Respiration in Organisms

• Why Do We Respire?

  • Cellular Energy: Breakdown of glucose to release energy
  • Basic Need: Survival, growth, and repair of cells
  • Role of Food: Stored food is broken down during respiration

• Types of Respiration

  • Aerobic Respiration
    • Occurs in the presence of Oxygen
    • Products: Carbon dioxide, water, and large amount of energy
    • Common in humans, animals, plants
  • Anaerobic Respiration
    • Occurs in the absence of Oxygen
    • Products: Alcohol, carbon dioxide, and energy (in yeast)
    • Lactic acid and energy (in human muscles during heavy exercise)
  • Muscle Cramps
    • Caused by lactic acid accumulation due to temporary anaerobic respiration

• Breathing

  • Definition: Taking in oxygen-rich air and giving out carbon dioxide-rich air
  • Inhalation: Drawing in air rich in oxygen
  • Exhalation: Giving out air rich in carbon dioxide
  • Breathing Rate: Number of times a person breathes in a minute
  • Mechanism in Humans
    • Diaphragm: Sheet of muscle at the floor of the chest cavity
    • Ribs move up and outward, diaphragm moves down during inhalation
    • Ribs move down and inward, diaphragm moves up during exhalation

• Respiration in Other Animals

  • Earthworms: Through moist and slimy skin
  • Insects (Cockroaches): Network of air tubes called tracheae and spiracles
  • Frogs: Through lungs as well as moist skin
  • Fish: Using special organs called gills rich in blood vessels

• Respiration in Plants

  • Gas Exchange Mechanism
    • Tiny pores on leaves called stomata
    • Roots take in oxygen from air spaces between soil particles
  • Process
    • Oxygen breaks down glucose (just like in animals)
    • Leaves respire day and night, photosynthesis occurs only in daytime