Hemodynamics & Vasculature

Question 1

What is transmural pressure?

Answer 1

The difference in pressure between the inside and outside of a vessel

Question 2

The biggest drop in pressure occurs from the __________.

Answer 2

arteries to the arterioles

Question 3

The systemic pressure is much _______ than the pulmonary pressure.

Answer 3

greater

Question 4

Why is the pulmonary pressure less than the systemic pressure?

Answer 4

Because the resistance is much less; this is an important concept, because the cardiac output is equal between the left and right sides

Question 5

Flow is _______ and is determined by ________.

Answer 5

volume/time; cardiac output (because the CV system is a closed loop, the flow at the aorta is equal to the flow throughout all of the capillaries)

Question 6

Velocity is ________ and is given by ______.

Answer 6

distance/time; Q (flow) / A (cross-sectional area)

Question 7

What is the equation for flow?

Answer 7

Q = (difference in pressure) / (total resistance)

Question 8

Flow is ________ the vessel radius.

Answer 8

proportional to the fourth power of (so increasing the radius by double increases the flow by sixteen times)

Question 9

Flow is inversely proportional to __________.

Answer 9

viscosity (primarily determined by hematocrit) and length

Question 10

In a system of parallel vessels, the total resistance is equal to _________.

Answer 10

1 / (sum of the reciprocals of the individual resistances)

Question 11

In a system of parallel vessels, the pressure will be _______ across each, but the flow will _____________.

Answer 11

the same; different due to varying resistances

Question 12

Resistances in series are _________.

Answer 12

additive

Question 13

In laminar flow, the velocity is greatest in the _________.

Answer 13

center

Question 14

What factors induce turbulent flow?

Answer 14

High velocity, low viscosity, damage to endothelium, larger diameters, and abrupt changes in diameter

Question 15

The pulse pressure is given by ________.

Answer 15

systolic pressure minus diastolic pressure

Question 16

What is the mean arterial pressure (MAP)?

Answer 16

diastolic pressure + 1/3 pulse pressure; the equation is set up like this because diastole is longer than systole–but at higher HRs the diastole is shorter and MAP approaches the mean of systole and diastole

Question 17

What is the equation for tension?

Answer 17

T = (transmural pressure x radius) / (wall thickness); this is why an aneurysm can lead to a ruptured vessel–increasing the radius puts more tension (stress) on a vessel.

Question 18

Bulk transport is __________.

Answer 18

the flow multiplied by the concentration of a substance

Question 19

Fick’s principle is _________.

Answer 19

flow multiplied by the change in concentration of a substance; this is used to measure how much of something is used

Question 20

Cardiac output is ___________.

Answer 20

the volume of blood pumped by the heart in a minute

Question 21

Increasing the number of parallel resistances _______ the total resistance.

Answer 21

decreases

Question 22

What is the equation for compliance?

Answer 22

C = (change in volume) / (change in pressure); thus, the more compliant a vessel is, the more it will it will change in volume for a given change in pressure

Question 23

What is fractional oxygen extraction?

Answer 23

E[O2] = (O2a - O2v) / O2a; this gives the percentage of oxygen that was extracted from the artery

Question 24

Using Poiseuille’s equation, we can see that three things determine vasculature resistance in the body: __________.

Answer 24

radii of vessels, viscosity, and length

Question 25

Vessels lose compliance with age, a process called __________.

Answer 25

arteriosclerosis