fluid shift across the capillary wall

Question 1

Interstitial fluid:

Answer 1

bathes the body cells, acting as the go-between blood and body cells

Question 2

describe the capillaries

Answer 2

• Single layer of endothelial cells
• Allow rapid exchange of gases, water and solutes with interstitial fluid
• Delivery of nutrients and O2 to cells
• Removal of metabolites from cells
• Blood flow in capillaries depends on contractile state of arterioles

Question 3

Terminal arterioles

Answer 3

• Regulate regional blood flow to capillary bed (CB) in most tissues

Question 4

Precapillary sphincters

Answer 4

Regulate regional blood flow to CB in few tissues

Question 5

Fluid movement follows its

Answer 5

pressure gradient

Question 6

Movement of gases and solutes follows

Answer 6

Fick’s Law of Diffusion (against concentration gradient)

Question 7

Lipid soluble substances go through the

Answer 7

endothelial cells

Question 8

Water soluble (hydrophilic) substances go through

Answer 8

the water-filled pores

Question 9

can Large molecules generally cross the capillary wall

Answer 9

no

Question 10

Transcapillary fluid flow is

Answer 10

Passively driven by pressure gradients across the capillary wall (Starling forces)

Question 11

Capillary hydrostatic pressure:

Answer 11

pressure exerted by blood in capillaries against the capillary wall, forces fluid OUT of capillary (favours filtration)

Question 12

Capillary osmotic pressure:

Answer 12

pressure exerted by proteins in the blood (albumin), in the capillaries, pulls fluid INTO blood (opposes filtration)

Question 13

Interstitial fluid hydrostatic pressure:

Answer 13

pressure of the fluid in the interstitium, forces fluid back INTO capillary (opposes filtration)

Question 14

Interstitial fluid osmotic pressure:

Answer 14

the pressure of the proteins in the interstitium, pulls fluid OUT the capillary (favours filtration)

Question 15

ultrafiltration -

Answer 15

exchange across the capillary wall of essentially protein-free plasma

Question 16

Starling forces favour —— and ——

Answer 16

filtration at arteriolar end,
reabsorption at venular end

Question 17

Filtration of fluid out of thecapillaryusually occurs on

Answer 17

the arterial side of thecapillary bed, mostly because of pressure from the arterial circulation (increased Pc) and high plasma fluid levels (decreased πc)

Question 18

Absorption of fluid into the capillary usually occurs on

Answer 18

the venous side of thecapillary bed, mostly because ofcapillary flow resistance (decreased Pc) and higher relativeplasma proteinlevels following water filtration into theinterstitium(increased πc)

Question 19

what percentage of Pulmonary resistance is that of systemic circulation

Answer 19

10%

Question 20

describe pulmonary capillary hydrostatic pressure

Answer 20

low compared to capillary osmotic pressure (25 mmHg) - favours filtration

Question 21

what does Lymphatic drainage do

Answer 21

removes any filtered fluid, preventing the accumulation of interstitial fluid

Question 22

what is oedema

Answer 22

Accumulation of fluid in intersitital space

Question 23

Pulmonary oedema:

Answer 23

diffusion distance increased - gas exchange comprimised as O2 and CO2 have to dissue through wide layer of interstital fluid

Question 24

causes of oedema 1

Answer 24

Raised capillary hydrostatic pressure
- arteriolar dilation
- raised venous pressure
- Left venticular faliure (pulmonary oedema)
- Right venticular faliure (peripheral oedema (ankle, sacral)
- Polonged standing (swollen ankles)

Question 25

describe pulmonary oedema

Answer 25

• accumulation of fluid in the interstitial and intraalveolar lung spaces
• manifested clinically by varying degrees of shortness of breath
• crepitations in auscultation of lung bases
• Chest X-ray shows haziness in perihilar region

Question 26

all causes of oedema

Answer 26

• Raised capillary hydrostatic pressure
• Reduced plasma osmotic pressure
• Lymphatic insufficiency
• Changes in capillary permeability

Question 27

cause of oedema 2

Answer 27

• Reduced plasma osmotic pressure

normal [plasma protein]p is 65-80g/l
Oedema if <30g/l due to:
- malnutrition
- protein malabsorption
- excessive renal excretion of protein
- hepatic faliure

Question 28

cause of oedema 3

Answer 28

Lymphatic insufficiency

• lymph node damage
• filariasis (a tropical disease caused by the presence of filarial worms, especially in the lymph vessels where heavy infestation can result in elephantiasis)

Question 29

cause of oedema 4

Answer 29

• Changes in capillary permeability

inflammation
histamine increases leakage of protein

Question 30

what is RAAS

Answer 30

Renin-Angiotensin-Aldosterone System (RAAS) is upregulated in heart failure resulting in more fluid retention