Gas Exchange in Mammals

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  • Created by: Jasmine
  • Created on: 19-02-16 20:17

Structure of the gaseous exchange system

  • Breathe in- air enters via the trachea 
  • Trachea splits in bronchi- one bronchus to each lung
  • Each bronchus then branches into bronchioles
  • Bronchioles end in small 'air sacs' called alveoli
  • Many alveoli in the lungs- large SA for diffusion
  • Ribcage, intercostal muscles and disphragm work to move air in and out
  • (
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Exchange Systems

Goblet Cells

  • Secrete mucus
  • Traps microorganisms, dust particles
  • Stops them from reaching the alveoli


  • Hair like structure
  • Surface of epithelial cells- celiated epitheliual cells
  • Moves the mucus (secreted from goblet cells)
  • Moves mucus up towards the throat and away from alveoli- then swallowed
  • Prevents lung infections
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Exchange Systems

Elastic Fibres

  • Walls of the trachea, bronchi, bronchioles and alveoli
  • Help with breathing
  • Breathing in- lungs inflate and the elastic fibres stretch
  • Fibres recoil which forces the air out when exhaling

Smooth Muscle

  • Walls of trachea, bronchi and bronchioles NOT ON ALVEOLI
  • Smooth muscle relaxes during exercise- tubes become wider
  • Less resistance to airflow so air can move in and out of lungs easily
  • Contracting and relaxing


  • Rings of cartilage on trachea and bronchi
  • Strong but flexible- stops collapsing when breathing in and pressure drops
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Distribution of features in the gaseous exchange s


  • Elastic fibres, smooth muscle, c shaped cartilage, ciliated epithelium containing goblet cells


  • Elastic fibres, smooth muscle, cartilage piece, ciliated epithelium containing goblet cells


  • Elastic fibres, smooth muscle, ciliated epithelium with some goblet cells


  • Elastic fibres, alveolar epithelium, capillary
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