Explore how SA-node excitation, the AV-node delay, pressure changes and valve movements shape each stage of the cardiac cycle in IB Biology HL B3.2.16.
Many biological processes are cyclical. Examples of cycles can be found at the level of the cell, the organism and the ecosystem.
Outline the role of the right atrium in the cardiac cycle.
right atrium collects (deoxygenated) blood from the body;
blood drains into atrium through/from the vena cava;
deoxygenated blood present in vena cava/right atrium/right ventricle;
right atrium pumps blood into the right ventricle;
during atrial systole/ventricular diastole/at the start of the cardiac cycle;
sinoatrial node is in the right atrium/sinoatrial node acts as the (natural) pacemaker / sinoatrial node initiates the heartbeat;
SA node sends out electrical signal to stimulate contraction in the (walls of the) atria/then propagated to the AV node / (walls of the) ventricles;