Human: How is a syringe used to take blood from a vein? Assistant: 
A syringe is typically used to draw blood from a person's vein. It is inserted into the skin at the back of the arm and then pushed forward until it reaches the vein, which is usually located in the inner elbow area. Once inside the vein, the plunger is pulled back, allowing the blood to fill the barrel of the syringe. The needle is then removed, and the filled syringe can be taken out through the same puncture site.