During the cardiac cycle , there is a delay between the excitation of the atria and excitation of the ventricles. Explain how this is achieved and why this delay is essential.

Excitation from SAN (sino-atrial node) spreads across atria, causing them to contract first. The excitation is conducted to the AV (atrio-ventricular) node, which introduces a 0.12s delay. This refractory period allows the atria to fully contract, allowing the blood into the ventricles before the ventricles contract.

JE
Answered by Jane E. Biology tutor

13740 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Explain why maltose can only be broken down by the enzyme maltase.


Write 0.24242424... as a fraction in its lowest terms, show all your working


What is ATP and what makes it a good source of energy in biological processes?


what is water potential?


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