How is the heart beat controlled?

Cardiac muscle is myogenic i.e has the ability to contract naturally, without external stimuli, such as action potentials arriving via nerves. For the whole heart to contract in an organised manner, there needs to be a rhythm generator. This is called the sinoatrial node.

The sinoatrial (SA) node generates electric impulses that propagate through the atrial walls via intermodal pathways, towards the atrioventricular node (AV). As they propagate, they depolarise atrial cardiac cells, triggering atrial contraction. Once they reach the AV node, these cells delay passing the electric impulses by 0.12 seconds. Then, the electric impulses are passed over to the Bundle of His, which splits into the Purkinje fibres going down the ventral septum, towards the apex, then up the ventricle walls. The purpose of this innervation is to allow an upwards push of ventricular blood, into the aorta and the pulmonary trunk.

CB
Answered by Cezar B. Biology tutor

2623 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

What is a mutation and what are they caused by?


Give the name and describe the process by which macrophages kill pathogens.


Why does the thickness of the heart's chamber walls vary?


How does a signal move from one neurone to another and how does this process change for different motor responses?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning