LECTURE 8

Question 1

cardiac cycle definition

Answer 1

A Cardiac cycle is one heart beat

Question 2

systole definition

Answer 2

Systole is contraction. Generally taken to mean ventricular contraction and ejection

Question 3

diastole definition

Answer 3

Systole is contraction. Generally taken to mean ventricular contraction and ejection

Question 4

First heart sound

Answer 4

turbulence caused by closure of the AV valves (happens when the ventricles contract)

Question 5

Second heart sound

Answer 5

turbulence caused by closure of the AV valves (happens when the ventricles contract)

Question 6

3rd and 4th sounds

Answer 6

3rd and 4th sounds from ventricular filling and atrial systole. 4th Sound audible when ventricles are stiff

Question 7

Cardiac cycle 1: Atrial systole

Answer 7

Atria contract, squeezing blood into the ventricles, through the valves.

AV valves open. Pulmonic and Aortic closed

Slight increase in atrial pressures

Question 8

Cardiac cycle: 2. isovolumetric contraction

Answer 8

All valves closed.
Beginning of systole.
Increase in intraventricular pressure from contraction.
Heart shape change but no blood is ejected.
Pushes AV valves closed. First sound

Question 9

Cardiac cycle: 3. rapid ejction

Answer 9

AV valves closed , others open.
When intraventricular P is higher than the aortic and Pulmonary P, the valves open and blood is ejected.
Atria continue to fill.

Question 10

What does sounds during ejection (cardiac cycle) indicate

Answer 10

No heart sounds in healthy patient. Ejection sounds indicate a shunt or valve disease.

Question 11

Cardiac cycle: 4. Reduced ejection

Answer 11

Aortic and pulmonary valves stay open and AV valves stay closed.

No movement of blood

Ventricular muscle relaxation.

Ventricular P decreases slightly but blood still leaves the heart (kinetic energy).

Atrial P increasing as atria continue to fill

Question 12

Cardiac cycle: 5. Isovolumetric relaxation

Answer 12

Valves close ( Heart sound 2).
Aortic first, then pulmonic valve.
Ventricle volume remains the same as valves are closed (dicrotic wave).
Atrial pressure and volume increase from venous return

Question 13

Cardiac cycle: 6. Rapid filling

Answer 13

AV valves open. Aortic and pulmonary valves close.
Ventricular filling. Relaxation phase (still.)
Amount of filling decreases when HR increases.
Atrial P falls
Third sound (not usually audible without specialist equipment)

Question 14

Cardiac cycle: 7. Reduced filling

Answer 14

When filling is nearly finished , ventricles at full stretch so P rises. P in large vessels drops as blood flows into circulation

Question 15

cardiiac output equation

Answer 15

Cardiac = Stroke x Heart
Output Volume Rate

Question 16

regulation of cardiac output

Answer 16

Neural control: physical or emotional stress
Sympathetic nervous system stimulates heart rate (SA node). Up to 100-200%
Parasympathetic nervous system steadies HR
Ion levels:
Calcium: too little: weak. Too much: long contractions
Potassium: involved in muscle contraction and nerve conduction.

Question 17

Regulation of Stroke Volume

Answer 17

The more the heart fills with blood, the more the muscle is stretched

The higher the arterial pressure, the lower the stroke volume