Adrenal Gland: Introduction, Parts and Functions of Adrenal Gland (For CBSE, ICSE, IAS, NET, NRA 2022)

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  • 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.

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