
Originally Posted by
andy k
physiology of the heart 101
listen to the heart - it ges "bumpBUMP"
contraction of the heart is caused by the spread of an elecrical pulse across the muscle
normally this electrical pulse starts from the Sino-Atrial Node and spreads across the Atria (upper chambers of the heart.) causing them to contract and push blood from the Atria into the Ventricles.
this is the "bump"
The pulse then passess tthrough a particular point - The Atrio Ventricular Node - from where it causes the Ventricles to contract ( just after they have been filled form the Atria - nicely co-ordinated). Contraction of the ventricles pushes blodd to the body / lungs.
Ventricular contraction is the "BUMP"
passage of the pulse between Atria and Ventricles via The Atrio Ventricular Node maintains co-ordinated contraction across the heart.
An AV - Atrio Ventricular - block is a delay in the passage of the pulse through the AV node. It causes a delay in ventricular contraction
so instead of the normal "bumpBUMP" you get "bump..... wait for it....... BUMP"
AF - Atrial Fibrillation is when the electrical pulse across the Atria is not properly / solely started from the Sino Atrial Node and instead of a co-ordinated contraction pushing blood into the ventricles the Atrium flutters and flaps and the everything gets a bit unco-ordinated
you get "bu, bu, bu, bu BUMP"