Blood clot by James Archer A thrombus, or blood clot, is the final product of the blood coagulation step in hemostasis. Blood clotting is an important mechanism to help the body repair injured blood vessels.
Blood consists of: -red blood cells containing hemoglobin that carry oxygen to cells and remove carbon dioxide (the waste product of metabolism) -white blood cells that fight infection -platelets that are part of the clotting process of the body -blood plasma, which contains fluid, chemicals and proteins that are important for bodily functions. Complex mechanisms exist in the bloodstream to form clots where they are needed. If the lining of the blood vessels becomes damaged, platelets are recruited to the injured area to form an initial plug. These activated platelets release chemicals that start the clotting cascade, using a series of clotting factors produced by the body. Ultimately, fibrin is formed, the protein that crosslinks with itself to form a mesh that makes up the final blood clot. Blood clots are healthy and lifesaving when they stop bleeding. However, blood clots can also form abnormally, causing a heart attack, stroke, or other serious medical problems. Most heart attacks and strokes result from the sudden formation of a blood clot on a waxy cholesterol plaque inside an artery in the heart or brain. When the plaque ruptures suddenly, thrombogenic substances inside the plaque are exposed to blood, triggering the blood clotting process. Blood clots may also form when blood fails to flow properly. Atrial fibrillation is an abnormal heart rhythm in which blood pools in the heart, potentially forming blood clots. If a blood clot dislodges and travels to the brain, it can cause a stroke. Prolonged immobilization can reduce blood flow in the legs, increasing the risk for blood clots in leg veins. Venous clots do not allow blood to return to the heart and symptoms occur because of this damming effect. Most often occurring in the legs or the arms, symptoms include: -swelling -warmth -redness -pain Arterial clots do not allow blood get to the affected area. Body tissue that is deprived of blood and oxygen begins to die and becomes ischemic (isch=to restrain + emia = blood). Pain is the initial symptom of the ischemia, or oxygen deprivation due to loss of blood supply. Other symptoms depend upon the location of the clot, and often the effect will be a loss of function. Heart attack and stroke are self-explanatory. In an arm or leg, in addition to pain, the limb may appear white, and weakness, loss of sensation, or paralysis may occur. If the blood supply is lost to an area of the bowel, in addition to intense pain, there may be bloody