Glucose Handling By The Kidneys: Health And Diabetes Explained

Glucose Handling By The Kidneys: Health And Diabetes Explained

Question 1. Glucose reabsorption in the kidneys in health and diabetes mellitus.
Answer:

Glucose reabsorption in health:

• Glucose is completely reabsorbed in kidneys
• It is actively transported through sodium cotransport mechanism
• According to it, glucose and sodium binds to common carrier called sodium dependent glucose transporter (SGLUT)-2
• By SGLUT-2, glucose and sodium is carried from luminal membrane into cell
• Energy produces by Na+ K+ ATPase helps to pump Na+ out of the cell into lateral intercellular spaces While glucose is transported from tubular cell into medullary interstitium by carrier protein called glucose transporter 2 (GLUT-2)

Glucose reabsorption in diabetes:

• Glucose reabsorption and excretion depends on plasma glucose concentration, PG

• Thus urine excretion rate increases with increase in plasma glucose concentration
• The plasma glucose level at which glucose first appears in urine is called renal threshold of glucose
• Value:
  • Renal threshold of arterial plasma 200 mg/dl
  • Renal threshold of venous plasma 180 mg/dl

Question 2. Functions of kidney.
Answer:

Functions of Kidney:

1. Role in homestasis
   • Kidney regulates carious activities in the body which are concerned with homeostasis
     • Filter the blood and excrete its waste products
     • Conserves water when it decreases 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
     • Erythropoeitin
     • Thrombopoeitin
     • Renin
     • 1,25 dihydroxycholecalciferol
     • Prostaglandins
4. Regulation of arterial blood pressure
   • Through renin angiotensin mechanism and through maintenance of ECF volume
5. Regulation of blood calcium level
   • Kidney regulates blood calcium level by activating 1,25 dihydroxycholecalciferol into vitamin D
   • Vitamin D helps in absorption of calcium from intestine