Cardiac Conduction

Question 1

Sinoatrial Node (SA Node)

Answer 1

The heartbeat originates in the sinoatrial (SA) node in the upper right atrium, the SA node generates electrical impulses that spread through both atria, causing them to contract

Question 2

Atrioventricular Node (AV Node)

Answer 2

The electrical signal reaches the atrioventricular (AV) node, located in the lower right atrium, the AV node delays the electrical signal slightly to allow the atria to contract fully before the ventricles start to contract,

Question 3

Bundle of His (AV Bundle)

Answer 3

After the brief delay at the AV node, the electrical signal travels down the Bundle of His, the Bundle of His divides into two branches, the left and right bundle branches, this part of the conduction system is not visible on the ECG.

Question 4

Purkinje Fibres

Answer 4

The electrical signal spreads rapidly through the Purkinje fibres, specialised muscle fibres in the ventricles, this rapid conduction ensures that the ventricles contract in a coordinated and efficient manner.

Question 5

Ventricular Repolarisation

Answer 5

Repolarisation is the process of returning the heart muscle cells to their resting state after contraction, while depolarisation occurs quickly during the QRS complex, ventricular repolarisation takes a bit longer,

Question 6

Atrial Repolarisation

Answer 6

The atria also repolarise during this time, but the QRS complex on the ECG masks their electrical activity

Question 7

P-Wave

Answer 7

Depolarisation of the atria, starting at the SA node and spreading through both atria.

Question 8

QRS Complex:

Answer 8

Depolarization of the ventricles starts at the Bundle of His and spreads through the Purkinje fibres.

Question 9

T-Wave

Answer 9

Repolarisation of the ventricles.