Answer:
because when you do it on accident it is unintentional and scares you because you werent expecting it. but when you do it on purpose it wont hurt because your brain stops you from doing it so hard that it hurts lol
Explanation:
the first answer as blood needs to be oxygenated to be passes round the body then when its deoxgenated it will return to the heart to be pumped around the body again
An eroded area of the stomach mucous membrane is called a peptic ulcer.
