Ch 1a + 1b

Question 1

What is pressure?

Answer 1

Driving force behind fluid flow

Question 2

What is required in order for flow to occur?

Answer 2

A pressure difference

Question 3

If the pressure difference is greater, will the flow rate be greater or poorer?

Answer 3

Greater, high pressure causing greater flow

(flow rate + pressure are directly proportional)

Question 4

What is volumetric flow rate in a long straight tube determined by?

Answer 4

Pressure difference (gradient) + resistance to flow (viscosity)

Question 5

If pressure difference increases, what happens to the volumetric flow rate?

Answer 5

It increases (b/c pressure + flow are directly proportional - they increase/decrease together)

Question 6

If flow resistance increases, what happens to volumetric flow rate?

Answer 6

Decreases (b/c is harder for flow to travel)

Question 7

What is the poise/viscosity of blood?

Answer 7

0.035 at 37 degrees C

(5x that of water)

Question 8

What 3 factors affect flow resistance?

Answer 8

-Fluid viscosity/poise
-Tube length
-Tube radius (half of width)

Question 9

If tube length increases, what happens to flow resistance?

Answer 9

It increases, length + resistance are directly proportional to each other

(b/c there is more surface area with a longer vessel for friction to occur, this causes resistance + lower flow rate)

Question 10

What is plug flow a form of?

Answer 10

Laminar flow

Question 11

Is the speed of fluid with plug flow constant or does it vary through the tube/vessel?

Answer 11

Is constant

Question 12

When would plug flow occur?

Answer 12

At entrance/start of a tube or vessel

(ex. when LV pushes blood to ascending AO)

Question 13

How do the streamlines appear with laminar flow?

Answer 13

Straight + parallel to each other (images shows flow going in same direction together)

Question 14

Is laminar flow speed max at the beginning or center of a tube/vessel?

Answer 14

At center

Question 15

Where is laminar flow speed at a minimum at in a tube/vessel?

Answer 15

At tube’s walls

Question 16

What is parabolic flow a form of?

Answer 16

Laminar flow

Question 17

Is the speed of fluid with parabolic flow constant or does it vary through the tube/vessel?

Answer 17

Varies, goes at different speeds

Question 18

Where would we see parabolic flow in a tube/vessel?

Answer 18

In center of vessel, not at entrance like plug flow

Question 19

The average flow speed across a vessel is equal to what?

Answer 19

One half the maximum flow speed (at the center)

Question 20

What is disturbed flow a form of?

Answer 20

Laminar flow

Question 21

What happens to the parallel streamlines with disturbed flow?

Answer 21

Altered from straight line form, no longer parallel

Question 22

When would disturbed flow occur?

Answer 22

-At a stenosis (a narrowed vessel, ex. losing parallel shape due to going over top a hurdle like plaque)
-At a bifurcation

Question 23

Do lanes of fluid still exist in disturbed flow?

Answer 23

Yes still organized, just no longer parallel to each other

Question 24

Is turbulent flow a form of laminar flow?

Answer 24

Nope, it is NOT parallel, very chaotic directions

Question 25

How do the streamlines appear with turbulent flow?

Answer 25

-Random with chaotic varying speeds + directions, flow going all over the place! -No organization to it! Lanes not organized.

Question 26

Is forward net flow still maintained in turbulent flow?

Answer 26

Yes

Question 27

What is the continuity rule?

Answer 27

As a stenosis gets worse (vessel diameter decreases + narrows even more), flow speed will increase to try + maintain flow

Question 28

What happens to flow once a vessel becomes occluded?

Answer 28

No flow present, completely blocked

Question 29

Is blood created or destroyed as it flows through a vessel?

Answer 29

Neither

Question 30

Should volumetric flow rate be constant proximal, within or distal to a stenosis?

Answer 30

Must be constant through all parts!

Question 31

Does flow speed increase or decrease at a stenosis following the continuity rule + what occurs distal to it?

Answer 31

Increases at a stenosis to maintain flow continuity, turbulence can occur distally (chaotic flow)

Question 32

What is the bernoulli effect?

Answer 32

-When pressure drops directly in the MIDDLE of a stenosis to a level less than before or after the stenosis -A reduction in pressure associated with high flow speed at a stenosis

Question 33

What is the rouleaux effect?

Answer 33

-A rouleaux are RBCs stuck together -Can represent diseases, although is typically an incidental finding in healthy adults

Question 34

What is poiseuille's equation?

Answer 34

Volumetric flow rate (Q) = pressure difference (P) / viscosity (n) Under line: anything that increases will decrease flow Above line: anything that increases will increase flow

Question 35

If diameter increases (vessel width), what happens to the flow rate?

Answer 35

Increases (b/c extra width allows more fluid to pass through causes less resistance)

Question 36

If length increases, what happens to the flow rate?

Answer 36

Decreases (b/c more surface area + friction causing more resistance)

Question 37

If viscosity increases, what happens to flow rate?

Answer 37

Decreases (b/c more resistance)