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Adrenal Medulla

Discover the fascinating functions of the adrenal medulla and how it plays a crucial role in regulating stress response and releasing adrenaline.

Adrenal Medulla


The adrenal medulla is an essential component of the adrenal glands, located on top of each kidney. This article aims to provide an informative guide about the adrenal medulla, its structure, function, and clinical significance.

Structure of Adrenal Medulla

The adrenal medulla is the innermost region of the adrenal gland. It comprises approximately 20% of the gland's total mass. The cells within the adrenal medulla are called chromaffin cells, which are modified postganglionic sympathetic neurons.

Function of Adrenal Medulla

The primary function of the adrenal medulla is to secrete hormones involved in the body's response to stress. These hormones, called catecholamines, include epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. Upon stimulation, the adrenal medulla releases these hormones directly into the bloodstream.

Regulation of Catecholamine Release

The secretion of catecholamines from the adrenal medulla is regulated by the sympathetic nervous system. When the body experiences stress or danger, the sympathetic nervous system is activated, leading to the release of neurotransmitters like acetylcholine. Acetylcholine stimulates the chromaffin cells in the adrenal medulla, causing the release of epinephrine and norepinephrine.

Physiological Effects of Catecholamines

Catecholamines have numerous physiological effects throughout the body. Some of these effects include:

  • Increased heart rate and blood pressure
  • Dilation of bronchioles for improved oxygen intake
  • Increased blood flow to muscles
  • Enhanced glucose release from the liver
  • Suppression of non-essential body functions (e.g., digestion)

Clinical Significance

Dysfunction of the adrenal medulla can lead to various clinical conditions. Some important clinical considerations include:

  • Pheochromocytoma: A rare tumor of the adrenal medulla that causes excessive secretion of catecholamines, leading to symptoms such as high blood pressure, palpitations, and sweating.
  • Adrenal crisis: In cases of adrenal insufficiency, the adrenal medulla's function may be compromised, resulting in an inadequate stress response. This can lead to a life-threatening condition characterized by low blood pressure, dehydration, and electrolyte imbalances.


The adrenal medulla plays a crucial role in the body's stress response by secreting catecholamines. Understanding its structure, function, and clinical significance is essential for medical professionals, particularly during the evaluation and management of adrenal disorders.

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