Fluid Shift across the capillary wall and systemic oedema Flashcards

1
Q

what acts as the go between the blood and body cells?

A

interstitial fluid

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2
Q

how many layers of endothelial cells are there in capillaries?

A

1

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3
Q

f’s: capillaries

A

allow rapid exchange of gases, water and solutes with interstitial fluid
delivery of O2 and nutrients to the cells
removal of metabolites from cells

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4
Q

What is BF in capillaries dependent of?

A

the contractile state of the arterioles

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5
Q

f: terminal arterioles?

A

regulate regional BF to the capillary bed CB in most tissues

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6
Q

f: precapillary sphincters

A

regulate flow in a few tissues eg mesentery

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7
Q

why is the BF in CB v slow?

A

to allow time for exchange

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8
Q

what is formed when capillaries unite?

A

venules

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9
Q

How are exchangeable proteins moved across the capillary wall?

A

via vesicular transport

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10
Q

How do lipid soluble substances pass across the capillary wall?

A

via endothelial cells

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11
Q

How do plasma proteins move across the capillary wall?

A

they don’t

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12
Q

How do small water soluble substances pass across the capillary wall?

A

across pores

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13
Q

What does fluid movement follow?

A

pressure gradient

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14
Q

What does the movement of gases and solutes follow?

A

Fick’s Law of diffusion

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15
Q

What is transcapillary fluid flow passively driven by?

A

pressure gradients across the capillary wall

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16
Q

d: ultra-filtration

A

filtration using a medium fine enough to retain colloidal particles, viruses, or large molecules

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17
Q

What is net filtration pressure (NFP) directly proportional to? What is the coeffient?

A
forces favouring filtration-forces opposing filtration
Filtration coefficient (Kf)
18
Q

Name the forces favouring filtration?

A

capillary hydrostatic pressure

interstitial fluid osmotic pressure

19
Q

Name the forces opposing filtration?

A

capillary osmotic pressure

interstitial fluid hydrostatic pressure

20
Q

What is the equation for NFP?

A

(PC + pi i)-(pi C + Pi)

21
Q

What can be concluded from NFP quation?

A

starling forces favour filtration at arteriolar end, reabsorption at end of venular end

22
Q

What is the general name given for the forces involved in transcapillary flow?

A

starling forces

23
Q

Name the major forces favouring filtration in systemic transcapillary flow?

A

Pc capillary hydrostatic pressure

24
Q

Name the major forces opposing filtration in systemic transcapillary flow?

A

Pi C capillary osmotic pressure

25
How is the excess fluid returned to the circulation?
via lymph system as lymph
26
what is the value of pulmonary osmotic pressure?
25mmHg
27
what prevents accumulation of interstitial fluid?
efficient lymphatic drainage
28
d: oedema
Accumulation of fluid in interstitial space
29
what is the effect of oedema in the lungs?
diffusion distance increases gas exchange is therefore compromised
30
Name the causes of oedema
raised capillary pressure reduced plasma osmotic pressure lympathetic insufficiency changes in capillary permeability
31
How does raised capillary pressure occur?
arteriolar dilatation | raised venous pressure
32
What is the effect of left ventricular failure?
pulmonary oedema
33
What is the effect of right ventricular failure?
peripheral oedema, ankle/ sacral
34
If you have a oedema and stand for a long time what can be caused?
swollen ankles
35
How does reduced plasma osmotic pressure occur?
``` Normal [plasma protein]p = 65-80 g/l Oedema if < ~ 30 g/l normal plasma protein falls if malnurished proetin malabsorption XS renal excretion of protein hepatic failure ```
36
how does lymphatic insufficiency occur?
lymph node damage filariasis-elephantiasis
37
How do changes in capillary permeability occur?
inflammation | histamine increases leakage of protein
38
what is a clinical sign of pulmonary oedema?
breathlessness
39
On examination how will pulmonary oedema be manifested?
crepitations in auscultation of lung bases
40
How will pulmonary oedema be demonstrated in CXR?
haziness in perihilar region