Glomerular Filtration and Calculations Flashcards Preview

Physiology 2130 > Glomerular Filtration and Calculations > Flashcards

Flashcards in Glomerular Filtration and Calculations Deck (37):
1

Is everything able to into Bowmans space?

No, due to 3 barriers of filtration

2

What limits surface area for filtration?

Slits between podocytes

3

What is the % of blood that is filtered into Bowmans space from each glomerulus?

20%

4

How does unfiltered blood exit the capillaries?

Leaves through the efferent arterial

5

What are the 4 pressures that affect glomerular filtration?

1. Hydrostatic Pressure of Glomerular Capillaries
2. Colloid Osmotic pressure of Glomerular Capillaries
3. Hydrostatic Pressure of Bowmans Capsule
4. Colloid Osmotic Pressure of Bowmans Capsule

6

What happens when net filtration pressure is positive?

Plasma will filter into Bowmans space

7

What happens when net filtration pressure is 0 or less?

Plasma will not filter out of the glomerular capillaries

8

What is proper filtration pressure?

10mmHg

9

What is Hydrostatic Pressure of Glomerular Capillaries?

The pressure of the fluid in the glomerulus
-pressure caused by blood flowing into the glomerulus
-promotes filtration
-largest pressure (55mmHg)

10

What is colloid osmotic pressure of glomerular capillaries?

Within the glomerulus there are proteins which are attracted to water.
-The pressure is caused by the presence of proteins in the glomerulus
-inhibits filtration (30mmHg)

11

What is Hydrostatic pressure of Bowmans capsule?

The pressure caused by filtrate that remains in Bowmans space
-inhibits filtration (15mmHg)

12

What is Colloid osmotic pressure of Bowmans Capsule?

Pressure caused by the presence of proteins IF in Bowmans capsule (because proteins shouldn't be in this space)
-Promotes filtration IF proteins are present in Bowmans Space

13

What is the Globular Filtration Rate (GFR)?

The amount of fluid/solutes that are filtered per unit time into Bowmans space

14

What happens when if renal blood flow or blood pressure increases?

Would result in an increase in net filtration

15

What are the 2 things that affect GFR?

Net Filtration Pressure

Filtration Coefficient

16

What is the filtration coefficient?

Due to the leakiness of the globular capillaries
-really hard to measure
-influenced by the surface area of the capillaries and the permeability between capillaries

17

What happens when GFR increases and decreases?

When GFR increases more solutes are excreted

When GFR decreases less solutes are excreted

18

What is Net Filtration pressure influenced by?

Renal Blood flow

Blood Pressure

19

What is the filtration coefficient influenced by?

The surface area of the capillaries available for filtration

The permeability of barriers between capillaries and Bowmans Capsule

20

How do wed regulate GFR?

Auto-regulatory mechanisms are triggered to maintain blood pressure within the glomerulus of each nephron even when body blood pressure is high

21

What are the 2 auto-regulatory mechanisms used to regulate GFR?

Myogenic response

Tubuloglomerular Feedback

22

What is the Myogenic response?

Quickly modifies how much fluid is being filtered
-modifies how fast blood is going through the corpuscle

23

What is tubuloglomerular feedback?

When the actual content of the filtrate can also regulate the GFR locally with help of the macula dense cells

24

What is the function of the macula dense cells?

Act as salt detectors in tubuloglomerular feedback

25

In tubuloglomerular feedback, what happens when blood pressure increases?

Increased blood pressure increases the amount of fluid being filtered. As a consequence of that is the increase in NaCl being filtered. When NaCl is too high, macula dense cells release a paracrine factor that stimulate the afferent arteriole specifically to constrict and therefore reduce GFR

26

How is the GFR mostly regulated?

Via local constriction of the afferent and efferent arterioles

27

What happens to filtration when the afferent arteriole constricts?

A decrease in diameter will decrease blood flowing into the glomerulus.
-less blood=less pressure=less fluid can filter

28

What happens when the efferent arteriole constricts?

A decrease in diameter increases the GFR
-Blood cant leave as fast, pooling up in the corpuscle
-Pressure of blood increases= increases filtration rate

29

What happens when both afferent and efferent arterioles are restricted?

GFR decreases
-but the first constriction (afferent) is more important
-there is less blood entering through afferent

30

How do you measure GFR?

Through urine analysis

31

What is the excretion equation?

Filtration - Reabsorption + Secretion

32

What is the right substance to test GFR with?

A substance that is filtered easily but not reabsorbed into the body and it fully excreted in the urine

33

What are some examples of the "right" substance to measure GFR in urine?

Waste products
Creatinine

34

Where does creatinine come from?

Creatinine comes from Creatine which is found in bones. The amount of Creatinine will depend on how much bone you have

35

What is renal handling?

What happened to the substance after it got filtered into Bowmans space

36

What is the filtered load equation?

[X]substance in plasma x GFR

37

How can % reabsorption change?

Depending on how much is ingested