control of heart rate Flashcards Preview

SHHS - Science - NEW AQA A-Level Biology (Year 2) > control of heart rate > Flashcards

Flashcards in control of heart rate Deck (4)
Loading flashcards...

Describe how a heartbeat is initiated and coordinated.

1. SAN sends wave of electrical activity causing atrial contraction.

2. Non-conducting tissue prevents immediate contraction of ventricles / prevents impulses reaching the ventricles;

3. AVN delays (impulse) whilst blood leaves atria / ventricles fill;

4. (AVN) sends wave of electrical activity / impulses down Bundle of His;

5. Causing ventricles to contract from base up;


The sinoatrial node (SAN) is in the right atrium of the heart. Describe the role of the sinoatrial node.

Sends out electrical activity / impulses;
Initiates the heartbeat / acts as a pacemaker / (stimulates) contraction of atria;


When a wave of electrical activity reaches the AVN, there is a short delay before a new wave leaves the AVN. Explain the importance of this short delay.

Allow atria to empty / contract / ventricles to fill;

Before ventricles contract;


Exercise increases HR, describe the role of receptors in controlling heart rate

Chemoreceptors detect a change in CO2

impusles sent to medulla/cardiac centre

more impulses to SAN

by sympathethic nerve