Question

Why does the blood not clot inside uninjured vessels? What happens if the blood clots inside an intact vessel?

Answer 1

a substance called fibrinogen is present in blood... 
when there is a cut, this fibrinogen converts into fibrin. Fibrin and platelets are together responsible for clotting.... 

if a clot is formed in a blood vessel..it can lead to many effects... 
if the vessel was near brain then clot is fatal... 
if clot is near heart then high chances of heart attack... 

clot mainly blocks the blood to flow...so where ever the vessel is. it will prevent flow...

Answer 2

bcz fibrinogen is only activated into fibrin when clotting factors are released by liver in response to injury.

if the blood clots inside an intact vessel it can result in brain streke or heart attack