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Flashcards in Fluid shift across the Capillary Wall Deck (40)
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1

What do precapillary sphincters in capillaries do?

Regulate flow in few tissues (e.g. mesentery)

2

What do capillaries unite to form?

Venules

3

What is the speed of blood flow through capillary beds?

Slow to allow time for exchange

4

In relation to transport across capillary walls, how do lipid-soluble substances pass through?

The endothelial cells

5

In relation to transport across capillary walls, how do small, water-soluble substances pass?

Through the pores

6

In relation to transport across capillary walls, how are exchangable proteins moved?

Across the endothelial cells by vesicular transport

7

What substances generally, cannot cross the capillary wall?

Plasma proteins

8

In relation to transport across the capillary wall, what does fluid movement follow?

Pressure gradient (bulk flow)

9

What is transcapillary flow passively driven by?

Pressure gradients across the capillary wall

10

What si ultra-filtration?

Transcapillary flow

11

What is exchange across the capillary wall of essentially protein free plasma?

Ultra-filtration

12

What is Net Filtration Pressure proportional to?

Forces favouring filtration - forces opposing filtration

13

What also affects net fluid filtration?

A filtration coefficient

14

What are forces called that are involved in transcapillary fluid flow?

Starling forces

15

Give two forces favouring filtration?

1. Capillary hydrostatic pressure
2. Pi(i) - interstitial fluid osmotic pressure

16

Give two forces opposing filtration?

1. Pi(c) - capillary osmotic pressure
2. Pe - interstitial fluid hydrostatic pressure

17

What is the equation for NFP?

NFP = (PC +Pi(i)) - (PiC + Pi)

18

Give the value of Capillary hydrostatic pressure (Pc) in arterioles and venules?

35 mmHg - arterioles
17 mmHg - venules

19

Give the value of Intersitital fluid osmotic pressure Pi(i)?

1 mmHg

20

Give the value for capillary osmotic pressure Pi(c)?

25 mmHg

21

Give the value for interstitial fluid hydrostatic pressure (Pi)

1 mmHg

22

Give the equation for NFP arteriolar end ?

NFP arteriolar end = (35 + 1) - (25 + 1) = +10 mmHgq

23

What is the equation for NFP venular end?

NFP venular end = (17 + 1) - (25 + 1) = -8 mmHg

24

What do Starling forces favour?

Favour filtration at arteriolar end, reabsorption at venular end

25

Name forces favouring filtration, in major forces involved in systemic transcapillary fluid flow?

Pc - Capillary hydrostatic pressure (35 mmHg arterioles, 17 mmHg veules)

26

Name forces opposing filtration, in major forces involved in systemic transcapillary fluid flow?

Pi(c) - capillary osmotic pressure (25 mmHg)

27

During a day what exceeds reabsoprtion by 2 - 4 litres?

Filtration

28

What happens to hte excess fluid after a days filtration exceeding reabsorption?

Returned to the circulation via the lymphatics as lymph

29

In the pulmonary capillaries, what is the osmotic pressure?

25 mmHg

30

What increases the diffusion distance and compromises gas exchange?

Pulmonary oedema

31

What are two factors making up raised capillary pressure, which is a cause of oedema?

1. Arteriolar dilatation
2. Raised venous pressure

32

What does left ventricular failrue cause?

Pulmonary oedema

33

What does right ventricualr failure cause?

Peripheral oedena

34

What way does heart failure shift the Frank-Starling curve?

To the right

35

What is a cause of oedema, relating to plasma osmotic pressure?

Reduced plasma osmotoic poressure

36

What is the value of normal plasma protein, and what is the value of occuring oedema?

65 - 80 g/l

37

Give two factors of lymphatic insufficiency in causing oedema?

1. Lymph node damage
2. Filariasis - elephantiasis

38

Give two factors which could lead to changes in capillary permeability, causing oedema?

Inflammation
Histamine increases leakage of protein

39

Where can pitting oedema occur?

Ankles and sacrum

40

What regulate regional blood flow to the capillary bed?

Terminalo arterioles