A young boy learns about his heart through the step-by-step construction of a simple circulatory system. He learns how his heart pumps, what blood and blood vessels do, how they do it, and some of the ways to help his heart stay healthy.
1965
2003
2005
1947
2008
1975
1931
1936
2019
1972
2022
1978
1970
—
1990
2004
1969