Cardiac cycle

Question 1

Why does the sinoatrial node delay signal slightly?

Answer 1

Delays electrical signal slightly to allow the ventricles to fill before passing it to the apex of the ventricles down the bundles of His which then leads to ventricular contraction.

Question 2

Why does the AV node conduct slower as stimulation increases?

Answer 2

• Allows time for ventricles to fill
• Prevents rapid conduction to ventricle in cases of atrial flutter/fibrillation

Question 3

Why does the AV node also have pacemaker potential?

Answer 3

So the ventricles can still pump blood even when there is damage or loss of the conduction system upstream of the AV node.

Question 4

Depolarisation=

Answer 4

Membrane potential becomes more positive

Question 5

Repolarisation=

Answer 5

Membrane potential becomes more negative