Physiology - Pulmonary and Sacral Oedema

Question 1

What is the role of precapillary sphincters?

Answer 1

They regulate blood flow in a few tissues such as mesentery. Slide 6

Question 2

How does fluid move from place to place and how do the hydrophilic/phobic particles move?

Answer 2

Following the pressure gradient.

Lipophilic go through the cells and hydrophilic go through the water-filled pores. Slide 8

Question 3

Large molecules e.g. plasma proteins can cross the capillary wall. True or False?

Answer 3

False, they cannot cross the capillary wall. Slide 9

Question 4

What does it mean when trasncapillary fluid flow is ultra-filtration?

Answer 4

There is exhange across the capillary wall of essentially protein free plasma. Slide 11

Question 5

What is NFP?

Answer 5

Net filtration pressure is the (forces favouring filtration) - (forces opposing filtration).
Calculated:
NFP = (Pc + Pi I) - (Pi C + Pi)
Slide 11+13

Question 6

What are the forces opposing and favouring filtration?

Answer 6

Favouring:

• Pc: capillary hydrostatic pressure
• Pi I: Interstitial fluid osmotic pressure

Opposing:

• Pi C: Capillary osmotic pressure
• Pi: Interstitial fluid hydrostatic pressure. Slide 12

Question 7

Starling forces favour filtration at the ______ end and reabsorption at the ______ end.

Answer 7

Arteriolar
Venular
Slide 13

Question 8

During a day, filtration exceeds reabsorption by 2-4 litres, where does the extra filtrated fluid go?

Answer 8

Excess fluid is returned to the circulation via the lymphatics as lymph.
Slide 16

Question 9

What is the low hydrostatic pressure in pulmonary capillaries and why is it beneficial?

Answer 9

It is usually 8-11mmHg

This is beneficial as it is lower than the capillary osmotic pressure so all the filtered fluid is reabsorbed. Slide 17

Question 10

What is oedema?

Answer 10

Accumulation of fluid in interstitial space. Slide 19

Question 11

Why is gas exchange compromised in pulmonary oedema and what other complications can occur with the lungs?

Answer 11

Diffusion distance increases.

A complication would be decreased compliance due to water tension. Slide 19

Question 12

What are the 4 causes of oedema?

Answer 12

Raised capillary pressure
Reduced plasma osmotic pressure
Lymphatic insufficiency
Changes in capillary permeability. 
Slide 20-24

Question 13

What can cause a raised capillary pressure?

Answer 13

Arteriolar dilation
Raised venous pressure
-Left/ right V failure
-Prolonged standing.
Slide 20

Question 14

What can cause a reduced plasma osmotic pressure?

Answer 14

If plasma protein conc. drops to < ~30g/l due to:
Malnutrition
protein malabsorption
Excessive renal excretion of protein
Hepatic failure. Slide 22

Question 15

What can cause lymphatic insufficiency?

Answer 15

Lymph node damage

Filariasis - elephantiasis. Slide 23

Question 16

What can cause changes in capillary permeability?

Answer 16

Inflammation

Histamine increases leakage of protein. Slide 24

Question 17

Kerley B lines are a sign of what?

Answer 17

Pulmonary oedema.