the kidney - nephron

Question 1

Bowman’s capsule

Answer 1

where ultrafiltration occurs

Question 2

Ultrafiltration

Answer 2

• blood enters glomerulus from the aorta (high pressure)
• the pressure forces fluid into Bowman’s capsule - glomerular filtrate
• filters - allowing small molecules through (e.g. glucose) but not large molecules (e.g. proteins)

Question 3

Selective reabsorption - which molecules are reabsorbed?

Answer 3

glucose - needed for respiration to release energy
amino acids - needed to build proteins
urea
sodium ions
chloride ions
water

Question 4

PCT

Answer 4

MOST REABSORPTION BACK INTO BLOOD HAPPENS HERE:
generally all of the reabsorbed molecules are actively transported into the blood (which requires energy)

Question 5

Loop of Henle

Answer 5

USED TO CONCENTRATE THE URINE

DESCENDING LIMB:
- water is reabsorbed via osmosis

ASCENDING LIMB:
- impermeable to water
- Na and Cl ions transported out of here to create LWP in the fluid so water moves out via osmosis in the descending limb

Question 6

DCT

Answer 6

USED TO ‘MOP UP’ ANY REMAINING REABSORPTION
- more Na and Cl ions reabsorbed
- more water reabsorbed
- ammonium ions are secreted into the filtrate

Question 7

Collecting duct

Answer 7

SELECTIVE REABSORPTION OF WATER

Question 8

What controls the permiability of Collecting duct?

Answer 8

ADH

Question 9

What does it mean if ADH IS PRESENT in the collecting duct?

Answer 9

open channels in collecting duct - allows more water to be reabsorbed - urine concentration increases, volume of urine decreases

Question 10

What does it mean if ADH IS NOT PRESENT in the collecting duct

Answer 10

Channels shut - water not reabsorbed - urine concentration decreases, volume of urine increases