Glomerular filtration

Question 1

What is the fundamental functional unit of the kidney?

Answer 1

The nephron

Question 2

Name the parts of the nephron in the order blood flows through them

Answer 2

Glomerulus
Bowman's space
Proximal tubule
Loop of Henle
Collecting duct

Question 3

What is the combine blood flow to the kidneys?

Answer 3

1.1 litres per minute

Question 4

What sort of membrane is there in the glomerulus?

Answer 4

Semi permeable

Question 5

Where does the filtrate form?

Answer 5

Bowman’s space

Question 6

What two forces drive the flow in glomerular ultrafiltration?

Answer 6

Hydrostatic

Osmotic/oncotic

Question 7

How is glomerular pressure controlled?

Answer 7

Dilation of afferent arterioles

Contraction of efferent arterioles

Question 8

What is the total osmotic glomerular pressure?

Answer 8

7.1 atm

Question 9

What is the osmolality in the glomerulus?

Answer 9

0.0009 Osm.kg

Pressure of 17mmHg

Question 10

What are the three layers that separate the blood from the lumen of Bowman’s capsule?

Answer 10

Endothelial cells of glomerular capillaries
Glomerular basement membrane
Epithelial cells of Bowman’s capsule

Question 11

What is present in the endothelial cells of the glomerular capillaries?

Answer 11

Fenestrations

60nm

Question 12

What charge do the endothelial cells have?

Answer 12

Negatively charged glycocalyx

Question 13

Where else would you find negatively charged proteins?

Answer 13

Collagen fixed in the basement membrane

Question 14

What is a podocyte?

Answer 14

Epithelial cell of Bowman’s capsule

Question 15

What is a pedicel?

Answer 15

Projections from podocytes

Form extra barrier to movement of fluid

Question 16

What is the filtration fraction?

Answer 16

Proportion of plasma flow that is filtered by the glomerulus

Question 17

How do we calculate the filtration fraction?

Answer 17

Glomerular filtration rate/ Renal plasma flow

Question 18

Describe molecules that are filtered

Answer 18

Less than 10kDa in size

Question 19

Why would large molecules make it through the glomerulus?

Answer 19

Positive charge

Damage to glomerulus

Question 20

What is the daily glomerular filtration rate?

Answer 20

180L a day

Question 21

How much does each nephron filter?

Answer 21

30-50nL per min

Question 22

What is the hydrostatic pressure in the Bowman’s capsule?

Answer 22

10mmHg

Question 23

How do we measure glomerular filtration rate?

Answer 23

Substances that are filtered but not absorbed

Eg inulin.

Question 24

How do we calculate glomerular filtration rate?

Answer 24

GFR = Concentration in urine x volume of urine over plasma concentration

Question 25

How do we calculate estimated glomerular filtration rate?

Answer 25

eGFR=k/Concentration in plasma k = (140-age)xmassxC C=1.23 for men and 1.04 for women

Question 26

Who can we use GFR for?

Answer 26

Only adults | As we age nephrons are lost and GFR falls

Question 27

What is proteinuria?

Answer 27

Proteins in the urine, evidence of glomerular dysfunction

Question 28

What is a cause of proteinuria?

Answer 28

Nephrotic syndrome

Question 29

What is the name given to predominant dysfunction of the glomerulus?

Answer 29

Glomerulonephritis

Question 30

What is congenital nephrotic syndrome?

Answer 30

Rare genetic disorder effecting either nephrin or podocin (found in podocytes) Glomerulus is more permeable