Nephron Function

Question 1

Stage 1 - ultrafiltration

Answer 1

Removal of nitrogenous waste and osmoregulation of the blood

Question 2

Pressure?

Answer 2

A arteriole is wider than e arteriole increases the pressure in the capillaries

Question 3

Pressure and ultrafiltration

Answer 3

Pressure forces blood out through capillary walls acts as a sieve
Fluid passes through basement membrane (2nd sieve)
Podocytes act as a 3rd filter make sure no platelets or rbc/ wbc get into tubule

Question 4

Ultrafiltrate

Answer 4

Plasma - h20 glucose urea aa and salts pass through into bowman’s capsule
Hypotonic to the blood ( more water)

Question 5

Reabsorption

Answer 5

In the proximal convoluted tube as vitamins hormones and glucose move back into blood via active transport
85% of nacl + h20 reabsorbed
Na+ by at
Cl- by diffusion

Question 6

Proximal convoluted tube adaptations

Answer 6

Covered in microvilli increase sa for absorption
Many mitochondria atp for at

Question 7

Reabsorption end

Answer 7

Constant blood blow maintains steep conc gradient
Filtrate at end of pct is isotonic with tissue fluid surrounding tubule + blood

Question 8

Loop of henle part 1

Answer 8

Top of the ascending limb Na+ and Cl- ions are actively pumped into medulla
It is impermeable to water
Water stays in tubule
Creates a low water in medulla pot because of high conc of ions

Question 9

Loop of henle part 2

Answer 9

As lwp in medulla water moves out of the descending limb by osmosis
Water is reabsorbed into the blood
Makes the filtrate (in nephron) more concentrated ions can’t move out impermeable

Question 10

Loop of henle part 3

Answer 10

Near bottom of ascending limb ions diffuse out into medulla lowering wp
Ascending limb is impermeable to water so remains in tubule

Question 11

Loop of henle part 4

Answer 11

Medulla ion conc is very high
Water move out of collecting duct
Water in medulla is reabsorbed through capillary network

Question 12

Remaining filtrate

Answer 12

Called urine
Travels down collecting ducts to pelvis then down ureters to bladder

Question 13

Counter current multiplier system

Answer 13

Filtrate down descending limb opp direction to fluid in ascending limb
Increasingly conc as move down and incr dilute as moves up
Allows conc urine to be produced

Question 14

Loop of henle length

Answer 14

Longer it is more Reabsorption- longer ascending limb more ions pumped out so more water moves out via osmosis