Download The Heart as a Pump

The Heart as a Pump
Key Question
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What happens during the pumping action of the heart?
Objective
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Students will explore the working of the heart by making comparisons
with the actions of a pump and recording their observations.
Materials
For every 2 students
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wide mouth jar (plastic)
balloons
skewer
two flexible straws
scissors
tub or pail to collect water spills
sponge
copy of worksheet for each group
Procedure:
1. Fill the jar half full of water. Cut the neck off of the balloon and stretch
the balloon over the mouth of the jar so it fits tightly. Save the neck of the
balloon for use instep three, below. With the skewer, poke two small holes
into the stretched balloon, about 2 cm apart.
2. Carefully insert a straw through each hole in the balloon. The straws
should fit snugly. If there are gaps between the straws and the balloon,
start over with a new balloon.
3. Use the neck from the balloon to make a valve. The valve goes on the end
of one straw as a flap. Secure lightly with tape. Bend down the straw with
the balloon valve (see diagram). Place the jar in a tub or pail.
4. Push and release the balloon stretched over the jar several times.
Can you get water to move through the straws? In what direction does the
water move?
Extensions
1. Study illustrations of the heart. What are the similarities between the
heart and the pump you assembled?
2. Remove the balloon flap (valve) from the apparatus. What happened?
3. Does the valve affect how well the water flows?
4. Can you think of other examples of valves and pumps?
Notes to the teacher: Lub Dub
The heart contains valves which direct the flow of blood in one direction.
Blood is forced through the flexible membranes which form the valves.
Once, the blood passes through the membranes, the valves collapse into a
barrier, preventing the blood from flowing backwards.
Students can find examples of pumps and valves in facets, aerosol sprays,
automobile fuel pumps, and many household items in daily use. Some
beverage containers use a valve that resembles the valves in the heart.
Point out to the students that the heart is a muscle and not a mechanical
pump. It can also be pointed out that comparisons of this kind are known as
reasoning by analogy and are an important part of scientific reasoning.
Name __________________ Date________ Period ________
The Heart as a Pump
Worksheet
1. When you compress the balloon downward what happens?
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2. Out of which straw does the water flow more easily- the one with the
balloon flap (valve) or the one with out?
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3. What do you observe happening as you release the compression on the
balloon?
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4. What happens if the straws are clogged?
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5. When you remove the balloon flap (valve) from the apparatus (straw),
what happened?
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6. How does the valve affect how the water flows?
_______________________________________________________
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7. How do you think this would affect the blood flow from your heart to
your lungs?
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8. What similarities are there between the heart and the pump you
assembled?
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