Hypodermic Needle

A hypodermic needle (from Greek ὑπο- (under-), and δέρμα (skin)) is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it. They may also be used to take liquid samples from the body, for example taking blood from a vein in venipuncture. Large bore hypodermic intervention is especially useful in catastrophic blood loss or shock.

A hypodermic needle is used for rapid delivery of liquids, or when the injected substance cannot be ingested, either because it would not be absorbed (as with insulin), or because it would harm the liver. There are many possible routes for an injection.

The hypodermic needle also serves an important role in research environments where sterile conditions are required. The hypodermic needle significantly reduces contamination during inoculation of a sterile substrate (biology). The hypodermic needle reduces contamination for two reasons: First, its surface is extremely smooth, which prevents airborne pathogens from becoming trapped between irregularities on the needle's surface, which would subsequently be transferred into our media (i.e. agar) as contaminants; second, the needle's surface is extremely sharp, which significantly reduces the diameter of the hole remaining after puncturing the membrane, which consequently prevents microbes larger than this hole from contaminating the substrate.