Adrenal hormones,adrenocorticotropic hormones, endocrinology physiology

1. AN INTRODUCTION TO:
ADRENOCORTICAL HORMONES
&
MINERALOCORTICOIDS
MALIHA FAROOQ (DPT 2ND YEAR)
MUHAMMAD AMMAZ NAVEED (DPT 2ND
YEAR)

8. MINERALOCORTICOIDS
• Mineralocorticoids are the corticosteroids that act on the
minerals (electrolytes),particularly sodium and potassium
• They are synthesized by zona glomerulosa
• They include:
1. Aldosterone (principal mineralocorticoid)
2. Dehydroxy corticosterone

9. FUNCTIONS OF MINERALOCORTICOIDS
• 90% of mineralocorticoid activity is provided by aldosterone
• It is very essential for life and maintains the osmolarity and
volume of ECF
• It is called as a life saving hormone because its absence cause
deatg within 3 days to 2 weeks.

10. ALDOSTERONE
Site of Formation:
• Zona glomerulosa
Daily secretion:
• 150μg/day
Normal Blood level:
• 6mg/100ml

11. MECHANISM OF ACTION
• Aldosterone has protein formation mechanism ( synthesis of Na+ - k+
ATPase)
On Renal Tubules:
1. Aldosterone cause increased Na+ absorption in exchange for K+ and
H+ ions in the distal convoluted tubule and collecting duct.
2. Cause increased H2O absorption due to concentration gradient created
by Na+ absorption increased ECF volume

12. On Circulation:
1. Cause increase in blood volume
2. Increase in cardiac output
3. Increase in blood pressure
On Sweat Glands and Salivary Glands:
1. Cause increase Na+ and Cl- reabsorption
2. Increase K+ secretion
On GIT:
1. Causes increased Na+ and Cl- absorption from intestine and prevent sodium loss
through feces
• Aldosterone deficiency leads to diarrhea, with loss of sodium and water

13. REGULATION OF SECRETION
• Regulated by four important factors which are given below:
 Increased K+ concentration in ECF
 Decreased Na+ concentration in ECF
 Decreased ECF volume
 ACTH Hormone

14. • Decrease in Na+ concentration and ECF volume stimulate
aldosterone secretion through Renin-angiotensin mechanism.
• Renin from juxtaglomerular apparatus of kidney acts on
angiotensinogen in plasma and convert it into angiotensin I which
is then converted into angiotensin II
• Angiotensin II acts on zona glomerulosa to secrete aldosterone
• Increased Na+ and ECF volume inhibit further release of renin

16. ALDOSTERONE ESCAPE
• When excess aldosterone is administered Excess Na+ and
water absorption Increased ECF volume Increased
blood volume Increased cardiac output Increased
blood pressure pressure diuresis and natriuresis This
secondary loss of Na+ and H2O is called aldosterone escape