Select all that are true of a vascular spasm.
Check All That Apply
Blood loss is slowed.
Blood flow is slowed.
Is initiated by the release of vasoactive chemicals.
Involves contraction of the tunica media.
The Correct Answer and Explanation is:
Correct Answers (Check All That Apply):
✅ Blood loss is slowed.
✅ Blood flow is slowed.
✅ Is initiated by the release of vasoactive chemicals.
✅ Involves contraction of the tunica media.
Explanation
A vascular spasm is the immediate and temporary constriction of a blood vessel in response to injury. It represents the first step in hemostasis, the process that stops bleeding. This response is crucial in minimizing blood loss and providing time for the next steps in hemostasis: platelet plug formation and coagulation.
When a blood vessel is damaged, vascular smooth muscle in the tunica media contracts, narrowing the lumen of the vessel. This contraction is mediated by a variety of signals, including nervous system reflexes, local myogenic responses, and especially vasoactive chemicals such as endothelins, thromboxane A2, and serotonin released by platelets and damaged endothelial cells.
This constriction results in two primary outcomes:
- Blood loss is slowed – By reducing the diameter of the vessel, less blood can escape through the injury, which limits hemorrhage.
- Blood flow is slowed – The reduced flow rate helps facilitate the accumulation of platelets at the injury site, promoting the formation of a platelet plug.
The tunica media, the middle layer of the vessel wall, is primarily composed of smooth muscle tissue, and its contraction is key to the vascular spasm. The strength and duration of the spasm vary depending on the size of the vessel and the extent of the injury. In small vessels, this mechanism can sometimes be enough to stop bleeding entirely.
Thus, vascular spasm is a rapid, localized, and short-lived response that initiates the body’s repair mechanisms. It buys time for longer-term clotting mechanisms to activate and restore vessel integrity.
