The arrow is the broadhead’s delivery system. The broadhead punctures the skin and cuts muscle, fat, arteries, veins, lungs, liver, heart or any other organ it passes through. When the broadhead cuts through blood vessels (arteries and veins), it produces massive blood loss.
Death is caused by a drop in blood pressure and a lack of oxygen to the brain – a process called hemorrhagic shock. An animal must lose about one-third of its blood to lose consciousness and then die of hemorrhagic shock, but this might vary depending on how fast the blood is lost.
Deer carry roughly one ounce of blood per pound of body weight in their circulatory system. They usually die quickly from massive blood loss, but the exact time can vary from seconds to hours, depending on size, how many vessels were cut, and whether the broadhead severed arteries or veins.