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Puffy Head, Bird Legs
Puffy Head, Bird Legs
Student Activities
PROBLEM
How does gravity affect blood circulation and the distribution of fluids in the body?
BACKGROUND
Gravity helps to push blood downward into the legs and feet of a person standing on the surface of
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Earth. When a person lies down with both legs straight up at a 90 angle, gravity acts to push blood
from the legs and feet to the head and chest. A similar fluid shift from the lower extremities to the
upper body occurs in astronauts while in microgravity conditions (one millionth of Earth’s gravity). In
this activity you will model on Earth the distribution of blood toward the upper body that astronauts
experience in microgravity conditions in space.
MATERIALS
Metric tape measure
Exercise pad or blanket (optional)
Clock with a second hand
Chair
PROCEDURE
1.
Work in groups of two or three. Select one of the members of the group to be the test subject.
2. With the test subject in a sitting position, observe the facial shape and skin features. Record your
description on the Student Data Sheet.
3. Measure the circumference of a calf at its widest point to the nearest millimeter. Record the data
on the Student Data Sheet. (Note: Mark the level on the calf where the measurement was made,
so the calf will be measured at the same place at the end of the experiment.)
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4. Have the subject lie down, with her/his back to the floor and legs against the wall at a 90 angle
to the torso. Have the subject maintain this position for 10 minutes
5. Observe and record facial shape and skin features while the
subject is still in the test position.
6. Ask whether the subject has any unusual feelings in the head and
face, and record his/her responses.
7. With the subject still in the test position, measure the calf
circumference at the same location as the pre test measurement.
Record your data on the Student Data Sheet.
8. Calculate the percent change in the calf circumference and record
your results.
9. Gather leg circumference data from the other groups and enter
the data on the Group Data Sheet.
10. Design a double bar graph to display the pre- and post-data
collected from each test subject in the class.
11. Write your conclusions.
Correct Position for
Puffy Head, Bird Legs

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STUDENT DATA SHEET
Name: _____________________________________________ Date: ____________ Period: ______
INVESTIGATION QUESTIONS:
1.
If your legs are raised above your head and torso,
a. what would you expect the observable effect on your head to be?
b. what would you expect the observable effect on your legs to be?
2. How would circulation be affected if gravity weren’t forcing blood down into the legs and feet of a
standing person?
INDIVIDUAL DATA:
1.
2.
Describe the facial shape and skin features of the test subject prior to experiment.
Measure the circumference of a calf prior to elevation (to the nearest millimeter): _________
3.
Describe the facial shape and skin features at the end of the experiment.
4.
Did the test subject report any unusual feelings in the head and face? If so, describe them.
4.
What was the circumference of the calf after elevation (to the nearest millimeter)? ___________
5.
What was the percent change in the circumference of the subject’s calf? _________
EQUATION:
-
% change = (Post Test Circumference
Pre Test Circumference) X 100
Pre Test Circumference

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Puffy Head, Bird Legs
GROUP DATA TABLE:
Compile data on the circumference of calves of test subjects before and after leg elevation.
Student Name
Pre Test (mm)
Post Test (mm)
% Change
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
GROUP DATA GRAPH: Remember to title and label your graph, including units of measurement.

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CONCLUSIONS:
1.
When a person’s legs are raised above the head and torso, do you observe any head and
facial changes? If so, why do you think these changes occurs?
2.
When a person’s legs are raised above the head and torso, do you observe any change in calf
circumference? If so, why do you think this change occurs?
3.
How would circulation be affected if gravity weren’t forcing blood down into the legs and feet of
a standing person?
4.
An astronaut with a “puffy head” and “bird legs” returns to Earth, after a short time in space.
Would you expect these changes in his body to be permanent? Why or why not?
Going Beyond:
1.
If an astronaut walked around on a planet with 2 G (two times the gravitational pull of Earth),
what changes would you expect in the face and head?
2.
On the same 2 G planet, what changes would you expect in the circumference of the legs?