Cardiac cycle + Heart conduction system

Question 1

What are the different stages of the cardiac cycle?

Answer 1

1. Cardiac diastole.
2. Atrial systole.
3. Ventricular diastole.
4. Atrial diastole.
5. Ventricular systole.

Question 2

What is cardiac diastole?

Answer 2

• All chambers are relaxed.
• Blood flows into the heart.

Question 3

What is atrial systole + ventricular diastole?

Answer 3

• Atria contract.
• Valves are relaxed.
• Ventricles are relaxed allowing blood to be pumped in.

Question 4

What is atrial diastole + ventricular systole?

Answer 4

• The atria will relax.
• Ventricles will contract.
• This pushes blood out of the heart.

Question 5

Describe the 1st stage of the heart conduction system.

Answer 5

• Action potentials originate in the sinoatrial node.
• Travel across the wall of the atrium.
• From the sinoatrial node to the atrioventricular (AV) node.

Question 6

Describe the 2nd stage of the heart conduction system.

Answer 6

• Action potentials pass through the atrioventricular (AV) node.
• Along the atrioventricular (AV) bundle.
• Which extends from the AV node through the fibrous skeleton into the interventricular septum.

Question 7

Describe the third stage of the heart conduction system.

Answer 7

• The AV bundle divides into right + left bundle branches.
• Action potentials descend to the apex of each ventricle along bundle branches.

Question 8

What is the 4th stage of the heart conduction system?

Answer 8

• Action potentials are carried by Purkinje fibres.
• From the bundle branches to the ventricular walls.