Blood
Blood
In Hollywood they call the stuff that splatters on movie and TV screens "reel" blood. Made from corn syrup, red dye and paste, it comes in a variety of shades including fresh, aged and old and dried. A typical horror film may use more than 30 gallons.
Movie blood may be a nifty special effect, but real blood--the sticky serum that life depends on--is far more awesome.
Consider these facts: Of the 50 trillion cells in your body, nearly half are blood. Every second, 2 million red blood corpuscles are destroyed, and 2 million more enter the bloodstream and join a massive transportation system that is responsible for nurturing every cell in your body.
Yet these corpuscles are so tiny that they can squeeze through capillaries thinner than a strand of hair, and they''''re packed so tightly together that an average woman could drain all four quarts of her blood into a stockpot.
"Blood truly is amazing. It really is the essence of life," says Mercedes Brenneisen, M.D., hematologist at Good Samaritan Hospital in Los Angeles.
How It Works
With each heartbeat, blood rushes life-sustaining oxygen to your cells and sweeps toxic carbon dioxide back to your lungs. At the same time, it helps warm your body and distributes hormones and chemicals that regulate every bodily function, from heart rate to childbirth. In addition, white blood cells and other disease fighters that constitute the immune system diligently circulate in your bloodstream, ready to pounce on any invading organism that might harm you.
Every hour, your body produces up to 10 billion new blood cells in your bone marrow and destroys an equal number of old ones in your spleen and liver. Early in life, your liver, spleen and almost any bone can produce red blood cells, but after you reach age two or three only the breastbone, ribs, skull, thighbones, pelvis and spine continue to create red blood cells and platelets. White blood cells are also manufactured by bone marrow, but some types are produced in the lymph nodes as well.
| What Your Blood Type Really Means In 1667 doctors attempted to transfuse sheep''''s blood into a young boy. The procedure failed, but fortunately, the patient lived. Since that first miserable stab at transfusion, doctors have learned there are several types of blood, and if blood types aren''''t compatible, a person receiving a transfusion could have an immune reaction and die. Blood is classified by the type of proteins that coat the cell. You have either type A, B, AB (meaning you have both A and B proteins) or O (meaning you have neither A nor B). People develop antibodies to the proteins that their blood cells don''''t have. The table below shows who can receive transfusions of what types of red blood cells. About 46 percent of people have type O, 42 percent have type A, 8 percent have type B and 4 percent have type AB. Another blood grouping system, the Rhesus (Rh) factor, divides people into Rh positive and Rh negative. About 85 percent of us are Rh positive. Transfusion of Rh positive blood into an Rh negative woman can cause a serious reaction if she has developed antibodies to Rh positive from previous transfusions. In addition to that, an Rh negative mother can conceive an Rh positive fetus if the father is Rh positive. If that happens, she needs treatment with a blood product called Rh immunoglobulin to prevent the production of antibodies that would destroy the red cells of an Rh positive fetus. | If You Have... | You Can Receive . . . | | | A | B | AB | O | | A | * | | | * | | B | | * | | * | | AB | * | * | * | * | | O | | | | * | |
Keeping It Healthy
Blood is fairly resilient and requires little care or maintenance to do its job. Eating a balanced diet that includes at least five servings of fruits and vegetables a day is the best way to ensure that your blood stays healthy, Dr. Brenneisen says. Here are some important things you can do.
Stoke up on iron. Without iron your body stops making red blood cells, and the red cells you do have have difficulty absorbing oxygen as they pass through your lungs. As a result, you can develop anemia, Dr. Brenneisen says.
Women are at greater risk for iron-deficiency anemia than men, because we lose iron-rich blood whenever we have menstrual bleeding. When our periods are normal and not heavy, we lose an extra one milligram of iron a day. Before menopause about 3 percent of us are likely to develop iron-deficiency anemia, the most common form of the disease in women. After menopause the incidence of iron-deficiency anemia falls to about 2 percent.
Because of increased risk of iron deficiency, it''''s important to try to get enough iron through your diet. Most women need about 18 milligrams of iron daily. Pregnant women need up to 30 milligrams a day. Good food sources of iron include lean meats, poultry (dark meat is best), clams, oysters, dried apricots and dark green leafy vegetables such as spinach and broccoli.
If you''''re worried about getting enough iron from your diet, talk to your doctor about taking an iron supplement. But doctors warn that you need to be careful about supplementation, because too much iron could prevent your body from absorbing other nutrients, such as zinc and copper. Excessive iron can also cause liver damage in some people.
Recharge with B12. Low levels of vitamin B12 disrupt reproduction of red blood cells and increase your risk of heart disease. B12 is found almost exclusively in animal products--fish, beef, poultry and dairy foods such as cheese and yogurt. Because the vitamin is easily stored in your body, Dr. Brenneisen says, B12 deficiencies are rare as long as you''''re eating some of these foods. If you''''re a vegetarian, you should discuss with your doctor whether to take a supplement.
Think folate. folate is another B vitamin that is crucial for the development of healthy red blood cells, Dr. Brenneisen says. Since we don''''t store folate, we need a daily dose of 400 micrograms. Lentils, wheat germ, oranges and green vegetables such as asparagus are good sources of folate.
A deficiency can cause fatigue, weakness, cramps, depression and other symptoms of anemia. folate deficiency has also been linked to birth defects, so women of child-bearing age need to be extra careful.
| What Can Go Wrong If you get sick, your blood probably isn''''t the culprit. "What''''s amazing is how well blood works and how uncommon diseases of the blood really are," says John Harlan, M.D., hematologist at the University of Washington School of Medicine in Seattle. Here are diseases you should be aware of. Anemia, a lack of red blood cells, is one of the most common blood diseases, mostly because of its everyday form, iron-deficiency anemia. It affects 3 out of every 100 premenopausal women and 2 out of every 100 postmenopausal women. When you have anemia, your blood has trouble getting enough oxygen to your vital organs and removing carbon dioxide from your body. Symptoms include pale skin, fatigue, weakness, fainting and heart palpitations. Iron-deficiency anemia is caused by lack of iron, but other anemias can be caused by deficiencies of vitamin B12 or folate. Leukemia is a cancer of blood-forming tissues--bone marrow, lymph nodes and spleen--that causes abnormal white blood cells to reproduce at an accelerated rate. These abnormal cells prevent the production of healthy red and white blood cells and platelets. As the disease progresses, it causes anemia, interferes with blood clotting and impairs the body''''s ability to fight off infections. Untreated, it can cause death. Leukemia afflicts about 1 in every 1,300 American women. Symptoms include chronic fatigue, bone pain, weight loss, easy bruising and bleeding and fever. Polycythemia, too many red blood cells, is usually a sign of an underlying ailment, such as lung or heart disease, that disrupts the flow of oxygen in your body. In response the bone marrow produces more red blood cells than are needed. Because polycythemia thickens the blood, clots are more common, and that increases the risk of heart attack and stroke. Malaria, caused by a parasite transmitted by mosquito bites, is a common blood disease in tropical regions. Parasites attack red blood cells, causing them to rupture. To prevent it, ask your doctor to prescribe an antimalarial drug before you travel to areas where the disease is prevalent. Hemophilia, a genetic bleeding disorder that prevents blood from clotting, is passed from mothers to sons. Women merely carry the recessive gene for hemophilia; they do not develop the disease, which affects 1 in 10,000 men in the United States. England''''s Queen Victoria was a famous carrier of the disorder, and several of her royal descendants, including Alexis, the last crown prince of Russia, developed the affliction. Sickle cell disease, an ailment that causes abnormal hemoglobin in 1 in every 1,000 African-Americans, is another rare but well-known inherited blood disease. In this disease sickle-shaped cells disrupt blood and oxygen flow to vital tissues. |
Get an E grade. Vitamin E, an antioxidant, may help protect membranes and keep aging blood cells vigorous, according to Stephen Shohet, M.D., professor of laboratory medicine at the University of California, San Francisco, School of Medicine. Vitamin E is most abundant in oils, nuts and seeds. Unfortunately, these foods are also high in fat. But taking a multiple vitamin daily will usually supply you with the Daily Value of 30 international units--that is, enough vitamin E to maintain your health.
Don''''t forget the C. Vitamin C, another antioxidant, also might help keep your blood cells healthy, says Joanne Curran-Celentano, R.D., Ph.D., associate professor of nutrition at the University of New Hampshire in Durham and nutrition research coordinator at the Center for Eating Disorders Management in Dover. It''''s abundant in the diet as long as you eat plenty of fruits and vegetables every day, such as oranges, strawberries, brussels sprouts and red bell peppers. Although 60 milligrams is the Daily Value, she recommends that you get 100 to 500 milligrams daily for healthy blood.
Take an aspirin. Aspirin can reduce the stickiness of blood platelets and reduce your risk of stroke and heart attack. Take one coated 325-milligram aspirin tablet every other day, suggests Dr. Brenneisen. But be sure to check with your doctor before taking aspirin regularly.
Ax the smokes. Smoking increases carbon monoxide levels in your bloodstream and destroys hemoglobin, a protein that helps transport oxygen in blood. Smoking also stimulates the production of extra red blood cells, which can thicken the blood and make you more vulnerable to strokes and heart attacks triggered by clots, says Arthur R. Thompson, M.D., Ph.D., hematologist and professor of medicine at the University of Washington in Seattle.
| A Blood Test Primer Like any great detective, your doctor is always looking for clues. Your blood is often a good starting point. Although normal results vary depending on a person''''s age, sex and the method the laboratory uses to conduct its tests, a typical blood screening can reveal a lot about you. Here''''s a look at the most common blood tests. Bilirubin. High levels of this pigment released when old blood cells are destroyed may be an indication of liver disease or anemia. Jaundice, a yellowing of the skin and eyes, also is caused by excessive amounts of bilirubin in the blood. Blood glucose (blood sugar). High levels could be a warning sign of diabetes. Carbon dioxide. High levels suggest lung problems such as emphysema or pneumonia. Chloride. Low levels of this important chemical that helps keep body fluids in balance may point toward infections, intestinal obstruction or severe diabetes. Complete blood count (CBC). The most basic test, it determines the number and appearance of red cells, white cells and other components present in the blood. A CBC will also tell your doctor how much oxygen your blood cells can carry and how well they can fight disease. Creatinine and blood urea nitrogen (BUN). Elevated blood levels of either of these two waste products normally excreted in urine may be an indication of a kidney ailment. Potassium. High levels may be a sign of kidney failure. Sodium. Excessive amounts in the blood could be a sign of dehydration or congestive heart failure. |
Limit liquor. Overindulging in alcohol can interfere with absorption of folate. Consume no more than one or two drinks a day, Dr. Brenneisen says.
See also Circulatory System, Lymphatic System
