Renal Filtration And Blood Flow Flashcards Preview

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Flashcards in Renal Filtration And Blood Flow Deck (34):
1

Is glomerular filtration active or passive

Passive

2

What does glomerular cap bp do to net filtration pressure

Favours filtration
As blood flows along cap remais constant all way

3

What does bowmas capsule hydrostatic pressure do

Result filtration have fluid which press against glomerular mem acting in opposite direction so opposing filtration

4

What is capillary oncotic pressure

Plasma protein associated
Pressure opposes filtration in cap have lots of plasma proteins these shouldn't be filtered into capsule
Proteins in blood as cannot pass mem

5

What is bowmans capsule oncotic pressure

No plasma proteins in lumen so should be zero

6

What are starling forces

Balance of hydrostatic pressures and osmotic pressures

7

What is GFR

Rate at which protein free plasma is filtered form the glomeruli into the bowmans capsule per unit time

GFR -= kf (Filtration coeffiencient -how hokey glomerular mem is) x net filtration pressure

8

What is the normal GFR

125ml/min

9

What is the ,a jot determinat of GFR

Glomerular capillary fluid blood pressure

10

What is the extrinsic regulation of GFR

Symp control via baroreceptors reflex

11

What so the intrinsic auto regulation of GFR

Myogenic mechanism

Tubuloglomerular feedback mech

12

What happens to the GFR when the arterial bp increases

Increase arterial bp
Increase glomerular cap pressure
Increase net filtration
Increase GFR

13

What happens if there is a severe haemorrhage what happens to the GFR

Fall in blood vol
Dec arterial bp
Detected by artic and carotid sinus baroreceptors
Increase symp activity
Vasoconstriction
Decrease afferent arterioles
Decrease GFR
Decrease urine vol compensate for loss

14

What is myogenic auto regulation

If vascular smooth muscle is stretched (arterial blood pressure increases) it contracts thus constricting arteriole

15

What is the Tubuloglomerular feedback autoregulation

Involves juxtaglomerular apparatus
If GFR rises more Nacl flows through tubule leading to constriction of afferent arterioles

16

What cells sense the sodium chloride content of tubular fluid

Macula densi of juxtaglomerular apparatus

17

What would happen if there is a kidney stone

Increase in bowmans capsule fluid pressure
Build up of fluid
Decreases GFR

18

What happens when an individual has diarrhoea

Increase in capillary oncotic pressure
Become dehydrated as lose fluid and not plamsa proteins
Decreases GFR

19

What happens if an individual is severely burned

Decrease in capillary oncotic pressure
Lose plasma proteins at site of injury
Increase GFR

20

What happens if there is a decrease in kf

Change of surface area for filtration
Decreases GFR

21

What is the plasma clearance a measure of

How effectively the kidneys clean the blood
Volume of plasma completely cleared of a particular substance per minute
Each sub has its specific clearance

22

How do u work put the clearance

Clearance of sub x = rate of excretion/roads a conc of x

Clearance of x = urine concentration of x (X) Vu / plasma concentration of x

Ml/min

23

What is a substance used for calculating clearance

Inulin

24

Why is inulin used for clearance

Freely filtered not abs nor sec
Not metab
Not toxic
Easily eausred in urine and blood

25

What can be sued for clearance and find GFR

Inulin or creatinine

26

When clearance=0

Substances completely reabs and not sec such as glucose

27

When clearance

For substances which are filtered partly reabs and not sec such as urea

28

When cleanrce > GFR

Subs which filtered sec but not reabs such as hydrogen ions

29

How to calculate renal plasma flow with para amino hippuric acid

Para amino hippuric acid is an exogenous organic anion not produced naturally by the body

Used clinically to measure renal plasma flow

PAH is freely filtered at glomerulus and sec into tubule completely cleared from plasma

30

What are the properties needed for a clearance marker

Non toxic
Inert not metab
Easy to measure

31

What is needed from a GFR marker and what is needed from a RPF marker

GFR - should be filtered freely not sec or abs

RPF - should be filtered and completely sec

32

What is the filtration fraction

Fraction of plasma flowing through the glomeruli that is filtered into tubules

33

How do you work out the filtration fraction

Filtration fraction = GFR/ renal plasma flow

34

What are the filtration barriers of glomerular filtration

Glomerular capillary endothelium
Basement membrane acellular
Slit processes of podocytes Interdigitate with adjacent cells