These DAV Class 5 Science Notes and DAV Class 5 Science Chapter 1 Notes – My Body act as excellent revision resources, particularly in preparation for board exams.
My Body Class 5 DAV Notes
→ Organs :
→ Organs are special structures in our body. They perform specific functions. Examples: heart, eyes and stomach.
→ Organ System: A group of organs which work together for a particular function is called an organ system. Examples: Breathing System and Digestive System.
→ The Breathing System:
→ Breathing: All living things take in oxygen and give out carbon dioxide. This process is called breathing. The breathing process continues throughout the life. If breathing stops for more than two minutes, the living being can die.
→ Parts Of The Breathing System
→ Human breathing system
Process of Breathing: The process of breathing involves two steps, viz. inhalation and exhalation.
- Inhalation: The process of taking in air is called inhalation. When the diaphragm moves down, it results in inhalation.
- Exhalation: The process of giving out air is called exhalation. When the diaphragm moves up, it results in exhalation.
→ Respiration: Oxygen is consumed by different parts of the body. Different organs use oxygen to produce energy. Production of energy with the help of oxygen inside the body is called respiration. Carbon dioxide is released after respiration. Carbon dioxide is then sent back to the lungs by blood.
→ The Skeletal System
The skeletal system is made up of bones. There are 206 bones in adult human beings.
→ Bones: Bones are made up of calcium, phosphorus and some other minerals. Bones are hard structures. They have channels which contain blood vessels. Bones also have nerves. When we get hurt we feel pain because of precence of nerves. Blood vessels keep the bones alive.
→ Functions Of Skeletal System:
- It makes the framework of the body.
- It gives shape and support to the body.
- It protects the inner delicate organs.
→ Parts Of The Skeletal System
Following are the main parts of the skeletal system:
1. Skull
2. Backbone
3. Rib Cage
4. Limbs
→ The Joints:
→ The place where two bones are joined is called a joint. The end 1 of each bone is covered by a tough, smooth and shiny substance called cartilage. The ends of two bones in a joint are kept apart by a thin slippery fluid. This fluid 
→ Cartilage and slippery fluid prevent bones from scratches and bumps when they move against each other. The bones are held together by strong stretchy bands called ligaments.
→ There are many joints in our body. The joints in the skull are immovable because they are fused joints. Other joints in the body are movable.
→ Types of Movable Joints
Following are different types of movable joints: Flinge Joint, Ball and Socket Joint, Pivot Joint and Gliding Joint
→ Sense Organs
→ You have read in your previous classes that we have five sense organs, viz. nose, eyes, ears, tongue and skin. The sense organs help us in knowing about our environment.
→ Eyes
Each eye is a ball-like structure and is hence called eyeball. Each eyeball is placed in a bony socket in the skull.
The eyelids and eyelashes protect the eyeballs from dust and dirt.
→ Structure of Eye: The eye has following main structures:
→ Nose
The nose gives us the sense of smell. Nerve endings are present in the nose. They carry message about the odour to the brain.
→ Ears
The human ear is divided into three parts, viz. external ear, middle ear and internal ear.
→ External Ear: The portion of the ear which is visible to us is called external ear. It directs the sound waves to the inner ear.
→ Middle Ear: The middle ear has an ear drum and three small bones. The drum and the bones in the middle ear transfer the sound waves to the inner ear.
→ Inner Ear: The inner ear finally catches the sound waves and sends the message to the brain. The inner ear also helps in maintaining the balance of the body.
→ Tongue
Taste buds are present on the tongue. We get the sense of taste because of taste buds. Different parts of the tongue are sensitive to different tastes.
- The front portion of the tongue is sensitive to sweet taste.
- The sides of the tongue are sensitive to salty taste.
- The back portion of the tongue is sensitive to bitter taste.
- The sides of the back portion are sensitive to sour taste.
→ Skin
Skin gives us the sense of touch. We feel pain, touch, pressure, hotness and coldness because of nerve endings present in the skin.
Sense Organs In Different Animals
→ Insects: cockroaches, housefly and butterfly have feelers on their bodies. The feelers give them the sense of smell and taste. The housefly tastes with its legs.
→ Water Animals: Fish have a lateral line on their body. This gives them the sense of waves which are produced in water by other creatures. Thus, the fish detect their prey and enemy.
→ Birds: Birds too have eyes, ears, nostrils and tongue; as sense organs. Additionally, birds make different sounds to inform other birds about a situation. Some birds fly in groups in search of food. They call other members of the group to take rest or to go for searching food.
→ Reptiles: Snakes feel their surroundings with the help of their tongue. Snake feels vibrations in the ground with its skin.
→ Mammals: All mammals have similar sense organs as humans have. But some animals may be an expert in terms of a particular sense. For example; dogs and bears have well developed sense of smell. Bats have special power of hearing high pitched sound. Due to this, bats can easily detect their prey in dark. Bats use ultrasound to detect their prey. Ultrasound is a high pitched sound; which cannot be heard by humans.
→ Breathing System: The organ system responsible for breathing is called breathing system or respiratory system.
→ Inhalation: The process of breathing in is called inhalation.
→ Exhalation: The process of breathing out is called exhalation.
→ Respiration: The biological process of utilizing oxygen to produce energy is called respiration.
→ Cartilage: A tough smooth, elastic structure which cushions the bones at their joint is called cartilage.
→ Ligament: A strong elastic band which attaches two bones together at joints is called ligament.
→ Ultrasound: High frequency sound which cannot be heard by humans.
→ Joint: The place where two bones join is called a joint.
→ Floating Ribs: Ribs which are only attached to the backbone are called floating ribs.
→ Vertebrae: The ring-like bones which make the vertebral column are called vertebrae.