|
|
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.
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.
The U.S. Preventive Services Task Force recommends that all women age 65 years of age or older should be screened with bone densitometry.