April 4, 2016 - Basic Nephro II

Question 1

Functions of the Loop of Henle

Answer 1

Sodium reabsorption

Water reabsorption

Urine dilution

Urine concentration

Question 2

Countercurrent Multiplier

Answer 2

Sodium is pumped out of the loop through a Na/K ATPase. This creates a “salty” medulla which allows water to follow the osmotic gradient and leave the loop to be reabsorbed.

Only water can be reabsorbed on the descending LoH, and only salts can be reabsorbed on the ascending LoH.

Question 3

Vasa Recta

Answer 3

Slow moving blood capillaries allows the blood vessels to reach equilibrium as well as providing blood to this part of the nephron.

Question 4

Macula Densa

Answer 4

The ascending part of the LoH.

It senses adenosine and chloride. If it senses that these are high, it means that the nephron is not doing a good job of filtering these and will constrict the afferent arteriole and prevent bloodflow from going into that nephron.

This is called tubuloglomerular feedback.