Obtain and Test Blood Samples

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Unit 66 Obtain and test blood samples 1.1 2.1 Capillaries are the smallest of all blood vessels and form the connection between veins and arteries. As arteries branch and divide into arterioles and continue to reduce in size as they reach the muscle they become capillaries. Here the capillaries form a capillary bed, which is a vast expanse of very small vessels forming a network throughout the muscle. However, unlike veins and arteries, their main function is not transporting blood. They are specially designed to allow the movement of substances, mainly gases Oxygen and Carbon Dioxide into and out of the capillaries. 2.2 A normal blood clotting process begins when the body sustains an injury to any blood vessels. The clotting process stops blood loss, creates a protective barrier, repairs the damage tissue and finally dissolves the protective barrier. The entire clotting process is known as haemostasis. During a normal clotting process, after a cut or other injury, an event called vasospasm can trigger the smooth muscles in small blood vessels to constrict. Vasospasm might reduce blood loss almost instantaneously. In another step, blood components that encounter an injured blood vessel will group together and form a platelet plug, through a chain reaction of blood clotting chemicals known as clotting factors. This process also creates a protein called fibrin, which is stronger than the platelet plug. The mesh-like structures of fibrin form the actual clot. In broken vessels, fibroblasts, which are a type of cell found in connective tissue, enter the clot and increase its strength. Anti-clotting factors in the blood balance the clotting factors to ensure that the clot does not become too large. As the injury heals, the blood clot is broken down, and it is absorbed by the body. The tough fibrin is dissolved by an enzyme known as plasmin. When blood

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