CBSE Class 6 Science Human Body and its Movement Exam Notes

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Class 6 Science: Human Body and its Movement (Exam Notes)

Locomotion

The movement of an organism's body from one place to another is called locomotion. Locomotion involves the whole body, but only a particular body part is used for locomotion.

Locomotion helps animals:

1. to move from an unfavourable environment to a favourable environment.
2. to find their food and water.
3. to protect themselves from their enemies.
4. to find their partners (mates) for reproduction.
5. to find a suitable place for laying eggs or rearing their young ones.

Body movements

A change in the position of any part of the body with respect to its axis is called movement. Stationary animals such as sponges, corals and sea anemones show this kind of movement. For example, when you agree or disagree with someone, you shake your head; this shaking of the head is called the movement of the head. For any body movement, energy and coordination between the different organ systems are required. All animals meet their energy requirements through nutrition and respiration.

Important movements in our body are:

1. movement of the heart muscles
2. movement of the teeth and jaw during eating
3. movement of the eyelids
4. circulation of blood in the body

Human body and its movements

Our body has a lot of flexibility. It can move its parts in different directions easily. For example:

1. You can bend your leg at the knee. You cannot bend it beyond 180°.
2. You can rotate your arm around your shoulder. You can move your arm sideways, upwards and downwards.
3. You can bend your arm at the elbow. You cannot bend it backwards.
4. You can turn your neck around, up and down and from side to side.

Joints

The place where two or more bones meet is called a joint. In other words, a joint is the region of movement between two bones that work on one another. In vertebrates there are three kinds of joints:

1. Perfect (movable) joints
2. Imperfect (slightly movable) joints
3. Immovable or fixed joints

Perfect joints are those which make free movement possible in various directions. They are of four types:

1. Ball and socket joints
2. Hinge joints
3. Pivot joints
4. Gliding joints

1. Ball and socket joints allow movement in most directions, e.g. the shoulder and hip joints. Shoulder joint: the shoulder joint of man is made up of the rounded upper end of the humerus, which fits into the shallow glenoid cavity.
   
   Hip joint: the hip joint is similar to the shoulder joint. The acetabulum of the pelvic girdle is much deeper than the glenoid cavity, and the ball on the upper end of the femur is larger than the head of the humerus.
2. Hinge joints permit only to-and-fro movement in one plane, e.g. the joint between the upper and lower arm (elbow joint), the thigh and lower leg (knee joint) and fore arm and wrist joint, and between the phalanges of all the digits.
3. Pivot joints allow rotation only. It is this type of joint which enables you to turn your head from side to side.
4. Gliding joints: the bones slide over each other, and the movements allowed are in all planes but very limited, e.g. the joints between the distal end of radius and ulna.

Labels of the shoulder joint figure: Articular Cartilage, Clavicle (Collarbone), Humerus (Upper Arm), Scapula (Shoulder Blade), Glenoid.

Imperfect joints: in this type, the bones are separated by a layer of cartilage, and a very limited amount of movement of one bone upon the other is made possible by the flexibility of the intervening cartilage.Immovable or fixed joints allow no movement. Such joints are present between the skull bones of an adult.

The skeletal system

The framework of bones and cartilages which supports the body of an animal or human is called its skeletal system. The human skeleton is made up of 206 bones and some cartilages. Bones are hard. Cartilages are soft and elastic. The human skeleton consists of the skull, backbone, ribs, breastbone, bones in the arms and legs, shoulder bones and hip (pelvic) bones.

Functions of the skeletal system

1. It forms the framework of the body.
2. It provides support and gives shape to the body.
3. It helps to protect and keep the delicate organs of the body in their proper positions, e.g. the bony cage made by the breastbone, ribs and backbone protects the heart and lungs.
4. The brain is protected by the bones of the skull.
5. The backbone protects the spinal cord.
6. Muscles help in the movement of the various parts of our body, e.g. any movement of our arms or legs is supported by the muscles in these parts of the body.

Organs of the skeletal system

The skull has two main parts:

1. Cranium: it covers and protects the brain. The bones of the cranium are flat and are held firmly in a zipper-like manner.
2. Facial bones: they consist of the upper and lower jaws and a few other bones. The lower jaw is movable. The movement of this jaw enables us to eat, talk and sing. The skull also includes a pair of eye sockets.

The backbone (or the vertebral column) extends from the base of the skull to the hip. It consists of 33 small ring-like vertebrae joined end to end. The first 24 vertebrae are joined by elastic cartilages. The main nerve cord (spinal cord) passes through the hollow bony tube formed by the vertebrae. The 5 vertebrae of the hip are fused and inseparable, and the 4 vertebrae of the tail are also fused. The backbone has 5 regions, starting from the top: neck → chest → belly → hip → tail.The chest bones form a cone-shaped bony cage. The elliptical bones of the cage are called ribs. 12 pairs of ribs curve round the sides, and the ribs are attached to the sides of the vertebrae at the back. 10 pairs of these ribs are attached to the breast bone at the front with the help of cartilage. The two pairs of ribs in the front which are free are called floating ribs. The chest bones protect the lungs and the heart.The shoulder bones are formed by the collar bone and the shoulder blade. They connect the upper part of the chest and the bones of the arm.The hip or pelvic bones: each hip bone is formed by the fusion of three bones. The hip bones together with the hip and the tail parts of the backbone form the pelvis.The hand bones: the hand consists of the upper arm, forearm, wrist, palm and fingers.

1. The upper arm has one long bone, attached to the shoulder bone.
2. The forearm has two bones (the radius and the ulna), and the wrist has several small bones.
3. Each finger consists of three small bones.

The leg bones: the leg includes the thigh, lower leg, ankle, foot and toes.

1. The thigh bone is the strongest and longest bone in the body.
2. The lower leg consists of two bones.
3. The ankle consists of several small bones.
4. In the front part of the knee, there is a disc-like cap called the patella.
5. The foot has five longer bones.
6. Each toe has three smaller bones.
7. In a normal foot, the bones are set to form an arch-like arrangement. The foot arches provide good support to the body.
8. In a flat foot, the bones are not arched. Some people with flat feet feel pain.

Cartilage: cartilages are not as hard as bones and can be bent. The upper part of the ear is made of cartilage. The lower portion of the ear (the ear lobe) is soft.

Gait of animals

Different animals use different organs to move from one place to another.

1. Birds: birds have two kinds of locomotion. They can walk on any surface with their legs; the bones of the hind limbs are fit for walking and perching. Birds fly in the air by spreading their wings. The body of a bird is streamlined and suitable for flying. Their bones are hollow and light in weight. The bony parts of the forelimbs are modified as wings. Ducks and swans can also swim in water.
2. Fish: fish have a spindle-shaped, streamlined body, which helps them to move in water. They use their muscular tail and fins for swimming. Air-filled swim bladders make the body buoyant. During swimming, the front part of the body and the tail part curve in opposite directions. This makes a jerk and pushes the body forward. The paired and unpaired fins help to keep the balance of the body and to keep the direction.
3. Snakes: the long body of a snake consists of a large number of vertebrae. The adjoining vertebrae, ribs and skin are interconnected with slender body muscles. The movement of a snake is called slithering.
4. Cockroach: a cockroach can walk and climb on a surface and can also fly a short distance in the air. In a cockroach the exoskeleton is jointed and permits movement. Three pairs of jointed legs attached to the chest region (thorax) help the cockroach to walk. Two pairs of wings are also attached to the thorax. In the thorax, there are strong and large muscles. One set of these muscles moves the legs for walking; another set moves the wings during flying.
5. Earthworm: earthworms and leeches move by contracting and expanding their bodies. There are bristle-like projections called setae which help in movement. The muscular movement pushes the body in the direction of the movement.
6. Snail: the body of a snail is covered with a hard shell. This shell cannot help in movement. The snail comes out of a circular hole in the shell. The snail has a muscular foot, which is a part of its belly and helps it in locomotion.

 

Fill in the blanks:

Question. Food pipe and wind pipe originate in the ______________ .
Answer : Pharynx.

Question. Person of blood group _______________ is called a universal donor.
Answer : ‘O’

Question. WBCs act as _____________ in our body.
Answer :  Soldiers

Question. Each lung has double layered covering, called as _____________.
Answer : pleura.

Question. Human heart is made up of involuntary ____________ muscles.
Answer : cardiac

 Match the following:
Answer :

1. Heartbeat           5000-6000 Per mm3
2. WBC                  2.4 - 41 lakh
3. Blood donation    Decastello and Sturils
4. Platelets             72
5. Study of blood    370C

True or False :

Question. Each lung has single layer covering pleura.
Answer : False.

Question. Cells need the Supply of Soluble nutrients and axygen for energy production.
Answer : True.

Question. Energy Production occur within the cells.
Answer : True.

Question. Blood group ‘O’ was discovered by Decastello and Sturli in 1902.
Answer : False.

Question. Heart pumps about 75 ml of blood during each beat.
Answer : True.

Name the following :

Question. Blood pressure of a Healthy person.
Answer : 120/80 mm to 13g/8g mm

Question. The small compartments present in the lungs.
Answer : Alveoli

Question. Person who recieves blood.
Answer : Blood donor.

Question. Iron containing protein in RBCs.
Answer : Haemoglobin

Question. The pH of Blood.
Answer : 7.4

Answer the following : 

Question. How does exchange of gases take place in lungs?
Answer : Gaseous exchange occurs continuously while blood is Circulating around the alveoli. An iron containing protein-hemoglobin is present in the RBCs of blood. Hemoglobin absorbs the oxygen from air within alveoli. Simultaneously, CO2 and water vapor’s move from blood into the alveoli. Thus, oxygen is taken into the blood and CO2 and water vapor’s are removed from the blood and given out by exhalation.

Question. State the importance of arteries, veins and capillaries.
Answer : (a) Arteries : Blood vessels which carry the blood away from heart are called as arteries. Except the one carrying blood towards lungs, all carry oxygenated blood. These vessels do not have valves.
(b) Veins : Vessels carrying the blood from lungs transport deoxygenated blood.
(c) Capillaries : Arteries gradually branch out with decrease in their diameter as they spread in the body and finally form fine hair like vessels called as capillaries. Capillary network in
present in each organ.

Question. Which life processes occur continuously in our body?
Answer : Respiratory process and circulation occurs continuously in our body.

Question. Which organ are present in the respiratory system.
Answer : Human respiratory system consists of nose, pharynx, wind pipe, lungs and diaphragm.

Question. What is Cellular respiration? 
Answer : Dissolved nutrients like glucose are slowly burnt (oxidized) with the help of oxygen and energy is released in the form of ATP.
Waste materials like CO2 and water vapor’s are produced during this process. Cellular respiration can be summarized as follows.
C6H12O6 + 6O26CO2 + 6H2O + Energy (38ATP).