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
Britain's Royal Society puts rare scientific manuscripts online
Nov 30, 2009 |
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Historic manuscripts by Sir Isaac Newton, Benjamin Franklin and other ground-breaking scientists will be published online for the first time, Britain's Royal Society said Monday.
Gene Testing In the Doctors Office
Nanotechnology / Bio & Medicine
Dec 02, 2009 |
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(PhysOrg.com) -- A portable instrument manufactured by Nanosphere Inc. and recently approved by the FDA, can detect genetic variations in blood that alter the effectiveness of some drugs.
Blood Enzyme Could Help Realize Clean Coal
Dec 03, 2009 |
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(PhysOrg.com) -- An enzyme in our blood that enables our lungs to exhale carbon dioxide could be the key to isolating carbon dioxide emissions from coal plants in order to store them safely underground. A ...
Study explains how exercise helps patients with peripheral artery disease
Dec 03, 2009 |
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Peripheral artery disease (PAD) affects 5 million individuals in the U.S. and is the leading cause of limb amputations. Doctors have long considered exercise to be the single best therapy for PAD, and now a new study helps ...
Popular diabetes drugs linked to increased risk of heart failure and death
Medicine & Health / Medications
Dec 04, 2009 |
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Sulphonylureas, a type of drug widely used to treat type 2 diabetes, carries a greater risk of heart failure and death compared with metformin, another popular antidiabetes drug.
Genetic studies reveal new causes of severe obesity in childhood
Dec 06, 2009 |
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Scientists in Cambridge have discovered that the loss of a key segment of DNA can lead to severe childhood obesity. This is the first study to show that this kind of genetic alteration can cause obesity. The results are published ...
Researchers identify new stem cell
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(PhysOrg.com) -- The skin is known for its ability to regenerate because the cells in the skin are constantly turning over. This "healing property" has attracted much attention from scientists wanting to know what makes the ...
Low-income women 4 times more likely to report fair or poor health
Nov 30, 2009 |
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Low-income women are four times more likely than higher-income women to report fair or poor health and nearly twice as likely to report a health condition that limits their basic physical activities, according to a new policy ...
Stroke and heart disease trigger revealed in new research
Nov 30, 2009 |
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(PhysOrg.com) -- Scientists have identified the trigger that leads to the arteries becoming damaged in the disease atherosclerosis, which causes heart attacks and strokes, in research published today in the ...
Dessert on your mind? Your muscles may be getting the message
Dec 01, 2009 |
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Even the anticipation of sweets may cause our muscles to start taking up more blood sugar, say researchers reporting in the December issue of Cell Metabolism. That message is delivered via neurons in the brain's hypothalamus contai ...
Cholesterol-lowering drugs also may protect stem cell transplant patients from GVHD
Dec 04, 2009 |
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Cholesterol-lowering drugs known as statins are among the most prescribed medicines in the U.S. Now a new study by researchers at Fred Hutchinson Cancer Research Center indicates that statins may protect stem cell transplant ...
Study describes new tool in the fight against autoimmune diseases, blood cancers
Nov 30, 2009 |
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A study led by a Scripps Research Institute scientist describes a new, highly pragmatic approach to the identification of molecules that prevent a specific type of immune cells from attacking their host. The findings add ...
Scientists discover genetic pattern that indicates early-stage lung cancer
Dec 01, 2009 |
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Wistar Institute researchers and collaborators from the University of Pennsylvania and New York University have identified immune system markers in the blood which indicate early-stage lung tumors in people at high risk for ...
Doctors Warn Against Holiday Heart Attack Spike
Dec 03, 2009 |
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(PhysOrg.com) -- Some studies indicate that death rates from heart attacks and stroke as well as non-heart-related causes spike during the holiday season.
Smoking cessation results mixed among Ohio's Appalachian women
Dec 03, 2009 |
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In the Appalachian region of the country — where smoking rates are high, tobacco is often a cash crop and income and education levels are low — a smoking cessation effort led by non-medical professionals was successful in ...
