What part of a syringe is responsible for pulling back?

The plunger is the component of a syringe that is responsible for pulling back. It is a solid cylinder that fits snugly within the barrel of the syringe and can be moved back and forth. When the plunger is pulled back, it creates a negative pressure inside the barrel, which allows fluid to be drawn into the syringe. This mechanism is essential for drawing up medications or fluids from a vial or another source for injection.

In contrast, the barrel serves as the outer casing that holds the liquid and is marked with measurement increments, but it does not have the ability to move or create suction. The hub is the part of the syringe where the needle connects, while the filter is found in certain types of syringes to prevent particulate matter from entering the syringe but is not involved in the operation of pulling back. Understanding the role of the plunger is crucial for effective and safe syringe use in medical practices.