TRANSPORTATION IN HUMANS SCI CLASS 10th
Human body is very complex. To run this machine properly and continuously we need a transportation system which provide essential substances to all the parts of the body. This is done by the circulatory system.
What is Circulatory System?
Circulatory system is consists of veins, arteries, blood and heart. Its function is to transport important substances like food, water and oxygen and also to transport waste material to the excretory organs. It also transport hormones from different glands to all parts of the body. It circulates deoxygenated blood from all the parts with the help of vein to the heart. After that the oxygenated blood is carried by arteries to all parts of the body. This cycle goes on continuously.
Blood:
Blood is a connective tissue which consists of RBC(Red blood cells) ,WBC(White blood cells) ,platelets and plasma. Blood is transported from one part to another by blood vessels(veins and arteries). And it is pumped by heart to all the parts. The RBC cells transport the food, oxygen and also transports waste. While WBC cells protect the body from outside material like bacteria and viruses. They provide immunity to our body. The platelets helped when there is a injury.
Blood Vessels:
There are two blood vessels in our body namely arteries and veins. They help in transportation of blood to all parts of the body.
Arteries: Arteries are thick and have elastic walls. Arteries carry oxygenated blood from heart to all parts of the body. Only pulmonary arteries carry deoxygenated blood to the lungs.
Veins: Veins are thin and have valves which ensure that the blood flow in one direction only. They are closer to the skin as compared to arteries. Veins carry deoxygenated blood from all parts of the body to the heart. Only pulmonary veins carry oxygenated blood to the body.
Human Heart:
Human heart is the pumping organ of the body. It pumps the blood to all parts of the body. It is a muscular organ as big as our fist. The heart has four chambers named as right atrium and ventricle and left atrium and ventricle. It always relaxes and contracts. The blood vessels provide oxygenated and deoxygenated blood to the heart. The deoxygenated blood comes from the upper body to the right atrium when the heart contracts ,it goes into right ventricle. Then the pulmonary arteries carries this deoxygenated blood to the lungs to become oxygenated. Then from lungs the oxygenated blood comes in pulmonary veins into the left atrium when the heart contracts ,it goes into the left ventricle. From left ventricle it goes into all the parts of body through aorta.
Double Circulation: The blood circulates in human heart twice so it is called Double circulation. While in other organisms like fish do only one circulation. Double circulation provide more amount of oxygen as compared to single circulation.
Lymph:
Lymph is a type of fluid involved in transportation. Lymph is form by plasma and proteins through the pores present in the capillaries. It is colorless and contains less protein. It carries digested fat and absorbed it from the intestine and drains excess fluid back into the blood.
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