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
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 ...
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 ...
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.
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Scientists use virus to kill cancer cells while leaving normal cells intact
18 hours ago |
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(PhysOrg.com) -- A virus that in nature infects only rabbits could become a cancer-fighting tool for humans. Myxoma virus kills cancerous blood-precursor cells in human bone marrow while sparing normal blood stem cells, a ...
Probing Question: Is forensic science on TV accurate?
19 hours ago |
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Turn on the television any evening and you're apt to see a scene such as this: Five crime scene investigators, or CSIs, return to the crime scene at night to follow up on some leads. CSI Kathryn Willows looks ...
Vitamin E extract could help tackle cancer tumours
20 hours ago |
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(PhysOrg.com) -- An extract of vitamin E could have a key role to play in the treatment of cancerous tumours, according to newly-published research today.
New data show breakthrough microRNA-targeted therapy holds promise as new treatment for hepatitis C
22 hours ago |
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A study published online in this week's Science shows that SPC3649, a breakthrough microRNA-targeted therapy developed by Santaris Pharma A/S, holds promise as a novel treatment for patients infected with the Hepatitis C viru ...
Papillomavirus silences innate immune response
Dec 03, 2009 |
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In the 1980s, Harald zur Hausen and his co-workers discovered that specific types of human papillomavirus (HPV) cause cervical cancer. Scientists soon found out how these pathogens cause cells to degenerate. ...
Cooling may benefit children after cardiac arrest
Dec 03, 2009 |
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When the heart is stopped and restarted, the patient's life may be saved but their brain is often permanently damaged. Therapeutic hypothermia, a treatment in which the patient's body temperature is lowered and maintained ...
Hope for patients with type 2 diabetes
Dec 03, 2009 |
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The outlook for individuals with type 2 diabetes and coronary artery disease is not as grim as originally believed, according to new Saint Louis University research published in Circulation, the Journal of the American He ...
High-risk women reluctant to take tamoxifen to prevent breast cancer, study finds
Dec 03, 2009 |
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Even when women at high-risk of breast cancer are well-informed about the risks and benefits of using the drug tamoxifen for prevention, only 6 percent said they were likely to take it.
Breastfeeding protects women from metabolic syndrome, a diabetes and heart disease predictor
Dec 03, 2009 |
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Breastfeeding a child may lower a woman’s risk of developing Metabolic Syndrome, a condition linked to heart disease and diabetes in women, according to a Kaiser Permanente study that was published today online ahead of print ...
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