Decompression sickness is still one of those things which are least understood by divers. Yes, most divers know the symptoms and treatment but what does actually happen in your body? Despite many articles and video’s on the internet I have yet to find an easy understandable explanation so even children would get what happens in your body.
First we are going to start with the air we breath. If there were a 100 particles in every breath of air we take, 79 of them would be nitrogen and 21 of them would be oxygen. This is a rough simplification because there are other gases in the air like C02, Argon etc. Imagine that those 100 particles are human and your body is a city. From those 100 persons 79 of them are tourist (Nitrogen) and 21 are residents (oxygen).
The gateway to the city (your body) are your lungs. With every breath 21 residents and 79 tourist land in your body via the airport which we call your lungs. The residents get by customs and in their car (red blood cells) en go to work to fuel your body. Without the residents the whole city would soon cease to exist.
However your body doesn’t like tourists and turns them around right at the airport to get the next flight out of town. Therefore you breath out nitrogen unused and the nitrogen isn’t useful to your body in any way. But when we go for a scuba dive everything changes in the city. The 79 tourist grow to 158 tourist at 10 meters / 33 feet. This is to many for the airport to handle and the tourists flood the city. They use the roads to get all over the city to do what tourist do, nothing. You body doesn’t interact with the nitrogen or uses it. More and more tourist pour into the city and not after long al lot of places in the city are full, this is called saturated. Some places are harder to reach for the tourist and take longer to saturate.
The que for the tourist to leaf is when we ascend, imagine it to be the end of the day. If we make a safe ascend all the tourist make there way to the airport in a orderly fashion. The form a que and nicely wait for there taxi to arrive and take them to the airport. There they get on there plane and leave our body.
But suddenly there is a tornado hitting the city. The tourist panic and try to exit the city as soon as possible. Tourist pile on each other to get the first taxi to race to the airport. The big packs of tourist jam the sights and highways. In the panic some get lost and end up in the city-hall (your brain). All the trapped tourist just make an entire mess of the city and wreak havoc in it. This is the result of a too fast ascend while scuba diving and now you got decompression sickness.