Signals from the respiratory centre in your brain travel down nerves to your diaphragm and other muscles. The diaphragm is pulled flat, pushing out the lower ribcage and abdomen. At the same time, the muscles between your ribs pull your rib cage up and out. This expands the chest and draws air into the lungs.
There is a chance that the person receiving that insulin will get a bad immune response, and there is a possibility that the animal might have a disease or infectious organisms, that their insulin might contain, and putting it inside a human might transmit that disease.
