Dynamics of Glomerular Filtration Flashcards Preview

Physiology Renal ABS 2018 > Dynamics of Glomerular Filtration > Flashcards

Flashcards in Dynamics of Glomerular Filtration Deck (56):
1

What is the glomerular filtrate? Relation to plasma?

is what actually gets filtered. It is much like the plasma, only that it has very little protein.

2

Concentration in plasma=?

concentration in filtrate

3

What 2 substances are NOT filtered?

1. Proteins
2. RBCs

4

What substances get filtered?

1. H2O
2. ALL substates
3. ALL electrolytes

5

What does it mean for a substance to be freely filtered?

Substances that move from the plasma to the filtrate at the same concentration

AKA nothing gets in its way.

Goes freely from the plasma into nephron

6

Name 4 types of known freely filtered substances.

*Many low-molecular-weight components of blood
1. Ions (Na,K,Cl,HCO3)
2. Neutral organics (glucose and urea, uric acid)
3. ALL Amino acids
4. ALL Peptides (insulin and ADH)

7

What is the net filtration of glomerular capillaries compared to the regular capillaries of the body per day?

Glomerulus= 180 L/day
Regular Capillaries= 4 L/day

8

Why can we filter so much more through the glomerular capillaries than other capillaries?

The glomerulus has an efferent arteriole (HIGH PRESSURE) as opposed to an efferent venule like normal capillaries. This allows for much greater filtration

9

Average total volume of plasma in humans?

3 L

10

How many times is all of your plasma filtered/day?

60 times/day (because glomerulus filters 180 L/day)

11

Normal GFR?

Glomerular Filtration Rate= 180 L/day

12

What's in/ not in the glomerular filtrate?

In: ALL OTHER SUBSTANCES

Not in:
1. Blood Cells
2. ONLY has limited proteins (very few are filtered)

13

What are the 3 cell types of the glomerulus?

1. Podocytes
2. Endothelial cells
3. Mesangial cells

14

What determine the glomerular filtration barrier?

AKA what determines the size of the holes

The 3 types of glomerular cells
1. podocytes
2. endothelial cells
3. mesangial cells

15

Endothelial cells of the glomerulus have what?

Fenestrations between these cells-
They will filter out things based on SIZE.
Only things small enough will pass through

16

What are Podocytes? Their role? name?

1. "podo"= foot - have foot processes
2. Interdigitation with podocytes next to one another
3. Filtration slits- substance must be small enough to pass through this
4. Help keep things out based on SIZE as well.

17

What are Mesangial cells? Significance? Mechanism?

1. Modified smooth muscle cells
2. Lay down ECM proteins
3. These cells keep things out based on CHARGE by having the same charge as cells which causes repulsion
4. Constriction: will decrease GFR
Dilation: will increase GFR

18

What charge do extracellular matrix proteins have?

1. VERY/ MANY Negative charges
2. Fill the spaces around our cells with negative charges

19

What are the charges of proteins and cells?

NEGATIVE

20

What 2 glomerular cell types keep substances out based on size?

1. Endothelial cells
2. Podoctyes

21

What glomerular cell type keeps substances out based on charge?

1. Mesangial cells

22

What 5 substances are normally freely filtered?

1. H2O
2. Urea
3. Glucose
4. Sucrose
5. Inulin

23

What substances aren't able to be filtered?

LARGE PROTEINS
1. Serum albumin
2. Hemoglobin
3. Egg albumin

24

What substance is partially freely filtered?

SMALL PROTEINS
1. Myoglobin

25

What is the relationship between protein size and filtration?

Increase in protein size= decrease in filtration (vise versa)

26

What is Net Filtration Pressure? (NFP)

all pressures associated with the glomerulus. (SUM of hydrostatic and oncotic pressures from protein, oncotic or colloid osmotic pressure)
How does it determine what gets in?

27

What are the Starling forces?

[HP(capillary)+ Oncotic pressure (Bowmans's space) } - [HP (Bowman's Space) + Oncotic pressure (capillary)]

28

What is hydrostatic pressure? Where does it come from ?

1. Pushes fluid OUT
2. Comes from blood pressure

29

What is oncotic pressure? Where does it come from
?

1. Keeps/Pulls fluid IN
2. Comes from proteins and cells in the blood- and wants to keep fluid around those cells- will oppose the movement of water out

30

NFR Equation

[HP(g) + oncotic (BS)] - [oncotic (g) + HP (BS)]

31

Where does HP (capillary/glomerulus) push fluid?

Into Bowman's capsule

32

Where does the Oncotic pressure (capillary) push fluid?

Keeps it in the blood/ glomerulus

33

Where does the Oncotic pressure (Bowman's space) push fluid

Keeps it in Bowman's space

34

Fluid OUT for filtration = ?

+

35

Fluid IN for filtration

-

36

Do we have an oncotic pressure in Bowman's space? Why?Why not?

NO
1. There are no proteins in Bowman's space- therefore there is no oncotic pressure to keep fluid in Bowman's space.

37

How many forces favor filtration?What are they?

1. Hydrostatic Pressure of glomerulus

38

How many forces oppose filtration? What are they?

1. Oncotic Pressure of the glomerulus
2. Hydrostatic Pressure of Bowman's space

39

NEW NFP equation?

[HP (g) ]+ [Oncotic (g) + HP (BS])

40

Rate of Filtration equation? Define each component.

GFR= kf (constant) x NFP
kf= amount of surface area
NEW NFP= P (G)- P(BS)- Oncotic (G)

41

Rate of Filtration equation? Define each component.

GFR= kf (constant) x NFP
kf= amount of surface area
NEW NFP= HP (G)- HP(BS)- Oncotic (G)

42

What 4 forces that play a role in GFR?

1. Kf= surface area
2. HP (G)
3. HP(BS)
4. Oncotic (G)

43

When will Kf change? 5 Scenarios?

1.Only when surface area changes-- the number of nephrons change
2. In the case of renal disease- where nephrons are killed
A. end stage renal disease
B. diabetes
C. hypertension
D. Donating of kidney- decreases by half
E. Drugs causing mesangial cells to constrict

44

HP (BS) constant or not? Exceptions?

1. VERY CONSTANT.
2. Obstruction of flow through the nephron- caused maybe by kidney stones
- will cause fluid to come back and BS fills with fluid

45

When will we see a change in oncotic pressure?

a change in the amount of proteins

46

What happens when we increase or decrease oncotic (G), respectively?

a decrease in GFR, Increase GFR respectively

47

HP (G) comes from where? Can it be regulated? How?

Blood Pressure

48

Constriction of efferent arterioles does what to GFR?

Increase

49

Constriction of afferent arterioles does what to GFR?

Decrease

50

Dilation of afferent arterioles does what to GFR?

Increases

51

Dilation of efferent arterioles does what to GFR?

Decrease

52

What is Filtered Load? Equation?

The amount of substance that gets filtered /unit time
FL= GFRx [Plasma concentration of substrate]

53

Filtered load works for which types of substances?

Freely Filtered substance (b/c it moves in at the same concentration as the plasma)

54

What is the normal level of Na in the body?

140 mEq/L

55

What is autoregulation?

Helps keep GFR constant with changes in BP

56

What are 2 autoregulatory mechanisms? Functions

1. Myogenic response= smooth muscle contraction/ dilation of blood vessels (short term effect)

2. Tubuloglomerular Feedback= long term effect- RAS system
- macula densa cells detect low flow--> communicate with juxtaglomerular cells (glomerulus) --> increase RENIN--> converts angiotensin I to angiotension II--> 5 effects to increase BV/ BP