丁香园AV

What You Need

• Paper towel tube or a length of plastic tubing that will fit the mouths of the funnels you have
• 2 Funnels, one larger (~8cm wide mouth) and one smaller (2 or 3cm)
• 1 balloon
• Duct tape
• A watch that shows seconds
• A friend

What To Do

Part 1: Make your own stethoscope

This is the tool that doctors use to listen to your heartbeat.

Cut the bottom off a balloon and put it over the wide end of the larger funnel. Get it as tight as possible 鈥� you should be able to tap it like a drum. Tape the cut edge of the balloon to the funnel.

Attach the funnels to the plastic tubing 鈥� one at each end. Secure with duct tape. If you are using a paper towel tube, you will only need the large funnel. Put the narrow end into the paper towel tube and secure the join with duct tape. The small funnel end is the listening piece and the larger one is the part you place on yourself or someone else to hear the heartbeat.

Part 2: Now you get to experiment

Predict how many times in a minute your heart will beat? How often do you think your parents or friends will beat in the same time?

a.    Check it out by gently placing the listening end of the stethoscope onto your friend鈥檚 chest when they are lying down on the ground or on the sofa. Put your ear to the other end and listen. It will sound like lub dub, lub dub 鈥�. . Each 鈥榣ub dub鈥� is one heartbeat. Count the beats for ten seconds. Multiply this by 6 to get the beats per minute. This is your friend鈥檚 baseline heartbeat. Now switch and have your friend check your heartbeat for ten seconds. Multiply by 6. Are they different?

Now think about whether the heart beat might change at all. What do you think would happen if you measured your heartbeat standing up? After running really fast outside? After eating a big bowl of chocolate ice cream? Does whether you are hot or cold make a difference to your heartbeat?

b.    Check it out. Use the stethoscope to listen to the heartbeat after different activities. Always count the beats for the same length of time (ten seconds and then multiply by 6) so you can compare.

c.     What did you find out?

d.    Why do you think your heart might beat faster after exercise for example?

What about other animals?

e.    If you have a cat or dog, use your stethoscope to see what their heart beats are per minute.

What鈥檚 Going On?

Your heart is a pretty important and hardworking muscle. Its job is to pump blood all around your body. This brings oxygen and nutrients to our cells, from our heads to our toes.  

Young people usually have a heart rate of around 80 beats a minute. Adults have a little slower rate, around 70 beats every minute.

When you exercise, the muscles around your body (for example in your legs) need more oxygen, so your heart pumps faster to supply it. 颅颅 

Did you know that an elephant鈥檚 heart beats 25 times a minute, and a mouse has a heartbeat of 650 times a minute? Wow!