Lecture #3 (cardiac cycle table)

What is phase 1?

Atrial Systole

What occurs during phase 1?

- Atria contracts

- Atrial pressure rises higher than Ventricular pressure so AV valves open

- Blood pushed into ventricles

AV and SL valves during phase 1?

AV - open

SL - closed

What is phase 2a?

Ventricular systole - Isovolumetric contraction

What occurs during phase 2a?

• Ventricles BEGIN contracting

• Ventricular pressure rises above Atrial P so AV valves close (lubb)

• Both AV and SL valves are closed so no blood enters or leaves ventricles

AV and SL valves during phase 2a?

AV - closed (lubb)

SL - closed

What is phase 2b?

Ventricular systole - ventricular ejection

What occurs during phase 2b?

• Ventricles continue contracting

• Ventricular pressure rises above Arterial pressure so SL valves open

• Blood is pumped out

AV and SL valves during phase 2b?

AV - closed

SL - open

What is phase 3a?

Ventricular diastole - isovolumetric relaxation

What's occurs in phase 3a?

• Ventricles BEGIN relaxing

• Ventricular pressure falls below Arterial pressure so SL valves close (dubb)

• Both AV and SL valves are closed so no blood enters or leaves ventricles

AV and SL valves during phase 3a?

AV - closed

SL - closed (dubb)

What is phase 3b?

Ventricular diastole - passive ventricular filling

What occurs during phase 3b?

• Ventricles continue relaxing

• Ventricular pressure falls below Atrial pressure and AV valves open

• Blood starts passively filling the ventricles

AV and SL valves during phase 3b?

AV - open

SL - closed