Site icon New

MINERALOCORTICOIDS – FUNCTIONS & REGULATION

amit18289

MINERALOCORTICOIDS – FUNCTIONS & REGULATION

MINERALOCORTICOIDS – FUNCTIONS & REGULATION 

Adrenal glands:

  • Paired structures situated above kidney
  • Layers – Outer cortex & inner medulla.

Adrenal cortex:

  • Essential for life 

3 layers –

  • Zona glomerulosa
  • Zona fasciculata
  • Zona reticularis.

Secretions by adrenal cortex – 

  • Corticosteroid 
  • Classified into glucocorticoids, mineralocorticoids & androgens. 
  • All corticosteroid hormones act on intracellular cytoplasmic receptors
  • Zona glomerulosa – Outermost layer & site of mineralocorticoid synthesis. 
Mineralocorticoid hormone:

Aldosterone – 

  • Chief mineralocorticoid
  • Secreted by adrenal cortex (Zona glomerulosa layer)
  • Small amount of deoxycorticosterone (DOC)

– With much less mineralocorticoid activity.

Actions of aldosterone:

  • Acts primarily on kidney.

1. Action on sodium: 

  • Increases sodium reabsorption in distal convoluted tubules & collecting ducts.
  • Occurs in exchange for K+ & H+
  • Increased Na2+reabsorption from sweat & digestive juices out of glandular ducts.
2. Potassium hemostasis:
  • Aldosterone is a major controller of K+ homeostasis.
  • K+ & H+ excretion increased.
3. Regulation of electrolyte & fluid balance:
  • In regulation of fluid and electrolyte balance

– Despite effect on Na2+ & water reabsorption 

– Secondary to sodium retention, water also retained

Receptors:
  • Expressed at high levels in renal distal tubules & cortical collecting ducts.
  • Multiple sites in brain (hippocampus), myocardium, peripheral vasculature, brown adipose tissue, colon & salivary glands.

REGULATION OF SECRETION:

  • Stimulated by hyperkalemia, angiotensin-II, ACT, and hyponatremia, in reducing order of efficacy.
  • Stimulation in response to hyperkalemia – 

– Most important renal regulation of potassium balance.

In response to angiotensin II – 

  • Through renin-angiotensin system.
  • Important for hypovolemia & hypotension correction in salt depletion/renal ischemia.

In response to ACTH – 

  • Results in diurnal variation of aldosterone secretion. 
  • Not an important physiological regulator.
  • Hyponatremia – weak stimulator.
Inhibiting factors:
  • Atrial natriuretic peptide (ANP):
  • Inhibits hormone synthesis.

Exam Important

MINERALOCORTICOIDS – FUNCTIONS & REGULATION 

Adrenal cortex:

  • Essential for life 
  • Zona glomerulosa – Outermost layer & site of mineralocorticoid synthesis. 
Mineralocorticoid hormone:

Aldosterone – 

  • Chief mineralocorticoid.
  • Acts primarily on kidney.

1. Action on sodium: 

  • Increases sodium reabsorption in distal convoluted tubules & collecting ducts.
  • Occurs in exchange for K+ & H+
2. Potassium hemostasis:
  • Aldosterone is a major controller of K+ homeostasis.
  • K+ & H+ excretion is increased.
Mineralocorticoid (aldosterone) receptors:
  • Expressed at high levels in renal distal tubules & cortical collecting ducts.
  • Also in brain (hippocampus), myocardium, peripheral vasculature, brown adipose tissue, salivary gland & colon.

REGULATION:

  • Stimulated by hyperkalemia, angiotensin-II, ACT, and hyponatremia, in reducing order of efficacy.
  • Stimulation in response to hyperkalemia – 

– Most important renal regulation of body potassium balance.

  • In response to angiotensin II – 

– Through renin-angiotensin system.

  • In response to ACTH – 

– Results in diurnal variation of aldosterone secretion. 

Don’t Forget to Solve all the previous Year Question asked on MINERALOCORTICOIDS – FUNCTIONS & REGULATION
Click Here to Start Quiz

Share this:

Exit mobile version