Curious1
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Everyone knows that blood is one of the most important parts of the human body, but not everyone is sure of what it is or does. Blood is pumped by the heart through the circulatory system. It has two main functions – carrying oxygen to the body’s cells and taking away carbon dioxide waste. The vessels that carry oxygenated blood are arteries, while veins carry blood back to the heart and lungs to receive more oxygen. Blood is important for several other reasons besides oxygenation.
Blood is composed of three different types of cells: red blood cells, white blood cells, and platelets. These cells are carried in a yellow-tinted fluid called plasma. Plasma is mostly water, but it also contains proteins, hormones, and nutrients. Red blood cells contain hemoglobin, an iron-rich protein that absorbs oxygen from the lungs. When hemoglobin is full of oxygen, it turns red. White blood cells are part of the immune system. They use the circulatory system as a means of traveling to anyplace in the body that gets infected, usually by bacteria and viruses. White blood cells are responsible for directly attacking invaders and for creating antibodies, special proteins that attack only a specific type of virus or foreign invader. When people are sick, the body produces more white blood cells. Doctors can often tell if someone is sick by how many white cells are in the blood. Platelets are made in the marrow of bones. They are responsible for clotting. When a blood vessel breaks, platelets, along with special clotting proteins, clog the area to seal the leak. If the cut large, there may not be enough platelets to seal the cut. The person will need medical attention or they may die because no oxygen is getting to the body.
 Posted 5355 day ago
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