Respiration

• Respiration


  Chemical reaction that involves breakdown of food mainly glucose to release energy
• Types of respiration


  • Aerobic respiration
  • Anaerobic respiration
• Aerobic respiration


  Total breakdown of glucose using energy to release large amount of energy
• Anaerobic respiration


  Incomplete breakdown of glucose in absence of oxygen releasing small amount of energy
• Breathing


  Muscular movement to keep the respiratory surface supplied with oxygen
• Inspiration


  Inhalation/taking in of air
• Expiration


  Exhalation/breathing out of air
• Respirometer


  Measures rate of respiration of living organisms
• Spirometer


  Measures the depth of breathing of humans
• Breathing rate


  Number of breaths per minute
• Breathing depth


  Volume of air entering the lungs
• Heart rate


  Number of beats per minute/in one minute
• Stroke volume


  Volume of blood pumped by heart/in one beat
• Cardiac output


  The number of beats per minute multiplied by the volume of blood pumped in one beat
• Oxygen debt


  The oxygen needed by the body after exercise due to insufficient supply of oxygen while exercising
• Chemoreceptors


  Receptors in the brain that are responsible for detecting change in pH of the blood
• Lactic acid


  An acid produced during anaerobic respiration which is toxic and causes muscle cramps
• Gas exchange system


  • Functions
• Trachea


  Airway that allows air to flow into lungs
• Bronchus


  Airway that allows passage of air into right lung
• Larynx


  Structure that makes sounds
• Ribs


  Move up/down to increase/decrease volume
• Internal intercostal muscles


  Contracts to lower the ribs in forced exhalation
• External intercostal muscles


  Contracts to decrease air pressure in lungs
• Diaphragm


  Contracts to increase volume of chest cavity in inhalation
• Alveoli


  Site of gas exchange
• Trachea adaptation


  • Lined with ciliated epithelial cells and goblet cells
  • Goblet cells secrete mucus which traps dust and bacteria
  • Cilia beats
  • To move/sweep mucus out of lungs back to throat to be swallowed and killed by stomach acid
  • Rings of cartilage to keep trachea open and prevent it from collapse, for continuous air flow
• Alveoli adaptation


  • Many alveoli - For larger surface area
  • Wall is one cell thick - For shorter diffusion distance
  • Good/many blood capillaries/supply - To carry gas to and from the cells and for faster gas exchange by diffusion
  • Moist lining - To dissolve gases and prevent dryness of wall
• Gases move into the alveoli by diffusion
• Inhalation/Inspiration


  1. External intercostal muscles - Contract

  2. Internal intercostal muscles - Relax

  3. Ribs - Up and Outwards

  4. Diaphragm - Contract and flattens

  5. Volume of chest cavity - Increases

  6. Pressure in lungs - Decreases

  7. Direction of air - Into
• Composition of inhaled air

  • 21% Oxygen
  • 0.04% Carbon dioxide
  • 78% Nitrogen
  • Water vapour is variable/changeable
• Exhalation/Expiration


  1. External intercostal muscles - Relax

  2. Internal intercostal muscles - Contract

  3. Ribs - Down and Inwards

  4. Diaphragm - Relax and moves Upwards

  5. Volume of chest cavity - Decreases

  6. Pressure in lungs - Increases

  7. Direction of air - Out
• Composition of exhaled air

  • 16% Oxygen
  • 4% Carbon dioxide
  • 78% Nitrogen
  • Warm temperature (heat excreted)
  • Moisture/Water vapour is saturated/high
• Oxygen is being used up for aerobic respiration by respiring cells, and carbon dioxide is a product of respiration, which is toxic and needs to be excreted out of the body
• When the diaphragm contracts, the volume of the thorax/chest cavity increases and the pressure decreases
• Soda lime is used in a respirometer to absorb CO2 so that insects are not killed by excess CO2 present
• Types of respiration


  • Aerobic
  • Anaerobic
• Aerobic respiration


  1. C6H12O6 + 6O2 ---> 6CO2 + 6H2O

  2. Uses oxygen

  3. Total breakdown of glucose

  4. Releases large amount of energy

  5. Occurs in mitochondria
• Anaerobic respiration


  1. C6H12O6 ---> 2C3H6O3

  2. Releases energy in absence of oxygen

  3. Occurs in cytoplasm

  4. Causes build-up of lactic acid in muscles

  5. Causing muscle cramps

  6. Releases small amount of energy

  7. Oxygen debt present
• Cardiac output


  Heart rate x stroke volume