Pulmonary and Systemic Oedema

Question 1

what does interstitial fluid do?

Answer 1

acts as the go-between blood and body cells

Question 2

what is the role of capillaries?

Answer 2

allows rapid exchange of gases, water and solutes with interstitial fluid

• delivery of nutrients and O2 to the cells
• removal of metabolites from cells

Question 3

what does blood flow in the capillaries depend on?

Answer 3

the contractile state of the arterioles

Question 4

what regulates regional blood flow to the capillary bed in most tissues?

Answer 4

terminal arterioles

Question 5

what are precapillary sphincters?

Answer 5

they regulate flow in a few tissues

Question 6

describe blood flow through the capillary bed

Answer 6

very slow to allow adequate time for exchange

Question 7

describe fluid movement across the capillary wall

Answer 7

it follows pressure gradient (bulk flow)

follows fick’s law of diffusion

Question 8

how do lipid soluble substances pass across the capillary wall?

Answer 8

through the endothelial cells

Question 9

how do water soluble substances pass across the capillary wall?

Answer 9

through water-filled pores

Question 10

what does ultrafiltration of transcapillary fluid flow mean?

Answer 10

exchange across the capillary wall is essentially protein-free plasma

Question 11

what is net filtration pressure?

Answer 11

forces favouring filtration-forces opposing filtration

Question 12

what are the starling forces?

Answer 12

forces involved in transcapillary fluid flow

Question 13

what are the forces favouring filtration?

Answer 13

Pc- capillary hydrostatic pressure

pieI- interstitial fluid osmotic pressure

Question 14

what are the forces opposing filtration?

Answer 14

pieC- capillary osmotic pressure

Pi- interstitial fluid hydrostatic pressure

Question 15

which end are the forces favouring filtration ?

Answer 15

arteriolar

Question 16

which end are the forces favouring reabsorption?

Answer 16

venular

Question 17

what is the equation for NFP?

Answer 17

(PC + pieI) - (pieC+PI)

Question 18

where does excess fluid of systemic capillaries go?

Answer 18

it is returned to the circulation via the lymphatics as lymph

Question 19

how is accumulation of interstitial fluid prevented?

Answer 19

efficient lymphatic drainage removes any filtered fluid

Question 20

what is oedema?

Answer 20

accumulation of fluid in interstitial space

diffusion distance increase- gas exchange compromised in pulmonary oedema

Question 21

what are the 4 causes of oedema?

Answer 21

raised capillary pressure
reduced plasma osmotic pressure
lymphatic insufficiency
changes in capillary permeability

Question 22

what happens during raised capillary pressure?

Answer 22

arteriolar dilatation

raised venous pressure

Question 23

what does left ventricular failure cause?

Answer 23

pulmonary oedema

Question 24

what does right ventricular failure cause?

Answer 24

peripheral oedema

Question 25

what does HF do to the frank-stirling curve?

Answer 25

shifts it to the right

Question 26

what happens in reduced plasma osmotic pressure?

Answer 26

``` lower plasma protein concentration (<30g/L results in oedema) malnutrition protein malabsorption excessive renal excretion of protein hepatic failure ```

Question 27

what causes lymphatic insufficiency?

Answer 27

lymph node damage | filariasis- elephantiasis

Question 28

what happens if there is changes in capillary permeability?

Answer 28

inflammation | histamine increases leakage of protein

Question 29

what is pulmonary oedema?

Answer 29

accumulation of fluid in the interstitial and intraalveolar lung spaces

Question 30

what are the clinical signs of pulmonary oedema?

Answer 30

SoB crepitations in lung bases chest x ray shows haziness in perihilar region

Question 31

where can pitting oedema be found?

Answer 31

ankles | sacrum