Which substance is released by body
cells to prevent blood from clotting inside blood vessels? (A) Fibrin, (B) plasma, (C)
dystrophin, (D) tropomyosin, or (E) heparin.
Have you ever had an injury that
caused you to bleed from the wound? If you have, you probably noticed
that the bleeding stopped after a short while. Eventually, a scab can form from
dried blood clots over the wound, which heals over time.
Blood clots tend to form when blood
vessels are damaged. The clot plugs up the damaged blood
vessel, thereby preventing the excess loss of blood. As you probably know, the flow of
blood in our blood vessels is crucial to our survival, as blood supplies the cells
in our organs with oxygen and nutrients and carries away their waste products.
Generally, clots will only form to
plug up damaged blood vessels, but sometimes they form even when damage has not
occurred. Can you imagine what might happen
if a blood clot formed when it wasn’t needed? This type of clot is called a
thrombus, and it can block the blood flow through the vessel, which could have
serious consequences for the body’s vital organs. Without a supply of blood, the
organs of the body could shut down, which might lead to permanent organ damage or
Thankfully, the body has a way of
preventing this from happening by producing a protein called heparin. Heparin is produced by cells in the
liver and lungs, and it prevents the formation of blood clots in blood vessels. It does this by preventing the
formation of fibrin, which would usually form in an insoluble fibrous mesh, trapping
red blood cells and platelets, thereby strengthening the blood clots. Without fibrin, blood clots cannot
form, so eventually normal blood flow will resume.
Now we know enough information to
find the correct answer to our question. The substance released by body
cells to prevent blood from clotting inside blood vessels is (E), heparin.