A needle syringe is a device used for injecting, removing or infusing fluids. They are most commonly known in health care settings for injecting medications and for use in removing blood from the body. Syringes can differ in size and type, and they can be made of glass or plastic. The syringe chosen usually depends on its intended purpose. The syringe consists of a plunger, barrel, hub, needle and the needle's protective cover. It is important that all parts of a syringe coming into contact with the body be kept free of contamination.
The plunger is located at the end of the syringe and can be made of clouded or colored glass or plastic. Its purpose is to fill or empty the barrel. The plunger is pulled back to fill the barrel and is pushed forward for emptying.
The barrel is the part of the syringe that contains the fluid, whether it is a medication, blood or a solution drawn from the body. It is usually calibrated in tenths (a tenth is equal to 0.1 milliliters) to make precise measurements of the quantity of the fluid that is to be given or removed. The barrel can range in size from 0.5 mL to 50 mL.
The lower end of the syringe, opposite the plunger, terminates into a needle hub. The hub consists of a needle adapter that allows the needle to be attached to the syringe. The hub also functions to lock the needle in place while using the syringe for its desired function.
The needle consists of the shaft, lumen and bevel. Needles vary in length, size of the shaft and size of the lumen. The shaft is the metal's length and is usually chosen depending upon the route and site of administration, physical mass of the client, and the thickness of the medication. The lumen, also known as the bore, is the hollow space within the needle. The diameter of the lumen is known by the needle's number gauge. The lumen is chosen with the same specifications as the shaft. The last part of the needle, the bevel, is the pointed end and determines the needle's sharpness.
The protective cover/cap is provided to maintain the needle's sterility. Needle sticks are a common way of transporting infections to health care providers and clients. The needle's bevel is covered to limit the amount of accidents that could happen involving needles and to ensure that only the intended client receives the needle stick. In an attempt to reduce contamination and increase safety, most needles are disposable and are thrown out after a single use.