Respiration & respiratory system

• Respiration


  A series of enzyme-controlled reactions that release energy (in the form of ATP) from the breakdown of organic compounds (e.g. glucose)
• Respiration


  • Involves a sequence of exothermic chemical reactions occurring in the mitochondria and cytoplasm of cells
  • Is important because a constant supply of energy is required for many essential processes in living cells e.g. movement, homeostasis and active transport
• Types of respiration


  • Aerobic
  • Anaerobic
• Aerobic respiration


  Glucose + oxygen → carbon dioxide + water (+ energy)
• Anaerobic respiration


  Glucose → lactic acid (+ energy)
• Anaerobic respiration


  Takes place without oxygen (e.g. during vigorous exercise) and releases energy from the partial breakdown of glucose
• Anaerobic respiration


  Produces an 'oxygen debt' due to lactic acid build-up. To 'repay' this, extra oxygen must be taken in after anaerobic respiration to break down lactic acid in the liver
• Large multicellular organisms


  • Require a respiratory system because they have a small SA/V ratio and diffusion is insufficient to provide all cells with the required O2 and to remove all CO2
• Pathway of gas through the respiratory system

  Nose → trachea → bronchi → bronchioles → alveoli → capillaries

  
• ventilation?

  • movement of fresh air into the lungs and stale air out of lungs e.g. inspiration (breathing in) & expiration (breathing out)
• Inspiration?


  ribs move up and out, diaphragm contracts and flattens, volume of thorax increases, Thoracic pressure falls below air pressure, air moves into the trachea
• expiration?

  • ribs move down and in, diaphragm relaxes and reverts to dome shape, volume of thorax decreases, Thoracic pressure rises above air pressure, air moves out of trachea
• how can a bell jar model be used as a model of ventillation?

  • as rubber sheet is drawn down during inspiration, volume of the bell jar increases and its pressure falls below air pressure.
• Limitations of bell jar model?

  • balloons are empty, bell jar does not move, glass tube is rigid, rubber sheet drawn downwards
• alveoli?

  • a cluster of air sacs found in the lungs where gas exchange occurs
• How does O2 diffuse in alveoli

  • O2 diffuses from air in alveoli into blood in capillaries
• How does CO2 diffuse in alveoli?

  • diffuses from the blood in the capillaries into air in alveoli
• How is alveoli adapted for gas exchange?

  • large surface area, has a network of capillaries, rapid blood flow, thin walls
• how do you test for the presence of CO2?

  • bubble gas through limewater CO2 turns lime water milky
• list the effects of smoking?

  carcinogens, tar, nicotine, carbon monoxide
• how does carcinogen cause a effect?


  Chemicals that increase the risk of cancer, e.g. lung, oesophagus, mouth
• how does tar cause a effect from smoking?


  Sticky substance deposited in the airways.
• how does nicotine have a effect from smoking?


  Addictive. Increases heart rate. Directly damages lungs.
• how does carbon monoxide have a effect from smoking?


  Binds with haemoglobin in red blood cells reducing the oxygen-carrying capacity of the blood.