A&P chpt 15 the heart part 2

specialized cells in the cardiac muscle that generate action potentials to stimulate contraction

• pacemaker cells

• Neurons

• Intercalated discs

• Gap junctions

The heart's primary pacemaker, where normal cardiac impulses arise

• sinoatrial node

• The lungs

• The brain

fibers that conduct impulses to the left atrium and both atria begin to contract

• interatrial bundle

• Ventricular bundle

• Atrioventricular node

• Sympathetic nerves

group of pacemaker cells in the interatrial septum that relays impulses from the atria to the ventricles

• atrioventricular node (AV)

• Bundle of His

• Sinoatrial node

• Purkinje fibers

Nerve like processes that extend from the bundle branches to the ventricular myocardium; for the last part of the cardiac conduction

• purkinje fibers

• Cardiac muscle fibers

• Cardiac pacemaker cells

• Atrioventricular node

Match the following firing rates with the heart's pacemakers

• AV node

• 40-60 BPM

• Purkinje fibers

• 60-80 BPM

• SA node

• 20-40 BPM

record of the electrical currents in the heart

• Electrocardiogram (ECG)

• Ultrasound

• Magnetic Resonance Imaging (MRI)

• X-ray

On an electrocardiogram, the QRS complex represents

• atrial depolarization

• ventricular depolarization

• ventricular repolarization

• impulse transmission from the atria to the ventricles

Match the following terms

• P wave

• end of ventricular depolarization and beginning of ventricular repolarization

• T wave

• ventricular depolarization

• ST segment

• time it takes for the cardiac impulse to travel from the atria to the ventricles

• PR interval

• atrial depolarization

• QRS complex

• ventricular repolarization

Match the following arrhythmias

• atrial flutter

• when an ectopic focus in the atria fires rapidly, causing the atria to contract between 200-400 times per minute

• in atrial fibrillation

• atria quiver instead of contract. this allows blood to pool in the atria, leading to the potential of blood clots

• ventricular fibrillation

• life threatening emergency resulting for electrical signals arising from different regions of the myocardium