Cardiac Conduction System Flashcards
Cardiac conduction system:
> A network of nodes, cells, and signals that control your heartbeat
3 layers of the heart:
1) Pericardium (outer layer)
2) Myocardium (second layer)
3) Endocardium (inner layer)
Myocardium:
> Middle, muscle layer (thick and large)
Facilitates contraction and relaxation of the heart walls to receive and pump blood
A cardiac impulse is transmitted throughout - activating all muscle tissue (myogenic)
The septum is myocardial tissue which divides the heart into its double pump
Atria:
Top chambers of the heart - receive blood from the lungs and body
Ventricles:
Bottom chambers of the heart - pumps blood to lungs or body
Atrioventricular valves: (Bicuspid and Tricuspid)
Control blood flow from the atria to ventricles
Semi-lunar valves: (Aortic and Pulmonary)
Prevent back flow of blood into ventricles
Septum:
The muscular wall that separates the sides of the heart
Aorta:
Main artery of the system - transport oxygenated blood to the body
Vena Cava:
Main vein of the system - transports deoxygenated blood to the heart
Pulmonary artery:
Specialised artery - carries deoxygenated blood from the right atrium to the lungs
Pulmonary vein:
Specialised vein - carries oxygenated blood from the lungs to the left atrium
Sinoatrial Node: (SA)
Pacemaker of the heart, generates electrical impulses
Atrioventricular Node: (AV)
Distributes nerve signals from the SA node, delaying age contractions between the atria and ventricles
Bundle of HIS:
Carries the electrical signals from the AV node to the septum, the walls of the heart, and the purkinjie fibres
Purkinjie Fibres:
A network of fibres that receive conductive signals from the AV node, which then activates the ventricles causing them to contract and eject blood
Conduction system (5 steps):
1) The cardiac impulse originates at the SA node
2) The impulse travels down the atrial myocardium to the AV node
3) The impulse spreads to the bundle of HIS
4) The bundle connects the AV node to the septum via purkinjie fibres
5) The purkinjie fibres are connected to cardiac muscle fibres - the ventricles contract (systole)
