Explain the structural organisation of adrenal gland in mammals Describe its hormones and their functions. (IFS 2022/15 Marks)

Introduction:

The adrenal gland is a small, triangular-shaped gland located on top of each kidney in mammals. It is divided into two main regions: the adrenal cortex and the adrenal medulla.

Structural Organisation of Adrenal Gland in Mammals

1. Adrenal Cortex

• Outer Region: Constitutes about 80-90% of the gland.
• Zones: Divided into three layers:
  
  • Zona Glomerulosa (Outer): Produces mineralocorticoids.
  • Zona Fasciculata (Middle): Produces glucocorticoids.
  • Zona Reticularis (Inner): Produces androgens.
• Function: Secretes steroid hormones derived from cholesterol.

2. Adrenal Medulla

• Inner Region: Composed of chromaffin cells.
• Function: Secretes catecholamines (epinephrine and norepinephrine).
• Innervation: Controlled by the sympathetic nervous system.

Hormones of the Adrenal Gland and Their Functions

1. Hormones of the Adrenal Cortex

• Mineralocorticoids (e.g., Aldosterone):
  
  • Regulate sodium and potassium balance.
  • Control blood pressure and fluid balance.
• Glucocorticoids (e.g., Cortisol):
  
  • Regulate metabolism of carbohydrates, proteins, and fats.
  • Suppress inflammation and immune responses.
  • Help the body respond to stress.
• Androgens (e.g., DHEA):
  
  • Contribute to secondary sexual characteristics.
  • Serve as precursors to sex hormones (testosterone and estrogen).

2. Hormones of the Adrenal Medulla

• Epinephrine (Adrenaline):
  
  • Increases heart rate and blood pressure.
  • Enhances blood flow to muscles during the fight-or-flight response.
  • Promotes glycogen breakdown to glucose.
• Norepinephrine (Noradrenaline):
  
  • Constricts blood vessels to raise blood pressure.
  • Works synergistically with epinephrine in stress responses.

Conclusion:

The adrenal gland plays a crucial role in regulating various physiological processes in mammals through the production of different hormones from the adrenal cortex and adrenal medulla. Its structural organization allows for the efficient synthesis and secretion of these hormones to maintain homeostasis in the body.