Final answer:
If blood is spurting out of a large cut, an artery has likely been severed. Arteries are under high pressure and will cause blood to spurt in time with the heartbeat. The body attempts to stem blood loss through hemostasis, but severe cases require medical intervention.
Step-by-step explanation:
If blood is spurting out of a large cut, it is likely that an artery has been cut. Arteries are the types of blood vessels that carry oxygen-rich blood away from the heart under high pressure, which is why blood spurts out in a rhythmic pattern that matches the heartbeat. When an injury occurs that severs a blood vessel, blood and blood components such as erythrocytes (red blood cells), and leukocytes (white blood cells) are released from the break.
The body responds to such vascular injuries through a process known as hemostasis, which involves three steps to prevent further blood loss: vascular spasm, formation of a platelet plug, and coagulation. Vascular spasm causes the damaged vessel to constrict, reducing blood flow. Platelets then accumulate at the injury site, releasing clotting factors that lead to the formation of a blood clot, sealing the wound and preventing additional blood loss. However, with large vessel injuries like an arterial cut, medical intervention is usually required to control the bleeding.