The ductus arteriosus is a hole that allows the blood to skip the circulation to the lungs. However, when the baby is born, the blood must receive oxygen in the lungs and this hole is supposed to close. If the ductus arteriosus is still open (or patent) the blood may skip this necessary step of circulation. The open hole is called the patent ductus arteriosus.
Caring for a Bleeding Tooth. Some people mistakenly think that while brushing, a bleeding tooth is perfectly normal. It is not. Anytime there is any bleeding in the mouth, it is almost always a sign of periodontal disease. Even if you brush fairly hard, it should not cause healthy teeth and gums to bleed.
A tooth cavity may bleed for a number of reasons. Bleeding from the adjacent part of the gums. Pulp( the part inside your tooth containing nerves and blood vessels) exposure,in this case,depending on the size of exposure and the age of your tooth,your dentist will decide what needs to be done. Fractures that run deep an involve the pulp.