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Cardiovasular System > Control of Cardiac Output > Flashcards

Control of Cardiac Output Flashcards

1
Q

what is afterload

A

the pressure in the wall of the LV during ejection

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2
Q

what is preload

A

the amount the ventricles are stretched during diastole

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3
Q

what is the total peripheral resistance

A

resistance to blood flow

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4
Q

which blood vessels offer the greatest resistance to blood flow

A

arterioles

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5
Q

what happens to arterial and venous pressure if total peripheral pressure decreases

A

arterial pressure decreases but venous pressure increases

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6
Q

what happens to arterial and venous pressure if total peripheral pressure increases

A

arterial pressure increases but venous pressure decreases

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7
Q

what happens to arterial and venous pressure if cardiac output increases

A

arterial pressure increases but venous pressure decreases

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8
Q

what happens to arterial and venous pressure if cardiac output decreases

A

arterial pressure falls but venous pressure rises

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9
Q

true or false; narrowing the arterioles increases blood flow

A

false.

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10
Q

true or false constricting arterioles increases arteriole pressure but decreases venous pressure

A

true

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11
Q

true or false; constricting arterioles increases resistance

A

true

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12
Q

what happens to the arterioles and precapillary sphincters if tissues need more blood

A

they will dilate

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13
Q

what happens to the heart rate if the peripheral resistance falls

A

pumps more so that the arterial pressure doesn’t fall and venous pressure doesn’t rise

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14
Q

what are the 2 mechanisms of how the heart changes to control arterial and venous pressure

A

intrinsic and extrinsic

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15
Q

what is the intrinsic mechanism of heart response

A

where the heart response if due to factors within the heart

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16
Q

what is the extrinsic mechanism of the heart response

A

where the heart responds to factors outside of the CVS e.g. the ANS

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17
Q

what is cardiac output equal to

A

stroke volume x heart rate

18
Q

what is the stroke volume

A

end diastolic volume - end systolic volume

19
Q

what is the end diastolic volume of a normal heart

A

120ml

20
Q

what is the LV pressure of a normal heart at the end diastolic volume

A

10 mmHg

21
Q

what is the normal stroke volume

A

70 ml

22
Q

what does the Frank-Starling Law state

A

as the heart fills more, it contracts harder and so the stroke volume increases

23
Q

what must happen to the venous pressure to allow the heart to fill more

A

it increases

24
Q

what happens to contraction there is too much overlap of filaments in a sarcomere

A

the cell cant contract well

25
Q

what happens when the filaments in a sarcomere are stretched

A

the cell can contract better

26
Q

what happens to calcium sensitivity as cardiac muscle fibres are stretched

A

it increases

27
Q

is the frank starling mechanism an intrinsic or extrinsic control mechanism

A

intrinsic

28
Q

what is the mechanism by which increasing the filling of the heart increases stroke volume

A

Frank-Starling mechanism

29
Q

what does it mean by saying the pulmonary and systemic circulations operate in series

A

same volume of blood pumped to the body must also be pumped to the lungs

30
Q

what is contractility

A

the force of contraction for a given fibre length

31
Q

was do extrinsic mechanisms do

A

increases contractility without increasing fibre length

32
Q

what happens to aortic pressure when peripheral resistance is increased

A

it increases

33
Q

what happens to the filling of the heart when peripheral resistance is increased

A

it decreases as venous pressure is reduced

34
Q

what is cardiac output

A

how much the ventricles empty

35
Q

what does cardiac output depend on

A

how hard the heart contract and how hard it is to eject blood

36
Q

what increases contractility

A

sympathetic drive (extrinsic mechanisms)

37
Q

what happens to the total peripheral pressure when metabolism increases

A

decreases to supply more blood. this causes an increase in venous pressure and decrease in arteriole pressure so the heart responds by pumping more

38
Q

what happens to the TPR when eating

A

decreases as there is vasodilation. this decreases arteriole pressure and increases venous pressure so heart rate increases

39
Q

what happens to venous pressure when you stand

A

it decreases so cardiac output decreases causing arteriole pressure to decrease

40
Q

true or false; pressure changes in the veins and arteries when standing up can be corrected by intrinsic mechanisms

A

false. baroreceptor reflex and the ANS increase heart rate and TPR. if this doesn’t work you get postural hypotension

Cardiovasular System (16 decks)

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