Taller: How does Gravity Affect a Person's Height? (page 2)

Show Time!

1. How does gravity affect pulse rate? One way to simulate an increase in gravity is to add weight to the body. Compare the difference in your pulse rate before and after a 2-minute walk. Carry a heavy backpack and repeat the experiment. Which walk caused a greater increase in pulse rate? Ask volunteers to repeat the experiment, and keep records of their pulse rates before and after each walk. This information can be graphed and used as part of a project display.
2. Does your heart pump as hard as a giraffe's? Make a heart pump as shown in the diagram. Connect straws with duct tape to equal the measurement from the top of your head to the position in which your heart lies in your chest. Squeeze the pump with your hands until the liquid in the bottle rises out of the top straw. Make another pump, building a 6-foot (2-m) straw to represent a blood vessel leading from a giraffe's heart to its head, and squeeze the bottle as before. Compare the amount of effort needed to pump the liquid up both straw "blood vessels." Take photographs to use along with the actual pumps and straw ''vessels" as part of a project display. Prepare a written summary of the results.

Check it Out!

Astronauts discovered that a "weightless" environment caused many changes in their bodies. Some of the changes took days, and others were apparent within minutes. Find out why the following changes occurred when there was a reduced pull of gravity on the astronauts' bodies:

• Bones lost calcium
• Kidneys worked harder
• There was excess fluid in the face and chest.
• Muscles shrank.
• Heart shrank.

For information, read the article titled "Hang Time for Humans" in Super Science magazine, February 1990, Blue Edition, Scholastic Inc.

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