semilunar valve that prevents backflow of blood from aorta to heart
apex
rounded tip of heart, pointing left and downward
atrial appendage
ear-shaped continuation of left and right upper part of atria
atrioventricular node (AV node)
located in right atrium near lower portion of interatrial septum and composed of small mass of atypial cardiac muscle tissue
atrioventricular valves
valves betwee atria and ventricles of heart (left valve is bicuspid or mitral valve and right valve is tricuspid in some species)
atrium
left or right upper chamber of heart
bundle of His (atrioventricular bundle)
band of specialized cardiac muscle fibers that arise in atrioventricular node and branch down on both sides of interventricular septum, transmitting atrial contraction rhythm to ventricles
chordae tendineae
tendinous strings resembling cords that extend from cusps of atrioventricular valves to papillary muscles of heart
conus arteriousus (infundibulum of the heart)
upper, anterior angle of right ventricle where pulmonary artery begins
cor
heart
coronary arteries and veins
blood vessels of the heart
cusp
leafletlike segment of cardiac valve
diastole
relaxation stage of heart action
ductus arteriosus
blood vessel present in fetal circulation that connects pulmonary artery to descending aorta
endocardium
endothelial membrane lining chambers of heart
epicardium
outermost serous layer covering heart
foramen ovale
opening between atria in fetal heart, normally closed after birth
interventricular
between ventricles
myocardium
thick middle muscle layer of heart wall
pacemaker
sinoatrial node, which initiates heartbeat and regulates its rate
pericardium
external layer of membrane covering heart
pulmonary valve
valve at base of pulmonary artery (semilunar valve)
Purkinje fibers
specialized cardiac muscle fibers that are involved in impulse-conducting system of heart
semilunar valves
the half-moon-shaped valves at base of pulmonary artery and aorta
sinoatrial node
initiates heartbeat and regulates its rate (pacemaker)
systole
contraction stage of heart action
valves
membranous structures in passages that close to prevent reflux of contents