The circulatory system consists of three types of blood vessels: arteries, veins and lymphatic vessels. The functioning of the arteries involves carrying oxygenated blood from the heart to the tissues. In the normal course of blood circulation, small amounts of fluid and protein leak from arteries and veins.
Lymphatic vessels bring this protein-rich fluid back into the circulation. The third type of blood vessel is the vein, which transports oxygen depleted blood from the organs and tissues to the heart and lungs, where it is re-oxygenated.
The circulation of blood back to the heart tends to be passive and is enabled by muscular contraction in the arms and legs. The pressure of the blood in the veins is relatively lower and therefore, physical indications of any venous disease are often subtle and require further testing for complete diagnosis. Diseases of the veins fall into two broad categories: blockage from a blood clot (thrombosis) and inadequate venous drainage (insufficiency).
Blood clots are formed by the process of coagulation, which is defined as the blood’s natural tendency to clump and plug an injured blood vessel. Blood clots are made of blood cells and fibrin strands. They serve a valuable function in wound healing and impeding the flow of blood after an injury. Any form of wound, naturally commences the clotting process. Coagulation is marked by the compilation of blood platelets at the site of the injury and formation of a loose plug. These platelets release a number of chemicals that enhance and promote blood clotting. Soon after, a mesh of fibrin forms to create a stronger blood clot. This blood clot will remain in place until the healing process is complete. After it heals, still other chemicals are responsible for dissolving the clot. This process of forming and dissolving blood clots is called hemostasis.
Blood clots formed as part of the body’s natural healing mechanism are seldom risky. These undergo lysis or dissolution without causing any harm to the body functioning. However, blood clotting within the arteries and veins can prove to be dangerous as it disturbs the normal flow of blood. Blood clots can form in any vein or artery in the body. A blood clot that results in blocking a vein or artery partially is known as a thrombus. Whereas, a blood clot that dislodges from its original site and travels through the bloodstream until it becomes lodged in a smaller blood vessel, blocking the blood supply is called an embolus.
A blood clot that develops in the superficial vein is visible as a red streak along the course of an affected vein and is often accompanied by inflammation. Deep vein thrombosis may be noticeable in the form of swelling, fullness of the affected muscles and formation of a cord of clotted blood in the vessel. Without proper medical care, one-fourth of the cases of deep vein thrombosis result in pulmonary embolism. This occurs due to a portion of the clot detaching and lodging within the lungs. Complications of pulmonary embolism maybe begin with shortness of breath and end in death.
In the initial stages, a blood clot may be seen only as a red streak that causes discomfort due to swelling. However, this minor inflammation in the leg could gradually manifest into a life threatening condition.
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