Home Animal Physiology Adrenal Gland – Adrenal Cortex

Adrenal Gland – Adrenal Cortex

by Ramneet Kaur
625 views

ADRENAL GLAND

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.

Advertisements

ADRENAL CORTEX:

  • 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.

You may also like

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Lets make Biology simple

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

Subscribe
SUBSCRIBE NOW

Join Our Newsletter Today!

Stay updated with all latest MCQs, Topic Summary, Mnemonics, Videos, tips & tricks for Biology.
close-link

Send this to a friend

Skip to toolbar