Biology AQA 3.1.4 Lung Function

Biology AQA 3.1.4 Lung Function

1. The gross structure of the human gas exchange system limited to the alveoli, bronchioles,bronchi, trachea and lungs.

   • Diagram of the lungs.
   • Trachea
     • There is a layer of cells with cilla on top, also goblet cells produce mucus which traps any dust and dirt within the lungs.
       • Mucus is then passed down the oesophagus

2. The essential features of the alveolar epithelium as a surface over which gas exchange takes place

   • ADAPTIONS OF THE ALVEOLI
     • Large surface area
     • Thin
     • Partially permeable membrane
     • Movement of environmental medium (breathing)
     • Movement of internal medium (heart pumps blood)
     • Small capillaries

3. The exchange of gases in the lungs

   • Diffusion & (surface area x difference of concentration) / Length of diffusion pathway

4. pulmonary ventilation as the product of tidal volume and ventilation rate

   • Pulmonary ventilation (dm^3min^-1) = tidal volume (dm^3) x ventilation rate (min^-1)
     • PV: the total volume of air that is moved into the lungs
     • The volume of air taken in during each breath
     • The number of breath's taken in one minute

5. The mechanism of breathing

   • Inspiration
     • process of breathing in- uses energy in the form of ATP
       • EXTERNAL intercoastal muscles contract
       • Ribcage pulled upward and outward
       • Diagphragm contracts
       • Increased volume and lower pressure
   • Expiration
     • The process of breathing out
       • INTERcoastal muscles contract
       • Ribcage moved downwards and inwards
       • Diagphragm relaxes (curves upwards)
       • Volume decreases and pressure incread - ready for elastic recoil

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