5. The Loop Of Henele

Question 1

Step one

Answer 1

• At the top of the Ascending limb, Na+ ions are actively being transported out of the tubule into the medulla
• tubule here is impermeable to water so water stays inside tubule here and doesn’t enter medulla
• low water potential in medulla as high conc of sodium ions

Question 2

Step two

Answer 2

• as there is a lower water potential in the medulla than there is in the descending limb Water diffuses out by osmosis as the limb is permeable to water here
• there is a high conc of ions in the glomerular filtrate because ions can’t diffuse out as descending limb isn’t permeable to them
• water is reabsorbed back into capillary network

Question 3

Step three

Answer 3

• near bottom of ascending limb Na+ ions diffuse out of tubule into medulla
• this further decreases the water potential in the medulla
• because ascending limb is impermeable so water stays in tubule

Question 4

Step four

Answer 4

•water diffuses out of distal convoluted tube and is reabsorbed into blood

Question 5

Step five

Answer 5

• as the first 3 stages greatly increased the Na+ ions concentration in the medulla and there was a lower wage potential still.
• the collecting duct diffuses water out by osmosis into medulla where it becomes absorbed by capillary newtwprk into blood

Question 6

Animal size

Answer 6

Longer loop of HeNLE = larger animal = more water they can reabsorb from the glomeruar filtrate