1. Joints -
ü Some define a joint as a point where 2 bones connect. Others suggest it is a point where bones connect for the purpose of moving body parts.
ü There are six types of freely movable joints-
ü Ball and socket joint. Permitting movement in all directions, the ball and socket joint features the rounded head of one bone sitting in the cup of another bone. Examples include your shoulder joint and your hip joint.
ü Hinge joint. The hinge joint is like a door, opening and closing in one direction, along one plane. Examples include your elbow joint and your knee joint.
ü Condyloid joint. The condyloid joint allows movement, but no rotation. Examples include your finger joints and your jaw.
ü Pivot joint. The pivot joint, also called the rotary joint or trochoid joint, is characterized by one bone that can swivel in a ring formed from a second bone. Examples are the joints between your ulna and radius bones that rotate your forearm, and the joint between the first and second vertebrae in your neck.
ü Gliding joint. The gliding joint is also called the plane join. Although it only permits limited movement, it’s characterized by smooth surfaces that can slip over one another. An example is the joint in your wrist.
ü Saddle joint. Although the saddle joint does not allow rotation, it does enable movement back and forth and side to side. An example is the joint at the base of your thumb.
ü Fixed joint. The bones cannot move at some joints. Such joints are called fixed joints.There is a joint between the upper jaw and the rest of the head which is a fixed joint.
2. Human Skeleton -
ü It forms a framework that gives shape and support to the body.
ü It consists of 206 bones. It protects internal organs.
ü Skull- It protect the brain. It is rigid box made up of plates of bone firmly joined together.
ü Rib Cage- It is flexible case of ribs. Each rib curves round the side of the chest from the backbone and is joined in front to a plate of bone called sternum. Ribs are connected to one another by the muscles. Two lower most pairs of ribs are called ‘floating ribs’.
ü Backbone- It is also called the spine or vertebral column. It is a chain of small bones called vertebrae. It protect the spinal cord, which carries message between the brain and body. It also support the skull, ribs and limbs.
ü Limbs- It is made up of long bones with joints that allows them to move. They are mainly for support.
ü Hands- The consist of number of joints, the bones are joined at small distances which allow smooth body movement. The joints called as carpels.
ü Arms- fore-arms is made up of two bones and hands have several small bones. Shoulder bones have a pair of collar bones in front and a pair of shoulder blades.
ü Legs- Lower leg is made up of two bones and feet have several small bones. Hip bones or girdles bear weight of body and are attached to thigh bones.
ü Pelvic Bone- The region around the stomach is called as pelvic region. The bone below the stomach region is called pelvic bone.
3. Cartilage -
ü There are additional parts of the skeleton that are not as hard as the bones and which can be bent. These are called cartilage.
4. Muscle -
ü Muscles are present around the bones.
ü Contraction of muscle helps in movement of body part.
ü Muscles are highly responsible for body movements.
5. Gaits of Animals -
ü The different patterns of movement observed in animals due to the differences in their skeleton are called as gaits of animals.
ü Earthworm
Ø The earthworm does not have any internal skeleton.
Ø 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.
Ø The skin of earthworm also has a large number of tiny bristles that help it get a good grip on the ground.
Ø Repeated extension and contraction of the body muscles, enable the earthworm to move through the soil.
ü Snail
Ø Snails move with the help of their muscular, flat foot.
Ø They glide along a solid surface which is lubricated with mucus.
Ø This motion is powered by succeeding waves of muscular contractions of the foot.
ü Cockroach
Ø The body of a cockroach is covered with a hard outer skeleton that is made of different units joined together.
Ø It has three pairs of legs for walking and two pairs of wings attached to the breast for flying.
Ø It has distinct muscles that are used for movement.
Ø The muscles attached to the legs help in walking.
Ø The breast muscles attached to the wings help in flying, although they are not good flyers.
ü Birds -
Ø Birds have a special skeletal and muscular structures that help them to fly.
Ø The forelimbs are modified to become wings and the bones inside are hollow to suit flying.
Ø The bones of the hind limbs are used for perching and walking.
Ø The shoulder bones and breastbones are strong and support muscles of flight, which move the wings up and down.
ü Fish
Ø Fishes have a streamlined body that helps them swim with least resistance.
Ø They use tail fin for small jerks through water and other fins assist swimming.
Ø The tail fin is also used for changing directions.
Ø The body of fish is made such way that it can cut through water. The make up is called as streamed-line.
ü Snakes
Ø Snakes do not have legs for movement but use their long backbone along with muscles for movement.
Ø Their body curves into many loops, which gives it a forward push by pressing against the ground.
NCERT PRACTICE QUESTIONS
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.
Ans. - (a) movement (b) skeleton (c) hinge (d) muscles
2. Indicate true (T) and false (F) among the following sentences.
(a) The movement and locomotion of all animals is exactly the same. (False)
(b) The cartilages are harder than bones. (False)
(c) The finger bones do not have joints. (False)
(d) The fore arm has two bones. (True)
(e) Cockroaches have an outer skeleton. (True)
3. Match the items in Column I with one or more items of Column II.
4. Answer the following:
(a) What is a ball and socket joint?
(b) Which of the skull bones are movable?
(c) Why can our elbow not move backwards?
Ans. -
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 to forth movements.
Junior Science Topic - Body Movements. Chapter notes, video lectures, power point presentation and NCERT exercise solution. (Class 6, CBSE syllabus, chapter 08)
By - EduPorm India - The Educational Platform
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