The descending limb is the part of the loop of Henle where filtrate travels from renal cortex tissue to renal medulla tissue. This part of the loop of Henle is very water permeable.
Water flows out of the descending limb, as there is an osmotic gradient created from a higher sodium concentration in the renal tissues, outside of the loop.
The salt concentration of the medulla increases as filtrate travels down the loop. As water travels out of the descending limb, other ions in the filtrate remain, causing medullary hypertonicity to develop.
Water is absorbed from the descending loop of Henle into the surrounding renal tissues, helping to increase the loop of Henle’s medullary salt concentration.
The vasa recta is a term describing a series of capillaries that maintain the concentration gradient of renal tissue. These capillaries do so by transporting the sodium absorbed from the ascending limb around to the descending limb.
Sodium is reabsorbed into renal tissues in the ascending loop of Henle via active transport, in a process requiring ATP use.
The ascending limb of the loop of Henle has filtrate traveling towards the renal cortex tissue. It is more permeable to salts than the descending limb, and it is impermeable to water.
Na+, K+ and Cl- are actively reabsorbed by the Na+/K+/2Cl- cotransporter into the renal cells surrounding the loop of henle.
The filtrate becomes less concentrated as it exits the loop of Henle because Na+, K+ and Cl- are actively reabsorbed into surrounding renal cells. Additionally, the ascending loop is impermeable to water, thus the filtrate becomes less concentrated.
The ascending limb of the loop of Henle is impermeable to water, gradually making the filtrate less concentrated as it travels up the loop. This is because salts are transported out of the ascending limb, but water stays.
The loop of Henle exits to the distal tubule, which is the last major site of absorption in the nephron.
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