Blood … the fluid that gives us life! If you don’t know much about your blood, you’ve come to the right place. Tidbits has the details about this vital part of your body.

About 8% of your body weight is accounted for by blood, approximately 1.325 gallons. About 55% of the blood is composed of plasma, the liquid part of the blood in which blood cells are suspended.    40% is red blood cells, those cells that carry oxygen from the lungs to the body tissues, and transport carbon dioxide and waste products away from those tissues. Hemoglobin is the iron-containing protein in the red blood cells that carries the oxygen, and gives blood its red color. One ounce of blood contains 150 billion red blood cells, with 2.4 trillion in one pint. Each cell is about 7 microns in size, about one-millionth of a meter. The body is busy manufacturing 17 million red blood cells every second, primarily in the spongy marrow of the bones.

    Just 1% of blood is white blood cells, those that help fight infection, heal wounds, and support the immune system by attacking invaders.

    Platelets comprise 4% of the blood, much smaller cells than red and white cells. They group together in clumps to help control bleeding when a hole occurs in a vessel.

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    There are 60,000 miles of blood vessels in your body, vessels that include veins, arteries, and capillaries. So what’s the difference? Arteries carry blood away from the heart, while veins carry blood back toward your heart. The tiny capillaries, with a diameter smaller than that of a human hair, connect arteries and veins. The aorta is the main artery in the body, carrying blood from the left side of the heart to the rest of the body. Its diameter is about 0.8 inches (2 cm).

    There are four main blood types – A, B, AB, and O. What determines your blood type? Proteins known as antigens are on the surface of some red blood cells. Type A blood has the A antigen, while Type B has the B antigen, Type AB has both, but Type O has neither. A third type of antigen known as the Rh factor determines whether your blood type is positive or negative. If the protein is present, the type is positive, if not, it’s negative.

The most common blood type in the U.S. is O positive, and AB negative is the least common. Blood type can be dependent on ethnicity, with more African Americans and Asians having Type B positive than Caucasians and Hispanics. In Japan, the most common blood type is A positive.

    It’s a good idea to know your blood type in order to monitor your health. Yet, more Americans know their horoscope sign (66%) than their blood type (51%)! Research indicates that blood type affects risk of disease. People with Types A, B, and AB blood seem to have an increased risk of coronary heart disease, with Type A having a 24% higher risk of heart attack. Type AB people have a significantly higher risk of stroke. A, B, and AB also have a higher risk of blood clots as well as pancreatic cancer. Type 2 diabetes seems more prevalent in those with Type A and B. A neurological study revealed that people with Type AB have a high degree of risk for cognitive impairment and memory problems, while Type O had the smallest risk.

    High blood pressure is the result of too much force against the walls of the arteries.