Structures & Functions of the Gas Exchange System (Cambridge (CIE) AS Biology): Revision Note
Exam code: 9700
The gas exchange system: structure and functions
Ciliated epithelial cells, goblet cells and mucous glands play vital roles in maintaining the health of the gas exchange system
Cartilage, smooth muscle, elastic fibres and squamous epithelial tissue all play important structural roles in the gas exchange system
Structure | Function |
|---|---|
Ciliated epithelial cells | These cells line the trachea to the bronchi Each cell has tiny projections called cilia, which sweep mucus, dust, bacteria and other microorganisms up and away from the lungs to the mouth, where they are swallowed and digested by stomach acid |
Goblet cells | Goblet cells are embedded throughout the ciliated epithelium and are mucus-producing cells The mucus they produce traps dust, bacteria and microorganisms as mentioned above |
Mucous glands | The mucous glands work with goblet cells in the trachea and bronchi to produce mucus |
Cartilage | Rings of cartilage line the trachea, or windpipe Cartilage is a strong but flexible tissue and is essential for keeping the trachea open Because of its flexibility, the cartilage can move and flex as we breathe |
Smooth muscle | Smooth muscle is muscle not under conscious control and is found in the walls of the trachea, bronchi and bronchioles It helps to regulate the flow of air into and out of the lungs by dilating and widening when more air is needed |
Elastic fibres | Elastic fibres are found in the squamous epithelium of the alveolar walls Elastic fibres are a critical component of alveoli because they allow the tiny alveoli to stretch as they fill with air and recoil to help force air out It is the elastic abilities of alveoli which enable them to have such a large surface area |
Squamous epithelium | The squamous epithelium is made up of flattened cells that line the alveoli This layer is thin and permeable for the easy diffusion of gases |
Examiner Tips and Tricks
Make sure that you don’t confuse the cilia in the respiratory system for microvilli in the small intestine. At first glance they appear similar, but they have very different functions! Cilia are for sweeping mucus while microvilli are for the absorption of nutrients.
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