Afterward, there may be some throbbing . The arterial stick is more painful than venipuncture because arteries are deeper than veins, have thicker walls, and have more nerves. There is a slight risk of damage to surrounding tissues while the blood is obtained. Specimens are also obtained from lower risk sites, and techniques are used to minimize tissue damage. It is also used for regulation of body temperature, regulation of fluids, and acid-base equilibrium.
Plasma contains various substances dissolved in the fluid.
The cellular portion consists primarily of red blood cells, but also includes white blood cells and platelets . Because blood is used for multiple functions within the body, tests on the blood or its components may give valuable clues in the diagnosis of a multitude of medical conditions. Arterial blood differs from venous blood primarily in its content of dissolved gases. Testing of arterial blood shows the make-up of the blood before any of its contents are used by the body tissues. However, arterial sticks may occasionally be performed to obtain blood culture or serum chemistry samples.