Notes on Regional Transport
Rahul's Noteblog Notes on Nephrology Notes on Regional Transport
Proximal Tubule:
• 2/3rd of filtered sodium reabsorbed.
• 2/3rd of filtered water, potassium ion, chloride ion reabsorbed.
• All carbohydrates, proteins, peptides, amino acids, and ketones are reabsorbed.
• 80-90% of filtered bicarbonate is reabsorbed.
• All the above processes are powered by the Na-K pump.
Loop of Henle:
• 1/3 of volume going through Bowman's capsule enters the loop of Henle.
• Descending limb: permeable to water.
• Ascending limb: impermeable to water; Na / Cl / K pumped out.
• Collecting duct: ADH tells collecting duct to reabsorb water.
Distal Tubule and Collecting Duct Electrolytes:
• Na/K reabsorption stimulated by aldosterone.
• ADH: controls H2O and urea reabsorption.
• Aldosterone: controls NaCl and K+ secretion.
• Acidification of urine takes place here.
• Fixed acids and H+ excreted.
• Monohydrogen phosphate freely filtered.
• Ammonia manufactured.
• H+ excreted and bicarbonate reabsorption.
Potassium Dynamics:
• In an acid-base disturbance, there is H+ and K+ exchange between intra- and extracellular spaces.
• Acidosis: H+ enters cells; K+ leaves the cells.
• Alkalosis: H+ exits the cells; K+ enters the cells.
Additional Reading:
Basic Nephrology
1. Renal Control in Acid-Base Balance
2. Renal Processes
3. Renal Clearance
4. Regional Transport
5. What are the indications for hemodialysis?
Related Topics
1. Kidney Disorders
2. Histology of the Urinary System
3. Acid-Base Disturbance: Acidotic or Alkalotic? [Size: 427 kB; Format: PDF]
4. Abdominal Examination for Internal Medicine
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