H
the middle cavity of the thoracic cavity where the heart is located
mediastinum
upper chambers that receive blood
atria
lower chambers that discharge blood
ventricles
serous membrane that surrounds the heart; also called the pericardial sac
pericardium
electrical system of the heart that sets the basic rhythm; composed of SA node, AV node, bundle of His, R/L bundle branches, and Purkinje fibers
intrinsic conduction system
blood vessels that supply and drain the myocardium of the heart
coronary circulation
superior end of the heart that points toward the right shoulder
base
inferior end of the heart that points toward the left hip and rests on the diaphragm
apex
includes all the events in heartbeat which includes the contraction and relaxation of both atria and ventricles
cardiac cycle
blood flow from the heart to the lungs and back to the heart
pulmonary circulation
starts each heartbeat; also called the pacemaker
sinoatrial node
valves that control the flow of blood between the ventricles and the large vessels that exit the heart
semilunar valves
a recording of the flow of electrical impulses that travel through the heart
electrocardiogram
tendinous cords that anchor the AV valves to prevent them from blowing back up into the atria during ventricular contraction
chordae tendineae
thin-walled vessel that carries blood toward the heart; large veins have valves to prevent backflow
vein
refers to contraction of the ventricles
systole
refers to relaxation of the ventricles
diastole
blood flow from the heart to the body and back to the heart
systemic circulation
rapid heart rate; over 100 bpm
tachycardia
valves that control the flow of blood between the atria and ventricles
atrioventricular valves
tiny vessel that allows for diffusion of substances between the blood and cells
capillary
slow heart rate; fewer than 60 bpm
bradycardia
layer of the heart wall that lines the heart chambers
endocardium
thick muscular layer of the heart wall that contracts
myocardium
the amount of blood pumped out by each ventricle in one minute; heart rate x stroke volume
cardiac output