30/09 Lecture 32 - Sodium & Water Reabsorption

Bulk water reabsorption

This occurs in the PCT and descending nephron loop, where the epithelia is leaky to allow transcellular and paracellular reabsorption

Regulated water reabsorption

This occurs in the collecting duct and is regulated by ADH

Bulk sodium reabsorption

This occurs in the PCT and collecting duct, only moves via transcellular reabsorption

Regulated sodium reabsorption

This accounts for 7-8% of all sodium reabsorption, and is regulated by aldosterone 

Hyper-osmotic medullary gradient

This is a gradient formed by increasing osmolarity further into the medulla and creates the driving force for water reabsorption in the collecting duct

ADH

This hormone increases water reuptake in the kidneys

Aldosterone

This hormone increases sodium reuptake in the kidneys