Biology AQA 3.1.4 Lung Function

The gross structure of the human gas exchange system limited to the alveoli, bronchioles,bronchi, trachea and lungs.
1. Diagram of the lungs.
2. Trachea
  1. There is a layer of cells with cilla on top, also goblet cells produce mucus which traps any dust and dirt within the lungs.
    1. Mucus is then passed down the oesophagus
The essential features of the alveolar epithelium as a surface over which gas exchange takes place
1. ADAPTIONS OF THE ALVEOLI
  1. Large surface area
  2. Thin
  3. Partially permeable membrane
  4. Movement of environmental medium (breathing)
  5. Movement of internal medium (heart pumps blood)
  6. Small capillaries
The exchange of gases in the lungs
1. Diffusion & (surface area x difference of concentration) / Length of diffusion pathway
pulmonary ventilation as the product of tidal volume and ventilation rate
1. Pulmonary ventilation (dm^3min^-1) = tidal volume (dm^3) x ventilation rate (min^-1)
  1. PV: the total volume of air that is moved into the lungs
  2. The volume of air taken in during each breath
  3. The number of breath's taken in one minute
The mechanism of breathing
1. Inspiration
  1. process of breathing in- uses energy in the form of ATP
    1. EXTERNAL intercoastal muscles contract
    2. Ribcage pulled upward and outward
    3. Diagphragm contracts
    4. Increased volume and lower pressure
2. Expiration
  1. The process of breathing out
    1. INTERcoastal muscles contract
    2. Ribcage moved downwards and inwards
    3. Diagphragm relaxes (curves upwards)
    4. Volume decreases and pressure incread - ready for elastic recoil

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Biology AQA 3.1.4 Lung Function

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