|
|
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.
Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.
It is believed that the Incas used anesthesia. Evidence supports the theory that shamans chewed cocoa leaves and drilled holes into the heads of patients (letting evil spirits escape), spitting into the wounds they made. The mixture of cocaine, saliva, and resin numbed the site enough to allow hours of drilling.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.