4 Control of Cardiac Output Flashcards

1
Q

Define afterload.

A

Load heart must eject against

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2
Q

Define preload.

A

Amount ventricles stretched in diastole

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3
Q

Define Total Peripheral Resistance.

A

Resistance to blood flow from all systemic vasculature

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4
Q

What happens to the pressure in the capillaries on the venous side if the arterioles constrict?

A

Pressure falls (on venous side)

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5
Q

What happens to the pressure in the capillaries on the arterial side if the arterioles constrict?

A

Pressure rises (on arterial side)

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6
Q

Fill in the missing gaps (orange) with either increases or decreases.

A
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7
Q

Write out 2 equations which can be used to calculate stroke volume.

(Hint: use CO, SV, EDV, ESV)

A
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8
Q

What is the typical stroke volume for a 70kg man (at rest)?

A

70ml

(About 67% normal EDV)

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9
Q

What causes the ventricles to stop filling?

A

Pressure change

Intraventricular pressure is greater than/equal to venous pressure

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10
Q

What relationship does the ventricular compliance curve show?

A

Relationship between:

  • How much ventricles fill
  • Left ventricular pressure
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11
Q

What is the Frank-Starling law of the heart?

A

More heart fills, harder it contracts

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12
Q

How does the heart contract harder if it is filled more?

A

Increased Ca2+ sensitivity as muscles stretched

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13
Q

What is contractility?

A

Force of contraction for given fibre length

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14
Q

Draw the another line on this graph to show how the curve would change if there was an:

  • Increase in contractility
  • Decrease in contractility
A
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15
Q

Within the body, what causes contractility to increase or decrease?

A
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16
Q

What is Aortic impedence?

A

Pressure heart has to pump against

(sum of factors resisting venticular ejection)

(Same as pressure in aorta)

17
Q

Which part of the peripheral nervous system controls contractility and HR? (somatic or autonomic)

A

Autonomic Nervous System

18
Q

What happens in terms of PNS activity and SNS activity if the body’s blood pressure drops.

A

PNS activity decreases…

…SNS activity increases…

…increase HR and Contractility

19
Q

What causes postural hypotension? (include references to venous and arterial pressure)

A

Pooling of Blood

Venous pressure drops, CO drops, Arterial pressure drops

20
Q

How is cardiac output increased during exercise?

A
21
Q

Why is it useful to measure Jugular Venous Pulse?

A

Direct column of blood connected to right atrium

Central line can be inserted into internal jugular –> allows wave form to be seen

22
Q

What might cause the JVP to increase?

A
  • Right side of heart doesn’t pump blood out properly
  • Vol overload w./ IV infusion
  • Something impairs heart filling eg stab wound (distended neck veins)