Body Movements

Animals	Body parts used in moving to and fro	How does the animal move?
Birds	Wings
Insects
Fish		Swim
Humans		Walk
Cow	Legs
Snake
Frog

HUMAN BODY AND ITS MOVEMENTS

ü Various activities like bowling a ball, picking a glass of water, running, throwing etc. require the bending of your elbows, knees respectively.

ü The places where we can rotate, bend are called as joints.

ü Bones cannot be bent.

The different types of joints are:-

Ball and socket joint:

§ The bowl is like the part of the shoulder to which your arm is joined.

§ The rounded end of one bone fits into the cavity (hollow space) of the other bone.

§ Such a joint allows movements in all directions.

Pivot joint:-

§ 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.

Hinge joint:-

§ Open and close a door a few times.

§ Observe the hinges of the door carefully.

§ The elbow has a hinge joint that allows only a back and forth movement.

§ They allow the door to move back and forth.

Fixed joints

§ Some joints between bones in our head are different from those we have discussed so far.

§ The bones cannot move at these joints.

§ Such joints are called fixed joints.

§ All the bones in our body also form a framework to give a shape to our body.

§ This framework is called the skeleton.

ü Carpals:-

ü The very small bones located on your toes and fingers which can bend at every joint are called carpels.

ü These are very flexible.

Rib cage:-

ü The bones of the rib cage are a little curved or bent.

ü These bones join the chest and the backbone forming a protective cage of bones.

ü This cage is called the rib cage and it protects the lungs and the heart.

ü There are 12 pairs of ribs in humans.

Backbone:-

ü The bones elongated from the neck till the end of the back is called the backbone.

ü Backbone is made up of small bones called the vertebrae.

ü There are 33 vertebrae present in a backbone.

Shoulder blade:-

ü The bones on your back at the region of the shoulders are called shoulder blades.

ü There are 1 pair of shoulder blades one on each side.

Pelvic bones:-

ü The bones on which you sit are called pelvic bones.

ü These are present below the stomach.

ü They enclose the area below the stomach.

Skull:-

ü The bones which are present under your head is called skull.

ü They protect the most important organ- Brain

ü Many bones are combined and joint to form a skull.

Activity 1:

Feel your ear and the tip of your nose . What do you feel?

· There are bones softer than the main skeleton.

· These bones can be bent and are not as hard as the skeletal bones.

· They are called as the cartilages.

· Cartilages are found in between the joint.

· E.g. tip of the nose, outer ear.

Activity 2:

Bend your arm and feel the above portion of your arm.

· This bulged portion are the muscles.

· They are present mostly attached to the bones.

· Muscles have the property of contraction and relaxation.

How do bones move? Why do muscles have to work together?

Ø When contracted, the muscle becomes shorter, stiffer and thicker.

Ø It pulls the bone.

Ø Muscles work in pairs.

Ø When one of them contracts, the bone is pulled in that direction.

Ø The other muscle of the pair relaxes.

Ø To move the bone in the opposite direction, the relaxed musle contracts to pull the bone towards its original position, while the first relaxes.

Ø A muscle can only pull. It cannot push.

Ø Thus, two muscles have to work together to move a bone.

GAIT OF ANIMALS:-

a) Earthworm:-

v The body of an earthworm is made up of many rings joined end to end.

v An earthworm does not have bones.

v It has muscles which help to extend and shorten the body.

v During movement, the earthworm first extends the front part of the body, keeping the rear portion fixed to the ground.

v Then it fixes the front end and releases the rear end.

v It then shortens the body and pulls the rear end forward.

v This makes it move forward by a small distance.

v Repeating such muscle expansions and contractions, the earthworm can move through soil.

v Its body secretes a slimy substance to help the movement.

a) Snail:

v The rounded hard structure on the back of the snail is called the shell.

v It is the outer skeleton of the snail but is not made up if bones.

v The shell is a single unit and is immovable.

v It has to be dragged around from place to place.

v There is a thick structure and the head of the snail underneath the shell.

v The thick structure is it’s foot which is strong and made up of muscles.

b) Birds:-

v Birds fly in the air and walk on the ground.

v Some birds like ducks and swans also swim in water.

v The birds can fly because their bodies are well suited for flying.

v Their bones are hollow and light. They are also called pneumatic bones

v The bones of the hind limbs are typical for walking and perching.

v The bony parts of the forelimbs are modified as wings.

v The shoulder bones are strong.

v The breastbones are modified to hold muscles of flight which are used to move the wings up and down.

c) Cockroach:-

v Cockroaches walk and climb as well as fly in the air.

v They have three pairs of legs.

v These help in walking.

v The body is covered with a hard outer skeleton.

v This outer skeleton is made of number of plates joined together and that permits movement.

v There are two pairs of wings attached to the body behind head.

v The cockroaches have distinct muscles — those near the legs move the legs for walking.

v The body muscles move the wings when the cockroach flies.

d) Fish:-

v The shape of a fish is similar to a boat.

v The head and tail of the fish are smaller than the middle portion of the body – the body tapers at both ends.

v This body shape is called streamlined.

v The shape is such that water can flow around it easily and allow the fish to move in water.

v The skeleton of the fish is covered with strong muscles.

v During swimming, muscles make the front part of the body curve to one side and the tail part swings towards the opposite side.

v The fish forms a curve to the other side.

v This make a jerk and pushes the body forward.

v A series of such jerks make the fish swim ahead.

v This is helped by the fins of the tail.

v Fish also have other fins on their body which mainly help to keep the balance of the body and to keep direction, while swimming.

How do snakes move?

· 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 snake’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.