Hemodynamics

Question 1

Stressed vs unstressed volume

Answer 1

Arteries contain stressed volume and veins contain unstressed volume.

Question 2

What contains the most area of blood? The most volume?

Answer 2

Area - capillaries

Volume - veins

Question 3

Sympathetic activation of veins occurs via

Answer 3

Alpha 1 adrenergic receptors

Question 4

v =

Answer 4

Q/A

Flow/area

Question 5

Resistance =

Answer 5

(8nl)/(pi x r^4)

Question 6

Series resistance

Parallel resistance

Answer 6

Series - sum of individual resistances.

Parallel - sum of the reciprocals.

Question 7

Laminar flow

Answer 7

Streamlined flow where velocity is greatest at center and least at vessel walls.

Question 8

Turbulent flow

Answer 8

A disruption of laminar flow and takes more energy to drive turbulent flow forward.

Question 9

Bruit

Answer 9

When turbulent flow occurs in an artery and may indicate stenosis.

Question 10

What is the Reynolds number?

Answer 10

Used to predict whether flow will turbulent or laminar.

Less than 2000 indicates laminar flow.

Question 11

Shear

Answer 11

Changes in the velocity along the vessel. If all areas of the vessel had the same velocity, shear would be zero.

Question 12

Compliance of vessels

Answer 12

Ability to recoil.
Highest in veins.
Will decrease as patients age.

Question 13

Pulse pressure

Answer 13

SBP-DBP

Volume of blood ejected from the LV.

Question 14

MAP =

Answer 14

2/3(DBP) + 1/3(DBP)

Question 15

Arteriosclerosis causes what effects on SBP, pulse pressure and MAP?

Answer 15

Increases SBP, pulse pressure and MAP.

Question 16

Aortic stenosis causes what effects on SBP, pulse pressure and MAP?

Answer 16

All will decrease.

Question 17

Microcirculation

Answer 17

Capillaries.

Occurs via simple diffusion.

Question 18

Starling equation

Answer 18

Jv = Kf [(Pc-Pi) - (pi.c - pi.i)]
If positive, favors movement from the capillary.
If negative, favors movement into capillary.

Question 19

Kf

Answer 19

Hydrostatic conductance

Question 20

What factors favor filtration?

Answer 20

Capillary hydrostatic pressure (Pc)

Capillary interstitial pressure (pi.i)

Question 21

What factors oppose filtration?

Answer 21

Interstitial hydrostatic pressure (Pi)

Capillary oncotic pressure (pi.c)

Question 22

How can Kf be increased?

Answer 22

Burns, inflammation.

Question 23

Autoregulation

Answer 23

Maintaining constant blood flow during changes in pressure.

Question 24

Active hyperemia

Answer 24

Blood flow to an organ is proportional to its metabolic activity.

Question 25

Reactive hyperemia

Answer 25

Increased blood flow as a result of a period of decreased blood flow.

Question 26

Myogenic hypothesis

Answer 26

If smooth muscle is stretched, it will contract, and there will be an increase in arterial pressure.
Tries to explain autoregulation.

Question 27

Metabolic hypothesis

Answer 27

O2 delivery is matched to O2 consumption.

So if O2 consumption is high, metabolites will be released to cause vasodilation.

Question 28

JVD

Answer 28

Reflects the activity of the right heart.
Gives an indication of CVP and RAP.
Internal jugular is better to use than external jugular.

Question 29

What is the most common cause of JVD?

Answer 29

Elevated RV diastolic pressure.

Question 30

How to measure JVD?

Answer 30

Place patient in supine position and allow veins to engorge. Then raise to 30-45 degrees.
Normally will be between 0-9.

Question 31

Hepato Jugular Reflex

Answer 31

Distension of veins when pressure is placed over the liver.

Could indicate RV pathology, pericarditis.

Question 32

Edema grading

Answer 32

0 - 0 mm
1 - 2 mm (nonpitting)
2 - 4 mm
3 - 6 mm
4 - 8 mm