ecg lab quiz

what is the cardiac conduction system composed of?

specialized, noncontractile cardiac cells

what is the function of the cardiac conduction system?

transmit action potentials throughout the heart to promote coordinated, sequential heart muscle contractions

what is is responsible for travel of action potentials?

depolarization

what is depolarization caused by?

the influx of Ca2+ ions, which reverses membrane potential

what do action potentials trigger?

contractions

what is the pacemaker of the heart?

sinoatrial (SA) node

what is the gatekeeper of the heart?

atrioventricular (AV) node

what does the SA node do?

spreads depolarizing stimulus through both atria

what prevents impulses from passing directly into the ventricles?

insulating fibrous skeleton

what does the AV node do?

delays the action potential, ensuring the atria are completely contracted before ventricular contraction begins

what does the AV/Bundle of His do?

connect the atria to the ventricles

what do the left and right bundle branches do?

conduct action potentials through the interventricular septum

what are the Purkinji fibers also called?

subendocardial conducting network

what is happening during the p wave?

atrial depolarization

what is happening at the pr segment?

delay at AV node

what is happening at the qrs complex?

ventricular depolarization and atrial repolarization

what is happening at the st segment?

the ventricles are continuing to contract and empty

what is happening at the t wave?

ventricular repolarization

what is happening at the tp segment?

the ventricles are relaxing and filling

t/f: one waveform = one heartbeat.

true

bradycardia

slow heart rate

tracycardia

rapid heart rate

atrial fibrillation

rapid, random, ineffective contractions of the atrium

ventricular fibrillation

disorganized, ineffective twitching of the ventricles, resulting in no blood flow and a state of cardiac arrest

what do baroreceptors respond to?

changes in blood pressure

what do chemoreceptors respond to?

concentration of chemicals (O2, CO2, and pH)

what is the cardioinhibitory center stimulated by?

increase in BP, increase in O2, decrease in CO2, and increase in pH

what is the cardioacceleratory center stimulated by?

decrease in BP, decrease in O2, increase in CO2, and decrease in pH

what does the cardioinhibitory center do?

slow HR

what does the cardioacceleratory center do?

increase HR