Class 6, Science - Chapter 8 Body Movements Notes, NCERT Solutions & Frequently Asked Questions

Science

Class 6 - Chapter 8

Body Movements 

Notes, NCERT Solutions & Frequently Asked Questions 

-- Notes --

⭐Movements:- The ability of organisms to change position, by using their body parts, is called movement.

⭐Skeleton:- Skeleton is the internal structure in organisms, which helps in bringing about movement.

• It forms a framework that gives the shape of the body and provides support to organisms.

• The skeleton is made up of bones.

• Different kinds of bones are joined to each other in a particular manner.

• Joints facilitate various types of movements.

• In higher animals, bones, muscles and cartilage together make the movement possible.

⭐Functions of skeleton:-

• Skeleton system gives support to the body.

• It protects the inner organs.

• Together with muscles, it gives the body its shape.

• Red blood cells and some white blood cells are produced in the marrow of the bone.

⭐Muscles:- Muscles are parts of the body that help in bringing about movement.

• Muscles may be attached to bones, (humans) or may work alone (earthworm).

⭐Cartilage:- Part of the skeleton that is not hard as bones and can be bent, is cartilage.

• They are found in the upper part of the ear, the tip of the nose and at the tips of long bones.

⭐Tendons:- join muscles to the bones.

⭐Ligament:- joins two bones.

⭐Bristles:- Bristles are hair like structure, connected with muscles. The bristles help to get a good grip on the ground. 

⭐Cavity:- It is the hollow space or cavity in one bone, into which the other bone fits. Such joint allows movements in all directions.

⭐The skull:- The skull has three main parts:-

a) Cranium:- The bones of cranium are flat. They are held firmly like a zipper. It covers and protects the brain.

b) Facial bones:- The facial bones comprise the upper jaw, lower jaw and few other bones. The lower jaw is movable. The movement of lower jaw enables us to eat, talk and sing.

c) Eye sockets:- The skull also includes a pair of eye sockets. These form a safe pocket for eyes.

⭐ The backbone:- Backbone or vertebral column is composed of 33 small, ring like vertebrae joined end to end. 

• It forms a hollow bony tube. 

• The main nerve cord passes through it.

⭐The Chest bones:- 12 pairs of ribs along with backbone make a cone-shaped cage, called rib-cage, which protects the heart.

⭐The Shoulder bones:- The shoulder bone is formed by the collor bone and the shoulder blade. The shoulder bones are flat and large. They help in forming joints with long bones.

⭐Hip bones:- The hip bone is formed by the fusion of three bones. Like shoulder bones, the hip bones are also flat and large. They help in forming joints with long bones. Together with the last two parts of backbone, it forms a large bony bowl called pelvis.

⭐Bones of hands and legs:- Bones of arms, thighs, etc., are long. They give strength to our body. Bones of fingers and toes are short. They help us in holding things. The hands and legs are constructed in same pattern as described below:- 

⭐Bone Joints:- Joints are the points where two parts of the skeleton are fitted together to make movement possible.

• Eg:- hip joint, elbow joint, knee joint, etc.

⭐ Types of Joints:- 

a) Ball and Socket Joint:- Ball and socket joint are found where the rounded end of one bone fits into the cavity of the other bone.

• It brings in movement in all directions.

• It is seen in the hips and shoulders of the human body. 

b) Pivot Joint:- A pivotal joint is where a cylindrical bone rotates in a ring.

• It joins the neck to the head.

• It allows to bend the head forward and backwards and turn the head to our left or right.

c) Hinge Joints:- Hinge joints bring about movement in only back and forth direction.

• The knees and elbows have hinge joints.

• The following image is a hinge joint in the elbow.

d) Fixed Joints:- Fixed joints are immovable joints because the bones are joined together.

• Such joints are found in the skull.

⭐Gaits of Animals:- The different patterns of movement of animals due to the differences in their skeletal structure are called gaits of animals.

⭐Rib cage:- Ribs join with the chest bone and the backbone together to form a box. This is called rib cage.

⭐Movement:- Changing the position or the place of the body is called the movement. There are two kinds of movements:

a) The organisms move their body parts without changing their position.

b) Animals move from one place to another. This kind of movement is called locomotion.

⭐Locomotion in some Animals:-

a) Earthworm:-

• The earthworm does not have any internal skeleton.

• The body is made up of many rings joined end to end and muscles attached to these rings help to extend and shorten the body.

• The skin of earthworm also has a large number of tiny bristles that help it get a good grip on the ground.

• Repeated extension and contraction of the body muscles, enable the earthworm to move through the soil.

b) Snail:- 

• Snails move with the help of their muscular, flat foot.

• They glide along a solid surface which is lubricated with mucus.

• This motion is powered by succeeding waves of muscular contractions of the foot.

c) Cockroach:- 

• The body of a cockroach is covered with a hard outer skeleton that is made of different units joined together.

• It has three pairs of legs for walking and two pairs of wings attached to the breast for flying.

• It has distinct muscles that are used for movement.

• The muscles attached to the legs help in walking.

• The breast muscles attached to the wings help in flying, although they are not good flyers.

d) Birds:- 

• Birds have a special skeletal and muscular structures that help them to fly.

• The forelimbs are modified to become wings and the bones inside are hollow to suit flying.

• The bones of the hind limbs are used for perching and walking.

• The shoulder bones and breastbones are strong and support muscles of flight, which move the wings up and down.

e) Fish:- 

• Fishes have a streamlined body that helps them swim with least resistance.

• They use tail fin for small jerks through water and other fins assist swimming.

• The tail fin is also used for changing directions.

f) Snakes:- 

• Snakes do not have legs for movement but use their long backbone along with muscles for movement.

• Their body curves into many loops, which gives it a forward push by pressing against the ground.

-- NCERT Solutions --

Question 1.- Fill in the blanks:-

a) Joints of the bones help in the ——————— of the body.

b) A combination of bones and cartilages forms the _______ of the body.

c) The bones at the elbow are joined by a __________ joint.

d) The contraction of the _____________ pulls the bones during movement.

Solution:-

a) movement 

b) skeleton

c) hinge 

d) muscles 

Question 2.- Indicate true (T) and false (F) among the following sentences.

a) The movement and locomotion of all animals is exactly the same. ( )

b) The cartilages are harder than bones. ( )

c) The finger bones do not have joints. ( )

d) The fore arm has two bones. ( )

e) Cockroaches have an outer skeleton. ( )

Solution:-

a) False

b) False

c) False

d) True

e) True

Question 3.- Match the items in Column I with one or more items of Column II.

Solution:-

Question 4.- Answer the following questions:-

a) What is a ball and socket joint?

b) Which of the skull bones are movable?

c) Why can our elbow not move backwards?

Solution:-

a) The rounded end of one bone fits into the cavity (hollow space) of the other bone. Such a joint allows movements in all directions, which is called ball and socket joint.

b) Lower jaw

c) Our elbow cannot move backwards because it has hinge joints which only allow back and forth movement.

-- Frequently asked Questions --

Question 1.- What are the different parts of a human skeletal?

Answer:- Human skeletal system includes the skull, vertebral column, collarbone, shoulder blades, rib cage, pelvic girdle and the bones of the hands, arms, feet and legs. 

Question 2.- What are the different types of joints?

Answer:- Functionally the three types of joints are synarthrosis (immovable), amphiarthrosis (slightly moveable) and diarthrosis (freely moveable).

Question 3.- What are the uses of the pivot joints?

Answer:- A pivot joint allows movement in one plane, such as rotation about an axis.

- By Durgesh Pandey