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(Chapter-11) Gas exchange in humans, When u Inhale - Coggle Diagram

- - - - The presence of millions of alveoli in the lungs provides a very large surface for gaseous exchange.
    - - There is only a two-cell layer, at the most, separating the air in the alveoli from the blood in the capillaries
      - One layer is the alveolus wall; the other is the capillary wall.
      - Thus, the distance for diffusion is very short.
    - - The alveoli are surrounded by networks of blood capillaries.
      - The continual removal of oxygen by the blood in the capillaries lining the alveoli keeps its concentration low.
      - In this way, a steep diffusion gradient is maintained, which favours the rapid diffusion of oxygen from the air passages to the alveolar lining.
- - - - When you inhale, your diaphragm muscle contracts and moves downwards, and the intercostal muscles contract and move the ribs upwards and outwards.
        
        This increases the volume of the lungs, which reduces the pressure inside and so air moves into the lungs to equalise it.
        
        Air that is rich in oxygen moves into the gas exchange system and then the body when you breathe in.
      - When you exhale
        
        When you exhale, our diaphragm muscle relaxes and moves upwards, and the intercostal muscles relax and move downwards and inwards.
        
        This reduces the volume of the lungs, which forces air outwards.
        
        Air with more carbon dioxide is then removed when you breathe out.
  - - - Trachea
        
        This is also called the windpipe. This tube runs from the mouth, down the throat towards the lungs. It is lined with rings of cartilage which keep it open at all times.
        
        Bronchus
        
        The trachea splits into a left and right bronchus (plural: bronchi), each leads to a lung.
        
        Bronchiole
        
        Each bronchus splits again and again into thousands of smaller tubes called bronchioles which take the air deeper into the lungs.
        
        Alveoli
        
        At the ends of bronchioles are tiny air sacs called alveoli. Here oxygen moves into the blood and carbon dioxide moves out.
        
        Intercostal muscles
        
        These muscles run between the ribs and form the chest wall. They contract and relax with the diaphragm when a person breathes.
        
        Diaphragm
        
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