2 kidney selective Reabsorption

Question 1

Why selective reabsorption

Answer 1

As fluid from b capsule passes along nephron tubule its composition is altered by selective reabsorptjon

Substances absorbed back into the tissue fluid and b capillaries surrounding nephron

Question 2

Steps and where it happens

Answer 2

1) proximal convulated tube : fluid composition altered by reabsorption of all the sugars, most salts and some water
2) loop of henle :Salt is added to the fluid and water is remkved - low water potential in descending limb
3) ascending limb : high water potential as mineral ions are removed by active transport
4) collecting duct : Water potential decreased by removal of water

Ensures urine has a low water potential

Urine has higher conc of solutee then blood and tissues fluid

Question 3

Proximal consulated tube

Answer 3

fluid composition altered by reabsorption of all the sugars, most salts and some water

Question 4

Loop of henle

Answer 4

Salt is added to the fluid and water is remkved - low water potential in descending limb

Question 5

Ascending limb

Answer 5

: high water potential as mineral ions are removed by active transport

Question 6

Collecting duct

Answer 6

Water potential decreased by removal of water

Ensures urine has a low water potential

Urine has higher conc of solutee then blood and tissues fluid

Question 7

How the proximal convulaged tube rebabsorbs salts sugars and water

Answer 7

1) sodium ions actively pumped out of cells lining tubule
2) conc of s in cytoplasm decreases and creates conc gradient
3) s ions diffuse into cell through co transport protein by facilitated diffusion
4) high conc so difhse out of opp sides of cell into tissue fluid
5) reabsorpkom of salts and sugars ? Low wp in cells and high in tubule fluid so water enters by osmosis

Question 8

After selective reabsorption

Answer 8

Loop of henle creates low wp in medulla to ensure more water is reabsorbed from collecting duct –

Reabsorption of water