Blood, Electrolytes, and Intravenous Infusions
1-6
1-6. MUSCLE CONSTRICTION
At the same time, the muscles of the damaged vessel constrict. Shortly after the first plug forms, platelets fuse into a dense mass. This mass forms a temporary solid seal at the injury site. As the platelets agglutinize (clump), a second type of constriction occurs. The platelets release a chemical called "serotonin." This chemical causes the second type of constriction of the injured and neighboring blood vessels. After this series of platelet changes, the clotting mechanism occurs.
