MODEL RELEASED. Blood sampling. Doctor takes a blood sample from an obese man suffering from a heart condition. A syringe is used to draw blood from a vein in the patient's arm. Inside the syringe is a vacutainer, a small test-tube which sucks in the blood once the vein is punctured. A blue tourniquet is tied around the patient's upper arm, trapping blood in the lower arm and enlarging the vein to make it easier to pierce. Surgical gloves worn by the doctor help maintain sterile conditions.