Beyond Filtration: The Kidney’s Role In Homeostasis

Beyond Filtration: The Kidney’s Role In Homeostasis

Question 1. Draw a neat diagram of structural and functional unit of the kidney and label its parts. Mention the non excretory functions of kidney.
Answer:

Non excretory functions of kidney:

1. Role in homestasis

• Kidneys regulate various activities in the body, which are concerned with hemostasis
  • Filter the blood and excrete its waste products
  • Conserved water when it decrease and excretes when excess
  • Retains sodium when osmolarity decreases and eliminates sodium when osmolarity increases Maintains pH of the blood and body fluids

2. Hemopoietic function

• Stimulate erythropoiesis by the release of erythropoietin

3. Endocrine function

• Hormones secreted by kidney are:
  • Erythropoietin
  • Thrombopoietin
  • Renin
  • 1,25 dihydroxycholecalciferol
  • Prostaglandin
    1. Regulation of arterial blood pressure
    2. Regulation of blood calcium level

Question 2. Define glomerular filtration rate. Explain the factors influencing the glomerular filtration rate.
Answer:

Definition:

• Glomerular filtration rate is the total quantity of filtrate formed in all the nephrons of both the kidneys in the given unit of time.

Factors affecting glomerular filtration rate:

1. Renal blood flow

• It is directly proportional to GFR.

2. Tubuloglomerular feedback.

3. Glomerular capillary pressure

• It is directly proportional to GFR

4. Colloidal osmotic pressure

• It is inversely proportional to GFR
• In dehydration colloidal osmotic pressure increases which decreases GFR

5. Hydrostatic pressure in Bowman’s capsule

• It is inversely proportional to GFR
• Hydrostatic pressure increases in obstruction of urethra and edema of kidney

6. Blood pressure

• GFR not affected upto when BP is between 60 & 180 mm Hg

7. Sympathetic stimulation

• Mild to moderate stimulation produces no effect
• Strong stimulation causes severe constriction of blood vessels by releasing noradrenaline
• Initially there is increase in GFR later decreases

8. Surface area of capillary membrane

• It is directly proportional to GFR

9. Permeability of capillary membrane It is directly proportional to GFR

• Hormones