Body movements

 Body movements

Q.1. What do you understand by the term ‘Movement’ and how is it different from the term ‘Locomotion’?

Ans. A change in the position of an object is called ‘Movement’ like movement of hands while playing, doing exercise, blinking of eyes etc.

The ability of living being to move its body from one place to another is called ‘Locomotion’ like living beings walk, run, crawl etc.

Q.2. What are Joints and write a short note on each type of joint present in our body?

Ans. Bones can not bend. We can bend and move our body only at some points where bones meet, such points are called joints.

There are 4 types of joint present in our body:

1. A ball and socket joint - this is the joint in which ball like surface of one bone is fitted into hollow space of another bone (also called socket). Such a joint allows movements in all directions. These can be found in shoulder joint, hip joint etc.
2. A pivotal joint - this is the joint which allows rotation, twisting, extension and flexibility. In a pivotal joint a cylindrical bone rotates in a ring. For example: The joint where our neck joins the head is a pivotal joint. It allows us to bend our head forward and backward and turn the head to our right or left.
3. Hinge joints - this is the joint which are found between two bones where we need back and forth movement. For example: Knees, elbows and ankle joints.
4. Fixed Joint - These joints do not allow the movement of bones in any direction. For example: bones in our head do not move in any direction due to fixed joints.

Q.3. What do we mean by the term ‘Skeleton’? What are its advantages?

Ans. All the bones in our body also form a framework to give a shape to our body. This framework is called the skeleton. This framework is necessary to

• protect many internal organs present in our body.
• Support and help in various physical activities like standing, walking, etc.

The X-ray image of our body parts clearly shows the bones beneath the skin.

Q.4. How many bones are there in Human skeleton?

Ans. The Human skeleton is composed of around 305 bones at birth. The number of bones in the skeleton changes with age. It decreases to 206 bones by adulthood after some bones have fused together. 

Q.5. Muscles work in pairs. Explain.

Ans. A muscle can only pull. It cannot push. Thus, two muscles have to work together to move a bone.

Muscles work in pairs. When one of them contracts, the bone is pulled in that direction. The other muscle of the pair relaxes. To move the bone in the opposite direction, the relaxed muscle contracts to pull the bone towards its original position, while the first relaxes.

Q.6. Explain the movement in Earthworm.

Ans. The body of an earthworm is made up of many rings joined end to end. An earthworm does not have bones. It has muscles which help to extend and shorten the body.

During movement, the earthworm first extends the front part of the body, keeping the rear portion fixed to the ground. Then it fixes the front end and releases the rear end. It then shortens the body and pulls the rear end forward. This makes it move forward by a small distance. Repeating such muscle expansions and contractions, the earthworm can move through soil. Its body secretes a slimy substance to help the movement.

Under its body, it has a large number of tiny bristles (hair like structures) projecting out. The bristles are connected with muscles. The bristles help to get a good grip on the ground.

Q.7. Earthworm is called Farmer’s friend. Give reason.

Ans. The earthworm, actually, eats its way through the soil! Its body then throws away the undigested part of the material that it eats. Also, they burrow themselves into the soil thus making it loose and creating more gaps in soil for air & water.

These activities of an earthworm make the soil more useful for plants.

Q.8. When do we celebrate ‘International Day of Yoga’? Write some advantages of doing Yoga.

Ans. The United Nations declared 21 June as International Day of Yoga. Yoga keeps a person healthy.

• It helps in keeping the backbone erect, enabling you to sit straight and not slouch.
• Many postures in yoga require you to lift your own weight, which help in making the bones strong and help ward off osteoporosis. 
• It also helps in relieving joint pain, which is mostly observed in elderly people. 
• It tunes all muscles in the body and keeps them active. 
• It keeps the heart healthy and makes it work more efficiently.