Final answer:
Following vascular spasm, blood loss is reduced and the ends of the severed vessel may retract. Vascular spasm is an immediate response that reduces blood flow via smooth muscle contraction, aiding in hemostasis and minimizing blood loss until a platelet plug and coagulation can occur.
Step-by-step explanation:
Following a vascular spasm, blood loss is reduced, and the ends of the severed vessel may retract. Vascular spasm is the initial step in hemostasis, which is the process the body utilizes to prevent the loss of blood following an injury. The smooth muscles in the vessel walls contract with the release of endothelins by the vessel-lining cells and stimulation of pain receptors. This contraction includes both circular layers, which constrict blood flow, and, if present, longitudinal layers that draw the vessel into the surrounding tissue - thus possibly complicating surgical procedures to locate and secure the vessel ends.
The vascular spasm serves an essential purpose in the body's defense by providing time for the formation of a platelet plug and subsequent coagulation (blood clotting). If this or any subsequent step fails, it can result in hemorrhage, which is excessive bleeding. Coagulation and later stages of hemostasis, including fibrinolysis, continue the process of healing the blood vessel and ensuring that blood loss is minimized and normal blood flow is eventually restored.