementation throughout life.

Three zones of adrenal cortex from outermost to innermost

Zona glomerulosa → zona fasciculata → zona reticularis.

What is the zona glomerulosa?

The thin, outer cortical layer composed of dense, spherical clusters of cells.

Hormones produced by zona glomerulosa

Mineralocorticoids.

Principal mineralocorticoid

Aldosterone.

What does aldosterone regulate?

The ratio of sodium (Na⁺) and potassium (K⁺) ions in the blood.

How does aldosterone regulate sodium and potassium?

It stimulates sodium retention and potassium secretion in the kidneys.

Importance of sodium-to-potassium balance

Severe electrolyte imbalances can dramatically disrupt body functions and may result in death.

What is the zona fasciculata?

The middle and largest region of the adrenal cortex, composed of parallel cords of lipid-rich cells.

Hormones produced by zona fasciculata

Glucocorticoids.

Two most common glucocorticoids

Cortisol (hydrocortisone) and corticosterone.

Function of glucocorticoids

They elevate blood glucose levels and stimulate the use of lipids and proteins as energy resources, especially during stress and tissue repair.

What is the zona reticularis?

The innermost, narrow band of the adrenal cortex that produces small amounts of gonadocorticoids, primarily adrenal androgens.