ASTER PUBLIC SCHOOL,GR.NOIDA WEST HS-1,SECTOR -3

CLASS – VI SCIENCE

CHAPTER – 9

MOVEMENTS

IN

THE BODY

Mind map :

- EARTHWORM (via muscle contraction & expansion ; setae)

- SNAIL (foot)

- COCKROACH (three pairs of jointed legs)

- FISH (tail ,fins aided by streamlined body)

- BIRDS(streamlined body , feathers)

- SNAKE (muscular contraction )

- HUMAN BEINGS( skeleton and muscles)

Hinge joint Ball & socket joint Pivot joint Gliding joint

MOVEMENT

Skeletal system

skull

Spine

Limbs

Rib cage

Types of Joints

Immovable Slightly movable Freely movable

New terms :

▪ Mucous : a slimy substance secreted by snail’s foot that enables it

to move with ease.

▪ Ligament : at a joint , the two bones are held together by strong and

elastic bands called ligaments.

▪ Flexor : the muscle called flexor contracts and pulls the tendon to

bend a joint.

▪ Extensor : when muscle relaxes , the extensor pulls another tendon

to straighten the same joint.

▪ Floating ribs : the last two pairs of ribs which are not attached in

front with the sternum(breast bone).

Movement and locomotion :

• Movement : one of the characteristic features of living organisms

• Animals can move from one place to another , can move their

fingers, nod the head etc.

• Plants like Mimosa pudica can close its leaflet when touched .

• Certain types of flowers can open and close according to the time of

the day. Plants cannot change their position.They are fixed.

• Locomotion : the type of movement where an organism can change

its place .

• Different animals show different types of movements –

jump,hop,walk,crawl,run,fly,slither , swim and so on .

Movement in earthworm :

• The earthworm has an elongated body with no bones or limbs .

• Its body has many ring – like segments that have muscles.

• The earthworm moves from one place to another with the help of

these muscles. The muscles help it to contract and expand its body

providing a push that helps the body move forward .

• The earthworm also has special bristle like structures called setae on

the underside of its body .

Movement in Snail :

• A snail has a slimy body without bones and a shell for protection. It

has a pair of tentacles with eyes at the tips of its shell .

• The snail moves with the help of a muscular organ known as the

foot .It makes wave-like movements by expanding and contracting

the muscles in the foot. It also secretes a slimy substance known as

mucous that enables the snail to move with ease.

Movement in Cockroach :

• A cockroach can walk , run , climb and even fly short distances.

• The body of a cockroach is made up of three parts – head , thorax

and abdomen .

• The thorax is the middle part and bears two pairs of wings and three

pairs of jointed legs for movement.

• The cockroach also has a pair of sensitive antennae located at its

head .These enable it to sense and smell its surroundings.

• Cockroaches walk in a very unique manner moving three legs at a

time.

• On the end of the abdomen , there are a pair of cerci , projections

which are sensory organs .Cerci function in a similar manner to

antennae , sensing vibrations through air and ground.

Cockroach :

Movement in Fish :

• The body of a fish is specially designed for swimming.

• It has streamlined body.

• A fish swims primarily with the help of fins . The fins help a fish in

maintaining the balance of the body and changing direction while

swimming.

• A fish uses its tail fin , also called the caudal fin , to push forward

through water. In order to move forward , the fish moves its tail

from side to side . This zig-zag movement pushes the water and

propels the fish forward.

• The fish also has a sac-like structure in its body called the swim-

bladder ,which is filled with air and keeps the fish afloat.

• Fish moves with the help of its tail.

Movement in Fish :

Movement in Birds :

• Most birds can fly . In addition , birds can even walk , hop or run .

• Some birds such as ducks, geese and swans can even swim in water.

• Birds have a streamlined body.

• The bones of most birds are hollow. These bones make the body

light weight and fit for flying.

• Birds with heavy bodies , such as ostriches , penguins and emus ,

cannot fly.

• The forelimbs of birds are modified to form wings for flight.

• The body is covered with feathers . Apart from helping them in

flying , these feathers also keep the birds warm while flying at a

height.

• The chest muscles are very strong that enable birds to flap their

wings when flying.

Movement in Birds :

Movement in Snake :

• Snakes slither or crawl on the ground in a wave -like motion .

• Snakes have a long backbone. They have many thin muscles . They

are connected to each other even though they are far from one

another. Muscles also interconnect the backbone , ribs and skin.

• The snakes’s body curves into many loops . Each loop of the snake

gives it a forward push by pressing against the ground . Since its

long body makes many loops and each loop gives it this push , the

snake moves forward very fast and not in a straight line .

Movement in Human Beings :

• Our body shows a number of movements .

• In humans and other vertebrates , the bones are present within the

body or internally and thus , form an endoskeleton.

• The skeleton and muscles are involved in both locomotion and

movements .

The Human Skeleton :

• The skeleton is the framework formed by the bones of our body .

The skeleton of a normal adult human is made up of 206 bones .

Apart from bones and muscles, cartilage, ligaments , tendons and

joints also form a part of the skeletal system.

• FUNCTIONS OF SKELETON :

✓ It forms the framework of our body , provides shape and support ,

and holds the body upright.

✓ It helps in the movement of various parts of the body.

✓ It protects the internal organs of our body. The skull protects the

brain, ribs protect the heart and the lungs and so on.

✓ Bones are filled with a spongy mass from inside called the bone

marrow where blood cells are formed .

STRUCTURE OF THE SKELETON :

•The skeleton comprises of four main parts- the skull , the backbone or spine , the ribcage and the limbs.

•SKULL : The skull comprises of the bones of the face and the head region.

• It protects our brain. It also has holes for eyes , nose and ears .

•There are a total of 22 bones present in the skull.(14 form the face & jaw ,rest 8 bones present in the upper part of the head ).

•Most bones of skull are fixed and cannot move except that of the lower jaw.

•The movement of the lower jaw makes it possible for us to chew the food.

THE RIB CAGE :

•There are 12 pairs of ribs that is a total of 24 bones forming a cage-like structure called rib cage.

•The ribs are flat, thin and curved bones. These are joined with the backbone at the back and with the breastbone in the front.

The last two pairs of ribs are not attached in front and are hence called floating ribs.

•The rib cage protects important organs such as the heart and lungs as well as parts of the stomach and kidneys.

BACKBONE OR SPINE :

• It is also known as spine or vertebral column. It runs from the base of the skull to the lower back and forms the central supporting rod for the skeleton.

•It is made of 33 small bones called vertebrae(singular vertebra).

•These vertebrae are joined to each other . It is because of these joints that we are able to bend and twist our back .

•Each vertebra has a hole through it. The spinal cord passes through these holes.

•All animals that have a vertebral column are called vertebrates such as fish , amphibians , reptiles , birds and mammals.

LIMBS :

•Limbs allow us to perform various types of movements.

•We have two pairs of limbs – the fore limbs (arms) and the hind limbs (legs).

•Almost half of our bone are found in the limbs.

•There is one long bone in the upper arm called humerus. The lower arm has two bones called radius and ulna.

•The longest bone in our body is the thigh bone or the femur.The lower leg consists of two bones-the tibia and the fibula.Thepelvis or hip bone that supports the legs is attached to the lower end of the backbone .The wrists,fingers,ankles and feet have a large number of small bones.

JOINTS :

• Any type of movement in our body is made possible by joints.

• A joint is a place at which two bones meet and are joined together. Joints make our body flexible.

• At a joint, the two bones are held together by strong and elastic bands called ligaments.

• The part of a bone that joins with the other bone is covered with a substance known as cartilage.

• Cartilage is a tissue that prevents the bones from rubbing against each other. It acts like a cushion between the two bones at the joint.

• The earlobes are made up of cartilage.

• Based on the extent to which the joints allow movement , they are divided into three categories – immovable or fixed ,slightly movable and freely movable joints.

HINGE JOINT :

•The joints present in our elbow and knee .

•They allow movement in only two directions –backward and forward , or upward and downward.

•It can also be said that movement is allowed only in one plane. However , hinge joints in our body provide more movement tan just the back and forth swing . They allow some rotation.

•The finger joints are also examples of the hinge joint.

BALL AND SOCKET JOINT :

•Joint in which the end of one bone is round like a ball that fits into a cup-like cavity or socket of the other bone.

•This type of arrangement of bones allows movement in all directions – forward and backward as well as side to side.

•The joint between the upper arm and the shoulder is a ball and socket joint.In this joint , the head of the humerus bone fits into the socket of the shoulder bone. That is why we are able to move our hands in any direction.

• The other example – joint between the hip bone and the femur bone.

PIVOT JOINT :

•In pivot joint , the end of one bone is in the form of a cylinder. The end of the other bone is in the form of a ring (or a ring-like structure). The cylinder fits into the ring and rotates inside it , or the ring rotates around the cylinder.

GLIDING JOINT :

•This kind of joint allows bones to glide over one another and provide a slight movement. These bones have flat ends and can move from side to side as well as back and forth.

•The joints at the ankle and the wrist as well as the joints between the vertebrae are examples of gliding joints.

FIXED JOINTS :

•The bones in our head that protect our brain are joined together by fixed joints.

•They cannot move .

•Similarly , the upper jaw and the rest of the head are joined by a fixed joint .

MOVEMENT OF BONES :

•Bones cannot move by themselves .It is the muscles that make the bones move and help in body movement.

•Muscles are attached to bones by a tissue called tendon.

•Muscles work in pairs to produce movement. One muscle contracts to pull the bone in one direction and other contracts to pull the bone in the opposite direction.

•Muscles can pull the bones, but cannot push them. Therefore muscles work in pair to produce movement.

•Flexor and extensor are a pair of muscles that work together to move our arm.

X-RAYS :

•It is possible to see the image of bones in a living being using radiation known as X-rays.

•X-rays are special rays that can pass through the soft tissues but not through the bones. Hence , an image is created that reveals the nature of the bone.

•Bones are seen as white shapes against a black background.