Although my pictures are not the best they show the main concept in the model lung which I made. The bottle itself has a balloon across the bottom which acts as the diaphragm. As the 'diaphragm' is pulled down the is a pressure decrease within the bottle due to the increase in volume. This draws air into the straw, 'the trachea, gullet', which is in turn attached to a balloon in the bottle. As air is drawn in the balloon increases in volume, the balloon here is imitating the lung. when the diaphragm is pushed up the pressure increases in the bottle, 'rib cage', this forces air out the 'lung' and next returns outside. The model therefore shows the process of inhalation and exhalation caused by the movement of the diaphragm.
However there are some serious flaws to using this model to describe the complicated process of gas exchange. Firstly there are no intercostal muscles in this model, and the ribcage is immovable. Inhalation also requires the intercostal muscles on the ribcage to contract, this moves the ribcage up and out. This movement is not shown within this model. In the model there is only one lung and no branching as in the brochi are missing. This can be improved by having two balloons with a branched straw into the two balloons. This would show how air pressure causes both lungs to increase in size. The balloon used as the lung loses its structure as soon as the air is removed, this ofcourse does not occur in a real lung where the lung maintains its structure through the bronchi, bronchioles, and alveoli. To improve this the balloon could be stuffed with polysterene pellets, whcih would allow air to pass in and out but also maintain its structure.
Overall the model is good for teaching purposes, however it should not be taken as an actual model to base ideas on gas exchange upon as it has far too many flaws.
However there are some serious flaws to using this model to describe the complicated process of gas exchange. Firstly there are no intercostal muscles in this model, and the ribcage is immovable. Inhalation also requires the intercostal muscles on the ribcage to contract, this moves the ribcage up and out. This movement is not shown within this model. In the model there is only one lung and no branching as in the brochi are missing. This can be improved by having two balloons with a branched straw into the two balloons. This would show how air pressure causes both lungs to increase in size. The balloon used as the lung loses its structure as soon as the air is removed, this ofcourse does not occur in a real lung where the lung maintains its structure through the bronchi, bronchioles, and alveoli. To improve this the balloon could be stuffed with polysterene pellets, whcih would allow air to pass in and out but also maintain its structure.
Overall the model is good for teaching purposes, however it should not be taken as an actual model to base ideas on gas exchange upon as it has far too many flaws.