| Term | Definition |
| involuntary muscle | a muscle that is not under our conscious |
| voluntary muscle | a muscle that is under our conscious control |
| skeletal muscle | a muscle that is attached to the bones of the skeleton |
| tendon | strong connective tissue that attaches muscle to the bone |
| striated muscle | a muscle that appears banded |
| smooth muscle | involuntary muscle found inside many internal organs of the body |
| cardiac muscle | muscle tissue found only in the heart |
| cardiovascular system | the body system that consists of the heart, blood vessels, and the 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 |
| ventricle | each of the two lower chambers of the heart that pump blood out of the heart |
| valve | a flap of tissue in the heart or a vein that prevents blood from flowing backward |
| pacemaker | a group of cells located in the right atrium that sends out signals that make the heart muscle contract and regulates the heart rate |
| artery | a blood vessel that carries blood away from the heart |
| capillary | a tiny blood vessel where substances are exchanged between the blood and the body cells |
| vein | a blood vessel that carries blood back to the heart |
| aorta | the largest artery in the body, receives blood from the left ventricle |
| diffusion | the process by which molecules move from an area of higher concentration to lower concentration |
| blood pressure | the pressure that is exerted by the blood against the walls of blood vessels |
| coronary artery | an artery that supplies blood to the heart itself |
| pulse | the alternating expansion and relaxation of an artery wall as blood travels through it |