USMLE Renal Physiology: Loop of Henle Countercurrent Mechanism and NKCC Transporter Function
The Loop of Henle functions as a countercurrent multiplier system where the descending limb acts as a water-permeable concentrating segment and the thick ascending limb serves as a solute-active diluting segment impermeable to water. This architecture relies on the NKCC2 transporter in the thick ascending limb, which generates a positive luminal potential that drives paracellular reabsorption of calcium and magnesium while secreting potassium. These physiological mechanisms establish the medullary osmotic gradient essential for urine concentration and regulate electrolyte balance within renal physiology.
USMLE Renal Physiology: Loop of Henle Countercurrent Mechanism and NKCC Transporter Function
The Loop of Henle functions as a countercurrent multiplier system where the descending limb acts as a water-permeable concentrating segment and the thick ascending limb serves as a solute-active dilu…