The adrenal medulla () is the inner part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex.

Structure

The adrenal medulla consists of irregularly shaped cells grouped around blood vessels. These cells are intimately connected with the sympathetic division of the autonomic nervous system (ANS). These adrenal medullary cells are modified postganglionic neurons, and preganglionic autonomic nerve fibers lead to them directly from the central nervous system. The adrenal medulla affects energy availability, heart rate, and basal metabolic rate. Recent research indicates that the adrenal medulla may receive input from higher-order cognitive centers in the prefrontal cortex as well as the sensory and motor cortices, providing credence to the idea that there are psychosomatic illnesses.

Development

Chromaffin cells are derived from the embryonic neural crest, and are modified postganglionic sympathetic neurons.

Notable effects of adrenaline (epinephrine) and noradrenaline (norepinephrine) include increased heart rate and blood pressure, blood vessel constriction in the skin and gastrointestinal tract, smooth muscle (bronchiole and capillary) dilation, and increased metabolism, all of which are characteristic of the fight-or-flight response. Pheochromocytomas may generate sudden bursts of paroxysmal symptoms due to excess catecholamine secretion. In a classical presentation of these tumors, some symptoms that commonly occur are palpitations, sweating, and headaches; these last a variable amount of time (minutes to hours) and occur periodically. Other symptoms include but are not limited to pallor, nausea, and panic attacks. Pheochromocytoma is often called a medical "mimic" since it often presents with signs and symptoms that mimic other conditions. For example, pheochromocytoma can result in flushing, nausea, weight loss, fatigue, abdominal pain, constipation, chest pain, and onset of diabetes.

  • Neuroblastoma, a neuroendocrine tumor of any neural crest tissue of the sympathetic nervous system.

See also

  • Adrenal gland
  • Chromaffin cell
  • History of catecholamine research

References

  • — "Posterior Abdominal Wall: Blood Supply to the Suprarenal Glands"
  • — "Adrenal Gland"