| • Science | • People | • Locations | • Timeline |
| Contents | ||
There are differences in blood between species.
Human blood is a liquid tissue; its major function is to transport oxygen necessary to life throughout the body. It also supplies the tissues with nutrients, removes waste products, and contains various components of the immune system defending the body against infection. Endocrine hormones also travel in the blood. There are about 6 quarts (or 5.6 liters) of blood in an average human body, accounting for ~8% of body mass. Adult humans have ~60 millilitreThe millilitre (ml or mL, also spelt milliliter is a metric unit of volume that is equal to one thousandth of a litre. It is a non-SI unit accepted for use with the International Systems of Units (SI). It is exactly equivalent to 1 cubic centimetre (cm³,s of blood per kilogramThe kilogram (symbol: kg is the SI base unit of mass. A gram is defined as one thousandth of a kilogram. Conversion of units describes equivalent units of mass in other systems. Multiples SI prefixes are used to name multiples and subdivisions of the kilo of body weight.
Human blood is redRed is a color at the lowest frequencies of light discernible by the human eye. Red light has a wavelength of roughly 700 nm. Oxygenated blood is red due to the presence of hemoglobin. Red light is the first to be absorbed by sea water, so that many fish, ranging from bright red when oxygenated to dark red when not. It owes its colour to hemoglobinHaemoglobin ( BE) or hemoglobin ( AE), is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. The molecule consists of globin, the apoprotein, and four haem groups, an organic molecule with an ir, a metalloproteinIn biochemistry, a metalloprotein is a generic term for a protein that also contains a metal cofactor. The metal may be an isolated ion or may be coordinated with an nonprotein organic compound, such as the porphyrin found in hemoproteins. In some cases, compound containing ironThis article is about metallic iron. For the ironing device, see ironing manganese iron cobalt Fe Ru Full table General Name, Symbol, Number iron, Fe, 26 Chemical series transition metal Group, Period, Block 8 (VIIIB), 4 , d Density, Hardness 7874 kg/m3, in the form of hemeA haem or heme is a metal-containing cofactor that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin''. Although porphyrins do not necessarily contain iron, a substantial fraction of porphyrin-contain, to which oxygen binds. There exists a popular misconception that deoxygenated blood is blue and that blood only becomes red when it comes into contact with oxygen. Blood does not ever look blue. The veins appear blue because light is diffused by skin. Moreover, the blood inside is dark red and exhibit poor light reflection. From a physiological perspective, veins and arteries appear similar when skin is removed and are seen directly. Veins and arteries are actually whitish in color and slightly translucent. Arteries, because of the high pressure, have thicker walls than veins.
Blood moves in blood vessels and is circulated by the heart, a muscular pump. It passes to the lungs to be oxygenated, and then is circulated throughout the body by the arteries. It diffuses its oxygen by passing through tiny blood vessels called capillaries. It then returns to the heart through the veins. See circulatory system for a more detailed description of this circulation.
Blood also transports metabolic waste products, drugs and other foreign chemicals to the liver to be degraded and to the kidney to be excreted in urine.
A buffer of carbonic acid (H2CO3) and
bicarbonate (HCO3-) is present in the human blood stream,in order to maintain a pH between 7.35 and 7.45.
See also: