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PHAR20300 > HAEMODYNAMICS > Flashcards

HAEMODYNAMICS Flashcards

1
Q

What is the equation for SV?

A

SV = EDV - ESV

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2
Q

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

A

EDV

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3
Q

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

A

ESV

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4
Q

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

A

False - sympathetic and parasympathetic

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5
Q

What is meant by preload?

A

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

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6
Q

What is meant by afterload?

A

The resistance the left ventricle must overcome to circulate blood

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7
Q

What is cardiac output?

A

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

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8
Q

What is stroke volume?

A

The amount of blood pumped out of the heart per beat

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9
Q

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

A

False - the more energy needed

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10
Q

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

A

True

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11
Q

How can flow resistance be controlled?

A

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

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12
Q

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

A

False - an individual vessel or tube

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13
Q

What two things determine blood viscosity?

A

Haematocrit

Protein content

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14
Q

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

A

True

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15
Q

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

A

More resistance

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16
Q

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

A

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

17
Q

What happens to resistance as diameter of a vessel decreases?

A

Resistance increases

18
Q

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

A

It increases

19
Q

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

A

It decreases

20
Q

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?

A

False - equal to resistance of smallest diameter vessel

21
Q

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

A

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

22
Q

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

A

False - pressure drops but flow is the same

23
Q

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

A

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

24
Q

MAP is greater than CVP. True or false?

A

True

25
Q

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

A

True

26
Q

What is the equation for CO?

A

CO = MAP / TPR

27
Q

What is meant by compliance, in relation to vessels?

A

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

28
Q

Arteries have high compliance. True or false?

A

False - they have a thick muscular wall and low compliance

29
Q

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

A

High as they are very stretchable

30
Q

What is meant by critical closing pressure?

A

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

31
Q

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

A

False - systemic veins do

32
Q

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

A

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

33
Q

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

A

False - increases preload, without affecting afterload

34
Q

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

A

False - increases

35
Q

Vasoconstriction of large veins increases EDV. True or false?

A

True

36
Q

Does vasoconstriction of large veins increase or decrease stroke volume?

A

Increase

37
Q

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

A

False - veins are large

PHAR20300 (25 decks)

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