Chapter 7: Respiration in Humans

• Aerobic respiration


  The release of energy by the breakdown of glucose in the presence of oxygen
• Anaerobic respiration


  The release of energy by the breakdown of glucose in the absence of oxygen
• Aerobic respiration


  1. Breakdown of glucose

  2. Presence of oxygen

  3. Release of energy

  4. Carbon dioxide and water as byproducts
• Anaerobic respiration


  1. Breakdown of glucose

  2. Absence of oxygen

  3. Release of energy

  4. Lactic acid as byproduct
• Aerobic respiration releases a large amount of energy
• Anaerobic respiration releases a relatively small amount of energy
• Oxygen debt


  The amount of oxygen needed to remove lactic acid built up during anaerobic respiration in muscle cells
• Addressing oxygen debt


  1. Increased heart rate

  2. Deeper and faster breathing
• During vigorous activity


  Anaerobic respiration occurs in muscle cells to meet increased energy demand
• Breathing involves movement of air in and out of the lungs
• Respiration refers to cellular respiration
• Plants, small animals and microorganisms can be used to study aerobic respiration
• Yeast can be used to study anaerobic respiration
• Yeast produces carbon dioxide as a byproduct of anaerobic respiration
• Lactic acid causes pain and stiffness in muscles
• Lactic acid is an acid
• Anaerobic respiration


  1. Breaks down glucose in the absence of oxygen

  2. In muscle cells, lactic acid is produced as byproduct

  3. Produces a relatively small amount of energy

  4. Can be studied using yeast (Note: Yeast does not produce lactic acid but produce gives off carbon dioxide as one of the byproducts)
• Oxygen debt


  • Occurs when there is insufficient supply of oxygen in muscles during vigorous activity
  • Addressed through keeping the heart rate fast and breathing deeper and faster
• Lactic acid


  Is it an acid or base?
• Breathing exercise


  1. Breathe in and out for 1 min

  2. Hold breath for 10 seconds
• Why is breathing important?
• Chapter 7 Respiration in Humans

  • 7.1 Why Do Livings Respire?
  • 7.2 How Does Gas Exchange Occur in Humans?
  • 7.3 What Effects Does Tobacco smoke Have on Human Health?
• Larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries


  • State their functions in human gaseous exchange
• Alveolus


  Explain how its structure is related to its function of gaseous exchange
• Unicellular organisms have a large surface area-to-volume ratio for gas exchange to occur through diffusion
• Humans and complex organisms have relatively small surface area-to-volume ratio and therefore require special organs for gas exchange
• Flow of air in the human gas exchange system

  1. Nasal passages

  2. Larynx

  3. Trachea

  4. Bronchi

  5. Bronchioles

  6. Alveoli
• Parts of the human gas exchange system


  • Nasal passages
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
• Features of the air passages: warmed and moistened air, hair and mucus trapped unwanted particles, sensory cells detect harmful chemicals
• Trachea features: gland cells secrete mucus to trap unwanted particles and bacteria, ciliated cells have hair-like structures (cilia) to help remove dust-trapped mucus
• Lungs


  • Have numerous alveoli, walls of alveoli are one cell thick with a thin film of moisture on inner walls, surrounded by numerous blood capillaries
• Gas exchange in the alveolus


  Continuous flow of inhaled and exhaled air
• Oxygen transport around the body


  Where does this occur? Explain.
• Concept cartoon: Comment on their views.
• Composition of inspired and expired air


  • Nitrogen
  • Oxygen
  • Carbon dioxide
  • Others (e.g. water vapour, dust particles)
• How does inspired air differ from expired air?
• Reinforce the concepts of gas exchange through this interactive animation.
• How have smoking ads changed now? What are the restrictions on smoking now?
• Which of the following is a smoker's lungs? What do you think happened to the lungs?
• Major toxic components of tobacco smoke


  • Nicotine
  • Tar
  • Carbon monoxide