hemodynamics 3

Question 1

Fractional oxygen extraction (EO2)

Answer 1

1. is another application of Fick’s Principle

2. Ratio of what was used compared to the initial amount.

Question 2

Fractional oxygen extraction (EO2) equation

Answer 2

Eo2 = ( [O2]a -[O2]v) / [O2]a

Question 3

Transcapillary Transport:

Answer 3

Solute movement & Starling’s Law of the Capillary

Question 4

filtration is by

Answer 4

hydrostatic pressure

out of vessel

Question 5

reabsorption is by

Answer 5

oncotic pressure

into vessel

Question 6

Filtration & Reabsorption =

Answer 6

Two opposing forces that determine solute movement

Question 7

Net flux is a balance between

Answer 7

filtration and reabsorption

Question 8

Two forces drive transcapillary flux:

Answer 8

1. hydrostatic pressure and

2. oncotic pressure.

Question 9

hydrostatic pressure is

Answer 9

fluid pressure, which is typically just blood pressure in the capillary

Question 10

oncotic pressure is an

Answer 10

osmotic force exerted by solutes, primarily in the blood

Question 11

Flux equation

Answer 11

Flux = k [ (Pc-Pi) - (πc - πi)]

Flux = net flux across capillary wall
k = constant
Pc = capillary hydrostatic pressure
Pi = interstitial hydrostatic pressure
πc = capillary oncotic pressure
πi = interstitial oncotic pressure

Question 12

Hydrostatic pressure favors

Answer 12

filtration because Pc>Pi

Question 13

Oncotic pressure favors

Answer 13

absorption because more protein in blood than interstitial fluid (πc>πi)

Question 14

Net flux is not

Answer 14

constant from arterial to venous end of a single capillary

Question 15

Net flux, filtration is favored at ____, absorption at ____

Answer 15

filtration favored at arterial end, absorption at venous end

Question 16

Net flux differs in

Answer 16

different capillary beds — more filtration in kidney, more reabsorption in GI tract

Question 17

Transcapillary Transport: Diffusion of Lipid-soluble molecules

Answer 17

1. Lipid-soluble molecules diffuse freely through cell membranes
2. Diffusion follows down concentration gradients
3. Steroid hormones, some vitamins, many drugs
4. Gases – O2, CO2, nitric oxide

Question 18

Interendothelial Junctions

Answer 18

1. vary in size, density, and permeability in different tissues. 2. Bigger in lympathic capillaries.
2. Large molecules (such as proteins) generally cannot go through interendothelial junctions

Question 19

Small lipid-insoluble molecules travel

Answer 19

between blood and interstitial space via gaps between capillary endothelial cells.