9: Physiology 3 Flashcards Preview

Renal Week 1 2017/18 > 9: Physiology 3 > Flashcards

Flashcards in 9: Physiology 3 Deck (48)
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1

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

Endothelium of glomerular capillaries

Basement membrane

Podocytes of Bowman's capsule and their slit processes

2

Glomerular capillaries are more ___ than other capillaries.

permeable

3

What is the glomerular basement membrane made up of?

Type IV collagen

(Goodpasture's syndrome is a Type II hypersensitivity reaction where antibodies attack the Type IV collagen of the basement membrane)

4

What charge does the glomerular basement membrane have?

Negative charge

5

What's good about the negativity of the glomerular basement membrane?

Large negatively charged proteins can't pass through it

6

Is filtration an active or passive process?

Active process

7

What is hydrostatic pressure?

Fluid pressure

8

What is oncotic pressure?

Pressure exerted by negatively charged plasma proteins

9

The glomerular capillaries have a high, constant ___.

pressure

10

What is the fluid pressure within Bowman's capsule called?

Does it push fluid in or out of the glomerular capillaries?

Bowman's capsule HYDROSTATIC pressure

Pushes fluid INTO capillary

11

What type of pressure keeps plasma proteins within the capillary?

What causes this?

Capillary oncotic pressure

Negatively charged basement membrane

12

What is the value of the oncotic pressure of Bowman's capsule?

Zero

No plasma protein in the capsule

13

Which forces

a) aid filtration

b) block filtration?

a) Capillary blood pressure

b) Bowman's capsule hydrostatic pressure,  capillary oncotic pressure

14

What is the name for the total force which aids glomerular filtration?

What value does it have?

Net filtration pressure

10 mmHg

15

What is GFR?

Glomerular filtration rate

Rate of filtration of protein-free plasma into Bowman's capulse per unit time

16

What is the equation for GFR?

GFR = Kf x net filtration pressure

Kf = filtration coefficient​, or how permeable the glomerular membrane is

Net filtration pressure was 10 mmHg according to last slide

17

What is the main determinant of GFR?

Capillary hydrostatic pressure

which is the strongest force pushing plasma out of the capillaries

18

What is the normal GFR?

120 ml/min

19

What extrinsically regulates GFR?

Sympathetic nervous system

via Baroreceptor reflex

20

Increasing glomerular capillary blood pressure also increases ___.

GFR

21

What increases and decreases capillary blood flow and therefore blood pressure, GFR?

Vasodilation of afferent arteriole increases GFR

Vasoconstriction of afferent arteriole decreases GFR

22

How do you calculate MABP?

((2 x diastolic) (systolic)) / 3

23

How does renal blood flow and therefore GFR react to short term changes in blood pressure?

Not very much

autoregulation to prevent water and electrolyte imbalance

24

When is autoregulation of renal blood flow and GFR useful?

Exercise - BP increases but you don't want to lose too much water and electrolytes

Low BP - you still want to filter adequately

25

What is myogenic regulation of GFR?

Increased blood flow / BP causes walls of arteriole to stretch

Automatic constriction of smooth muscle to reduce blood flow > reduce GFR

Keeps GFR the same during short term hypertension/hypervolaemia

26

Which part of the distal tubule regulates GFR?

Juxtaglomerular apparatus

27

If solute concentration in the distal tubules increases, which cells cause smooth muscle constriction in the afferent arteriole to reduce blood flow and therefore GFR?

Macula densa cells detect inc salt

Granular/juxtaglomerular cells cause smooth muscle constriction

This is the short term regulation, juxtaglomerular apparatus also involved in RAAS which is the long term regulation

28

How do kidney stones affect GFR?

Blockage in collecting system, buildup of filtrate

so Bowman's hydrostatic pressure increases, stronger force AGAINST plasma movement into capsule from capillary, GFR decreases

29

How does diarrhoea affect GFR?

Dehydrated

Same amount of plasma protein

Capillary oncotic pressure increases (against movement OUT of capillary into bowman's)

GFR decreases

30

What is Kf a measure of?

Filtration coefficient

i.e surface area available for filtration