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Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
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.
Vital signs (blood pressure, temperature, pulse rate, respiration rate) should be taken before any drug administration. Patients should be informed not to use tobacco or caffeine at least 30 minutes before their appointment.
Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.