Gas exchange in humans

• Mammalian respiratory system

  A) Trachea

  B) Bronchus

  C) Bronchiole

  D) Alveoli

  E) Diaphram

  F) Heart

  G) Intercostal muscle

  H) Ribs

  I) Oesophagus

  
• Goblet cell

  • Produces mucus to trap dust particles and microorganisms

  
• How are alveoli adapted for high rate of diffusion?

  1. Large surface area
  2. alveoli are surrounded by capillaries so diffusion gradient is maintained
  3. Alveoli are 1 cell thick
  4. Red blood cells are slowed as they pass through capillaries next to alveoli = more time for diffusion
  5. Distance between air and red blood cells is reduced as red blood cells are flattened against capillary walls.

  
• Ventilation in humans

  Inspiration

  • Diaphragm muscles contract and flattens
  • External intercostal muscles contract, ribs move up and out
  • Volume in thorax increases and pressure in lungs decreases
  • Air moves in from high to low pressure

  Expiration

  • Diaphragm relaxes and creates a dome shape
  • External intercostal muscles relax pulling ribs down and in
  • Volume in thorax decreases and pressure in lungs increases
  • Air moves out from high to low pressure

  
• Elastic tissue allows the air to be forced out of lungs in expiration.

  
• Pulmonary ventilation rate = tidal volume x breathing rate
• Spirograph - a graph from when someone has used a spirometer

  A) Residual

  B) Expiratory reserve volume

  C) Lung capacity

  D) Vital

  E) Inspiritory

  F) Tidal

  G) Inspiration

  H) Expiration

  
• Rate of diffusion = Surface area x diffusion distance / thickness of exchange surface


  ROD = SAD / TOES