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Flashcards in Control Of Cardiac Output Deck (19)
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1
Q

Define Afterload

A

The load the heat must eject blood against (Equivalent) to aortic pressure

2
Q

Define Preload

A

Amount of blood that fills the ventricles in diastole

3
Q

Define Total Peripheral Resistance

What is it also known as

A

Resistance to blood flow offered by all the systemic vasculature

Systemic vascular resistance

4
Q

Which vessels have the greatest resistance to blood flow

How does resistance affect the pressure of the blood leaving the stenosis

A

Arterioles

More resistance-> Less pressure

5
Q

If Cardiac Output is constant and TPR falls, what is the effect on;

Arterial Pressure
Venous Pressure

A

Arterial pressure- Decreases

Venous pressure- Increases

6
Q

If Cardiac Output is constant and TPR increases, what is the effect on;

Arterial Pressure
Venous Pressure

A

Arterial pressure- Increases

Venous pressure- Decreases

7
Q

If TPR is constant and Cardiac Output increases, what is the effect on;

Arterial Pressure
Venous Pressure

A

Arterial pressure- Increases

Venous pressure- Decreases

8
Q

If TPR is constant and Cardiac Output falls, what is the effect on;

Arterial Pressure
Venous Pressure

A

Arterial pressure- Decreases

Venous pressure- Increases

9
Q

What 2 things does the heart respond to changes in?

Compare the mechanisms by which it does this

A

aterial Blood Pressure, aBP
Central Venous Pressure, CVP

Intrinsic- Due to Myoarcium + Myocardial cells
Extrinsic- Due to Neurohormonal mechanisms

10
Q

How do you calculate Stroke Volume, SV

In what 2 ways, can you increase SV

A

SV= EDV-ESV
(End Diastolic Volume- End Systolic Volume)

Increase EDV OR Decrease ESV

11
Q

When filling ventricles, when do the walls stop stretching?

Explain the Ventricular Compliance Curve relationship

A

When Intraventricular pressure= Venous pressure

Higher venous pressure= Heart fills more
Heart fills more= Higher left ventricle pressure

12
Q

Compare increased and decreased compliance of the heart

A

Increased- Dilated/ Enlarged heart

Decreased- Smaller heart

13
Q

What is the Frank-Starling Law

On a Starling curve,
What is on the Y and X axis

A

The more the heart fills, the harder it contracts, up to a limit, leading to a bigger stroke volume

Y- Stroke volume (ml)
X- LV EDP/ LV EDV

14
Q

Define Contractility

A

The force of contraction for a given fibre length

15
Q

what 2 factors determine Cardiac Output

A
  1. How hard it contracts
    Depends on EDV and Contractility
  2. How hard it is to eject blood
    Depends on Aortic impedance (Arterial Pressure) (Afterload)
16
Q

How does exercise cause increased Cardiac Output

A

Metabolism increases-> TPR Decreases to supply more blood

Arterial pressure falls, venous pressure rises
Heart responds by pumping more

17
Q

Where is the Jugular Venous Pulse measured from?
What angle must patient at, where must they face?
Why from here?

A
  • Right Internal Jugular Vein behind SCM Muscle
  • 45 degrees and facing away
  • A direct column of blood connected to right atrium
18
Q

Which 3 events increase JVP

A
  • Right side of heart doesn’t pump out blood properly
  • Volume overload with IV infusion
  • If filling of heart is impaired
19
Q

What 2 ways can you measure JVP

A
  1. Estimate highest visible pulsations+4cm

2. Insert Central line into Internal Jugular Vein