Fluid shift across the Capillary Wall

Question 1

What do precapillary sphincters in capillaries do?

Answer 1

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

Question 2

What do capillaries unite to form?

Answer 2

Venules

Question 3

What is the speed of blood flow through capillary beds?

Answer 3

Slow to allow time for exchange

Question 4

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

Answer 4

The endothelial cells

Question 5

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

Answer 5

Through the pores

Question 6

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

Answer 6

Across the endothelial cells by vesicular transport

Question 7

What substances generally, cannot cross the capillary wall?

Answer 7

Plasma proteins

Question 8

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

Answer 8

Pressure gradient (bulk flow)

Question 9

What is transcapillary flow passively driven by?

Answer 9

Pressure gradients across the capillary wall

Question 10

What si ultra-filtration?

Answer 10

Transcapillary flow

Question 11

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

Answer 11

Ultra-filtration

Question 12

What is Net Filtration Pressure proportional to?

Answer 12

Forces favouring filtration - forces opposing filtration

Question 13

What also affects net fluid filtration?

Answer 13

A filtration coefficient

Question 14

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

Answer 14

Starling forces

Question 15

Give two forces favouring filtration?

Answer 15

1. Capillary hydrostatic pressure

2. Pi(i) - interstitial fluid osmotic pressure

Question 16

Give two forces opposing filtration?

Answer 16

1. Pi(c) - capillary osmotic pressure

2. Pe - interstitial fluid hydrostatic pressure

Question 17

What is the equation for NFP?

Answer 17

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

Question 18

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

Answer 18

35 mmHg - arterioles

17 mmHg - venules

Question 19

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

Answer 19

1 mmHg

Question 20

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

Answer 20

25 mmHg

Question 21

Give the value for interstitial fluid hydrostatic pressure (Pi)

Answer 21

1 mmHg

Question 22

Give the equation for NFP arteriolar end ?

Answer 22

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

Question 23

What is the equation for NFP venular end?

Answer 23

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

Question 24

What do Starling forces favour?

Answer 24

Favour filtration at arteriolar end, reabsorption at venular end

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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

Question 27

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

Answer 27

Filtration

Question 28

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

Answer 28

Returned to the circulation via the lymphatics as lymph

Question 29

In the pulmonary capillaries, what is the osmotic pressure?

Answer 29

25 mmHg

Question 30

What increases the diffusion distance and compromises gas exchange?

Answer 30

Pulmonary oedema

Question 31

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

Answer 31

1. Arteriolar dilatation | 2. Raised venous pressure

Question 32

What does left ventricular failrue cause?

Answer 32

Pulmonary oedema

Question 33

What does right ventricualr failure cause?

Answer 33

Peripheral oedena

Question 34

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

Answer 34

To the right

Question 35

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

Answer 35

Reduced plasma osmotoic poressure

Question 36

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

Answer 36

65 - 80 g/l

Question 37

Give two factors of lymphatic insufficiency in causing oedema?

Answer 37

1. Lymph node damage | 2. Filariasis - elephantiasis

Question 38

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

Answer 38

Inflammation | Histamine increases leakage of protein

Question 39

Where can pitting oedema occur?

Answer 39

Ankles and sacrum

Question 40

What regulate regional blood flow to the capillary bed?

Answer 40

Terminalo arterioles