ultrafiltration

Question 1

where does ultrafiltration take place

Answer 1

the Bowman’s capsule

Question 2

what are the layers that the Bowman’s capsule comprises of

Answer 2

1) the wall of a capillary
2) the basement membrane
3) wall of the bowman’s capsule comprising of podocytes

Question 3

outline the basement membrane

Answer 3

an extra-cellular layer of proteins (collagen and glycoproteins) which acts as a molecular filter and selective barrier between blood and the nephron

Question 4

what are podocytes

Answer 4

• made up of squamous epithelial cells and processes of pedicles that wrap around the capillary pulling it closer to the basement membrane
• gaps between the pedicels are called filtration slits which acts as a sieve/ filter

Question 5

outline the processes which occur in the bowman’s capsule

Answer 5

1) blood arrives in the capillaries of the glomerulus from the afferent arteriole at high pressure
2) the high pressure in the capillaries forces solutes and water through the fenestrae of the capillaries
3) through the basement membrane
4) through the filtration slits of the pedicels and into the cavity of the Bowman’s capsule

Question 6

define ultrafiltration

Answer 6

filtration under high pressure

Question 7

what solutes are forced into the bowman’s capsule

Answer 7

1) water
2) glucose
3) salts
4) urea
5) amino acids

Question 8

outline what occurs to the products in the blood which aren’t filtered

Answer 8

1) only molecules small enough can pass through the basement membrane
2) molecules that are too big remain in the blood such as blood cells, plates and antibodies
3) blood leaves the glomerulus through the efferent arteriole at a lower water potential as so much water as left and there is a high protein conc still remaining

Question 9

why is there high pressures in the afferent arteriole

Answer 9

1) hearts contraction increases pressure

2) the afferent arteriole has a wider diameter than the efferent arteriole reducing friction