Arteries - Take the blood away from the heart. small arteries are called the arterioles, and most carry the oxygenated blood.

Capillaries - Microscopic blood vessels which is where gas exchange occurs; allows oxygen to enter the cells and picks up carbon dioxide from the cells.

Veins - Brings the blood back to the heart they have valves, venules (small veins), and most carry deoxygenated blood.

Tricuspid Valve - Between the right atrium/right ventricle

Pulmonary Valve - Between the right ventricle/pulmonary artery

Mitral Valve - Between the left atrium/left ventricle

Aortic Valve - Between the left ventricle/aorta

Right Atrium - Blood enters from the body.

Right Ventricle - Blood leaves here and goes to the lungs.

Left Atrium - Blood enters from the lungs.

Left Ventricle - Blood leaves here and goes to the body.

Atria - Two upper chambers of the heart and they receive blood that goes into the heart.

Ventricles - Two lower chambers of the heart and they send the blood out of the heart.

Interatrial Septum - Separates two upper chambers (atria)

Interventricular Septum - Separates two lower chambers (ventricles)

Endocardium - Innermost lining of the heart wall and heart valves

Myocardium - Middle, muscular layer of the heart wall (thickest)

Pericardium - Fibrous, membranous sac surrounding the heart (outer layer)