Learn about the three types of muscle tissue, how a muscle contracts, and how muscles are adapted for exercise. [3:40]

What do you know about the circulatory system? This site features several links to help you increase your knowledge of this fascinating human body system.

This lesson covers the topic of human bones and joints. Students learn about the skeleton, the number of and types of bones in the body, and how outer space affects astronauts' bones. Students also learn how to take care of their bones...