oxygen
gas that enters the blood through the lungs
capillary
smallest blood vessel
diastole
relaxation phase of the heartbeat
atrium
upper chamber of the heart
carbon dioxide
gas released by body cells; travels via blood to the lungs where it is exhaled
arteriole
small artery
endocardium
inner lining of the heart
atrioventricular bundle
specialized muscle fibers connecting the upper and lower heart chambers; bundle of His
systole
contraction phase of the heartbeat
aorta
largest artery in the body
artery
largest type of blood vessel
atrioventricular node
specialized tissue in the wall between the atria
pericardium
double-layered membrane surrounding the heart
pulmonary artery
artery carrying oxygen-poor blood from the heart to the lungs
pacemaker
specialized nervous tissue in the right atrium that beings the heartbeat
septum
partition or wall dividing a cavity
sinoatrial node
pacemaker of the heart
sphygmomanometer
instrument to measure blood pressure
coronary arteries
blood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle
systemic circulation
flow of blood from body tissue to the heart and then from the heart back to the body tissues
systole
contraction phase of the heartbeat
deoxygenated blood
blood that is oxygen-poor
diastole
relaxtion phase of the heartbeat
electrocardiogram
record of the electricity flowing through the heart
vena cava
longest vein in the body. The superior and inferior venae cavae return blood to the right atrium of the heart
tricuspid valve
located between the right atrium and the right ventricle
valve
structure in veins or in the heart that temporarily closes an opening so that blood flows in only one direction
murmur
abnormal heart sound caused by improper closure of the heart valves
myocardium
muscular, middle layer of the heart
normal sinus rhythm
heart rhythm originating in the sinoatrial node with a resting rate of 60 to 100 beats per minute
endocardium
inner lining of the heart
endothelium
innermost lining of the blood vessels
mitral valve
valve between the left atrium and the left ventricle
vein
thin-walled vessel that carries blood from body tissues and lungs back to the heart
venule
small vein
ventricle
lower chambers of the heart
pulmonary vein
vessels carrying oxygeneratede blood from the lungs to the left atrium of the heart
pulse
beat of the heart as felt through the walls of the arteries
pulmonary circulation
flow of blood from the heart to the lungs and back to the heart
pulmonary valve
valve positioned between the right ventricle and the pulmonary artery