|
|
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
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.
Oliver Wendell Holmes is credited with introducing the words "anesthesia" and "anesthetic" into the English language in 1846.
More than 34,000 trademarked medication names and more than 10,000 generic medication names are in use in the United States.
![An electrocardiogram (ECG, EKG) is a commonly used procedure in which the electrical events associat](https://biology-forums.com/gallery/47/medium_14755_01_10_12_7_54_15_920984.jpeg)
![J. P. Morgan, the financial genius, staved off ruinous competition among steel firms by combining mo](https://biology-forums.com/gallery/47/medium_27_24_08_15_1_27_03_223911186.jpeg)