Blood
hideBlood is a specialized bodily fluid that delivers necessary substances to the body's cells — such as nutrients and oxygen — and transports waste products away from those same cells.
In vertebrates, it is composed of blood cells suspended in a liquid called blood plasma. Plasma, which comprises 55% of blood fluid, is mostly water (90% by volume), and contains dissolved proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), platelets and blood cells themselves. The blood cells present in blood are mainly red blood cells (also called RBCs or erythrocytes) and white blood cells, including leukocytes and platelets. The most abundant cells in vertebrate blood are red blood cells. These contain hemoglobin, an iron-containing protein, which facilitates transportation of oxygen by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is almost entirely transported extracellularly dissolved in plasma as bicarbonate ion.
Vertebrate blood is bright-red when its hemoglobin is oxygenated. Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some molluscs use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this "blood" does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their tracheal system to suffice for supplying oxygen.
Jawed vertebrates have an adaptive immune system, based largely on white blood cells. White blood cells help to resist infections and parasites. Platelets are important in the clotting of blood. Arthropods, using hemolymph, have hemocytes as part of their immune system.
Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals having lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.
Medical terms related to blood often begin with hemo- or hemato- (also spelled haemo- and haemato-) from the Ancient Greek word αἶμα (haima) for "blood". In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen.
For more information about Blood, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with blood stream
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Eric Shaqfeh studies blood at Stanford University, using computer models that simulate how the fluid and the cells it contains move around. On November 11 at a meeting of the scientific society AVS, he will present his latest ...
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Researchers at the University of Maryland School of Medicine have made an important discovery about why potassium builds up to dangerous levels in the bloodstream, a relatively common medical problem that affects about eight ...
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If you're sick, traveling to a foreign land may boost your spirits, but jeopardize your health, according to a paper being presented at the American Society of Nephrology's 42nd Annual Meeting and Scientific Exposition in ...
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(PhysOrg.com) -- Cisplatin is one of the most powerful and effective drugs for treating a wide variety of cancers, but serious side effects ultimately limit the drug's use and effectiveness. Now, however, researchers have ...
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Aug 18, 2009 |
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A mutation in a gene that helps regulate high blood pressure is a cause of inherited kidney disease, according to a new study by researchers at Wake Forest University School of Medicine, Charles University in Prague and colleagues.
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Jul 20, 2009 |
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IVIg treatments, the addition of good antibodies into the blood stream, may hold promise for lowering the risk of Alzheimer's disease and other similar brain disorders, according to research published in the July 21, 2009, ...
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Jul 17, 2009 |
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(AP) -- Abbott Laboratories and AstraZeneca PLC on Thursday asked the Food and Drug Administration to approve a drug that combines their cholesterol pills TriLipix and Crestor.
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In Alzheimer's disease the brain accumulates a molecule called A-beta that can be quite toxic to brain cells. Many researchers believe that finding ways to clear A-beta may be a key to treatment or prevention of Alzheimer's ...
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Jan 23, 2009 |
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Scientists at UCSF have discovered an abnormality in a patient's immune system that may lead to safer therapies for autoimmune diseases such as rheumatoid arthritis and colitis, as well as potential new ways to treat transplant ...
