16.9 - Loop of Henle Flashcards
The structure and function of the loop of Henle How the loop of Henle concentrates urine The counter-current multiplier mechanism
What is the loop of Henle?
U-shaped tubule in kidney nephron
What are the two main sections of the loop of Henle?
- Descending limb
- Ascending limb
What is the permeability of the descending limb?
Highly permeable to water
What is the permeability of the ascending limb?
Impermeable to water
What is the main function of the loop of Henle?
Decrease water potential in medulla
How does the loop of Henle concentrate urine?
Water leaves descending limb
What happens in the descending limb?
Water leaves filtrate by osmosis
What happens in the ascending limb?
Ions diffuse and actively transported out
What is the effect of ion movement in the ascending limb?
Concentrates ions in interstitial space
What happens when filtrate enters the collecting duct?
Water moves out by osmosis
What is the countercurrent multiplier?
Intensifies salt gradient in kidney medulla
How does the countercurrent multiplier work?
Water potential of medulla lower than collecting duct
Why is the countercurrent system important?
Concentrates urine
