Lesson 11 – A Look inside the Body
(A) Think and tell.
Why do we pant when we have been running hard for some time?
Ans: During running, our heart pumps blood to our muscles, and our lungs pump more air to the body. As more work is done during running than in normal conditions, our heart beats faster due to excitation or exertion, and we pant.
| A | B | C |
|---|---|---|
Sheep | Cotton yarn | Sack |
Cotton | Fibres | Sweater |
Jute | Wool | Cloth |
| A | B | C |
|---|---|---|
Sheep | Wool | Sweater |
Cotton | Cotton yarn | Cloth |
Jute | Fibres | Sack |
(B) Answer the following questions.
1. What is meant by “internal organ”?
Ans: An organ that is situated inside the body and cannot be seen from the outside is called an internal organ.
2. Name the two cavities in the abdomen
Ans: The cavity inside the abdomen has two parts, the abdominal cavity and the pelvic cavity.
3. Which important organs are situated in the ribcage in the thoracic cavity?
Ans: The important organs situated in the ribcage in the thoracic cavity are the heart and the lungs.
4. Why does the chest swell when we breathe in?
Ans: When we breathe in air, the lungs expand a little. That is why our chest swells up when we breathe in.
5. Why is the brain situated in the casing of the skull?
Ans: The brain is a very important internal organ. Injury to the brain can make one disabled for life and can even cause death. Hence, the brain is situated in a casing formed by the skull around it.
(C) Fill in the blanks.
1. The internal organs that help digest food are ________.
Ans: present in the alimentary canal
2. We have ________ lungs.
Ans: two
3. Every _______ of the heart is called a heartbeat
Ans: contraction
4. We become ________ of all our emotions in the brain.
Ans: aware
5. The structure of the human body is very ________.
Ans: complex
(D) True or false?
1. The oesophagus is in the thoracic cavity.
Ans: True
2. The heart is a little bigger than our fist.
Ans: True
3. The food in the mouth forms a moist lump.
Ans: True
4. In the brain, we interpret the information collected by the sensory organs.
Ans: True
(E) Give reasons why.
1. The structure of the body is such that all internal organs remain secure in their places.
Ans: The structure of our body is such that our internal organs can remain secure in their places no matter how much we move. This is because there are hollow spaces for the protection of these organs inside the head and the torso, called cavities.
2. Blood must be kept flowing in the blood vessels throughout the body.
Ans: Our blood carries air to all parts of the body. The food that we eat gets digested. It is the blood that carries the digested part to every particle of the body. For these purposes, it is necessary to keep blood flowing through the blood vessels that spread throughout the body.
3. The brain has to be kept completely safe.
Ans: The brain is a very important internal organ. Injury to the brain can make one disabled for life and can even cause death. Hence, the brain has to be kept completely safe.
(F) Match the following :
| ‘A’ Group | ‘B’ Group |
|---|---|
Blood supply | Alimentary canal |
Breathing | Heart |
Carrying food to the stomach | Brain |
Controlling movements | Lungs |
Ans:
| ‘A’ Group | ‘B’ Group |
|---|---|
Blood supply | Heart |
Breathing | Lungs |
Carrying food to the stomach | Alimentary canal |
Controlling movements | Brain |