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Facts About The Human Blood

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Did you know that your body has over 60,000 miles of blood vessels? It only takes blood an average of twenty seconds to leave the heart, travel through the body and then return back to the heart. Blood accounts for about seven percent of the human body’s weight. Let’s learn more interesting facts about our blood.

A scanning electron microscope image of a normal red blood cell, a platelet and a white blood cellA scanning electron microscope image of a normal red blood cell, a platelet and a white blood cell. © National Cancer Institute.


Blood are made of various components. It consists of red bloods cells, white blood cells, platelets and plasma. Plasma makes up about 55% of blood and did you know that plasma is made up of 90% water? Each component in the human blood have a specific role.

Blood cells

Red blood cells are the ones that carry oxygen to the body from the heart. It picks up oxygen in the lungs then travels to the heart and then out to the rest of the body. The journey from the heart to the body and back takes about 20 seconds. Red blood cells also carry other nutrients. The white blood cells are the largest cell, and their sole purpose is to protect the body from harmful infections. They will attack and kill bacteria and viruses that enter the body. Platelets are what causes blood  to clot. They stick together and form clots to protect the body from bleeding out from a wound. And the plasma is what transfers all the cells through the body.

Components of a human bloodComponents of a human blood. © BruceBlaus.


Blood is very important to the body. There are no substances that can replace blood. When someone donates blood, the blood is separated and is used to help others. Blood carry nutrients to the body and also carry waste to kidneys, lungs and liver for it to be disposed of.

Blood clots

A blood clot in the blood is not a good thing. If it get stuck in the brain, it can cause a stroke and if it is caught in the heart, it can cause a heart attack. A traveling blood clot is called a thrombosis. There is a second type of clot that is called an embolism. These types of clots are stationary but if they get too big they will block arteries and can cause serious health problems.

More on human blood

  1. Discovery of blood groups
  2. Debate: cord blood banking