fluid movement across the memebrane

Question 1

What proportion of the body water is extracellular?

Answer 1

1/3

Question 2

What proportion of the body water is intracellular?

Answer 2

75%

Question 3

What makes up capillaries?

Answer 3

A dingle layer of endothelial cells

Question 4

What do capillaries allow?

Answer 4

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

Question 5

What is the main function of capillaries?

Answer 5

deliver nutrients and O2 to the cells

Removal of metabolites from cells

Question 6

What does the flow in the capillaries depend on?

Answer 6

contractile state of the arterioles

Question 7

What regulates regional flow to the capillary bed?

Answer 7

terminal arterioles

Question 8

What regulates flow in some tissues?

Answer 8

precapillary sphincters

Question 9

What is the rate of the blood through in the capillary bed and why?

Answer 9

slow to allow adequate time for exchange

Question 10

How do small water soluble substance cross the capillary?

Answer 10

through pores

Question 11

How do lipid soluble substances pass through the capillary?

Answer 11

They pass through the endothelial cells

Question 12

How do exchangeable proteins pass through the capillary?

Answer 12

They are moved across by vesicular transport

Question 13

How do plasma proteins cross the capillary?

Answer 13

They don’t. They usually stay within the blood

Question 14

How is trans capillary fluid flow driven?

Answer 14

it is driven by pressure gradients across the capillary wall

Question 15

What is ultra filtration?

Answer 15

exchange across the capillary wall of essentially protein- free plasma

Question 16

What is the equation for net filtration pressure?

Answer 16

NFP= sum of forces favouring filtration - sum of forces opposing filtration

Question 17

What is the filtration coefficient?

Answer 17

How permeable the membrane is to fluid

Question 18

What are two forces favouring filtration?

Answer 18

• Pc : capillary hydrostatic pressure

- interstitial fluid osmotic pressure

Question 19

What causes capillary hydrostatic pressure?

Answer 19

BP

Question 20

What are two forces opposing filtration?

Answer 20

• capillary osmotic pressure

- interstitial fluid hydrostatic pressure

Question 21

Starling forces favour filtration at arteriolar end and reabsorption at venular end. True/ False?

Answer 21

True

Question 22

What is the NFP at the venular end?

Answer 22

(-8mmHg), favouring movement from interstsitium back into the capillaries

Question 23

What is the NFP at the arteriolar end?

Answer 23

(10mmHg), favouring movement from capillary into the interstitium

Question 24

Where does excess fluid go?

Answer 24

excess fluid is returned to the circulation via the lymphatics as lymph

Question 25

What is the difference between pulmonary resistance and systemic resistance?

Answer 25

pulmonary resistance is much lower

Question 26

What is oedema?

Answer 26

Accumulation of fluid in interstitial space

Question 27

What two things are affected by oedema?

Answer 27

• diffusion distance is increased meaning gas exchange is compromised
• compliance is also affected

Question 28

What are the causes of oedema?

Answer 28

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

Question 29

What causes raised capillary pressure?

Answer 29

• arteriolar dilation

- raised venous pressure ie from LVF, RVF, valvular damage

Question 30

What effect does HF have on the Frank Starling curve?

Answer 30

It shifts the curve to the right

Question 31

at which plasma osmotic pressure does oedema occur?

Answer 31

Oedema occurs if pressure is less than 30g/l

Question 32

What causes a reduced plasma osmotic pressure?

Answer 32

• malnutrition
• protein malabsorption
• excessive renal excretion of protein
• hepatic failure

Question 33

What causes lymphatic insufficiency?

Answer 33

• lymph node damage

- filariasis

Question 34

What is the difference between oedema caused by HF than oedema caused by lymphatic insufficiency?

Answer 34

You wont have pitting oedema in lymphatic insufficiency

Question 35

What causes changes in capillary permeability?

Answer 35

• inflammation

- histamine which increases leakage of protein

Question 36

What are the clinical signs for pulmonary oedema?

Answer 36

• SOB
• crepitation in auscultations of lung bases
• haziness in peripheral regions on a CXR