The Heart as a Pump
Students will explore the working of the heart by making comparisons
with the actions of a pump.
- What happens during the pumping action of the heart?
For every 2 students
- wide mouth jar (plastic)
- two flexible straws
- tub or pail to collect water spills
Procedure1. 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
2. Carefully insert a straw through each hole in the balloon. The
straws should fit snugly. If there are gaps between the straws an 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
4. Push and release the balloon stretched over the jar several
Can you get water to move through the straws? In what direction does the
Watch a movie of this in action.
1. Study illustrations of the heart. What are the similarities between
the heart an 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.
Listen to the Heartbeats
Hear some different heart rates and try to guess which is which. Site
done by the Franklin Institute's online heart exploration.
How Your Heart Works
Along with a basic diagram of the heart, this page by Dr. Carl Bianco,
M.D. gives an overview of how the heart functions, especially concerning
the heart's chambers and valves.
This 3d tour inside the heart helps the viewer to grasp the concept of
the heart's inner workings, as well as providing an excellent internal
and external view of the heart.