Gas Exchange

Size & Surface Area
1. Smaller animals
  1. High surface area
  2. Low volume
2. Multicellular organisms
  1. Need exchange organs
  2. Diffusion too slow
3. Affects heat exchange
  1. Depends on SA
  2. Small means it is harder to loose heat
  3. Compact shape means less SA
Gas Exchange
1. Fish
  1. Counter-current
    1. Water & blood flow in different directions
      1. Maximises gas exchange
        Concentration of oxygen in water always higher than blood
  2. Filaments
    1. Increase SA
  3. Lamellae at right angle to filaments
2. Insects
  1. Tracheae
  2. Spiricles
    1. Pores on surface
    2. Oxygen travels down concentration gradient
3. Humans
  1. Lungs
    1. Trachea
      1. C-shaped cartilidge
        Supports and stops collapsing
    2. Bronchi
    3. Bronchioles
    4. Alveoli
      1. Thin exchange surface
        Short diffusion pathway
        Speeds up rate
      2. Large SA
        Large number of alveoli
      3. Surrounded by capillaries
        Maintains concentration gradient
  2. Inhalation
    1. Internal relax
    2. External contract
    3. Diaphragm contracts
      1. Flattens
  3. Exhalation
    1. External relax
    2. Internal contract
    3. Diaphragm relax
Effects of lung disease
1. TB
  1. Reduces tidal volume
    1. Gas exchange surface damaged
  2. Can cause fibrosis
2. Fibrosis
  1. Formation of scar tissue
    1. Less recoil
    2. Reduced FEV
3. Asthma
  1. Inflamed airways
  2. Large amounts of mucus
  3. FEV reduced
4. Emphysema
  1. Inflammation
  2. Break down of elastin
    1. Less recoil

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Gas Exchange

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	Created by Alex Lyes almost 8 years ago