Haemodynamics

Question 1

What is the equation for SV?

Answer 1

SV = EDV - ESV

Question 2

Central venous pressure affects the passive filling of the ventricles and hence EDV or ESV?

Answer 2

EDV

Question 3

Aortic pressure affects the ejection of blood from the left ventricle and hence EDV or ESV?

Answer 3

ESV

Question 4

HR is only influenced by the sympathetic system. True or false?

Answer 4

False - sympathetic and parasympathetic

Question 5

What is meant by preload?

Answer 5

The volume of blood in the ventricle after diastole (EDV) - the stretch of the ventricular muscle

Question 6

What is meant by afterload?

Answer 6

The resistance the left ventricle must overcome to circulate blood

Question 7

What is cardiac output?

Answer 7

The amount of blood pumped out of the heart in a minute

Question 8

What is stroke volume?

Answer 8

The amount of blood pumped out of the heart per beat

Question 9

The greater the afterload, the less energy needed for ventricular contraction. True or false?

Answer 9

False - the more energy needed

Question 10

Arterial pressure is directly proportional to flow resistance of the vascular network. True or false?

Answer 10

True

Question 11

How can flow resistance be controlled?

Answer 11

By changes in vessel diameter - i.e. constriction/relaxation

Question 12

Poiseuille’s law describes flow resistance in an entire branch. True or false?

Answer 12

False - an individual vessel or tube

Question 13

What two things determine blood viscosity?

Answer 13

Haematocrit

Protein content

Question 14

As protein content and haematocrit levels in blood increase, viscosity increases. True or false?

Answer 14

True

Question 15

Do longer vessels have more or less resistance than shorter ones?

Answer 15

More resistance

Question 16

Changes in vascular resistance are rarely due to changes in vessel length. Why?

Answer 16

Because vessel length doesn’t change - only when a person grows

Question 17

What happens to resistance as diameter of a vessel decreases?

Answer 17

Resistance increases

Question 18

As the number of vessels in series with each other increases, what happens to resistance?

Answer 18

It increases

Question 19

As the number of vessels within a section (parallel) increases, what happens to resistance?

Answer 19

It decreases

Question 20

When flow is sequential, i.e. from one vessel to the next, the total resistance is approx. equal to the total resistance of the biggest diameter vessel. True or false?

Answer 20

False - equal to resistance of smallest diameter vessel

Question 21

What is resistance equal to when the flow is distributed to vessels of similar diameter in parallel?

Answer 21

total resistance of a single vessel divided by the number of vessels

Question 22

In a branching network, both the flow and pressure drop through each section. True or false?

Answer 22

False - pressure drops but flow is the same

Question 23

Why are arterioles the critical section of circulation for determining TPR?

Answer 23

Because they have a small diameter and small number relative to capillaries so they exert greatest resistance
They are the smallest diameter vessel lined by smooth muscle

Question 24

MAP is greater than CVP. True or false?

Answer 24

True

Question 25

The difference between MAP and CVP is the pressure gradient that drives blood through the systemic circuit. True or false?

Answer 25

True

Question 26

What is the equation for CO?

Answer 26

CO = MAP / TPR

Question 27

What is meant by compliance, in relation to vessels?

Answer 27

Measure of the ability of blood vessels to stretch as the pressure inside them rises

Question 28

Arteries have high compliance. True or false?

Answer 28

False - they have a thick muscular wall and low compliance

Question 29

Veins have a thin muscle wall. Does this mean compliance will be high or low?

Answer 29

High as they are very stretchable

Question 30

What is meant by critical closing pressure?

Answer 30

When arterial pressure falls below 20mmHg, tension in the artery wall collapses the vessel and flow shuts down

Question 31

In a person at rest, the systemic arteries contain the most amount of blood. True or false?

Answer 31

False - systemic veins do

Question 32

A pharmacological agent that selectively constricts arteriolar smooth muscle increases both afterload and preload. True or false?

Answer 32

False - increases afterload without affecting preload. (constriction increases resistance to flow)

Question 33

A pharmacological agent that selectively constricts venous smooth muscle increases afterload without affecting preload. True or false?

Answer 33

False - increases preload, without affecting afterload

Question 34

Vasoconstriction in large veins decreases venous return pressure in ventricles (preload). True or false?

Answer 34

False - increases

Question 35

Vasoconstriction of large veins increases EDV. True or false?

Answer 35

True

Question 36

Does vasoconstriction of large veins increase or decrease stroke volume?

Answer 36

Increase

Question 37

Constriction of veins has a huge effect on flow resistance. True or false?

Answer 37

False - veins are large