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Transportation in Animals organisms need food, water and oxygen for survival. they need to transport all these substances to various parts of their body. Further, animals need to transport wastes to parts from where they can be removed. This transportation is done by the Circulatory System. Circulatory System Blood : Blood is the fluid which flows in blood vessels. It transport substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body. Blood is composed of fluid, called plasma in which different types of cells are suspended. One type of cells are the red blood cells (RBC) which contains a red pigment called haemoglobin. Haemoglobin blinds with oxygen and transport it to all the parts of the body and ultimately to the cells. It will be difficult to provide oxygen efficiently to all the cells of the body without haemoglobin. The presence of haemoglobin makes blood appear red. The blood also have white blood cellls (WBC)which fight against germs that may enter your body. the blood also have plateletswhich helps in clotting and prevents of blood lose in injury.

blood vessels: There are different types of blood vessels in the body. These blood vessels transport blood, nutrients and oxygen to the different tissues of the body. There are three main types of blood vessels:

1) Arteries: carry oxygen rich blood away from the heart to all the parts of the body.Since blood flow in rapid and at high pressure, the arteries have thick elastic walls.

2) Veins: carry carbon dioxide rich blood from all the parts of the body back to the heart.The veins have thin walls. There are valves present in the veins which allow blood to flow only towards the heart.

3) Capillaries: are small, thin walled vessels that connect arteries and veins.

Heart: The heart is an organ which beats continuously to act as a pump for the transport of blood, which carries other substances with it. The heart is located in the chest cavity with its lower tip slightly tilted towards the left. The heart has four chambers. The two upper chambers are called the atria and the lower two chambers are called the ventricles. The partition between the chambers helps to avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.