Quiz 4, Part 1- Hemodynamics

Question 1

As cross sectional area increases, velocity _____

Equation?

Answer 1

decreases

Flow= Velocity x Area
Velocity= Flow/Area

Question 2

Ohm’s Law - What two factors determine blood flow thru vessel?

Equation?

Answer 2

voltage diff and resistance.

Q= (PressureArterial - PVenous) or ∆P= QxR
_____________________
Resistance

Question 3

According to Ohm, increasing resistance ___ flow

Answer 3

decreases

Question 4

According to Ohm, increases resistance ___ pressure

Answer 4

increases

Question 5

Define BP

Answer 5

the force exerted by the blood against any unit area of the vessel wall

Question 6

Conversion factor from mmHG to cmH20

Answer 6

1mmHg = 1.36cm h20 pressure

Question 7

Cerebral perfusion pressure

Answer 7

MAP - CVP or ICP (whichever is higher)

Question 8

What dose Poiseuille’s Law talk about?

Answer 8

Determinants of FLOW

1) Radius*
2) Viscosity
3) Length
4) Pressure Gradient (a.k.a gravity)

Question 9

According to Poiseuille, flow is ___ proportional to the pressure gradient

Answer 9

directly

Question 10

According to Poiseuille, flow is ____ proportional to the radius

Answer 10

directly

Question 11

According to Poiseuille, flow is INDIRECTLY proportional to ____ and ____

Answer 11

viscosity and length

Question 12

***According to Poiseuille’s law what factor has the greatest impact on the rate of blood flow thru a vessel

Answer 12

Radius to 4th power

Question 13

If radius is doubled, flow increases by how much? Tripled?

Answer 13

16 fold

64 fold

Question 14

What is resistance and can resistance be measured directly?

Answer 14

The impediment to blood flow in a vessel.

NO

Question 15

SVR Formula?

Normal?

Answer 15

SVR= (MAP-CVP) x 80
_________
CO

700-1600

Question 16

PVR Formula?

Normal?

Answer 16

PVR= (MPAP-PCWP) x 80
_________
CO

100-300

Question 17

Blood vessels in series =

Answer 17

R total= R1+R2+R3..

The sum of resistances of each vessel

Question 18

Blood vessels in parallel =

Answer 18

1/R1 + 1/R2 + 1/R3…

Question 19

Flow thru each of the parallel vessels is determined by

Answer 19

the pressure gradient and its own resistance

Question 20

If you add another blood vessel what happens to total vascular resistance

Answer 20

decreases

..d/t increase/widening of pressure gradient?

Question 21

Laminar flow is most related to

Answer 21

Viscosity

Question 22

Turbulent flow is most related to

Answer 22

Density

Question 23

Laminar flow - blood near vessel wall is ___, blood in middle is ___

Answer 23

slow, fast

= parabolic nature

Question 24

What formula predicts laminar vs turbulent?

Values?

Answer 24

Reynolds #
When > 2000, turbulence usually occurs*

<2000- laminar
2000-3000- variable
>3000- turbulent

Question 25

Reynolds number formula

Answer 25

(density x tube diameter x mean velocity) ________________________________ viscosity

Question 26

Increasing hematocrit ____ viscosity

Answer 26

increases | HCT= % of blood that is RBCs

Question 27

Reduced hematocrit causes ___ viscosity, which causes ____ (high or low) turbulence

Answer 27

decreased/ high because viscosity is inversely related to Reynolds number

Question 28

Higher viscosity , ___ Reynolds #

Answer 28

decreases # | = more laminar flow/ less tendency for turbulent flow

Question 29

As blood pressure increases within a vessel.. why does FLOW increase much greater than one would expect?

Answer 29

``` because of DILATION (arterial resistance decreased) and Sympathetic stimulation (increasing pa-pv gradient) ```

Question 30

Flow takes the path of

Answer 30

Least resistance

Question 31

Whats a predictor of when laminar flow becomes turbulent?

Answer 31

Reynolds #

Question 32

What are the 3 factors that affect resistance? Proportional or inversely proportional to resistance?

Answer 32

1) Radius- inversely proportional to 4th power 2) Viscosity- proportional 3) Length- proportional

Question 33

Vessel RESISTANCE is ____ proportional to radius to the 4th power

Answer 33

inversely

Question 34

FLOW is ___ proportional to radius to 4th

Answer 34

directly

Question 35

(Bernoulli) stenosis - Velocity ___ as diameter decreases

Answer 35

increases

Question 36

SVR is primarily determined by

Answer 36

vessel diameters

Question 37

When the volume of flow starts to decrease, arterial resistance ___. because the organ is saying I need ____!

Answer 37

decreases , dilates. volume... (doesn't constrict thinking its a BP problem)

Question 38

Bernoulli Principle: | ______ energy and _______ energy can be interconverted to that total energy remains unchanged

Answer 38

Kinetic energy | pressure energy