Unit4- 1.5~ Control and regulation of cardiac cycle

Question 1

What is the cardiac cycle?

Answer 1

Referes to a complete heartbeat that includes diastole (Heart is in a state of relaxation and fills with blood), systole (heart chambers contract and pump blood) and the intervening pause.

Question 2

What is the location of the sinuatrial node (SA node)?

Answer 2

Located near the opening of the superior vena cava on the superior lateral wall of the right atrium

Question 3

What is the role of the SA node?

Answer 3

• Can contract faster than any other tissue, it sets the pace of cardiac contractions, referred as the pacemaker of the heart
• Its able to spread its impulse to the rest of the right & left atria

Question 4

What is the location of the atrioventricular node AV node?

Answer 4

Located medial and posterior to the tricuspid valve

Question 5

What is the role of the AV node?

Answer 5

Cells are slower than SA nodes, and act as a response to activity from the SA node

Question 6

Explain purkinje fibres in the cardiac cycle.

Answer 6

• The AV node is connected to a network of fibres that runs in the walls of ventricles, pathway called the bundle of His
• The bundle of his goes into the left & right bundle branches which carry impulses
• Both branches give off numerous brancehes known as purkinje fibres that supply the ventricular myocardium.