Adrenal Medulla

The adrenal medulla is an innermost part of the adrenal glands, which are small, triangular-shaped endocrine glands located on top of each kidney. It is composed of chromaffin cells, which synthesize and secrete hormones called catecholamines.

Anatomy

The adrenal medulla is situated in the central portion of the adrenal glands and is surrounded by the adrenal cortex. It is formed by clusters of cells arranged in irregular cords and nests, which are highly vascularized.

Function

The main function of the adrenal medulla is to assist the body in responding to stress or emergency situations, commonly known as the “fight or flight” response. It achieves this by secreting catecholamines specifically adrenaline (epinephrine) and noradrenaline (norepinephrine) into the bloodstream.

Hormones Secreted

The adrenal medulla predominantly produces two hormones:

• Epinephrine (Adrenaline): This hormone plays a key role in preparing the body for physical activity and stressful situations. It increases heart rate, blood pressure, and blood sugar levels while dilating the pupils and airways.
• Norepinephrine (Noradrenaline): This hormone works in conjunction with epinephrine to elicit the fight or flight response. It helps increase blood flow to the muscles, improve cognitive function, and maintain blood pressure.

Regulation

The secretion of hormones from the adrenal medulla is regulated by the sympathetic nervous system. When the body senses stress or danger, the sympathetic nerve fibers stimulate the chromaffin cells to release catecholamines into the bloodstream, causing physiological changes to prepare for the perceived threat.