intro to renal W1

Question 1

functions of the kidneys?

Answer 1

filtration of blood
detoxification
regulation of blood pressure
regulation of blood pH
regulation of haematopoiesis
making vitamin D

Question 2

common waste products produced by the body?

Answer 2

creatinine
urea

Question 3

what is used to measure the rate of kidney filtration? why?

Answer 3

creatinine is used to measure the rate of kidney filtration as the amount filtered equals the amount excreted

Question 4

functional view of kidney filtration?

Answer 4

non specific filter then selective recovery

Question 5

what is the finest filter in the kidney?

Answer 5

the slit diaphragm

Question 6

what are cells that make up the slit diaphragm called?

Answer 6

podocytes

Question 7

structure of the slit diaphragm?

Answer 7

podocytes are wrapped around a capillary and filter anything which may leak out

Question 8

what percentage of the slit diaphragm is slit (hole)?

Answer 8

3%

Question 9

what molecules make up the slit diaphragm

Answer 9

nephrins, neph 1 and neph 2
(proteins)

Question 10

why do we need high pressure in the kidneys?

Answer 10

must oppose osmotic pressure in the other direction - because there is more fluid in the filtrate side as there are smaller molecules here (as oppose to the blood side which contains larger molecules)

also must oppose hydrostatic pressure due to small slits (only 3% of diaphragm)

Question 11

effect of restricting afferent arteriole?

Answer 11

blood pressure in capillaries drops
filtration rate drops

Question 12

effect of restricting efferent arteriole?

Answer 12

blood pressure in glomerular capillaries rises
filtration rate rises

Question 13

how are trapped proteins removed?

Answer 13

pinocytosis - cell membrane surrounds protein, buds into vesicle in cell, breaks down protein

Question 14

limitations of pinocytosis?

Answer 14

only works for smaller proteins. additional filters are needed to keep out larger proteins

Question 15

layers of the kidney filter? outer to inner

Answer 15

fenestrated endothelium
GBM
podocytes (‘visceral epithelium’)

Question 16

what is the GBM?

Answer 16

extracellular matrix which acts as a ‘sieve’ against larger proteins

Question 17

how are different layers of the filter maintained?

Answer 17

endothelial cells - cleaned by blood flow + phagocytes
GBM - renewed by mesangial cells
podocytes - cleaned by pinocytosis by podocytes

Question 18

larger structure of kidney filtration? - terminology

Answer 18

whole thing called corpuscle. glomerulus is inside part where the capillaries are. bowman’s capsule is the holding space between the capillaries and the wall of the corpuscle.

Question 19

how many renal corpuscles do humans have on average

Answer 19

1mil renal corpuscles!!

Question 20

what acts as an artificial glomerulus? how?

Answer 20

dialysis machine
contains thin dialysis membrane with small holes. small molecules pass through and larger ones are blocked.

Question 21

4 problems with kidney transplants?

Answer 21

availability
social
rejection
tumours

Question 22

social problems with kidney transplantation?

Answer 22

legal in some countries to sell your kidney. this can result in theft or those with no other option selling their kidney for money.