are very dangerous and can lead to death if not taken care of. Sounds to me like you are very healthy but need to eat more whole wheats and fiber. try to eat more oatmeal and grain breads, this clears out all of the "yucky" stuff in your system. Also, cardio workouts are good. This causes the heart to pump more and works the blood through the arteries and veins clearing them. Get massages to help with the circulation. IT is very healthy for you.
I do not know if you are worried about this for a reason, but talk to your parents and let them know your concerns. IF this is just a curiousity question just because you want to be healthier, then that is great.