Glomerular Filtration

Question 1

Where does filtration occur?

Answer 1

At the interface between vascular and epithelial structures

Question 2

What determines permeability across the GF barrier?

Answer 2

• Size
• Charge
• Shape

Question 3

What is SNGFR?

Answer 3

Single nephron glomerular filtration rate

Question 4

What forces govern intravascular and transcellular fluid movements?

Answer 4

Starling forces

Question 5

When do you find proteins/osmolytes in the primary ultrafiltrate?

Answer 5

Defective filtration

Question 6

What is glomerulonephritis?

Answer 6

Bacterial infection causing injury to the glomerulus

Question 7

What is Goodpasture’s syndrome?

Answer 7

Antibodies attack the basement membrane

Question 8

What is Alport Syndrome?

Answer 8

Collagen IV defect so bm splits

Question 9

What is the result of High dose lithium treatment?

Answer 9

GSK inhibition which leads to impaired filtration barrier

Question 10

Why does net ultrafiltration pressure decrease at the efferent end?

Answer 10

Capillary oncotic pressure builds up as filtration proceeds

Question 11

Why does net ultrafiltration pressure decrease at the efferent end?

Answer 11

Capillary oncotic pressure builds up as filtration proceeds

Question 12

What regulates glomerular filtration?

Answer 12

• Hormonal
• Autoregulation
• Tubuloglomerular feedback

Question 13

What hormone regulates GF?

Answer 13

RAAs system

Question 14

What provides tubuloglomerular feedback?

Answer 14

JG apparatus

Question 15

Describe tubuloglomerular feedback?

Answer 15

When there is high flow rates there is inefficient removal of NaCl this is sensed by macula densa cells. These release ATP and adenosine to increase glomerular mesangial cell constriction and decrease glomerular capillary filtration area

Question 16

How can you measure GFR non invasively?

Answer 16

Clearance of special substances.

Question 17

What is inulin?

Answer 17

Used for clearance because it is freely filtered, non toxic, not secreted, not absorbed, and not metabolized. The amount that filtered should be the amount secreted

Question 18

What are GFR and inulin clearance not dependent on?

Answer 18

[Pin]

Question 19

What is creatinine?

Answer 19

Product of protein metabolism that can be measured to measure GFR

Question 20

What is a pro to using creatinine measurements over inulin?

Answer 20

No need for infusion and can collect samples over a longer period of time

Question 21

What is the pros of using inulin over creatinine?

Answer 21

It gives you a more accurate GFR

Question 22

What amount of cardiac output is delivered to the kidney?

Answer 22

1/5 (20%)

50% of this is plasma

Question 23

What percentage of plasma crosses into the bowman’s capsule?

Answer 23

20-30%

Question 24

How much of the filtered plasma is actually excreted?

Answer 24

<1%

Question 25

How many layers are in the basement membrane?

Answer 25

3

Question 26

What charge of molecules do not cross the basement membrane?

Answer 26

Negatively charged molecules because the bm is negatively charged itself

Question 27

What is the lumenal oncotic pressure in a healthy individual?

Answer 27

0. No big molecules should be in the ultrafiltrate

Question 28

Why does oncotic pressure in the efferent capillary increase?

Answer 28

You are taking away your solvent and you have more solutes at the end of the glomerulus

Question 29

At what renal blood flow is oncotic pressure the highest?

Answer 29

Low blood flow

Question 30

When is the net Puf the lowest?

Answer 30

At low flow

Question 31

What happens to GFR if there is a drop in PA (arterial pressure)?

Answer 31

Decreases rapidly after 100mmHg without any signals (autoregulation)

Question 32

What is the autoregulatory range?

Answer 32

This is the range of PA that the GFR and RBF are maintained at constant values without any signals from other systems (80mmHg-200mmHg)