<p>I'm sorry, I don't know how to upload pictures here but I'll try to answer your question as best I can without it. Insects have tiny apertures on the exoskeleton called spiracles. These spiracles are connected to tubes called trachea and they allow oxygen to flow into the bodies of the insect for respiration. The oxygen goes directly through the aperture, then the trachea and to their cells. The spiracles serve the purpose  of letting air in and out of the insect. Much like the human nostrils. The smaller insects have the gases move in and oufy without any effort. This is because of their small size and as such small spiracles. It is called passive transport. The bigger insects on the other hand have to use their muscles to aid in the process. This is what is called active transport</p><p>Insects unlike humans, have no blood and as such, have no haemoglobin. Instead they have what is called hemolymph. It is a fluid in them which carries white blood cells, nutrients and waste materials. </p>