Arterial Hemodynamics

Question 1

what causes blood to move through the circulatory system?

Answer 1

movement of any fluid requires a pathway AND a pressure/energy differential

Question 2

what determines the amount of flow

Answer 2

energy difference and resistance

Question 3

blood moves from ____ to _____

Answer 3

high pressure
low energy pressure

Question 4

potential (pressure) energy

Answer 4

ejection of blood from th heart into the arteries

Question 5

kinetic (motion) energy

Answer 5

movement of blood as it is ejected from the heart

Question 6

gravitational energy (hydrostatic pressure)

Answer 6

weight of the column of blood from the heart to the level where the pressure is measured

Question 7

define plug flow

Answer 7

streamline velocities that are similar from wall to wall along the flow profile. more common at transitions in vessel size and especially at branches and bifurcations.

Question 8

define parabolic flow

Answer 8

flow that is faster in the center of the vessel (streamline)

Question 9

what is the Reynolds number for laminar flow

Answer 9

<1500

Question 10

what is the Reynolds number for turbulent flow

Answer 10

> 2000

Question 11

resistance is DIRECTLY proportional to

Answer 11

viscosity and length

increased resistance, increased viscosity and length

Question 12

resistance is INVERSELY proportional to

Answer 12

vessel radius

decreased radius, increased resistance

Question 13

describe Poiseuille’s law and what is the formula

Answer 13

formula:
Flow=Pressure/Resistance

defines how blood moves through a given vessel segment and the entire system

Question 14

pulsatile flow, describe early systole

Answer 14

cardiac contraction
aortic valve opens
high velocity ejection of blood

see page 50

Question 15

pulsatile flow, describe late systole/early diastole

Answer 15

rapid deceleration and aortic valve closes

“dicrotic notch” represents aortic valve closure

see page 50

Question 16

pulsatile flow, describe late diastole

Answer 16

low flow velocity or no forward flow

depends upon the resistance of the vascular bed

see page 50

Question 17

describe area/velocity relationship

Answer 17

area and velocity are inversely proportional

decreased area, increased velocity

Question 18

describe Bernoulli’s principle

Answer 18

Relationship between velocity and pressure

velocity and pressure are inversely proportional

increased velocity, decreased pressure

Question 19

describe what happens when hematocrit increases

Answer 19

increases viscosity (thickness of blood)

Question 20

what happens when patient is anemic

Answer 20

decreased viscosity

Question 21

describes systolic upstroke, and what does it mean when there is a delay

Answer 21

shows where the blood came from

delayed systolic upstroke means stenosis proximal

Question 22

describe diastolic flow, and how does it relate to resistance

Answer 22

shows where the blood is going

the resistance of the downstream vascular bed