======Build a Model Lung======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Bottle Lung Model
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====Summary====                   
{{$demo.summary}}



====Procedure====  
  - Cut the bottom off a 2-liter plastic bottle to form the chest cavity.  
  - Make a Y-shaped straw connector: cut one straw to create legs for the “Y,” then attach it airtight to another straw with a diamond-shaped opening.  
  - Attach a balloon to each end of the Y-shaped connector to act as lungs, securing them with tape or elastic bands.  
  - Place the straw and balloon structure inside the bottle and thread the straw through the bottle’s neck. Seal the opening airtight with tape or plasticine.  
  - Tie a knot in a third balloon, cut across its widest part, and stretch it tightly over the bottom opening of the bottle, taping in place. This acts as the diaphragm.  
  - To operate, gently pull down on the knotted balloon to simulate inhalation and release it to simulate exhalation.



====Links==== 
DIY model lungs - MEL Chemistry: 
{{youtube>fybV8zIGyu8?}}\\

Respiration: Lung model in a bottle - QEST Inc: 
{{youtube>qf9moNMuUyM?}}\\

📄 Build a model lung - Inverness Science Festival: [[https://www.uhi.ac.uk/en/t4-media/one-web/university/stem/isf/fayre-22/make-a-lung.pdf]]\\


====Variations====
  * Use transparent balloons for the lungs so inflation is more visible.  
  * Try different bottle sizes to model different chest cavity volumes.  
  * Connect multiple straws and balloons to model additional branching bronchi.



====Safety Precautions====
  * Use scissors carefully when cutting the bottle and straws.  
  * Supervise children with balloons, as broken pieces can pose a choking hazard.  
  * Ensure all seals are tight to avoid frustration if the model doesn’t work initially.




====Questions to Consider====
  * What happens when the diaphragm balloon is pulled downward? (The chest cavity volume increases, lowering air pressure and drawing air into the lung balloons.)  
  * What happens when the diaphragm balloon is released? (The chest cavity volume decreases, pushing air out of the lung balloons.)  
  * What part of the body does the bottle represent? (The chest cavity.)  
  * Why do the lungs inflate and deflate without being squeezed directly? (Air pressure changes inside the cavity cause the balloons to expand and contract.)