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
