The Circulatory System is built of the heart and blood vessels comprising of arteries, veins and capillaries. The principal function of the of the heart, the main organ in the circulatory system, is to push blood throughout the body. The work of the arteries is to carry blood away from the heart.
Veins carry blood back to the heart that is a hollow, muscular pump. A network of minute capillaries links the arteries and veins. The capillaries, though very small, are one of the most important parts of the circulatory system because they deliver nutrients and oxygen to the cells. In addition, these capillaries also remove waste products such as carbon dioxide.
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The Functions of the Circulatory System
In humans, the principal function of the Circulatory System includes:
- To deliver oxygen and nutrients to all parts of the body;
- To enable respiration; and
- To remove wastes.
The Circulatory System is composed of three separate system that function together; these three systems are- the heart, the lungs and the blood vessels. The circulatory system consists of the pulmonary circulation, a ‘loop’ between the heart and the lungs, in which blood is made oxygen rich (the process is known as oxygenated). It also ensembles the systematic circulation that moves through the rest of the body to cater oxygenated blood to the different parts of the body.
When alien substances and organisms attack and enter the body, it is swiftly informed to the disease fighting white blood cells and antibodies by the circulatory system that conveys them to the regions under attack.
It is important to mention here the Unique Vein. The veins are blood vessels that carry de-oxygenated blood. The only vein in the human body that carries oxygenated blood is the pulmonary vein that is, thus, considered to be unique.
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Function of Blood
Blood, a transport system that conveys oxygen and the essential chemicals to where they are required in the body, fights disease and repairs damage done to the human body. And not only this blood, after picking up the waste that are no longer needed by different parts of the body, delivers that waste to parts responsible to get rid of it.
Further, blood transports heat around human bodies, to keep their fingers and toes warm and checks human brains from overheating. More than half of blood is plasma, a clear pale yellow liquid, that transports all the blood cells and platelets and chemicals like hormones and glucose.
The solid part of blood is composed of the red blood cells, white blood cells and platelets. The brute fact is that blood is so necessary to our bodies that it is often termed the “river of life”.
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Red Corpuscles or red blood cells, as they are also pronounced, are red coloured cells in blood that has their colour from a chemical termed Haemoglobin that has its presence in each and every cell of the body.
This chemical Haemoglobin, containing iron, transport oxygen from the lungs to all of the body, and gets rid of the carbon dioxide that the body does not require by getting it back to the lungs. In one small drop of blood there remain millions of red corpuscles.
Red corpuscles have the shape of a disc, concave at each side. They do not have a cell nucleus to accommodate maximum space for haemoglobin. They are made in the bone marrow inside many bones of the body and live for about four months, and then, are broken up and with much of the context new blood cells are made. More than nine-tenth of the blood comprises red blood cells that are also called erythrocytes.
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While Blood Cells: the fighters
As they fight against harmful bacteria that provokes disease and function as the defenders of the body against germs of alien bodies like splinters. The Blood Cells function with antibodies (special proteins) that also moves in the blood, to protect us, the human begins, against diseases. These Cells have no specified shape and they move about by changing their shape.
Some while cells extinguish bacteria by surrounding and digesting them, while others produce antibodies whose work is to destroy bacteria, viruses and other invaders. White blood cells, also called leucocytes, are generally larger, and fewer in number than red blood cells.
For approximately every 1000 red cells, there remains only one while cell. In one milliliter of blood there are normally around 5,000 to 7,000 white cells.
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These are sticky little cells that marches around in blood until a blood vessel gets injured in some way and due to which bleeding begins. When a blood vessel is cut, platelets stick to its edges and to one another making a plug. These platelets stick together with he help of a protein called fibrinogen to form a sort of web, and make a clot that prevents the flow of blood out of a blood vessel.
Platelets, also called thrombocytes, are shaped like discs and are the smallest kind of blood cell. The normal amount of platelets in a human body is between 150,000 and 300,000.
Movement of the Blood
The movement of blood from the heart to every part of the body and back through the arteries and veins takes less than a minute. The right side of our heart, sort of two pumps in one, gets blood from the body and pumps it to the lungs, whereas the left side of the heart does the exact opposite and gets blood from the lungs and pumps it out to the body.
When the heart pumps, the left side of our body transports oxygen-rich blood to the body that takes the oxygen out of the blood and uses it in our body’s cells. The cells, when they use the oxygen, make carbon dioxide and other stuff that is carried away by the blood. The returning blood makes its entry to the right side of the heart. The right ventricle pumps the blood to lungs to freshen it up. In the lungs, in this process, carbon-dioxide is extricated from the blood, and transported out of the body when we exhale; and always remember that it all happens in about only one minute!
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