|
|
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.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Methicillin-resistant Staphylococcus aureus or MRSA was discovered in 1961 in the United Kingdom. It if often referred to as a superbug. MRSA infections cause more deaths in the United States every year than AIDS.
There are 60,000 miles of blood vessels in every adult human.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.
![It is important to ask patients what other health care providers they are seeing, such as the dentis](https://biology-forums.com/gallery/47/medium_2137_17_05_12_2_17_18.jpeg)
![A client is having an endoscopy performed by a physician who views the upper gastrointestinal intern](https://biology-forums.com/gallery/47/medium_18099_24_10_12_4_35_00.jpeg)
![In 2008, the U.S. economy suffered a gaping wound as several trillion dollars were ripped out of it.](https://biology-forums.com/gallery/47/medium_262797_12_08_15_1_33_47_22176335.png)