injection

injection introduction of a fluid into the body, usually by means of a needle and syringe. The material injected may be a test substance (as in determining allergic sensitivity or immunity to a disease), an anesthetic, a therapeutic drug, a nutrient (in cases where intravenous feeding is necessary), blood, or blood plasma (see blood transfusion ). An intracutaneous injection is the introduction of a small amount of fluid between the skin layers. A subcutaneous injection is directed to the tissues under the skin. When quicker absorption of a drug is required, an intramuscular injection may be used; even more rapid action is obtained by injection into a vein (intravenous). In certain emergencies involving the heart, such as cardiac arrest, an intracardiac injection can penetrate directly into a chamber of the musculature of the heart. Anesthetics are sometimes injected into the spine. In an injection by means of a jet injector gun, fluid penetrates through the skin by means of air pressure and there is no visible puncture mark. Micro-injections can be made into fetuses, even individual cells, with tiny capillary injectors.

in·jec·tion / inˈjekshən/ • n. 1. an instance of injecting or being injected: painkilling injections an injection of capital was needed. ∎  a thing that is injected: a morphine injection. ∎  the action of injecting: sometimes a polio vaccine is given by injection. ∎ short for fuel injection. 2. the entry or placing of a spacecraft or other object into an orbit or trajectory.

injection In medicine, use of a syringe and needle to introduce drugs or other fluids into the body to diagnose, treat or prevent disease. Most injections are either intravenous (into a vein), intramuscular (into a muscle), or intradermal (into the skin).