Rubber Syringe

Hypodermic needles are used with hypodermic needles to inject liquid or gas in the tissues of the body, or dispose of the body. The injection of air into a blood vessel is undesirable because it can cause an air embolism, the prevention of embolism in removing air from the syringe is one of the reasons why the familiar image of the holding a hypodermic syringe upside down, pressing it, and expelling small amounts of liquid before injection into the bloodstream.

The barrel of a syringe, plastic or glass, and has generally received marks indicating the volume of liquid in the syringe, and is almost always transparent. glass syringes may be sterilized in an autoclave. However, most modern medical syringes are plastic with a rubber piston, because this type much better seal between the piston and the cylinder and because they are cheap enough to eliminate having been used only once, reducing the risk of spread of diseases transmissible by blood. Reuse of needles and syringes has caused the spread of diseases, including HIV and hepatitis among intravenous drug users. The syringes are, however, often re-used by diabetics, which is safe, if the syringe is used by one person.

medical syringes are sometimes used without a needle for oral liquid medications for young children or animals, or milk for children younger animals, because the dose can be measured accurately, and it is easier to inject drug in the subject's mouth instead of reassuring the subject to drink from a measuring spoon.