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Cardiovascular System > The heart as a Pump > Flashcards

The heart as a Pump Flashcards

1
Q

Systole

A

Chamber contracts and ejects blood

~0.3s

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2
Q

Diastole

A

Relaxation Phase

~0.5s
*when HR increases, diastole is most affected.

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3
Q

Specific sequence of events

A 
Atrial Systole
Isovolumic contraction
Rapid Ejection
Reduced Ejection
Isovolumic relaxation
Rapid Filling
Reduced filling
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4
Q

Atrial Systole

A

Soon after the start of the “P” wave; Atrial Depolarization

  • top-up ventricles by contracting, completes filling
  • Responsible for small increase in A/V pressure and venous volume.
  • ‘a’ wave
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5
Q

When is atrial contraction really necessary?

A

-Contraction not usually necessary as much filling is passive. But at high HR, extra boost is important

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6
Q

Isovolumic Contraction

A
  • Phase between the start of ventricular systole and the opening of the Semilunar valves
  • Onset coincides with R-wave peak
  • Volume constant but Pressure steeply rises
  • c-wave
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7
Q

Rapid Ejection

A

Semilunar (aortic and pulmonary) valves open

  • Rapid increase in aortic flow
  • Rapid drop in LV volume
  • Atrial pressure drops; base moves towards apex and stretches atria
  • Sharp increase in LV and Aortic pressure
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8
Q

Reduced Ejection

A

-Runoff from aorta to periphery exceeds LV output> aortic P drops > aortic flow drops

  • Aortic pressure just > LV pressure
  • Forward momentum continues ejection
  • Atrial pressure rising (filling from veins)
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9
Q

How much blood is ejected from LV

A

55%-75%

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10
Q

ESV?

A

~60mL

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11
Q

Isovolumic Relaxation

A
  • Aortic valve closes due to Pressure-Gradient Reversal. Semilunar also closed
  • Incisura
  • 2nd heart sound
  • Rapid fall in LV pressure, no change volume
  • Aortic Pressure remains high
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12
Q

Incisura/dicrotic notch

A

Small notch of aortic pressure during isovolumic relaxation
-coincides with SL valve closure, as the blood reversal occurs and blood tries to flow back into the LV, there is a increase in Aortic presure due to the elastic recoil of the artery

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13
Q

Rapid FIlling

A

Major part of V filling
LV rapid increase in LV volume, as blood flows from the atria > ventricles
V pressure is still dropping

3rd Heart sound sometimes heard

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14
Q

Slow filling

A

Diastasis

  • Equalised pressures, slow rise in A and V and venous pressures, and ventricular volume
  • Blood returns from peripheral veins > RV and blood from lungs > LV
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15
Q

What are heart sounds?

A

Due to turbulence cause by valves closing

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16
Q

1st heart sound

A

Due to AV valves closing. During begining ofisovolumic contraction, rapid P development, opening of semilunar valves and outflow

17
Q

2nd Heart sound

A

Due to semilunar valves closing/tensing > resulting vibrations. During Isovolumic relaxation.

18
Q

Heart Vibrations

A

Very low frequencies, amplitudes and durations
30-250Hz

Heard via auscultation

19
Q

Venous pulse/pressure Waves: “a” wave”

A

Retrograde pressure pulse in jugular when atria contract

20
Q

Venous pulse/pressure Waves: “c” wave”

A

during early phase of ventricular systole

21
Q

Venous pulse/pressure Waves: “v” wave”

A

gradual pressure increase during reduced ejection and isovolumic relaxation

22
Q

How to the RV and LV pressures differ

A

RV pressures are similar to LV, just slightly lower, same with atrial pressures. Also a slight difference in timing.

Same venous pulses

This is due to pulmonary circulation having a lower resistance

23
Q

Abnormal Heart Sounds:

A

Regurgitation: Blood leaks back through valve in the wrong direction

Mitral Valve prolapse: mitral valve has “floppy” flaps and doesn’t close tightly. Sometimes causes regurgitation

Stenosis: Valves doesn’t open enough restricting blood flow

24
Q

Cardiac catherterization

A

Long thin flexible tube is put in blood vessel in arm, groin or neck and threaded to your heart. Saline filled. Far less invasive

25
Q

Swan Ganz catheter

A

Way to measure Left atrial P

through SVC> RA> RV>pulmonary artery, which is between R heart and left atrial pressure.
Balloon at tip, can be inflated, pressure sensore at the tip
Balloon inflated: pressure after (left arterial P) can be measured! “a, c and v” waves

26
Q

Thermodilation: measure CO

A

Cold saline released in right atria, tip (at pulmonary artery) measure temp change and pressure change is measured.

Better then diodilution as less toxic/invasive

27
Q

TPR looks at

whereas PVR looks at

A

total resistance of systemic circulation to flow

total resistance of pulmonary circulation to flow

Cardiovascular System (34 decks)

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