Respiration: Meaning of Respiration, Human Respiratory System (For CBSE, ICSE, IAS, NET, NRA 2022)

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Meaning of Respiration

  • It is a metabolic process carried out in all living species.
  • The nutrients are converted into useful energy within the cell.
  • There is a production of energy with the intake of oxygen and the release of carbon dioxide within the same process.
  • Insects and worms do not have lungs to perform respiration.
  • Lungs are the primary respiratory organ in animals like birds, lions, cows, elephants, snakes, including humans.

Human Respiratory System

Human Respiratory System


  • Respiration occurs through spiracles in cockroach.
  • Spiracles are the small openings on the sides of the body.
  • Trachea is the respiratory organ of cockroach.
  • Trachea is also a dense array of a network of air tubes found in the internal system.
  • The pressure inside the system is balanced by trachea.
  • The oxygen rich air (enters through spiracles) diffuses into various tissues and cells of the body.
    • Oxygen is used for liberating energy.
  • Carbon-dioxide rich air passes into the trachea.
    • Moves outward through spiracles.
  • It is due to the respiratory process the carbon dioxide is given out.
Respiration in Cockroach


  • Earthworms do not have any special respiratory organs.
  • The skin feels moist and they are called slimy creatures.
  • The skin is the breathing organ in earthworms.
  • Air can easily pass through the skin of an earthworm.
  • Through the moist skin and capillaries, the exchange of gases takes place.
  • The hemoglobin dissolved in the blood picks up the oxygen and the carbon dioxide are released.
  • The skin is also used to move water and salts by active transport.
  • The earthworm՚s skin must be kept moist for diffusion to occur.
Earthworm Head

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