Home Animal Physiology Adrenal Gland – Adrenal Cortex

Adrenal Gland – Adrenal Cortex

by Ramneet Kaur


It occurs in pairs, just above the kidney on either side of the spinal column.

It consists of 2 parts:

  • Outer Adrenal cortex
  • Inner Adrenal medulla.

Present outer to the cortex is a fibrous capsule.



  • It is formed from embryonal mesoderm.
  • Adrenal cortex produces corticosteroids/ corticoids. They are modifications of cholesterol.
  • Corticotrophin-releasing hormone of Hypothalamus stimulates anterior Pituitary to secrete Adrenocorticotrophic hormone (ACTH). ACTH then stimulates Adrenal cortex to secrete Corticosteroids
  • Adrenal cortex consists of 3 layers:

Outer Zona Glomerulosa

Middle Zona Fasiculata

Inner Zona Reticularis

  • Hormones secreted by Adrenal Cortex:

MINERALOCORTICOIDS: secreted by Zona Glomerulosa.

  • Target cells: Kidney cells.
  • Its main hormone is ALDOSTERONE ( salt balancing hormone).
  • It regulates electrolyte-water balance. It acts on Distal Convoluted Tubules & Collecting Ducts of Kidney, activating Na+K+pump. Causes reabsorption of Na & excretion of K. Due to this water enters by osmosis, increasing the blood volume.

It helps in maintenance of electrolyte, body fluid volume, the osmotic pressure of blood & blood pressure.

Hyposecretion causes loss of Na, Cl & water by urine and increases K in blood, thus reducing blood pressure (Hypotension)

Hypersecretion causes high blood pressure (Hypertension), nervous & muscular weakness.

GLUCOCORTICOIDS: secreted by Zona Fasciculata.

  • Target cells: Liver cells.
  • Its main hormone is CORTISOL.
  • It causes the liver to synthesize carbohydrate from non-carbohydrate precursors like amino acids & glycerol (Gluconeogenesis). Increasing glucose level in blood – so it’s a Hyperglycemic hormone.
  • Causes Proteolysis – breakdown of proteins & stimulates an increase of amino acids in the blood.
  • Causes Lipolysis – breakdown of fats in adipose tissue. Releases fatty acid in the blood.
  • Has anti-insulin effect.
  • Anti-inflammatory: it helps in reducing pain by preventing the phagocytic action of WBC. Hence used for persons suffering from Oedema, Arthritis, Rheumatism.
  • Immuno-suppressive: checks immune reactions by antibodies. It suppresses synthesis of antibodies. Hence used in the treatment of allergies and also in organ transplant.
  • Maintains cardiovascular system as well as kidney function.
  • Stimulates RBC production.
  • Stress hormone: as it has the capability to cope stress.

GONADOCORTICOIDS/ SEX HORMONES: secreted by Zona Reticularis.

  • Target cells: Gonads.
  • Similar to sex hormones of gonads.
  • Produced in very small amounts.
  • Male hormone is ANDROGEN & female hormone is OESTROGEN.
  • They cause the development of secondary sexual characters.

Disorders of adrenal cortex:

Addison’s disease: 

Occurs due to deficiency of Aldosterone & Cortisol.

It causes low BP, low blood sugar, low Na, high K, nausea, vomiting, & diarrhea.

Cushing’s disease: 

Occurs due to excess of Cortisol.

It causes high blood sugar, high BP, the appearance of sugar in urine, rise in Na & fall in K in plasma.

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