Adrenal glands

Adrenal glandsAnatomy and function of the adrenal glands. Adrenal cortex and medulla. Adrenal hormones
~ 5 min

In this note, we will discuss the anatomy and function of the adrenal glands or suprarenal glands (glandulae suprarenales).

Suprarenal glands (glandulae suprarenales)
Suprarenal glands (glandulae suprarenales)

These endocrine glands produce hormones that play a crucial role in the regulation of metabolism and our adaptation to stressful conditions.

The right and left adrenal glands are located at the upper pole of the respective kidney. They are situated retroperitoneally, within Gerota’s fascia, with a layer of the fascia separating them from the kidneys.

Right adrenal gland (glandula suprarenalis dextra)
Right adrenal gland (glandula suprarenalis dextra)
Left adrenal gland (glandula suprarenalis sinistra)
Left adrenal gland (glandula suprarenalis sinistra)

Anteriorly to the right adrenal gland the right lobe of the liver and the inferior vena cava are located, while posteriorly to it lies the right crus of the diaphragm.

Anteriorly to the left adrenal gland the pancreas, spleen, and stomach are located, and posteriorly it is the left crus of the diaphragm.

Right adrenal gland (glandula suprarenalis dextra)
Right adrenal gland (glandula suprarenalis dextra)
Left adrenal gland (glandula suprarenalis sinistra)
Left adrenal gland (glandula suprarenalis sinistra)

The adrenal gland is covered by a capsule. Deep to this capsule is the adrenal cortex (cortex),

Cortex (cortex)
Cortex (cortex)

and under the cortex is the medulla of the adrenal gland (medulla).

Medulla (medulla)
Medulla (medulla)

The adrenal glands produce two groups of hormones: steroid hormones and catecholamines. Steroid hormones are produced in the cortex, which consists of three zones: the zona glomerulosa, the zona fasciculata, and the zona reticularis. The adrenal cortex is activated by adrenocorticotropic hormone (ACTH) of the anterior pituitary.

The zona glomerulosa produces hormones known as mineralocorticoids. The most important is aldosterone, which increases the reabsorption of sodium and the excretion of potassium in the kidneys.

The zona fasciculata produces glucocorticoids, including cortisol. They have numerous effects, such as stimulating glucose production.

The zona reticularis produces gonadocorticoids (androgens and estrogens). They serve as precursors to reproductive hormones that are synthesized in the gonads.

In the medulla of the adrenal glands, there are chromaffin cells that produce the second group of hormones – catecholamines. These include dopamine, adrenaline, and noradrenaline, the latter two also known as epinephrine and norepinephrine. These hormones are synthesized in response to the activation of the sympathetic nervous system, commonly referred to as the “fight or flight” response.

Arterial blood is supplied to the adrenal glands by three arteries: the superior adrenal artery (a. suprarenalis superior),

Superior adrenal artery (a. suprarenalis superior)
Superior adrenal artery (a. suprarenalis superior)

which branches off from the inferior phrenic artery, the middle adrenal artery (a. suprarenalis media),

Middle adrenal artery (a. suprarenalis media)
Middle adrenal artery (a. suprarenalis media)

which arises from the abdominal aorta, and the inferior adrenal artery (a. suprarenalis inferior),

Inferior adrenal artery (a. suprarenalis inferior)
Inferior adrenal artery (a. suprarenalis inferior)

which is a branch of the renal artery.

Venous drainage from the adrenal glands is provided by the adrenal veins. The right adrenal vein (v. suprarenalis dextra) drains into the inferior vena cava,

Right adrenal vein (v. suprarenalis dextra)
Right adrenal vein (v. suprarenalis dextra)

while the left adrenal vein (v. suprarenalis sinistra) drains into the left renal vein.

Left adrenal vein (v. suprarenalis sinistra)
Left adrenal vein (v. suprarenalis sinistra)

Innervation is provided by fibers of the celiac plexus (plexus coeliacus).

Celiac plexus (plexus coeliacus)
Celiac plexus (plexus coeliacus)

Lymphatic drainage from the adrenal glands flows to the paraaortic group of lymph nodes.

Glossary

Adrenal glands

adrenal glands
glandulae suprarenales
adrenal cortex
cortex suprarenalis
adrenal medulla
medulla suprarenalis
superior adrenal artery
a. suprarenalis superior
middle adrenal artery
a. suprarenalis media
inferior adrenal artery
a. suprarenalis inferior
right adrenal vein
v. suprarenalis dextra
left adrenal vein
v. suprarenalis sinistra
celiac plexus
plexus coeliacus
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