Adrenal Gland: Introduction, Parts and Functions of Adrenal Gland
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Introduction
Adrenal glands or Suprarenal glands are the endocrine glands responsible for producing a variety of hormones including adrenaline and the steroids aldosterone and cortisol.
These glands are found on top of each kidney.
Human body consists of two adrenal glands the right gland is pyramidal in shape and the left gland is semilunar in shape.
The left adrenal gland is larger than the right one.
Size of these glands are usually about 5×3 cm with the combined weight ranging from 7 to 10 grams.

Adrenal Gland
Parts and Functions of Adrenal Gland
Adrenal Capsule
It acts as the protective layer of fat and surrounds each adrenal glands.
The primary objective of this capsule layer is enclosed and protect each of the adrenal glands.
Adrenal Cortex
It is the outermost layer of the adrenal gland.
It is responsible for producing aldosterone, cortisol, and androgens hormones.
Three Layers of Cortex (Zones)
These layers can be examined under a microscope.
Zona Glomerulosa
It performs the function of secreting mineralocorticoids like aldosterone.
Mineralocorticoid is a corticosteroid which is involved with maintaining the salt balance in the body.
Aldosterone is essential for sodium conservation in the kidney, salivary glands, sweat glands and colon.

Zona Glomerulosa
Zona Fasciculata
It produces corticosteroids like cortisol.
Small amounts of androgens such as testosterone and androstenedione are also secreted.
Androstenedione is an endogenous weak androgen steroid hormone used for making medicine.
Androstenedione further increases the production of the hormone testosterone to enhance athletic performance, build muscle, reduce body fat, etc.
Zona Reticularis
It is responsible for producing DHES or dehydroepiandrosterone also called androsterone.
Androsterone is an endogenous steroid hormone precursor which functions as a metabolic intermediate in the biosynthesis of the androgen and estrogen sex steroids.
Adrenal Medulla
Medulla is the last and innermost part of the adrenal gland.
It is located at the center of the gland, being surrounded by the adrenal cortex.
It further contains the Chromaffin cells, which produce the body’s main source of catecholamines like (adrenaline and noradrenaline) along with endorphins.
Other Important Functions
The hormones produced by adrenal glands re very crucial for the normal functioning of the body. For e.g. cortisol (a steroid hormone) that has anti-inflammatory properties and aids the immune system.
This gland helps in regulating metabolism and blood pressure through various other hormones.