Disruption of the endothelium leads to increase in smooth muscle constriction due to increased production of the vasoconstrictor substances, endothelin and endothelium-derived constricting factor(s).1
This spasm is triggered by chemicals released from damaged endothelial cells and pain receptors[1].
[What chemicals are released endothelial cells and pain reeptors?
Vasoconstriction that serves to decrease blood flow.
Collagen is exposed at the site of injury and the collagen promotes platelets to adhere to the injury site.
Platelets release cytoplasmic granules which contain serotonin, ADP and thromboxane A2, all of which increase the effect of vasoconstriction.