Physiology 3 - Glomerular Filtration

Question 1

What are the three filtration barriers which make up the glomerular membrane?

Answer 1

Glomerular capillary endothelial cells, basement membrane, podocytes

Question 2

The glomerular capillary endothelial cells act as a barrier to filtration of what?

Answer 2

Red blood cells

Question 3

The basement membrane and podocytes act as barriers to filtration of what?

Answer 3

Large plasma proteins

Question 4

Is the basement membrane of the glomerulus positively or negatively charged?

Answer 4

Negative

Question 5

What is the major determinant of GFR?

Answer 5

Glomerular capillary blood pressure

Question 6

Does filtration across the glomerular membrane require energy?

Answer 6

No

Question 7

Does the glomerular capillary blood pressure favour or oppose filtration?

Answer 7

Favour

Question 8

Does the capillary oncotic pressure favour or oppose filtration?

Answer 8

Oppose

Question 9

Does the Bowman’s capsule hydrostatic pressure favour or oppose filtration?

Answer 9

Oppose

Question 10

Does the Bowman’s capsule oncotic pressure favour or oppose filtration?

Answer 10

Favour

Question 11

What is the net filtration pressure of the glomerulus under normal circumstances?

Answer 11

10mmHg

Question 12

How can the GFR be regulated extrinsically?

Answer 12

Sympathetic control

Question 13

If the afferent arteriole constricts, what effect does this have on GFR?

Answer 13

Decreased

Question 14

If the afferent arteriole dilates, what effect does this have on GFR?

Answer 14

Increased

Question 15

Why do changes in systemic arterial blood pressure not necessarily result in changes in GFR?

Answer 15

Autoregulation

Question 16

If the GFR is too high, what effect does tubuloglomerular feedback have to correct this?

Answer 16

Constriction of the afferent arteriole

Question 17

If the GFR is too low, what effect does tubuloglomerular feedback have to correct this?

Answer 17

Relaxation of the afferent arteriole

Question 18

The presence of kidney stones causes an increased Bowman’s capsule hydrostatic pressure due to a build-up of fluid in the system. What effect does this have on GFR?

Answer 18

Decreased

Question 19

The presence of diarrhoea causes dehydration which leads to an increased glomerular capillary oncotic pressure. What effect does this have on GFR?

Answer 19

Decreased

Question 20

In a patient with severe burns, there will be a decreased glomerular capillary oncotic pressure due to the loss of plasma proteins. What effect does this have on GFR?

Answer 20

Increased

Question 21

The filtration fraction is defined as the fraction of plasma flowing through the glomeruli that is filtered into the tubules. Under normal circumstances, expressed as a percentage, what would the filtration fraction be?

Answer 21

20%

Question 22

What substance is ideal for measuring GFR as it is neither absorbed nor secreted in the renal tubules; however, it is not used clinically since it is an exogenous substance?

Answer 22

Inulin

Question 23

What endogenous substance is best for measuring GFR since only a very small amount of it is secreted?

Answer 23

Creatinine

Question 24

For substances which are filtered, completely reabsorbed and not secreted, what is the clearance?

Answer 24

0

Question 25

For substances which are filtered, partly reabsorbed and not secreted, is the clearance more or less than the GFR?

Answer 25

Less

Question 26

For substances which are filtered, secreted but not reabsorbed, is the clearance more or less than the GFR?

Answer 26

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