SCIENCE Class 5 CBSE Chapter 7: Bones & Muscles Body consists of several parts of organs. Example: lungs, heart, stomach & eyes. Organs of the body do not work alone, they work with other organs. Several organs work together to perform one major function of the body. Example: teeth, salivary gland, stomach & intestines work together to digest food. The organs that work together are called an organ system. Example: digestive system. Body system Main organs Functions Nervous system Brain, spinal cord, nerves Controls all the functions of our body. Skeletal system Bones Gives shape to the body and protects internal organs. Muscular system Muscles Helps in the movement of body parts. Circulatory system Digestive system Heart, blood, blood vessels Teeth, stomach, small and large intestines Carries food and oxygen to all the parts of the body and collects waste materials. Digests food which provides energy. Breathing system Nose, lungs Absorbs oxygen and gives out carbon dioxide. Excretory system Kidneys & skin Removes waste from the body.
Reproductive system Different in males and females Production of children. The skeletal system: Bones in the body forms a framework called as the skeletal system. It gives shape and strength to the body. It protects the brain, heart, lungs and other soft organs inside the body. Bones are hard and are of different shapes and sizes. Example: leg & hand boneslong; chest bones- thin & rounded; head- flat & rounded; fingers-short. Adult skeletal system has 206 bones. Outside of the bone is hard & tough & inside, it is soft & spongy. Inside of the bone has a jelly-like material called bone marrow, this produces blood cells in your body. Bones are living and can mend themselves if they break. Parts of the skeleton: A. The skull B. The backbone C. The ribs D. The limbs (arms & legs) E. The joints The skull: 1. Bones of the head make up the skull. 2. It protects the brain & contains holes for eyes, nose, ears and mouth. 3. It is made up of 22 different bones that are joined together. 4. Upper part of skull is made up of 8 bones. 5. Face is made up of 14 bones. 6. Lower jaw bone is the only moving bone in the skull. The backbone: 1. It has 33 small bones called vertebrae in the back that are joined to form backbone. It is also called spine or vertebral column. 2. Joints allow slight movement of vertebrae. You can bend and twist the back due to this movement. 3. Each vertebrae has a hole in it. The delicate spinal cord passes through this hole. Therefore the vertebral column protects the spinal cord.
The ribs: 1. Ribs are thin & flat, curved bones that form a cage around your heart and lungs to protect them. 2. We have 12 pairs of ribs. They join the backbone at the back and most are joined to the breastbone in the front. 3. 2 pairs of lower ribs are not attached to the breast bone, and are called as floating ribs. The limbs: 1. Hind limbs or legs: Hipbone is made of 3 bones joined together. Bones of lower limbs are attached to this hipbone. Upper half of the leg has a long bone called femur bone or thigh bone. Lower half of the leg has the shin bone and calf bone. At the end of the leg is foot which has a number of small bones. 2. Forelimbs or hands: The upper limbs (arms) are attached to the shoulder blades. Upper arm has one long bone called humerus. Lower arm has two long bones. Wrist and hand has several small bones. The joints: 1. Joints help the bones of the skeletal system move. 2. Joints are places where two bones are joined together. 3. These bones are held together by long stretchy bands called ligaments. 4. There are many joints in the body, different joints allow different type of movements, and only bones of the skull don t allow movement. 5. Main types of movable joints are: a. Hinge joint b. Ball & socket joint c. Pivot joint d. Gliding joint Hinge joint: Very long joints. Allow only back and forth movements. Example: knees & elbows
Ball & socket joint: Here one bone s end is rounded like a ball and it fits into hollow socket of another bone s end. It allows movement in all directions. Example: hip & shoulder Pivot joint: It allows the movement from right to left and also up and down. Example: joint between skull & neck that slows the movement of our head. Gliding joint: Here the bones can slide over each other. Allows for side to side motion and forward and backward movement. Example: wrist & ankles. The muscular system: 1. Bones cannot move by themselves, they need something to move them. Muscles attach to bones & pull to make them move at joints. Every movement needs muscles. 2. 640 muscles in the human body & they make up 40% of body weight. 3. They are made of tough elastic tissue 4. Muscles attach to bones by a tough band of tissue called tendons. 5. Muscles can only pull at bones, they cannot push. So to move bones in one direction, at least 2 muscles are required. Example: to move the lower arm you need 2 muscles- biceps & triceps. When you raise your arm, biceps become shorter (contract). To lower the arm, the triceps at the back contract and pull the arm down. Kinds of muscles: 1. Voluntary muscle: these muscles control the movements of your body and are under your control, hence they are called as voluntary muscles. Example: muscles of hands and legs. 2. Involuntary muscles: these are muscles of the body which are not under your control and they work on their own. Example: stomach, intestines, walls of the blood vessels.
3. Cardiac muscle: The heart is made up of special kind of tough muscle called cardiac muscle. It is involuntary and works throughout your life and never gets tired.