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Decompression Sickness
As we’ve already seen, the low pressure of space prevents oxygen fromremaining dissolved in your blood. This vacuum-like environment does the same for other gasses, like nitrogen. This causes tiny nitrogen bubbles to form all throughout your circulatory system (which is the literal definition of the bends). One side effect these bubbles have is extreme joint pain, but far worse are the effects the bubbles have when they create blockages in your veins and arteries. Bubbles in your brain can cause stroke and seizures. A bubble in your heart can cause sudden heart failure and death.
No Blood Pressure
As you can tell by now, space has horrible effects on the human body. Both internally and externally, you are stretched, ballooned, and otherwise contorted. As a result, your misshapen body will struggle to maintain anormal blood pressure. For example, a person can easily generate enough force to drink soda through a normally sized straw. But what if the straw’s diameter was 10 times as large? Similarly, your heart would not be capable of pumping blood through your enlarged veins. Your blood pressure would effectively drop to zero and you would die.
Boiling Blood
The lower the pressure is in an environment, the lower the boiling point will be for any liquid in that same environment. This is because when there’s less pressure, it’s easier for the molecules to move around, so it takes less heat energy to transform the packed-in molecules of a liquid to a less-dense gas.
This is why water boils more easily at higher altitudes. In space, the boiling point of your blood could realistically drop down until it’s the same as your own body temperature—at which point your blood would begin to boil. The temperature of your blood would still be normal, but in the vacuum of space that might be all it needs to boil.
Suffocation By Hypoxia
When exposed to the vacuum of space, a person will be totally deprived of oxygen, but not in the way you might think. The condition is known ashypoxia: Without earth-like pressure, the oxygen in your bloodstream will begin to reverse-dissolve and escape from your blood. This will render your cardiovascular system useless, and no oxygen will be delivered to your muscles or vital organs. The fact that you are no longer able to breathe in any new oxygen just exacerbates the problem. In addition, the suffocating effect would begin to turn your skin blue. A person can last approximately 10 seconds in this condition before they black out.
