2. Complete Activity 7.2 (Page 74). Take a small funnel of 6-7 cm in diameter. Fix a rubber tube (50 cm long) tightly on the stem of the funnel. Stretch a rubber sheet (or a balloon) on the mouth of the funnel and fix it tightly with a rubber band. Put the open end of the tube on one of your ears. Place the mouth of the funnel on your chest near the heart. Now try to listen carefully. Do you hear a regular thumping sound? The sound is that of heart beats. How many times did your heart beat in a minute? Count again after running for 4-5 minutes. Compare your observations.
Record your own pulse rate and heartbeat and that of your friends while resting and after running and record in Table 7.2. Do you find any relationship between your heartbeat and pulse rate?
Answer:
The Activity 7.2 should be carried out in the following way:
Aim: To compare rate of heartbeat and pulse rate in different situations such as while at rest and after running and make the necessary conclusions.
Materials Required: Small funnel (6-7 cm in diameter), 50 cm long rubber tube, rubber sheet, rubber band.
Procedure:
(i) Take the 50 cm long rubber tube and attach it tightly to the stem of the funnel. Cover the mouth of the funnel with a rubber sheet and hold it in place with a rubber band. Refer to the figure for clarity.
(ii) Place the mouth of the funnel on the chest near the heart while holding the open end of the tube to one of your ears as shown in the figure and listen carefully. Make note of what you hear. This should be done when you are at rest (no physical activity).
(iii) Count how many times your heart beats in a minute i.e. the rate of heartbeat when you are at rest. Record your observations in Table 7.2.
(iv) Then calculate the rate of heartbeat after running for 4-5 minutes. Record your observations in Table 7.2.
Note the differences between (iii) and (iv).
(v) You will also need to calculate your pulse rate both when you are at rest and after running for 4-5 minutes. Record your observations in Table 7.2.
(vi) Also report the pulse rate and rate of heartbeat of your friends both while resting and after running in Table 7.2.
Observations: The observations are noted as follows:
- You will hear your heart beating with a regular thumping sound when you place the mouth of the funnel on your chest near the heart.
- When you are at rest the rate of heartbeat should be around 72-80 beats per minute. After running for 4-5 minutes the rate of heartbeat should be higher – around 90-170 beats per minute.
- The pulse rate when you are at rest will be equal to the rate of heartbeat when you are at rest. Similarly, the pulse rate after running for 4-5 minutes will be equal to the rate of heartbeat after running for 4-5 minutes.
The completed table 7.2 is shown below:
Heartbeat and pulse rate
| Name of student | While resting | After running (4-5 minutes) | ||
| Heartbeat | Pulse rate | Heartbeat | Pulse rate | |
| Ramesh | 72 | 72 | 110 | 110 |
| Riya | 75 | 75 | 116 | 116 |
| Sachin | 73 | 73 | 112 | 112 |
| Anisa | 74 | 74 | 114 | 114 |
| Self | 76 | 76 | 118 | 118 |
Conclusions:
We can conclude the following:
- The regular thumping sound you hear in your chest is the beating of your heart.
- The rate of heartbeat and the pulse rate when you are at rest will be the same. This is because every time your heart beats it generates one pulse in your arteries, which you can feel when you touch your wrist.
- After running for 4-5 minutes, the rate of heartbeat and the pulse rate will still be equal to each other. However, the values will be greater than when you are at rest because during intense physical activity the heart pumps blood faster to meet the extra demand for oxygen.
“Complete Activity 7.2 (Page 74). Take a small funnel of 6-7 cm in diameter. Fix a rubber tube (50 cm long) tightly on the stem of the funnel. Stretch a rubber sheet (or a balloon) on the mouth of the funnel and fix it tightly with a rubber band. Put the open end of the tube on one of your ears. Place the mouth of the funnel on your chest near the heart. Now try to listen carefully. Do you hear a regular thumping sound? The sound is that of heart beats. How many times did your heart beat in a minute? Count again after running for 4-5 minutes. Compare your observations.
Record your own pulse rate and heartbeat and that of your friends while resting and after running and record in Table 7.2. Do you find any relationship between your heartbeat and pulse rate?” – Solved.
Related Links:
Solution to Extended Learning Question 1
Solution to Extended Learning Question 2
Solution to Activity 7.1
Solution to Activity 7.3
Solution to Chapter 7 Transportation in Animals and Plants
