cardiovascular system
The body system that consists of the heart, blood vessels, and blood;
also called the circulatory system.
heart
A hollow, muscular organ that pumps blood throughout the body
atrium
Each of the two upper chambers of the heart that receives blood that
comes into the heart.
pacemaker
A group of cells located in the right atrium that sends out signals
that make the heart muscle contract and that regulates heart rate.
ventricle
A lower chamber of the heart that pumps blood out to the lungs and body.
valve
A flap of tissue in the heart or a vein that prevents blood from
flowing backward.
capillary
A tiny blood vessel where substances are exchanged between the blood
and the body cells.
aorta
The largest artery in the body; receives blood from the left ventricle.
coronary artery
An artery that supplies blood to the heart itself.
vein
An artery that supplies blood to the heart itself.
pulse
The alternating expansion and relaxation of an artery wall as blood
travels through an artery.
diffusion
The process by which molecules move from an area of higher
concentration to an area of lower concentration.
blood pressure
The pressure that is exerted by the blood against the walls of blood vessels.
plasma
The liquid part of blood
red blood cell
A cell in the blood that takes up oxygen in the lungs and delivers it
to cells elsewhere in the body.
hemoglobin
An iron-containing protein that binds chemically to oxygen molecules;
makes up most of red blood cells.
white blood cell
A blood cell that fights disease.
platelet
A cell fragment that plays an important part in forming blood clots.
lymphatic system
A network of veinlike vessels that returns the fluid that leaks out
of blood vessels to the bloodstream.
lymph
The fluid that the lymphatic system collects and returns to the bloodstream.
lymph node
A small knob of tissue in the lymphatic system that filters lymph,
trapping bacteria and other microorganisms that cause disease.
artery
A blood vessel that carries blood away from the heart.