( ( When ( ( a ( small ( blood vessel ) ) ) ( is injured ) ) ) ( , ( platelets ( ( ( ( ( adhere ( to ( each other ) ) ) ( around ( ( the edges ) ( of ( the injury ) ) ) ) ) , ) ( forming ( a clot ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT a) (JJ small) (NN blood) (NN vessel)) (VP (VBZ is) (VP (VBN injured))))) (, ,) (NP (NNS platelets)) (VP (VBD adhere) (PP (TO to) (NP (DT each) (JJ other))) (PP (IN around) (NP (NP (DT the) (NNS edges)) (PP (IN of) (NP (DT the) (NN injury))))) (, ,) (S (VP (VBG forming) (NP (DT a) (NN clot))))) (. .)))
When a small blood vessel is injured, platelets adhere to each other around the edges of the injury, forming a clot.
(ROOT (S (NP (NNS Platelets)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (DT the) (NN cell) (NNS fragments)) (VP (VBN involved) (PP (IN in) (NP (NP (NN blood) (NN clotting)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBP stick) (PP (PP (TO to) (NP (NP (NNS tears)) (PP (IN in) (NP (NN blood) (NNS vessels))))) (CC and) (PP (TO to) (NP (DT each) (JJ other)))))))))))))) (. .)))