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Waste

Waste

:For other uses of the word, see Waste (disambiguation). Waste (disambiguation)] Waste is unwanted or undesired material. Waste can exist in any phase of matter (solid, liquid, or gas). When released in the latter two states, gas especially, the wastes are referred to as emissions. It is usually strongly linked with pollution.

Sources of waste

pollution Waste produced in the wild is reintegrated through natural recycling processes, such as dry leaves in a forest decomposing into soil. Outside of the wild these wastes may become problematic, such as dry leaves in an urban environment. The highest volume of waste, outside of nature, comes from human industrial activity: mining, industrial manufacturing, consumer use, and so on1. Almost all manufactured products are destined to become waste at some point in time, with a volume of waste production roughly similar to the volume of resource consumption. Post-consumer waste is the waste produced by the end-user (the rubbish one puts outside in the rubbish bin). This is the waste people usually think of. But though the most visible, this is very small compared to the waste created in the process of mining and production.

Human waste

Post-consumer waste Human waste is a term in the English language usually used to refer to byproducts of digestion, such as feces and urine. Human waste can be a serious health hazard, as it is a good vector for both viral and bacterial diseases. A major accomplishment of human civilization has been the reduction of disease transmission via human waste through the practice of hygiene and sanitation, including the development of theories of sewage systems and plumbing. Human waste can be reduced and reused through use of greywater, waterless urinals and humanure systems. In very rural places without sewage systems, small populations allow for the continued use of honey buckets and sewage lagoons without the threat of disease presented by places with more dense populations. honey bucket]

See also


- Waste management
- Nuclear waste

References

This page contains material imported from [http://develop.consumerium.org/] please see the [http://develop.consumerium.org/wiki/index.php?title=Waste&action=history history] of the [http://develop.consumerium.org/wiki/index.php/Waste original article]. The original material was licensed under the GFDL v 1.2. # [http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=392 Total waste generation by sector - EEA Countries 1992-1997], European Environmental Agency, retrieved 5 January 2005.

External links


- [http://www.bbc.co.uk/dna/h2g2/A4643787 BBC - h2g2 - Waste]
- ko:쓰레기 ja:廃棄物

Waste (disambiguation)

Waste can refer to any of the following:
- Waste, unwanted or undesired material left over after the completion of a process. See also
  - Waste management
  - Passenger train human waste disposal
  - Industrial waste
  - Toxic waste
  - Radioactive waste
  - E-waste, which is waste from or caused by electronics. This is physically existing waste, not email spam.
- Waste is a legal term used in a legal action that can be brought to address a change in condition of property brought about by a current tenant that damages or destroys the future interest in real property.
- Waste can mean unused or underused land: see Wasteland (disambiguation page),
  - and also for T. S. Eliot's 1922 poem "The Waste Land"
- Wasting, the process by which a debilitating disease causes muscle and fat tissue to "waste" away.
- wasting can mean to use up something or time unprofitably, or to let it pass or disappear unprofitably.
- Harley Granville Barker's 1906 play Waste
- W.A.S.T.E., the underground postal service in Thomas Pynchon's 1966 novel The Crying of Lot 49
- WASTE, a piece of software for establishing friend-to-friend file sharing networks.
- W.A.S.T.E. is the name of rock group Radiohead's official fan club, which is used for distribution of tickets and merchandise.

Solid

A solid is a phase of matter characterized by resistance to deformation and to changes of volume. At the microscopic scale, a solid has these properties:
- The atoms or molecules that comprise the solid are packed close together.
- These constituent elements have fixed positions in space relative to each other. This accounts for the solid's rigidity.
  - If sufficient force is applied, either of these properties can be violated, causing permanent deformation.
- Because any solid has some thermal energy, its atoms vibrate. However, this movement is very small and very rapid, and cannot be observed under ordinary conditions. The branch of physics that deals with solids is called solid-state physics, and is a type of condensed matter physics. Materials science is primarily concerned with properties of solids such as strength and phase transformations. It overlaps strongly with solid state physics. Solid-state chemistry overlaps both of these fields, but is especially concerned with the synthesis of novel materials. The lightest known solid is man-made and is called aerogel. The lightest aerogel produced has a density of 1.9 mg per cm3 or 1.9 kg/m3 (526.3 times lighter than water).

See also


- List of phases of matter
- Cooling curve Category:Condensed matter physics Category:Materials science ko:고체 ms:Pepejal ja:固体 simple:Solid

Liquid

A liquid (a phase of matter) is a fluid whose volume is fixed under conditions of constant temperature and pressure; and, whose shape is usually determined by the container it fills. Furthermore, liquids exert pressure on the sides of a container as well as on anything within the liquid itself; this pressure is transmitted undiminished in all directions. If a liquid is at rest in a uniform gravitational field, the pressure p at any point is given by :p=\rho gz where \rho is the density of the liquid (assumed constant) and z is the depth of the point below the surface. Note that this formula assumes that the pressure at the free surface is zero, and that surface tension effects may be neglected. Liquids have traits of surface tension and capillarity; they generally expand when heated, and contract when cooled. Objects immersed in liquids are subject to the phenomenon of buoyancy. Liquids at their respective boiling point change to gases, and at their freezing points, change to a solids. Via fractional distillation, liquids can be separated from one another as they vaporise at their own individual boiling points. Cohesion between molecules of liquid is insufficient to prevent those at free surface from evaporating. It should be noted that glass at normal temperatures is not a "supercooled liquid", but a solid. See the article on glass for more details.

See also


- List of phases of matter
- Cooling curve
- Ripple
- Specific gravity
- Liquid dancing Category:Condensed matter physics ko:액체 ms:Cecair ja:液体 simple:Liquid

Emission

The word emission generally means sending something out. It can be used in the following contexts:
- In chemistry emissions are the products of a reaction, either chemical or nuclear.
- In physics and physical chemistry emissions are outputs of electromagnetic radiation or particles.
- In common usage, emission is often the giving off of gases from industrial processes of factories and transport. As they occur on an industrial scale, even relatively harmless gases can have an undesired effect (such as carbon dioxide contributing to the greenhouse effect). See also emissions trading, automobile emissions control, greenhouse gas, and pollution.
- In physics, emission theories assumed that light leaves the object that emits it at a particular speed. This idea is most commonly identified with Isaac Newton and Walter Ritz.
- In the history of optics, light was supposed by adherents of emission theory (vision) to be emitted by the eyes. Visual perception was accomplished by such rays of light acting like feeling hands.

Soil

Soil is unconsolidated rock particles mixed with organic matter from plant decay. Soil is vital to all life on Earth because it supports the growth of plants, which supply food and oxygen and absorbs carbon dioxide and nitrogen. Soil serves as a habitat for animal life from microorganisms to small animals.

Soil components

Soils vary widely in composition and structure from place to place. Soils are formed through the weathering of rock and the breakdown of organic matter. Weathering is the action of wind, rain, ice, sunlight and biological processes on rocks, which breaks them down into small particles. The proportions of minerals and organic matter determine the structure and other characteristics of a particular soil. Soils can be divided into two general layers or strata: topsoil, the topmost layer, where most plant roots, microorganisms, and other animal life are located, and subsoil, which is deeper and often more dense and less rich in organic matter. Water and air are also components of most soils. Air, trapped in spaces between soil particles, and water, trapped in spaces and on the surface of particles, comprises about half of the soil by volume. Both are important to plant growth and other life in the soil profile of a particular ecosystem. The rock and mineral content of soil is categorized according to particle size as sand (coarsest), silt or clay (finest); the ratio of these particles to a great degree determines the soil classification and characteristics. Former soils which become buried below the effects of organisms are called paleosols. Soil develops naturally over time through the action of plants, animals, and weathering. Soil is also affected by human habitation. People can alter soil to make it more suitable for plant growth through the addition of organic material and natural or synthetic fertilizer, and by improving its drainage or water-retaining capacity. Human actions also can degrade soil through the depletion of nutrients, pollution, contamination, and compaction, and by increasing the rate of erosion, which is the relocation of soil through the movement of water or wind.

Natural soil development

An example of soil development from bare rock occurs on recent lava flows in warm regions under heavy and very frequent rainfall. In such climates plants become established very quickly on basaltic lava, even though there is very little organic material. The plants are supported by the porous rock becoming filled with nutrient bearing water, for example carrying dissolved bird droppings or guano. The developing plant roots themselves gradually break up the porous lava and organic matter soon accumulates but, even before it does, the predominantly porous broken lava in which the plant roots grow can be considered soil.

Chemical processes in soils

Weathering releases ions such as Potassium (K+) and Magnesium (Mg2+) into the soil solution. Some of these elements (as ions) are taken up by plants, but the majority not left in solution are absorbed through ion exchange by clays such as montmorillonite. When the level of ions is low in the soil an equilibrium process forces ions back into solution, where they can be used by plants. However if acid is introduced into soil, e.g. by acid rain, hydrogen ions bind in preference to clays, forcing ions out where they can be washed away during rain. Acidity also encourages the weathering of clays, releasing toxic aluminium ions (of which clays are composed) into the solution. To stop this occurring, farmers may apply alkaline materials such as slaked lime. Although the elements nitrogen, potassium and phosphorus, which are necessary for plant growth, may be abundant in soil, only a fraction of these elements may be in a chemical form which plants can use. In processes such as nitrification and mineralisation, bacteria and other organisms convert unusable forms (such as NH4+) to usable forms (such as NO3-). The raw products are initially present as gases in the atmosphere. Processes such as the nitrogen cycle and carbon cycle continually exchange nutrients between the soil and atmosphere. The organic component of soils originate in plant debris (such as fallen leaves), animal excreta, and other decomposing organic materials. These materials, when broken down, form humus, a dark, nutrient-rich material. Chemically, humus is composed of very large molecules including esters of carboxylic acid, phenolic compounds, and derivatives of benzene. Organic material in soil provides nutrients necessary for plant growth. Organic material also contributes to water retention, drainage ability, and oxygenation of soil. If oxygen enters a wet soil, because of lowered ground water table, organic matter in the soil will be broken down further by oxidation, which can lead to subsidence. An example of this can be seen in soils in the Everglades region of Florida, which have been drained by canals for agriculture, primarily sugar production. Originally very high in organic content, oxygenation and compaction have led to breakdown of the soil structure and nutrient content, and degradation of the soil's ability to support continued high crop yields.

Biological processes in soil

Wetland soil processes

The diffusion of dissolved oxygen in saturated soils is slower than in unsaturated soils. Wetland (also referred to as hydric) soils form due to soil microbial cellular respiration in excess of soil oxygen supply, resulting in oxygen depletion. Anaerobic soil chemistry results, which creates a reducing environment. This eliminates plants and creatures not adapted for life in saturated soil conditions.

Biological soil crusts

Biological soil crusts are formed by living organisms and their by-products, creating a surface crust of soil particles bound together by organic materials.

References


- Soil Survey Staff. (1975) Soil Taxonomy: A basic system of soil classification for making and interpreting soil surveys. USDA-SCS Agric. Handb. 436. U.S. Gov. Print. Office. Washington, DC.
- Soil Survey Division Staff. (1993) Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18.
- Logan, W. B., Dirt: The ecstatic skin of the earth. 1995 ISBN 1573220043
- Faulkner, William. Plowman's Folly. New York, Grosset & Dunlap. 1943. ISBN 0933280513
- Jenny, Hans, Factors of Soil Formation: A System of Quantitative Pedology 1941
- [http://jan.ucc.nau.edu/~doetqp-p/courses/env320/lec1/Lec1.html Why Study Soils?]
- [http://www.hort.purdue.edu/newcrop/tropical/lecture_06/chapter_12l_R.html Soil notes]
- [http://www.home2garden.org/soil.html Soil articles]

See also:


- Alluvium
- Compost
- Denitrification
- Derelict soil
- FAO - Soil Unit Classification Scheme
- Humus
- Manure
- Nitrification
- Nitrogen cycle
- Nitrogen fixation
- Pedology
- Pedogenesis
- Soil degradation
- Soil moisture
- Soil pH
- Soil profile
- Soil salination
- Soil science
- Soil structure
- Soil survey (soil mapping)
- Soil test
- Soil types
- Topsoil
- USA soil taxonomy Category:Ecology Category:Soil science ja:土

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein, or (coal) seam. Materials recovered by mining include bauxite, coal, diamonds, iron, precious metals, lead, limestone, nickel, phosphate, rock salt, tin, and uranium. Any material that cannot be grown from agricultural processes must be mined. Mining in a wider sense can also include extraction of petroleum, natural gas, and even water.

History

water]] The oldest known mine in the archaeological record is the "Lion Cave" in Swaziland. At this site, which has a radiocarbon age of 43,000 years, paleolithic humans mined for the iron-containing mineral hematite, which they ground to produce the red pigment ochre. Sites of a similar age where Neanderthals may have mined flint for weapons and tools have been found in Hungary. Another early mining operation was the turquoise mine operated by the ancient Egyptians at Wady Maghareh on the Sinai Peninsula. Turquoise was also mined in pre-Columbian America in the Cerillos Mining District in New Mexico, where a mass of rock 200 feet (60 m) in depth and 300 feet (90 m) in width was removed with stone tools; the mine dump covers 20 acres (81,000 m²). Black gun powder in mining was first time used in a mineshaft under Banská Štiavnica, Slovakia in 1627.

Mining techniques

Mining techniques can be divided into two basic excavation types: :1. Surface mining ::
- Open-pit mining ::
- Quarrying ::
- Strip mining ::
- Placer mining ::
- Mountaintop removal :2. Sub-surface mining ::
- Drift mining ::
- Slope mining ::
- Shaft mining ::
- Hard rock mining ::
- Borehole mining

Extractive metallurgy

The science of extractive metallurgy is the study of extraction of valuable metals and minerals from their ores. Although extractive metallurgy is all-encompassing, mineral processing (or mineral dressing) is often the term used for the study of processing coal, industrial minerals and precious stones, as these are not metals.

Environmental effects

mineral processing mineral processing, even though the molybdenum mine has been closed for decades.]] Modern mining companies in many countries are required to follow strict environmental and reclamation codes, ensuring the area mined is returned to its original state, or an even better environmental state than before mining took place. Past mining methods have had, and methods used in countries with lax environmental regulations continue to have, devastating environmental and public health effects. The result can be unnaturally high concentrations of some chemical elements over a significantly wider area of surface. Combined with the effects of water and the new 'channels' created for water to travel through, collect in, and contact with these chemicals, a situation is created where mass-scale contamination can occur. Some examples of environmental problems associated with mining operations are: :Tar Creek, an abandoned mining area in Picher, Oklahoma that is now an Environmental Protection Agency superfund site. Water in the mine has leaked through into local groundwater, contaminating it with metals such as lead and cadmium. [http://www.health.state.ok.us/PROGRAM/envhlth/sites/ottawa.html] :Scouriotissa, a copper mine in Cyprus that has been abandoned. Contaminated dust blows off this site. :Berkeley Lake, an abandoned pit mine in Butte, Montana that has filled with water which is now acidic and poisonous. Although such issues have been associated with some mining operations in the past, modern mining practices have improved significantly and are subject to close environmental scrutiny. Problems remain especially in countries with lax environmental regulations or enforcement.

Mining industry

While exploration and mining can sometimes be conducted by individual entrepreneurs or small business, most modern-day mines are large enterprises requiring large amounts of capital to establish. Consequently, the industry is dominated by large, often multinational, mostly publicly-listed companies. See :Category:Mining companies for a list.

Mine Planning Software

One of the most dramatic changes in the mining industry has been the role that sophisticated three dimensional 3-D mine planning software packages have had. Initially relatively simple tasks - like rendering graphic images of drill holes - meant that it became easier for surveyors, geologists, mine planners, mining engineers and other technical staff to manipulate and visualize data. However, in recent years the range of integrated mine planning tools have meant that massively complex models can be built to optimize the extraction and processing of mineral resources.

See also


- Acid mine drainage
- Coal mining
- Remediation
- Ore grade

References


- Tom Morrison. 1992. Hardrock Gold: A Miner's Tale (ISBN 0806124423)
- Geobacter Project: [http://www.geobacter.org/press/2001-07-21-economist.pdf Gold mines may owe their origins to bacteria] (in PDF format) Category:Mining ja:鉱業 th:การทำเหมืองแร่

References

In general, a reference is something that refers or points to something else, or acts as a connection or a link between two things. The objects it links may be concrete, such as books or locations, or abstract, such as data, thoughts, or memories. The object which is named by a reference, or to which the reference points, is the referent. The term reference is used with different specialized meanings in a variety of fields, as follows:

Semantics

In semantics, reference is generally construed as the relation between nouns or pronouns and objects that are named by them. Hence the word "John" refers to John; the word "it" refers to some previously specified object. The objects referred to are called the "referents" of the word. Sometimes the word-object relation is called "denotation". Reference is not in general the same as meaning, as words can often be meaningful without having a referent. Fictional and mythological names such as "Bo-Peep" and "Hercules" show that this is possible. As Frege discovered, reference cannot be treated as identical with meaning: "Hesperos" (an ancient Greek name for the evening star) and "Phosphorus" (an ancient Greek name for the morning star) both refer to Venus, but the astronomical fact that '"Hesperos" is "Phosphorus"' can still be informative, even if the 'meanings' of both "Hesperos" and "Phosphorus" are already known. This problem led Frege to distinguish between the sense of a word and its reference.

Art

In Art, a reference is an item from which a work is based. This may include an existing artwork, a reproduced (i.e. photo) or directly observed (i.e. person) object, or the artist's memory.

Computer science

In computer science, references are datatypes which refer to an object elsewhere in memory, and are used to construct a wide variety of data structures such as linked lists. Most programming languages support some form of reference. See reference (computer science). The C++ programming language has a specific type of reference also referred to as a reference; see reference (C Plus Plus).

Geometry

A reference point is a location used to describe another one, by giving the relative position. Similarly we have the concept of frame of reference (both in physics and figuratively), etc.

Libraries

In a library, the word reference may refer to a dictionary, encyclopedia, or other reference work that contains many brief articles that cover a broad scope of knowledge in one book, or a set of books. However, the word reference is also used to mean a book that cannot be taken from the room, or from the building. Many of the books in the reference department of a library are reference works, but some are books that are simply too large or valuable to loan out. Conversely, selected reference works may be shelved with other circulating books, and may be loaned out.

Scholarship

A reference may also be a text (not necessarily a reference text) that has been used in the creation of a piece of work such as an essay, report, or oration. Its primary purpose is to allow people who receive such work to examine the author's sources, either for validity, or simply to learn more about the subject. Such items are often listed at the end of an article or book in a reference list.Copying of copyrighted material without required permisions amounts to 'plagiarism'.

Personal references

In the labour market, a reference is a letter to a prospective employer regarding a job applicant's characteristics. Usually the person providing the reference - the referee - is a previous boss, or someone of some distinction in government, the clergy, or education, who can personally vouch for the applicant's employability.

Canadian law

A Reference is a procedure through which the government of Canada can submit legal questions to the Supreme Court of Canada. The Court will consider the question and publish an opinion which is treated as binding in law.

See also


- Library reference desk
- List of reference tables
- Reference work
- Self-reference

Human

Humans or human beings define themselves in biological, social, and spiritual terms. Biologically, humans are classified as the species Homo sapiens (Latin for "wise man" or "thinking man"): a bipedal primate of the superfamily Hominoidea, together with the other apes: chimpanzees, gorillas, orangutans, and gibbons. Humans have an erect body carriage that frees their upper limbs for manipulating objects and a highly developed brain capable of abstract reasoning, speech, language, and introspection. Bipedal locomotion appears to have evolved before the development of a large brain. The origins of bipedal locomotion and of its role in the evolution of the human brain are topics of ongoing research. The human mind has several distinct attributes. It is responsible for complex behaviour, especially language. Curiosity and observation have led to a variety of explanations for consciousness and the relation between mind and body. Psychology attempts to study behaviour from a scientific point of view. Religious perspectives emphasise a soul, qi or atman as the essence of being, and are often characterised by the belief in and worship of God, gods, spirits, or other people. Philosophy, especially philosophy of mind, attempts to fathom the depths of each of these perspectives. Art, music and literature are often used in expressing these concepts and feelings. Like all primates, humans are inherently social. They create complex social structures composed of co-operating and competing groups. These range from nations and states down to families. Seeking to understand and manipulate the world around them has led to the development of technology and science. Artifacts, beliefs, myths, rituals, values, and social norms have all helped to form humanity's culture.

Terminology

In general, the word "people" is a collective or plural term for any specific group of individual persons. However, when used to refer to a group of humans possessing a common ethnic, cultural or national unitary characteristic or identity, "people" is a singular count noun, and as such takes an "s" in the plural (examples: "the English-speaking peoples of the world", "the indigenous peoples of Brazil"). ethnic Juvenile males are called boys, adult males men, juvenile females girls, and adult females women. Humans are commonly referred to as persons or people, and collectively as Man (capital M), mankind, humankind, humanity, or the human race. Until the 20th century, "human" was only used adjectivally ("pertaining to mankind"). Nominal use of "human" (plural "humans") is short for "human being", and not considered good style in traditional English grammar. As an adjective, "human" is used neutrally (as in "human race"), but "human" and especially "humane" may also emphasise positive aspects of human nature, and can be synonymous with "benevolent" (versus "inhumane"; cf. humanitarian). A distinction is maintained in philosophy and law between the notions "human being", or "man", and "person". The former refers to the species, while the latter refers to a rational agent (see, for example, John Locke's Essay concerning Human Understanding II 27 and Immanuel Kant's Introduction to the Metaphysic of Morals). The term "person" is thus used of non-human animals, and could be used of a mythical being, an artificial intelligence, or an extraterrestrial. An important question in theology and the philosophy of religion concerns whether God is a person. In Latin, "humanus" is the adjectival form of the noun "homo", translated as "man" (to include males and females). The Old English word "man" could also have this generic meaning, as demonstrated by such compounds as "wifman" ("female person") → "wiman" → "woman". For the etymology of "man" see mannaz.

Biology

Anatomy and physiology

mannaz] Humans exhibit fully bipedal locomotion. This leaves the forelimbs available for manipulating objects using opposable thumbs. Humans vary substantially around the mean height and mean weight. Some of this variation is explained by locality and historical factors. Although body size is largely determined by genes, it is also significantly influenced by diet and exercise. The mean height of a North American adult female is 162 centimetres (5 feet 4 inches) and the mean weight is 62 kilograms (137 pounds). North American adult males are typically larger: 175 centimetres (5 feet 9 inches) and 78 kilograms (172 pounds). Human skin appears to be relatively hairless in comparison to other primates; however, most humans have a larger number of hairs on their body than a chimpanzee. The main difference is that human hairs are shorter, finer, and less coloured then the average chimpanzee's, thus rendering them harder to see. The colour of human hair and skin is determined by the presence of coloured pigments called melanins. Most researchers believe that skin darkening was an adaptation that evolved as a defence against UV solar radiation; melanin is an effective sunblock. The skin colour of contemporary humans can range from very dark brown to very pale pink. It is geographically stratified and in general correlates with the environmental level of UV. Human skin and hair colour is controlled in part by the MC1R gene. For example, the red hair and pale skin of some Europeans is the result of mutations in MC1R. Human skin has a capacity to darken (sun tanning) in response to UV exposure. Variation in the ability to sun tan is also controlled in part by MC1R. sun tanning] Because humans are bipedal, the pelvic region and spinal column tend to become worn, creating locomotion difficulties in old age. The individual need for regular intake of food and drink is prominently reflected in human culture, and has led to the development of food science. Failure to obtain food leads to hunger and eventually starvation, while failure to obtain water leads to dehydration and thirst. Both starvation and dehydration cause death if not alleviated. In modern times, obesity amongst humans has increased to almost epidemic proportions, leading to health complications and increased mortality in some developed countries, and is becoming problematic elsewhere. The average sleep requirement is between seven and eight hours a day for an adult and nine to ten hours for a child. Elderly people usually sleep for six to seven hours. It is common, however, in modern societies for people to get less sleep than they need, leading to a state of sleep deprivation. The human body is subject to an ageing process and to illness. Medicine is the science that explores methods of preserving bodily health.

Life cycle

health] The human life cycle is similar to that of other placental mammals. New human life develops from conception. An egg is usually fertilised inside the female by sperm from the male through sexual intercourse, though in vitro fertilisation methods are also used. The fertilised egg is called a zygote. The zygote divides inside the female's uterus to become an embryo which over a period of thirty-eight weeks becomes the fetus. At birth, the fully grown fetus is expelled from the female's body and breathes independently as a baby for the first time. At this point, most modern cultures recognise the baby as a person entitled to the full protection of the law, though some jurisdictions extend personhood to human fetuses while they remain in the uterus. Compared with that of other species, human childbirth is relatively complicated. Painful labours lasting twenty-four hours or more are not uncommon, and may result in injury to the child or the death of the mother, although the chances of a successful labour increased significantly during the twentieth century in wealthier countries. Natural childbirth remains an arguably more dangerous ordeal in remote, underdeveloped regions of the world, though the women who live in these regions have argued that their natural childbirth methods are safer and less traumatic for mother and child. Natural childbirth Human children are born after a nine-month gestation period, with typically 3–4 kilograms (6–9 pounds) in weight and 50–60 centimetres (20–24 inches) in height in developed countries. [http://www.childinfo.org/eddb/lbw] Helpless at birth, they continue to grow for some years, typically reaching sexual maturity at twelve to fifteen years of age. Boys continue growing for some time after this, reaching their maximum height around the age of eighteen. These values vary too, depending on genes and environment. The human lifespan can be split into a number of stages: infancy, childhood, adolescence, young adulthood, maturity and old age, though the lengths of these stages, especially the later ones, are not fixed. There are striking differences in life expectancy around the world. The developed world is quickly getting older, with the median age around 40 years (highest in Monaco at 45.1 years), while in the developing world, the median age is 15–20 years (the lowest in Uganda at 14.8 years). Life expectancy at birth is 77.2 years in the U.S. as of 2001. [http://www.cdc.gov/nchs/fastats/lifexpec.htm] The expected life span at birth in Singapore is 84.29 years for a female and 78.96 years for a male, while in Botswana, due largely to AIDS, it is 30.99 years for a male and 30.53 years for a female. One in five Europeans, but one in twenty Africans, is 60 years or older, according to The World Factbook. [http://www.cia.gov/cia/publications/factbook] African.]] The number of centenarians in the world was estimated by the United Nations [http://www.un.org/ageing/note5713.doc.htm] at 210,000 in 2002. The maximum life span for humans is thought to be over 120 years. Worldwide, there are 81 men aged 60 or over for every 100 women, and among the oldest, there are 53 men for every 100 women. The philosophical questions of when human personhood begins and whether it persists after death are the subject of considerable debate. The prospect of death may cause unease or fear. People who are near death sometimes have a near-death experience, in which they have visions. Burial ceremonies are characteristic of human societies, often inspired by beliefs in an afterlife. Institutions of inheritance or ancestor worship may extend an individual's presence beyond his physical lifespan (see immortality).

Genetics

Humans are a eukaryotic species. Each diploid cell has two sets of 23 chromosomes, each set received from one parent. There are 22 pairs of autosomes and one pair of sex chromosomes. At present estimate, humans have approximately 20,000–25,000 genes and share 95% of their DNA with their closest living evolutionary relatives, the two species of chimpanzees. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12368483] Like other mammals, humans have an XY sex determination system, so that females have the sex chromosomes XX and males have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that recessive diseases associated with X-linked genes affect men more often than women. For example, genes that control the clotting of blood reside on the X chromosome. Women have a blood-clotting gene on each X chromosome so that one normal blood-clotting gene can compensate for a flaw in the gene on the other X chromosome. But men are hemizygous for the blood-clotting gene, since there is no gene on the Y chromosome to control blood clotting. As a result, men will suffer from haemophilia more often than women.

Race and ethnicity

haemophilia, Black, White (Hispanic), and Asian. Top row males, bottom row females.]] Humans often categorise themselves and others in terms of race or ethnicity. In the United States, racial categories are primarily based on language and ethnicity, although biological qualities, such as skin colour, blood type, facial features, ancestry, and other genetic variances are also key factors. Self identification with an ethnic group is usually based on kinship and descent, as well as presumed advantage. When race and ethnicity lead to variant treatment it is thought to impact social identity, giving rise to the theory of identity politics. Although most humans recognise that variances occur within a species, it is often a point of dispute as to what these differences entail, and if discrimination based on race (racism) is acceptable in the early twenty-first century. Race and intelligence, scientific racism, xenophobia and ethnocentrism are just a few of the many basis' for such practices.

Habitat

The view most widely accepted by the anthropological community is that the human species originated in the African savanna between 100 and 200 thousand years BCE, colonised the rest of the Old World and Oceania by 40,000 years BCE, and finally colonised the Americas by 10,000 years BCE. Homo sapiens displaced groups such as Neanderthals and Homo floresiensis through more successful reproduction and competition for resources, and/or extermination. (See Human evolution, Vagina gentium, and Environment of Evolutionary Adaptedness.) Technology has allowed humans to colonise all of the continents and adapt to all climates. Within the last few decades, humans have been able to explore Antarctica, the ocean depths, and space, although long-term habitation of these environments are not yet possible. Humans, with a population of about six thousand million, are one of the most numerous mammals on Earth. Most humans (61%) live in the Asian region. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with 5% in Oceania. (See list of countries by population and list of countries by population density.) list of countries by population density (The arctic is at the centre of the map and the numbers are millennia before present).]] The original human lifestyle is hunting-gathering, which is adapted to the savanna. Other human lifestyles are nomadism (often linked to animal herding) and permanent settlements made possible by the development of agriculture. Humans have a great capacity for altering their habitats by various methods, such as agriculture, irrigation, urban planning, construction, transport, and manufacturing goods. Permanent human settlements are dependent on proximity to water and, depending on the lifestyle, other natural resources such as fertile land for growing crops and grazing livestock, or seasonally by populations of prey. With the advent of large-scale trade and transport infrastructure, immediate proximity to these resources has become unnecessary, and in many places these factors are no longer the driving force behind growth and decline of population. Human habitation within closed ecological systems in hostile environments (Antarctica, outer space) is expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Life in space has been very sporadic, with a maximum of thirteen humans in space at any given time, starting with Yuri Gagarin's space flight in 1961. Between 1969 and 1974, up to two humans at a time spent brief intervals on the Moon. As of 2005, no other celestial body has been visited by human beings, although there has been a continuous human presence in space since the launch of the initial crew to inhabit the International Space Station on October 31, 2000.

Population

2000 From 1800 to 2000, the human population increased from one to six billion. It is expected to crest at around ten billion during the 21st century. In 2004, around 2.5 billion out of 6.3 billion people lived in urban centres, and this is expected to rise during the 21st century. Problems for humans living in cities include various forms of pollution, crime, and poverty, especially in inner city and suburban slums. Geneticists Lynn Jorde and Henry Harpending of the University of Utah have concluded that the variation in the total stock of human DNA is minute compared to that of other species; and that around 74,000 years ago, human population was reduced to a small number of breeding pairs, possibly as small as 1000, resulting in a very small residual gene pool. Various reasons for this bottleneck have been postulated, the most popular, called the Toba catastrophe theory, being the eruption of a volcano at Lake Toba.

Human evolution

The study of human evolution encompasses many scientific disciplines, but most notably physical anthropology and genetics. The term "human", in the context of human evolution, refers to the genus Homo, but studies of human evolution usually include other hominids and hominines, such as the australopithecines. Biologically, humans are defined as hominids of the species Homo sapiens, of which the only extant subspecies is Homo sapiens sapiens (Latin for "very wise man"); Homo sapiens idaltu (roughly translated as "elderly wise man") is the extinct subspecies. Modern humans are usually considered the only surviving species in the genus Homo, although some argue that the two species of chimpanzees should be reclassified from Pan troglodytes (Common Chimpanzee) and Pan paniscus (Bonobo/Pygmy Chimpanzee) to Homo troglodytes and Homo paniscus respectively, given that they share a recent ancestor with man. [http://news.nationalgeographic.com/news/2003/05/0520_030520_chimpanzees.html] Full genome sequencing resulted in these conclusions: "After 6 [million] years of separate evolution, the differences between chimp and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice." [http://news.ft.com/cms/s/43445728-1a44-11da-b279-00000e2511c8.html Chimp and human DNA is 96% identical] It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from gorillas about eight million years ago. However, in 2001 a hominine skull approximately seven million years old, classified as Sahelanthropus tchadensis, was discovered in Chad and seems to indicate an earlier divergence. Two prominent scientific theories of the origins of contemporary humans exist. They concern the relationship between modern humans and other hominids: The single-origin or "out of Africa" hypothesis proposes that modern humans evolved in Africa and later replaced hominids in other parts of the world. The multiregional hypothesis proposes that modern humans evolved at least in part from independent hominid populations. Human evolution is characterised by a number of important physiological trends:
- expansion of the brain cavity and brain itself, which is typically 1,400 cm³ in volume, over twice that of a chimpanzee or gorilla. The pattern of human postnatal brain growth differs from that of other apes (heterochrony), allowing for an extended period of social learning in juvenile humans. Physical anthropologists argue that a reorganisation of the structure of the brain is more important than cranial expansion itself;
- canine tooth reduction;
- bipedal locomotion;
- descent of the larynx, which makes speech possible. Humans are classified as Homo sapiens sapiens. A camp of physical anthropologists see neanderthalensis as a subspecies and classify the neanderthals as Homo sapiens neanderthalensis. A second camp of physical anthropologists see the neanderthals as a distinct species diverging from the modern human lineage over 500,000 years ago. Under this classification, neaderthals are Homo neanderthalensis. Recent DNA analysis suggests that neanderthalensis were not a subspecies. How these trends are related and what their role is in the evolution of complex social organisation and culture are matters of ongoing debate. larynx]]

Intelligence

Most humans consider their species to be the most intelligent in the animal kingdom. Certainly, humans are the only technologically advanced animal. Along with the brain's internal complexity, the brain to body mass ratio is generally assumed to be a good indicator of relative intelligence. Humans have the second highest ratio, with the tree shrew having the highest [http://www.hindustantimes.com/news/181_935198,00300006.htm], and the bottlenose dolphin very similar to humans. The human ability to abstract may be unparalleled in the animal kingdom. Human beings are one of five species to pass the mirror test — which tests whether an animal recognises its reflection as an image of itself — along with chimpanzees or bonobos, orangutans, and dolphins. Human beings under the age of four usually fail the test.

Culture

dolphin]] Culture is defined here as a set of distinctive material, intellectual, emotional, and spiritual features of a social group, including art, literature, lifestyles, value systems, traditions, rituals, and beliefs. Culture consists of at least three elements: values, social norms, and artifacts. A culture's values define what it holds to be important. Norms are expectations of how people ought to behave. Artifacts — things, or material culture — derive from the culture's values and norms together with its understanding of the way the world functions.

Origins

Essentially every culture has its characteristic origin beliefs. Creationism or creation theology is the belief that humans, the Earth, the universe and the multiverse were created by a supreme being or deity. The event itself may be seen either as an act of creation (ex nihilo) or the emergence of order from preexisting chaos (demiurge). Many who hold "creation" beliefs consider such belief to be a part of religious faith, and hence compatible with, or otherwise unaffected by scientific views while others maintain the scientific data is compatible with creationism. Proponents of evolutionary creationism may claim that understood scientific mechanisms are simply aspects of supreme creation. Otherwise, science-oriented believers may consider the scriptural account of creation as simply a metaphor.

Language

metaphor, Chinese, Korean, Hebrew and Greek]] Values, norms and technology are dependent on the capacity for humans to share ideas. The faculty of speech may be a defining feature of humanity, probably predating phylogenetic separation of the modern population. (See Proto-World language, Origins of language.) Language is central to the communication between humans. Some scientists argue that non-human animals are able to use some form of language too, and that non-human primates are able to learn human sign language [http://www.mnsu.edu/emuseum/cultural/language/chimpanzee.html] [http://www.msubillings.edu/asc/PDF-WritingLab/3-Minute%20Spr05/APA%20sample%20paper.pdf] (pdf). Language is central to the sense of identity that unites cultures and ethnicities. The invention of writing systems some 5000 years ago, allowing the preservation of speech, was a major step in cultural evolution. Language, especially written language, is sometimes thought to have supernatural status or powers. (See Magic, Mantra, Vac.) The science of linguistics describes the structure of language and the relationship between languages. There are estimated to be some 6,000 different languages, including sign languages, used today.

Music

Music is a natural intuitive phenomenon operating in the three worlds of time, pitch, and energy, and under the three distinct and interrelated organisation structures of rhythm, harmony, and melody. Composing, improvising and performing music are all art forms. Listening to music is perhaps the most common form of entertainment, while learning and understanding it are popular disciplines. There are a wide variety of music genres and ethnic musics.

Emotion and sexuality

Human emotion has a significant influence on, or can even be said to control, human behaviour. Emotional experiences perceived as pleasant, like love, admiration, or joy, contrast with those perceived as unpleasant, like hate, envy, or sorrow. There is often a distinction seen between refined emotions, which are socially learned, and survival oriented emotions, which are thought to be innate. Human exploration of emotions as separate from other neurological phenomena is worth note, particularly in those cultures were emotion is considered separate from physiological state. In some cultural medical theories, to provide an example, emotion is considered so synonymous with certain forms of physical health that no difference is thought to exist. The Stoics believed excessive emotion was harmful, while some Sufi teachers (in particular, the poet and astronomer Omar Khayyám) felt certain extreme emotions could yield a conceptual perfection, what is often translated as ecstasy. ecstasy"]] In modern scientific thought, certain refined emotions are considered to be a complex neural trait of many domesticated and a few non-domesticated mammals, developed commonly in reaction to superior survival mechanisms and intelligent interaction with each other and the environment; as such, refined emotion is not in all cases as discrete and separate from natural neural function as was once assumed. Still, when humans function in civilised tandem, it has been noted that uninhibited acting on extreme emotion can lead to social disorder and crime. Human sexuality, besides ensuring reproduction, has important social functions, creating physical intimacy, bonds and hierarchies among individuals, and that may be directed to spiritual transcendence, and/or to the enjoyment of activity involving sexual gratification. Sexual desire, libido, is experienced as a bodily urge, often accompanied by strong emotions, both positive (such as love or ecstasy) and negative (such as jealousy). As with other human self-descriptions, humans propose it is high intelligence and complex societies of humans that have produced the most complex sexual behaviors of any animal. Human sexual choices are usually made in reference to cultural norms, which vary widely. Restrictions are largely determined by religious beliefs.

Body image

norms, Japan]]The physical appearance of the human body is central to culture and art. In every human culture, people adorn their bodies with tattoos, cosmetics, clothing, and jewellery. Hairstyles and hair colour also have important cultural implications. The perception of an individual as physically beautiful or ugly can have profound implications for their lives. This is particularly true of women, whose external appearance is highly valued in most, if not all, human societies. Anthropologists believe this to be an important factor in the development of personality and social relations in particular physical attractiveness. There is a relatively low sexual dimorphism between human males and females in comparison with other mammals.

Trade and economics

sexual dimorphism.]] Trade is the voluntary exchange of goods, services, or both, and a form of economics. A mechanism that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Modern traders instead generally negotiate through a medium of exchange, such as money. As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade. Trade exists for many reasons. Due to specialisation and division of labor, most people concentrate on a small aspect of manufacturing or service, trading their labour for products. Trade exists between regions because different regions have an absolute or comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade between locations benefits both locations. Economics is a social science that studies the production, distribution, trade and consumption of goods and services. Economics, which focuses on measurable variables, is broadly divided into two main branches: microeconomics, which deals with individual agents, such as households and businesses, and macroeconomics, which considers the economy as a whole, in which case it considers aggregate supply and demand for money, capital and commodities. Aspects receiving particular attention in economics are resource allocation, production, distribution, trade, and competition. Economic logic is increasingly applied to any problem that involves choice under scarcity or determining economic value. Mainstream economics focuses on how prices reflect supply and demand, and uses equations to predict consequences of decisions.

Artifacts, technology, and science

supply and demand.]] Human cultures are both characterised and differentiated by the objects that they make and use. Archaeology attempts to tell the story of past or lost cultures in part by close examination of the artifacts they produced. Early humans left stone tools, pottery and jewellery that are particular to various regions and times. Improvements in technology are passed from one culture to another. For instance, the cultivation of crops arose in several different locations, but quickly spread to be an almost ubiquitous feature of human life. Similarly, advances in weapons, architecture and metallurgy are quickly disseminated. Such techniques can be passed on by oral tradition. The development of writing, itself a type of artifact, made it possible to pass information from generation to generation and from region to region with greater accuracy. Together, these developments made possible the commencement of civilisation and urbanisation, with their inherently complex social arrangements. Eventually this led to the institutionalisation of the development of new technology, and the associated understanding of the way the world functions. This science now forms a central part of human culture. In recent times, physics and astrophysics have come to play a central role in shaping what is now known as physical cosmology, that is, the understanding of the universe through scientific observation and experiment. This discipline, which focuses on the universe as it exists on the largest scales and at the earliest times, begins by arguing for the big bang, a sort of cosmic explosion from which the universe itself is said to have erupted ~13.7 ± 0.2 billion (109) years ago. After its violent beginnings and until its very end, scientists then propose that the entire history of the universe has been an orderly progression governed by physical laws.

Mind

physical laws Consciousness is a state of mind, said to possess qualities such as, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. The way in which the world is experienced is the subject of much debate and research in philosophy of mind, psychology, brain biology, neurology, and cognitive science. Humans (and often others as well) are variously said to possess consciousness, self-awareness, and a mind, the fruition of being our senses and perceptions. Each of us has a subjective view of existence, the passage of time, and free will. There are many debates about the extent to which the mind constructs or experiences the outer world, and regarding the definitions and validity of many of the terms used above. Cognitive scientist Daniel Dennett, for example, argues that there is no such thing as a narrative centre called mind, but that instead there is simply a collection of sensory inputs and outputs: different kinds of software running in parallel (Dennett, 1991).

Psychology and human ethology

Psychology (Classical Greek: psyche = "soul" or "mind", logos = "study of") is the study of behaviour, mind and thought and the neurological basis for them. Psychoanalysis, the examination of the subconscious was, devised by Sigmund Freud and expanded and refined by the Swiss psychiatrist Carl Gustav Jung (initially one of Freud's followers and friends) and others. Carl Gustav Jung Freud divided the mind into the id (an individual's basic needs and instincts), the superego (personal and cultural values and norms), and the ego (the central, organising self, whose job it is to satisfy the id but not upset the superego). [http://allpsych.com/psychology101/ego.html] C. G. Jung founded the school of analytical psychology and introduced the notion of the collective unconscious, a term taken from philosophy and used by Jung to describe symbols or archetypes that he believed might be common to all cultures. There are also the Conscious, Subconscious, and Superconsciousness, a related but not identical set of categories. The behaviour and mental processes of animals (human and non-human) can be described through animal cognition, ethology, and comparative psychology as well. Human ecology is an academic discipline that investigates how humans and human societies interact with their environment, nature and the human social environment.

Philosophy

social environment in detail from Raphael's School of Athens]] Philosophy is a discipline or field of study involving the investigation, analysis, and development of ideas at a general, abstract, or fundamental level. It is the discipline searching for a general understanding of values and reality by chiefly speculative rather than observational means comprising as its core logic, ontology or metaphysics, epistemology, and axiology which includes the branches of ethics and aesthetics. The term covers a very wide range of approaches, and is also used to refer to a worldview, to a perspective on an issue, or to the positions argued for by a particular philosopher or school of philosophy. Metaphysics is a branch of philosophy concerned with the study of "first principles" and "being" (ontology). Problems that were not originally considered metaphysical have been added to metaphysics. Other problems that were considered metaphysical problems for centuries are now typically relegated to their own separate subheadings in philosophy, such as philosophy of religion, philosophy of mind, philosophy of perception, philosophy of language, and philosophy of science. In rare cases subjects of metaphysical research have been found to be entirely physical and natural. The mind is the term most commonly used to describe the higher functions of the human brain, particularly those of which humans are subjectively conscious, such as personality, thought, reason, memory, intelligence and emotion. Other species of animals share some of these mental capacities, and it is also used in relation to supernatural beings, as in the expression "the mind of God." The term is used here only in relation to humans. There are many Philosophies of mind, the most common relating to the nature of being, and ones way of being, or purpose. Adi Shankara in the East proposed Advaita Vedanta, a popular argument for monism (the metaphysical view that all is of one essential essence, substance or energy). Another type of monism is physicalism or chemically convert the substance into nutrients. Digestion occurs at the multicellular, cellular, and sub-cellular levels. Digestion usually involves mechanical manipulation and chemical action. In most vertebrates, digestion is a multi-stage process in the digestive system, following ingestion of the raw materials, most often other organisms. The process of ingestion usually involves some type of mechanical manipulation.

Human digestion

See: Gastrointestinal tract In humans, digestion begins in the mouth where food is chewed with the teeth. The process stimulates exocrine glands in the mouth to release digestive enzymes such as salivary amylase, which aid in the breakdown of food, particularly carbohydrates. Chewing also causes the release of saliva, which helps condense food into a bolus that can be easily passed through the esophagus to the stomach. In the stomach, food is churned and thoroughly mixed with acid and other digestive enzymes with digestive fluid to further decompose it chemically. As the acidic level changes in the stomach and later parts of the digestive tract, more enzymes are activated or deactivated to extract and process various nutrients. After being processed in the stomach, food is passed to the small intestine, it is pushed through the small intestine via a process called peristalsis, this is a squeezing action, it then passes through the pyloric sphincter where it is further mixed with secretions such as bile, which helps aid in fat digestion, and the enzymes maltase, lactase and sucrase, to process sugars. (Bile also contains pigments that are by-products of red blood cell destruction in the liver; these bile pigments are eliminated from the body with the feces). Most nutrient absorption takes place in the small intestine, after which food is passed to the large intestine. Blood which has absorbed nutrients passes through the liver for filtering, removal of toxins and help processing of nutrients. In the large intestine, water is reabsorbed, and leftover waste is excreted by defecation.

Digestive organs

Organisms develop specialized organs to aid in the digestion of their food, for example different types of tongues or teeth. Insects may have a crop (or the enlargement of esophagus) while birds and cockroachs may develop a gizzard (or a stomach that acts as teeth and mechanically digests food). A herbivore may have a caecum that contains bacteria which can produce cellulase that helps break down the cellulose in plants. Ruminants, for example cows and sheep, have a specialised fore-stomach called a rumen where microbes help to break down cellulose before the food passes onto the "true" stomach or abomasum.

Digestive hormones

There are at least four hormones that aid and regulate the digestive system:
- Gastrin - is in the stomach and stimulates the gastric glands to secrete pepsinogen and hydrochloric acid. Secretion of gastrin is stimulated by food arriving in stomach. The secretion is inhibited by low pH .
- Secretin - is in the duodenum and signals the secretion of sodium bicarbonate in the pancreas and it stimulates the bile secretion in the liver. This hormone responds to the acidity of the chyme.
- Cholecystokinin (CCK) - is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gall bladder. This hormone is secreted in resonse to fat in chyme.
- Gastric inhibitory peptide (GIP) - is in the duodenum and decreases the stomach churning in turn slowing the emptying in the stomach.

Digestion in plants and fungi

Not only animals digest food. Some carnivorous plants capture other organisms, usually invertebrate animals, and chemically digest them. Fungi also are very effective at digesting organic material in a saprobiontic manner, releasing digestive enzymes externally and then absorbing the digested products.

External links


- [http://www2.ufp.pt/~pedros/qfisio/digestion.htm Human Physiology - Digestion] Category:Digestive system Category:Metabolism ja:消化

Feces

:This biological article about feces refers to animals in general. For feces derived from the human body, see human feces. human feces Feces (American English) or faeces/fæces (Commonwealth English) are semi-solid waste products from an animal digestive tract expelled through the anus (or cloaca) during defecation. In humans, defecation may occur (depending on the individual and the circumstances) from once every two or three days to many times a day. Hardening of the feces may cause prolonged interruption in the usual routine and is called constipation. The word faeces is the plural of the Latin word faex meaning "dregs". There is no singular form in English language. [http://www.medterms.com/script/main/art.asp?articlekey=3400] The distinctive odor of feces is due to bacterial action. Bacteria produce compounds such as indole, skatole, and mercaptans (sulfur containing compounds), as well as the inorganic gas hydrogen sulfide. These are the same compounds that are responsible for the odor of flatus. Feces can help scientists learn about animals because of the food an animal eats. By carefully analyzing the contents of the feces, the scientist can understand the consistency and odors that comprise the scat. Then, a careful analysis can be conducted which reveals the creature's eating habits. Feces are generally a taboo subject (see toilet humour). Scientists have long noted that many species hide or bury their feces, because the odor can attract predators, and these species often exhibit anxious behavior when their feces cannot be concealed. In humans, this phenomenon manifests itself in a stigma on feces. The feces of animals is often used as fertilizer: see manure. manure

Related terminology

manure Feces are also known as scat and scatology is the study of feces. Informally, the word "excrement" has become synonymous with faeces; a usage based upon the incorrect belief that faeces are a product of excretion. The words shit and crap are vulgar terms for feces in English. Coprophagia is the practice of eating feces. This is unusual, but some herbivores with a high-fiber/low-protein diet (such as rabbits) eat their own feces as a normal part of metabolism. Plant matter the animal consumes is digested in two passes, with the product of the first pass being re-ingested directly from the anus. After the material is re-digested, the indigestible waste that remains is excreted and left alone. Coprophilia, also known as fecophilia, is a sexual attraction to fecal matter. Coprophobia, also known as fecophobia, is a strong fear of feces. Fossilized feces are known as coprolites, and form an important class of objects studied in the field of paleontology.

Fecal contamination

A quick test for fecal contamination of water sources or soil is a check for the presence of E. coli bacteria performed with the help of McConkey agar plates or Petri dishes. It turns out that E. coli bacteria (and almost no other ones) develop red colonies at temperature about 110 F overnight (110 degrees Fahrenheit = 43 degrees Celsius). While nearly all strains of E.coli are harmless, their presence is indicative of fecal contamination, and hence a high possibility of other, more dangerous organisms, e.g., those of hepatitis.

Human feces

Main article: Human feces Human fecal matter varies significantly in appearance, depending on diet and health. Normally it is semisolid, with a mucus coating. Its brown colouration comes from a combination of bile and dead red blood cells. In newborn babies, fecal matter is initially yellow/green after the meconium. This colouration comes from the presence of bile alone. In time, as the body starts expelling excess dead red blood cells, it acquires its familiar brown appearance.

See also


- Intestinal parasite
- A1 broth
- Manure
- Scatology
- Guano

External links and references


- [http://www.umanitoba.ca/faculties/medicine/units/biochem/coursenotes/blanchaer_tutorials/Frank_II/urobilinogen.html Urobilinogen]
- [http://www.mcevoy.demon.co.uk/Medicine/Pathology/Biochem/Liver/Biochem.html Liver biochemistry]
- History of Shit by Dominique Laporte (ISBN 0262621606) Category:animal physiology ja:糞

Urine

Urine is liquid waste excreted by the kidneys and is produced by the process of filtration. This waste is eventually expelled from the body in a process known as urination. Most commonly the excretion of urine serves for flushing waste molecules collected from the blood by the kidneys, and for the homeostasis of the body liquids; however, many species also use it for olfactory communication. olfactory communication

Composition

Urine is a transparent solution that is clear to amber in color, and usually is light yellow. It is the byproduct or waste fluid secreted by the kidneys, transported by the ureters to the urinary bladder where it is stored until it is voided through the urethra. Urine is made up of a watery solution of metabolic wastes (such as urea), dissolved salts and organic materials. Fluid and materials being filtered by the kidneys, destined to become urine, comes from the blood or interstitial fluid. The composition of urine is adjusted in the process of reabsorption when essential molecules needed by the body, such as glucose, are reabsorbed back into the blood stream via carri