Chapter 8 - Arterial hemodynamics

Question 1

Hydrostatic pressure equals

Answer 1

• rho g h

Question 2

Specific gravity of blood

Answer 2

1.056 g/cm3

Question 3

Conservation of energy based on what principle

Answer 3

Bernoulli’s principle

Question 4

Potential energy in blood

Answer 4

P + rho g h

Question 5

Kinetic energy in blood

Answer 5

1/2 rho v2

Question 6

Most common loss of energy in blood as it moves

Answer 6

heat

Question 7

Ways of energy loss in flowing blood

Answer 7

1) viscous loss - friction 2) inertial loss - change in velocity/direction

Question 8

Factor that dictate viscosity in blood

Answer 8

Hematocrit

Question 9

Poisseuille’s law

Answer 9

EQUATION AFTER FIGURE 8.1

Question 10

Resistance contribution by arterioles, capillaries and medium-sized arteries and veins

Answer 10

arterioles + capillaries = 60% medium sized arteries = 15% veins = 10%

Question 11

Average blood flow in the human leg

Answer 11

300-500 ml/min

Question 12

Blood flow to LE muscle

Answer 12

2 ml/100g/min

Question 13

Exercise-induced increase in LE blood flow

Answer 13

5-10x

Question 14

Triphasic blood flow explained

Answer 14

1) systolic pulse 2) reverse due to high resistance of arterioles 3) forward flow in late diastole

Question 15

Boundary layer

Answer 15

portion of fluid adjacent to tube wall

Question 16

Boundary wall separation key points

Answer 16

1) low shear stress 2) formation of plaques 3) intimal thickening

Question 17

Vascular impedance definition

Answer 17

Resistance or opposition of peripheral vascular bed to pulsatile blood flow

Question 18

Inertial energy losses across stenotic area due to two effects

Answer 18

Contraction effect - at entrance Expansion effects - at exit of stenotic segment

Question 19

Critical stenosis definition

Answer 19

Extent of arterial narrowing to produce significant reduction in blood pressure or flow

Question 20

Three components of a collateral system

Answer 20

1) stem arteries - large distributing branches 2) midzone - small intramuscular channels 3) reentry vessels

Question 21

Collateral vs native peripheral bed difference in resistance

Answer 21

Collateral resistance is fixed does not change flow with exercise

Question 22

Thickness of pseudointima after implantation of prosthetic graft

Answer 22

0.5-1 mm decreases inner diameter of grafts

Question 23

Tangential stress calculation

Answer 23

stress = pressure x radius / thickness