The human heart is an amazing organ. It's regular and constant beating are essential to maintain human life. An animation of a beating heart shows the movement of the various parts of the heart that are critical for pumping blood through the body.
How does the heart pump blood? The muscles in the walls of the heart contract. Contraction is accomplished by a shortening of the muscle fibers. An animation of the contraction of a piece of skeletal muscle tissue shows how various parts of the muscle tissue move with respect to one another. Notice the dark and light lines separated by wide gray bands. Also notice how the distance between these features changes as the muscle tissue contracts and relaxes.
How does the muscle tissue contract? It involves the interaction of two proteins: actin & myosin, joined together in fiber bundles. A diagram of a myofibril (a muscle fiber) shows some of its structural details. A higher magnification diagram shows the shape of the actin and myosin molecules and how they interact in the muscle fiber.
What causes a heart attack? Most often, it is due to a clogged artery on the heart. Arteries can become clogged when a plaque develops. Plaques consist of cholesterol and other substances attached to the inner wall of the artery. Take a journey down a coronary artery to see how a plaque might develop.
The graphics and animations on this page were obtained from the The Center for Creative Instruction at the Medical College of Ohio in Toledo, Ohio USA.
To learn more about how the structure of these proteins is involved in their function, in the contraction of muscle tissue, in the beating of the human heart, and in human life, contact:
W. Robert Midden
Chemistry Department
Bowling Green State University
Bowling Green OH 43403 USA
Voice: 419/372-6889
FAX: 419/372-9809
Internet (preferred): midden@bgnet.bgsu.edu
