20 terms

Chapter 48 - The Cardiac Cycle - Review

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cardiac cycle
includes all of the events occurring in the heart during one single heartbeat
systole and diastole
each chamber of the heart goes through these two phases during the cardiac cycle
systole
is when both the atria and ventricles contract and empty of blood
diastoleis
the relaxation phase of the heart during which the chambers are refilling with blood
electrocardiograph
records both the intensity and the actual time it takes for each part of the cardiac cycle to occur
EKG measures
electrical conductive impulses of the heart muscle and allows physicians to see any disturbances or disruptions in normal heart activity
sinoatrial (SA) node
is the main part of the system that specialized electrical conduction system of the hear initiates each heartbeat
60 to 100 times per minute
the SA node controls the rate of the heart contraction by initiating electrical impulses up to
contraction almost simultaneously
each cardiac cycle or heartbeat starts with the SA node generating an electrical impulse that travels in a wavelike pattern across the cardiac muscle of the atria causing the muscles to
atrioventricular (AV) node
the SA node stimulates this electrical impulse of the ___________ which is located in the posterior, superior portion of the right atrial septal wall, at this point allows the atria to empty completely
bundle of His
the electrical impulse is then transmitted to a special group of conduction fibers which are located in the upper part of the interventricular septal wall
right bundle branch
carries impulses to the right ventricle
left bundle branch
carries impulses to the left ventricle
purkinje fibers
the right and left bundle of branches divide into smaller and smaller branches, ending in the ____________ which spread across the apex of the heart and through the myocardium, stimulating ventricular contraction
ventricles contract
in a twisting sort of action, forcing the blood out of the chambers and into the pulmonary artery on the right side of the heart and the aorta on the left side of the heart
normal sinus rhythm (NSR)
refers to a regular heart rate that falls within the average range of 60 to 80 beats per minute (beats/min)
sinus bradycardia
referrers to a heart rate less than 60 beats/min
sinus tackycardia
referrers to a heart rate greater than 100 beats/min
pathologic
in both sinus bradycardia and tackycardia the heart rhythm remains even but the rate is
arrhythmia
an irregular cardiac rhythm, in which certain conditions interrupt the conduction pathway, SA node to the AV node to bundle of His to right and left bundle branches