Dynamic model of human respiratory system (electric type):

The human breathing mechanics model consists of a mechanical case, ribs, intercostal muscles, a breastbone, a diaphragm, a windpipe, bronchi, bronchioles, lungs, a mechanical unit and a synchronous electronic circuit.
Operating Instruction:
The process of demonstration:
1. Inspiration: It is brought about by the chest expanding.
a. The ribs swing outwards and upwards. This is brought about by contraction of the intercostals muscles.
b. The diaphragm moves downwards, so that instead of being dome-shaped, it becomes flattens.

All these movements result in an increase in the volume of the thoraxThis creates a negative pressure-a suction force-inside the thorax.
a. The light in the lungs and the windpipe becomes brighter. That shows the walls of the lungs are pulled outwards and air is drawn into them.
2. Expiration: It is brought about by the reverse process.
a. The rids swing downwards and inwards, the breastbone moves back slightly.
b. The diaphragm bows upwards. The volume of the thorax decreases and this creates a positive pressure inside it.
c. The light in the lungs and the windpipe becomes dim. That shows air is forced out of the lungs.