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Some interesting facts about human blood vessels
The way the continuous flow of blood is maintained throughout our body through the intricate network of blood vessels is just amazing.
Blood vessels form an intricate network of tubular branched chambers which suppies blood throughout the body. Blood, being the specialized carrier fluid, supplies fresh oxygen,water and vital nutrients to different parts of the body and also carries back all the waste matters away from them to manatain the proper function of the body.
Arteries, veins and cappilleries are the three types of blood vessels.Beisdes those, there are extremely small vessels called Sinusoid which are located in certain organs like bone marrow spleen and liver.The arteries carry pure blood from the heart to different cells and tissues of the body wheras the impure blood drives back to the heart through veins. The thin hollow tubular junctions which connect between arteries and veins are called capilleries. Those narrow junction are permeable and allows the exchange of oxygen, nutrients along with fluid present in the surrounding cells and in exchange take all the impurities like Carbon dioxide and the impure blood is led to veins which further carry the blood back to the heart. As arteries move away from the heart they start getting narrower and connect to capilleries. The veins which conect cappilleries are also narrow compared to veins of other areas of the body and are called venules. The only exceptional vein is Pulmonary vein which, unlike other veins, carry oxygenated blood from the lungs to the heart.The circulation of blood through arterioles, cappilleries and venules is termed as microcirculation.
Structurally, arteries and arterioles are similar and both are strong, made up of thick walls of smooth muscle fibres. Functionally, arterioles have an additional role as compared to arteries i.e, to regulate blood pressure of the body. The flow of blood is regulated in both of them by contraction and relaxataion movement which is in turn, again regulated by sympathetic nervous system. The capplileries are one cell thick and are permeable in nature which facilitate the exchange of nutrients, oxygen and water. Most of the organs and tissues are generally surrounded by huge numbers of cappilleries establishing a complicated network. From cappilleries, deoxygenated blood gets drained to the venules and several of the venules unite together and connect to one vein. Veins are less elastic and thinner in structure compared to arteries .The flow of blood in vain is very slow in comparion with the flow in arteries. In veins, the transport of the de-oxygenated blood is regulated by valves which prevent flow of blood in opposite directions. The inferior venaceva and superior venaceva which put the deoxygenated blood into the left side heart are the thickest arteries in the body. In the right side of the heart is aorta , the largest artery of the body and which gives rise to other arteries through which all oxygenated blood flows out of the heart . If this highly branched networked blood vessels of the body are streched out, it will be approximately 160000 km long.