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Aphytophagy

Aphytophagy

Phagy or phagia is an ecological or behavioral term that is used to identify particular nutritional systems or feeding behaviors. The suffixes -phagy, -phagous and -phage are used to name different types of phagy or animals that perform it, which include:
- Monophagy — feeding on a single type of food
- Polyphagy — feeding on many kinds of food
- Phytophagy — the eating of plants
- Ophiophagy — feeding on snakes
- Hematophagy — feeding on blood
- Coprophagy — feeding on faeces
- Geophagy — feeding on earth
- See Pica (disorder) for some more. Phagy can also be used to name eating in a specified manner, normal or abnormal (for exemple dysphagia, a dysfunction of deglutition). This word root can also be used as a prefix in other words, such as in phagocytosis (the function of specialized cells that can feed on inorganic or organic matter, including other cells). The term comes from Greek language phagein, to eat; with Indo-European language roots in bhag.

Ecology

Ecology, or ecological science, is the scientific study of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment. The environment of an organism includes both the physical properties, which can be described as the sum of local abiotic factors like climate and geology, as well as the other organisms that share its habitat. The term oekologie was coined in 1866 by the German biologist Ernst Haeckel; the word is derived from the Greek oikos ("household") and logos ("study")–therefore, "ecology" means the "study of the household of nature".

Scope

Ecology is usually considered a branch of biology, the general science that studies living organisms. Organisms can be studied at many different levels, from proteins and nucleic acids (in biochemistry and molecular biology), to cells (in cellular biology), to individuals (in botany, zoology, and other similar disciplines), and finally at the level of populations, communities, and ecosystems, to the biosphere as a whole; these latter strata are the primary subjects of ecological inquiries. Ecology is a multi-disciplinary science. Because of its focus on the higher levels of the organization of life on earth and on the interrelations between organisms and their environment, ecology draws heavily on many other branches of science, especially geology and geography, meteorology, pedology, chemistry, and physics. Thus, ecology is said to be a holistic science, one that over-arches older disciplines such as biology which in this view become sub-disciplines contributing to ecological knowledge. Agriculture, fisheries, forestry, medicine and urban development are among human activities that would fall within Krebbs' (1972: 4) explanation of his definition of ecology: "where organisms are found, how many occur there, and why". As a scientific discipline, ecology does not dictate what is "right" or "wrong". However, maintaining biodiversity and related ecological goals have provided a scientific basis for expressing the goals of environmentalism and have given scientific methodology, measure, and terminology to environmental issues. Additionally, a holistic view of nature is stressed in both ecology and environmentalism. Consider the ways an ecologist might approach studying the life of honeybees:
- the behavioral relationship between individuals of a species is behavorial ecology — for example, the study of the queen bee, and how she relates to the worker bees and the drones.
- The organized activity of a species is community ecology; for example, the activity of bees assures the pollination of flowering plants. Bee hives additionally produce honey which is consumed by still other species, such as bears.
- The relationship between the environment and a species is environmental ecology — for example, the consequences of environmental change on bee activity. Bees may die out due to environmental changes (see pollinator decline). The environment simultaneously affects and is a consequence of this activity and is thus intertwined with the survival of the species.

Disciplines of ecology

: Main article: Disciplines of ecology Ecology is a broad science which can be subdivided into major and minor sub-disciplines. The major sub-disciplines include (in a nested series from the smallest to the largest in scope):
- Physiological Ecology (or ecophysiology), which studies the influence of the biotic and abiotic environment on the physiology of the individual, and the adaptation of the individual to its environment;
- Behavioral ecology, which studies the ecological and evolutionary basis for animal behavior, and the roles of behavior in enabling animals to adapt to their ecological niches;
- Population ecology (or autecology), which deals with the dynamics of populations within species, and the interactions of these populations with environmental factors;
- Community ecology (or synecology) which studies the interactions between species within an ecological community;
- Ecosystem ecology, which studies the flows of energy and matter through ecosystems;
- Landscape ecology, which studies the interactions between discrete elements of a landscape;
- Global ecology, which looks at ecological questions at the global level, often asking macroecological questions. Ecology can also be sub-divided on the basis of target groups:
- Animal ecology, plant ecology, insect ecology; Ecology can also be sub-divided from the perspective of the studied biomes:
- Arctic ecology (or polar ecology), tropical ecology, desert ecology (temperate zone ecology could also exist as a distinct sub-field, but ecology as a whole has an overwhelmingly temperate bias, so the sub-field is redundant). Spanning all of the above is:
- Evolutionary ecology.

History of ecology

: Main article: History of ecology
Fundamental principles of ecology

Biosphere and biodiversity
Main articles: Biosphere, Biodiversity, Unified neutral theory of biodiversity For modern ecologists, ecology can be studied at several levels: population level (individuals of the same species), biocoenosis level (or community of species), ecosystem level, and biosphere level. The outer layer of the planet Earth can be divided into several compartments: the hydrosphere (or sphere of water), the lithosphere (or sphere of soils and rocks), and the atmosphere (or sphere of the air). The biosphere (or sphere of life), sometimes described as "the fourth envelope", is all living matter on the planet or that portion of the planet occupied by life. It reaches well into the other three spheres, although there are no permanent inhabitants of the atmosphere. Relative to the volume of the Earth, the biosphere is only the very thin surface layer which extends from 11,000 meters below sea level to 15,000 meters above. It is thought that life first developed in the hydrosphere, at shallow depths, in the photic zone. Multicellular organisms then appeared and colonized benthic zones. Terrestrial life developed later, after the ozone layer protecting living beings from UV rays formed. Diversification of terrestrial species is thought to be increased by the continents drifting apart, or alternately, colliding. Biodiversity is expressed at the ecological level (ecosystem), population level (intraspecific diversity), species level (specific diversity), and genetic level. Recently technology has allowed the discovery of the deep ocean vent communities. This remarkable ecological system is not dependant on sunlight but bacteria, utilising the chemistry of the hot volcanic vents, are at the base of its food chain. The biosphere contains great quantities of elements such as carbon, nitrogen and oxygen. Other elements, such as phosphorus, calcium, and potassium, are also essential to life, yet are present in smaller amounts. At the ecosystem and biosphere levels, there is a continual recycling of all these elements, which alternate between the mineral and organic states. While there is a slight input of geothermal energy, the bulk of the functioning of the ecosystem is based on the input of solar energy. Plants and photosynthetic microorganisms convert light into chemical energy by the process of photosynthesis, which creates glucose (a simple sugar) and releases free oxygen. Glucose thus becomes the secondary energy source which drives the ecosystem. Some of this glucose is used directly by other organisms for energy. Other sugar molecules can be converted to other molecules such as amino acids. Plants use some of this sugar, concentrated in nectar to entice pollinators to aid them in reproduction. Cellular respiration is the process by which organisms (like mammals) break the glucose back down into its constituents, water and carbon dioxide, thus regaining the stored energy the sun originally gave to the plants. The proportion of photosynthetic activity of plants and other photosynthesizers to the respiration of other organisms determines the specific composition of the Earth's atmosphere, particularly its oxygen level. Global air currents mix the atmosphere and maintain nearly the same balance of elements in areas of intense biological activity and areas of slight biological activity. Water is also exchanged between the hydrosphere, lithosphere, atmosphere and biosphere in regular cycles. The oceans are large tanks, which store water, ensure thermal and climatic stability, as well as the transport of chemical elements thanks to large oceanic currents. For a better understanding of how the biosphere works, and various dysfunctions related to human activity, American scientists simulated the biosphere in a small-scale model, called Biosphere II.
The ecosystem concept
: Main article: Ecosystem The first principle of ecology is that each living organism has an ongoing and continual relationship with every other element that makes up its environment. An ecosystem can be defined as any situation where there is interaction between organisms and their environment. The ecosystem is composed of two entities, the entirety of life (called the biocoenosis) and the medium that life exists in (the biotope). Within the ecosystem, species are connected and dependent upon one another in the food chain, and exchange energy and matter between themselves and with their environment. The concept of an ecosystem can apply to units of variable size, such as a pond, a field, or a piece of deadwood. A unit of smaller size is called a microecosystem. For example, an ecosystem can be a stone and all the life under it. A mesoecosystem could be a forest, and a macroecosystem a whole ecoregion, with its watershed. The main questions when studying an ecosystem are:
- How could the colonization of a barren area be carried out?
- What are the ecosystem's dynamics and changes
- How does an ecosystem interact at local, regional and global scale
- Is the current state stable?
- What is the value of an ecosystem? How does the interaction of ecological systems provide benefit to humans, especially in the provision of healthy water? Ecosystems are often classified by reference to the biotopes concerned. The following ecosystems may be defined:
- As continental ecosystems (or terrestrial), such as forest ecosystems, meadow ecosystems (meadows, steppes, savannas), or agro-ecosystems (agricultural systems).
- As ecosystems of inland waters, such as lentic ecosystems (lakes, ponds) or lotic ecosystems (rivers)
- As oceanic ecosystems (seas, oceans). Another classification can be done by reference to its communities (for example a human ecosystem).
Dynamics and stability
: Main articles: biogeochemistry, Homeostasis, Population dynamics Ecological factors which can affect dynamic change in a population or species in a given ecology or environment are usually divided into two groups: abiotic and biotic. Abiotic factors are geological, geographical, hydrological and climatological parameters. A biotope is an environmentally uniform region characterized by a particular set of abiotic ecological factors. Specific abiotic factors include:
- Water, which is at the same time an essential element to life and a milieu
- Air, which provides oxygen, nitrogen, and carbon dioxide to living species and allows the dissemination of pollen and spores
- Soil, at the same time source of nutriment and physical support
- Soil pH, salinity, nitrogen and phosphorus content, ability to retain water, and density are all influential
- Temperature, which should not exceed certain extremes, even if tolerance to heat is significant for some species
- Light, which provides energy to the ecosystem through photosynthesis
- Natural disasters can also be considered abiotic Biocenose, or community, is a group of populations of plants, animals, micro-organisms. Each population is the result of procreations between individuals of same species and cohabitation in a given place and for a given time. When a population consists of an insufficient number of individuals, that population is threatened with extinction; the extinction of a species can approach when all biocenoses composed of individuals of the species are in decline. In small populations, consanguinity (inbreeding) can result in reduced genetic diversity that can further weaken the biocenose. Biotic ecological factors also influence biocenose viability; these factors are considered as either intraspecific and interspecific relations. : Intraspecific relations are those which are established between individuals of the same species, forming a population. They are relations of co-operation or competition, with division of the territory, and sometimes organization in hierarchical societies. : Interspecific relations— interactions between different species—are numerous, and usually described according to their beneficial, detrimental or neutral effect (for example, mutualism (relation ++) or competition (relation --)). The most significant relation is the relation of predation (to eat or to be eaten), which leads to the essential concepts in ecology of food chains (for example, the grass is consumed by the herbivore, itself consumed by a carnivore, itself consumed by a carnivore of larger size). A high predator to prey ratio can have a negative influence on both the predator and prey biocenoses in that low availability of food and high death rate prior to sexual maturity can decrease (or prevent the increase of) populations of each, respectively. Selective hunting of species by humans which leads to population decline is one example of a high predator to prey ratio in action. Other interspecific relations include parasitism, infectious disease and competition for limiting resources, which can occur when two species share the same ecological niche. The existing interactions between the various living beings go along with a permanent mixing of mineral and organic substances, absorbed by organisms for their growth, their maintenance and their reproduction, to be finally rejected as waste. These permanent recyclings of the elements (in particular carbon, oxygen and nitrogen) as well as the water are called biogeochemical cycles. They guarantee a durable stability of the biosphere (at least when unchecked human influence and extreme weather or geological phenomena are left aside). This self-regulation, supported by negative feedback controls, ensures the perenniality of the ecosystems. It is shown by the very stable concentrations of most elements of each compartment. This is referred to as homeostasis. The ecosystem also tends to evolve to a state of ideal balance, reached after a succession of events, the climax (for example a pond can become a peat bog).
Spatial relationships and subdivisions of land
: Main articles: Biome, ecozone Ecosystems are not isolated from each other, but are interrelated. For example, water may circulate between ecosystems by the means of a river or ocean current. Water itself, as a liquid medium, even defines ecosystems. Some species, such as salmon or freshwater eels move between marine systems and fresh-water systems. These relationships between the ecosystems lead to the concept of a biome. A biome is a homogeneous ecological formation that exists over a vast region, such as tundra or steppes. The biosphere comprises all of the Earth's biomes -- the entirety of places where life is possible -- from the highest mountains to the depths of the oceans. Biomes correspond rather well to subdivisions distributed along the latitudes, from the equator towards the poles, with differences based on to the physical environment (for example, oceans or mountain ranges) and to the climate. Their variation is generally related to the distribution of species according to their ability to tolerate temperature and/or dryness. For example, one may find photosynthetic algae only in the photic part of the ocean (where light penetrates), while conifers are mostly found in mountains. Though this is a simplification of more complicated scheme, latitude and altitude approximate a good representation of the distribution of biodiversity within the biosphere. Very generally, the richness of biodiversity (as well for animal than plant species) is decreasing most rapidly near the equator (as in Brazil) and less rapidly as one approaches the poles. The biosphere may also be divided into ecozone, which are very well defined today and primarily follow the continental borders. The ecozones are themselves divided into ecoregions, though there is not agreement on their limits.
Ecosystem productivity
In an ecosystem, the connections between species are generally related to food and their role in the food chain. There are three categories of organisms:
- Producers -- plants which are capable of photosynthesis
- Consumers -- animals, which can be primary consumers (herbivorous), or secondary or tertiary consumers (carnivorous).
- Decomposers -- bacteria, mushrooms which degrade organic matter of all categories, and restore minerals to the environment. These relations form sequences, in which each individual consumes the preceding one and is consumed by the one following, in what are called food chains or food network. In a food network, there will be fewer organisms at each level as one follows the links of the network up the chain. These concepts lead to the idea of biomass (the total living matter in a given place), of primary productivity (the increase in the mass of plants during a given time) and of secondary productivity (the living matter produced by consumers and the decomposers in a given time). These two last ideas are key, since they make it possible to evaluate the load capacity -- the number of organisms which can be supported by a given ecosystem. In any food network, the energy contained in the level of the producers is not completely transferred to the consumers. Thus, from an energy point of view, it is more efficient for humans to be primary consumers (to get nourishment from grains and vegetables) than as secondary consumers (from herbivores such as beef and veal), and more still than as a tertiary consumer (from eating carnivores). The productivity of ecosystems is sometimes estimated by comparing three types of land-based ecosystems and the total of aquatic ecosystems:
- The forests (1/3 of the Earth's land area) contain dense biomasses and are very productive. The total production of the world's forests corresponds to half of the primary production.
- Savannas, meadows, and marshes (1/3 of the Earth's land area) contain less dense biomasses, but are productive. These ecosystems represent the major part of what humans depend on for food.
- Extreme ecosystems in the areas with more extreme climates -- deserts and semi-deserts, tundra, alpine meadows, and steppes -- (1/3 of the Earth's land area) have very sparse biomasses and low productivity
- Finally, the marine and fresh water ecosystems (3/4 of Earth's surface) contain very sparse biomasses (apart from the coastal zones). Humanity's actions over the last few centuries have seriously reduced the amount of the Earth covered by forests (deforestation), and have increased agro-ecosystems (agriculture). In recent decades, an increase in the areas occupied by extreme ecosystems has occurred (desertification).
Ecological crisis
Generally, an ecological crisis is what occurs when the environment of a species or a population evolves in a way unfavourable to that species survival. It may be that the environment quality degrades compared to the species needs, after a change in an abiotic ecological factor (for example, an increase of temperature, less significant rainfalls).
It may be that the environment becomes unfavourable for the survival of a species (or a population) due to an increased pressure of predation (for example overfishing).
Lastly, it may be that the situation becomes unfavourable to the quality of life of the species (or the population) due to a rise in the number of individuals (overpopulation). Ecological crises may be more or less brutal (occurring within a few months or taking as long as a few million years). They can also be of natural or anthropic origin. They may relate to one unique species or to many species (see the article on Extinction event). Lastly, an ecological crisis may be local (as an oil spill) or global (a rise in the sea level due to global warming). According to its degree of endemism, a local crisis will have more or less significant consequences, from the death of many individuals to the total extinction of a species. Whatever its origin, disappearance of one or several species often will involve a rupture in the food chain, further impacting the survival of other species. In the case of a global crisis, the consequences can be much more significant; some extinction events showed the disappearance of more than 90% of existing species at that time. However, it should be noted that the disappearance of certain species, such as the dinosaurs, by freeing an ecological niche, allowed the development and the diversification of the mammals. An ecological crisis thus paradoxically favored biodiversity. Sometimes, an ecological crisis can be a specific and reversible phenomenon at the ecosystem scale. But more generally, the crises impact will last. Indeed, it rather is a connected series of events, that occur till a final point. From this stage, no return to the previous stable state is possible, and a new stable state will be set up gradually (see homeorhesy). Lastly, if an ecological crisis can cause extinction, it can also more simply reduce the quality of life of the remaining individuals. Thus, even if the diversity of the human population is sometimes considered threatened (see in particular indigenous people), few people envision human disappearance at short span. However, epidemic diseases, famines, impact on health of reduction of air quality, food crises, reduction of living space, accumulation of toxic or non degradable wastes, threats on keystone species (great apes, panda, whales) are also factors influencing the well-being of people. During the past decades, this increasing responsibility of humanity in some ecological crises has been clearly observed. Due to the increases in technology and a rapidly increasing population, humans have more influence on their own environment than any other ecosystem engineer. Some usually quoted examples as ecological crises are:
- Permian-Triassic extinction event 250 million of years ago
- Cretaceous-Tertiary extinction event 65 million years ago
- Global warming related to the Greenhouse effect. Warming could involve flooding of the Asian deltas (see also ecorefugees), multiplication of extreme weather phenomena and changes in the nature and quantity of the food resources (see Global warming and agriculture). See also international Kyoto Protocol.
- Ozone layer hole issue
- Deforestation and desertification, with disappearance of many species.
- The nuclear meltdown at Chernobyl in 1986 caused the death of many people and animals from cancer, and caused mutations in a large number of animals and people. The area around the plant is now abandoned because of the large amount of radiation generated by the meltdown.
See also

- ELDIS, a database on ecological aspects of economical development.
- Ecology movement
- List of ecologists
- List of ecology topics
- List of biology topics
- Important publications in ecology Category:Environmental science Category:Agronomy als:Ökologie ko:생태학 ms:Ekologi ja:生態学 simple:Ecology th:นิเวศวิทยา

Nutrition

Nutrition is the study of the relationship between diet and states of health and disease. It is defined as the study of food. Absence of adequate nutrients can cause certain diseases to take hold that can potentially result in death. Between the extremes of optimal health and death from starvation or malnutrition, there is an array of disease states that can be caused or alleviated by changes in diet. Deficiencies, excesses and imbalances in the diet can produce negative impacts on health, which may result in diseases such as scurvy, obesity or osteoporosis. Also, excess ingestion of elements that have no apparent role in health (e.g. lead, mercury, PCBs, dioxins) may have toxic and potentially lethal effects depending on dose. The science of nutrition attempts to understand how and why specific aspects of diet have specific influences on health.

Overview

The human body comprises chemical compounds such as water, amino acids (proteins), fatty acids (lipids), nucleic acids (DNA/RNA), and carbohydrates (e.g. sugars). These compounds in turn consist of elements such as carbon, hydrogen, oxygen, nitrogen, and phosphorus, and may or may not contain minerals such as calcium, iron, and zinc. Minerals also ubiquitously occur in the form of salts and electrolytes. All of these chemical compounds and elements occur in various forms and combinations (e.g. hormones/vitamins, phospholipids, hydroxyapatite), both in the human body and in organisms (e.g. plants, animals) that humans eat. The human body must necessarily comprise those elements that humans eat and absorb into the bloodstream. The digestive system, except in the unborn fetus, is the first step in helping to make the different chemical compounds and elements in food available for the trillions of cells of the body. In the digestive process of an average adult, about seven (7) litres of liquid, known as digestive juices, exit the internal body and enter the lumen of the digestive tract. The digestive juices help break chemical bonds between ingested compounds as well as modulate the conformation and/or energetic state of the compounds/elements. Yet many compounds/elements are absorbed into the bloodstream unchanged, though the digestive process helps to release them from the matrix of the foods where they occur. Any unabsorbed matter is eliminated in the feces. Only a minimal amount of digestive juice is eliminated this way; the intestines reabsorb most of it otherwise the body would rapidly dehydrate (hence the devastating effects of persistent diarrhea). Study in this field must take into careful account the state of the body before ingestion and after digestion as well as the chemical content of both the food and the waste. The specific types of compounds and elements that are absorbed by the body can be determined by comparing the waste to the food. The effect that the absorbed matter has on the body can be determined by finding the difference between the pre-ingestion state and the post-digestion state. The effect may only be discernible after an extended period of time in which all food and ingestion must be exactly regulated and all waste must be analyzed. The number of variables (e.g. 'confounding factors') involved in this type of experimentation is very high. This makes scientifically valid nutritional study very time-consuming and expensive, which accounts for why a proper science of human nutrition is rather new. In general, eating a variety of fresh, whole (unprocessed) foods has proven hormonally and metabolically favourable compared to eating a monotonous diet based on processed foods. In particular, fresh, whole foods provide higher amounts and a more favourable balance of essential and vital nutrients per unit of energy, resulting in better management of cell growth, maintenance, and mitosis (cell division) as well as of appetite and energy balance. A generally more regular eating pattern (e.g. eating medium-sized meals every 3 to 4 hours) has also proven more hormonally and metabolically favourable than infrequent, haphazard food intake.

Nutrition and health

Ill health can be brought about by an imbalance of nutrients, producing either an excess or deficiency which in turn affects body functioning in a cumulative manner. Moreover, because most nutrients are, in some way or the other, involved in cell-to-cell signalling (e.g. as building block or part of a hormone or signalling 'cascades'), deficiency or excess of various nutrients affects hormonal function also indirectly. Thus, because they largely regulate the expression of genes, hormones represent a link between nutrition and how our genes are expressed, i.e. our phenotype. The strength and nature of this link are continually under investigation, but observations especially in recent years have demonstrated a pivotal role for nutrition in hormonal activity and function and therefore in health. Mineral and/or vitamin (tocotrienol and tocopherol) deficiency or excess may yield symptoms of diminishing health such as goitre, scurvy, osteoporosis, weak immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders). The list goes on and on; for reference, see Modern Nutrition in Health and Disease by Shils et al. As of 2005, twelve vitamins and about the same number of minerals are recognized as 'essential nutrients', meaning that they must be consumed and absorbed - or, in the case of vitamin D, alternatively synthesized via UVB radiation - to prevent deficiency symptoms and death. Certain vitamin-like substances found in foods, such as carnitine, have also been found essential to survival and health, but these are not strictly 'essential' to eat because the body can produce them from other compounds. Moreover, thousands of different phytochemicals have recently been discovered in food (particularly in fresh vegetables), which have many discovered and yet to be discovered properties including antioxidant activity (see below). Other essential nutrients include essential amino acids, choline and the essential fatty acids. In addition to sufficient intake, an appropriate balance of essential fatty acids - omega-3 and omega-6 fatty acids - has been discovered to be crucial for maintaining health. Both of these unique "omega" long-chain polyunsaturated fatty acids are substrates for a class of eicosanoids known as prostaglandins. The omega-3 eicosapentaenoic acid (EPA) (which can be made in the body from the omega-3 essential fatty acid alpha-linolenic acid (LNA), or taken in through marine food sources), serves as building block for series 3 prostaglandins (e.g. weakly-inflammation PGE3). The omega-6 dihomo-gamma-linolenic acid (DGLA) serves as building block for series 1 prostaglandins (e.g. anti-inflammatory PGE1), whereas arachidonic acid (AA) serves as building block for series 2 prostaglandins (e.g. pro-inflammatory PGE1). Both DGLA and AA are made from the omega-6 linoleic acid (LA) in the body, or can be taken in directly through food. An appropriately balanced intake of omega-3 and omega-6 partly determines the relative production of different prostaglandins, which partly explains the importance of omega-3/omega-6 balance for cardiovascular health. In industrialised societies, people generally consume large amounts of processed vegetable oils that have reduced amounts of essential fatty acids along with an excessive amount of omega-6 relative to omega-3. The rate of conversions of omega-6 DGLA to AA largely determines the production of the respective prostaglandins PGE1 and PGE2. Omega-3 EPA prevents AA from being released from membranes, thereby skewing prostaglandin balance away from pro-inflammatory PGE2 made from AA toward anti-inflammatory PGE1 made from DGLA. Moreover, the conversion (desaturation) of DGLA to AA is controlled by the enzyme delta-5-desaturase, which in turn is controlled by hormones such as insulin (up-regulation) and glucagon (down-regulation). Because different types and amounts of food eaten/absorbed affect insulin, glucagon and other hormones to varying degrees, not only the amount of omega-3 versus omega-6 eaten but also the general composition of the diet therefore determine health implications in relation to essential fatty acids, inflammation (e.g. immune function) and mitosis (i.e. cell division). Several lines of evidence indicate lifestyle-induced hyperinsulinemia and reduced insulin function (i.e. insulin resistance) as a decisive factor in many disease states. For example, hyperinsulinemia and insulin resistance are strongly linked to chronic inflammation, which in turn is strongly linked to a variety of adverse developments such as arterial microinjuries and clot formation (i.e. heart disease) and exaggerated cell division (i.e. cancer). Hyperinsulinemia and insulin resistance (the so-called metabolic syndrome) are characterized by a combination of abdominal obesity, elevated blood sugar, elevated blood pressure, elevated blood triglycerides, and reduced HDL cholesterol. The negative impact of hyperinsulinemia on prostaglandin PGE1/PGE2 balance may be significant. The state of obesity clearly contributes to insulin resistance, which in turn can cause type 2 diabetes. Virtually all obese and most type 2 diabetic individuals have marked insulin resistance. Although the association between overfatness and insulin resistance is clear, the exact (likely multifarious) causes of insulin resistance remain less clear. Importantly, it has been demonstrated that appropriate exercise, more regular food intake and reducing glycemic load (see below) all can reverse insulin resistance in overfat individuals (and thereby lower blood sugar levels in those who have type 2 diabetes). Overfatness can unfavourably alter hormonal and metabolic status via resistance to the hormone leptin, and a vicious cycle may occur in which insulin/leptin resistance and overfatness aggravate one another. The vicious cycle is putatively fuelled by continuously high insulin/leptin stimulation and fat storage, as a result of high intake of strongly insulin/leptin stimulating foods and energy. Both insulin and leptin normally function as satiety signals to the hypothalamus in the brain; however, insulin/leptin resistance may reduce this signal and therefore allow continued overfeeding despite large bodyfat stores. In addition, reduced leptin signalling to the brain may reduce leptin's normal effect to maintain an appropriately high metabolic rate. There is debate about how and to what extent different dietary factors - e.g. intake of processed carbohydrates, total protein, fat, and carbohydrate intake, intake of saturated and trans fatty acids, and low intake of vitamins/minerals - contribute to the development of insulin- and leptin resistance. In any case, analogous to the way modern man-made pollution may potentially overwhelm the environment's ability to maintain 'homeostasis', the recent explosive introduction of high Glycemic Index- and processed foods into the human diet may potentially overwhelm the body's ability to maintain homeostasis and health (as evidenced by the metabolic syndrome epidemic). Antioxidants are another recent discovery. As cellular metabolism/energy production requires oxygen, potentially damaging (e.g. mutation causing) compounds known as radical oxygen species or free radicals may form. For normal cellular maintenance, growth, and division, these free radicals must be sufficiently neutralized by antioxidant compounds, such as certain vitamins (vitamin C, vitamin E, vitamin K and the aforementioned phytochemicals as well as other compounds, some of which the body itself produces. Different antioxidants are now known to function in a cooperative network, e.g. vitamin C can reactivate free radical-containing glutathione or vitamin E by accepting the free radical itself, and so on. It is now also known that the human digestion system contains a population of a range of bacteria which are essential to digestion, and which are also affected by the food we eat. The role and significance of the intestinal bacterial flora is under investigation.

Nutrition and sports

(Stub, please expand.) Nutrition is very important for improving sports performance. The most common means to improve performance through diet is the practice of eating large quantities of protein, usually red meat, when attempting to build muscle mass; its efficacy is doubtful, as daily protein intake even on a normal diet usually outweighs the amount of muscle protein which can be synthesized in a day, and protein is a much less efficient source of the energy needed to build new muscle tissue than are fats and carbohydrates.

Nutrition and longevity

Lifespan is somehow related to the amount of food energy consumed: this was first systematically investigated in the seminal study by Weidruch, et al. (1986). A pursuit of this principle of caloric restriction followed, involving research into longevity of those who reduced their food energy intake while attempting to optimize their micronutrient intake. Perhaps not surprisingly, some people found that cutting down on food reduced their quality of life so considerably as to negate any possible advantages of lengthening their lives. However, a small set of individuals persists in the lifestyle, going so far as to monitor blood lipid levels and glucose response every few months. See [http://www.calorierestriction.org/ Calorie Restriction Society]. Underlying this research was the hypothesis that oxidative damage was the agent which accelerated aging, and that aging was retarded when the amount of carbohydrates (and thereby insulin release) was reduced through dietary restriction. However, recent research has produced increased longevity in animals (and shows promise for increased human longevity) through the use of insulin uptake retardation. This was done through altering an animal’s metabolism to allow it to consume similar food-energy levels to other animals, but without building up fatty tissue. (Bluher et al, 2003) This has set researchers off on a line of study which presumes that it is not low food energy consumption which increases longevity. Instead, longevity may depend on an efficient fat processing metabolism, and the consequent long term efficient functioning of our organs free from the encumbrance of accumulating fatty deposits. (Das et al, 2004) Thus, longevity may be related to maintained insulin sensitivity. However, several other factors including low body temperature seem to promote longevity also and it is unclear to what extent each of them contribute. Antioxidants have recently come to the forefront of longevity studies which have included the FDA and [http://www.brunswicklabs.com/ Brunswick labs]. In 2005 the FDA issued a statement recommending that Americans should be consuming 7,000 ORAC units daily or 12 full servings of fruit in order to curb the cancer epidemic. The dietary supplement industry has responded by shifting focus away from hormone replacements to “super” antioxidants such as [http://www.proleva.com/ Proleva] which contain whole fruit extracts and ORAC scores near 5,000 units mark or two thirds of the new level set by the FDA.

Nutrition, industry and food processing

Since the Industrial Revolution some two hundred years ago, the food processing industry has invented many technologies that both help keep foods fresh longer and alter the fresh state of food as they appear in nature. Cooling is the primary technology that can help maintain freshness, whereas many more technologies have been invented to allow foods to last longer without becoming spoiled. These latter technologies include pasteurisation, autoclavation, drying, salting, and separation of various components, and all appear to alter the original nutritional contents of food. Pasteurisation and autoclavation (heating techniques) have no doubt improved the safety of many common foods, preventing epidemics of bacterial infection. But some of the (new) food processing technologies undoubtedly have downfalls as well. Modern separation techniques such as milling, centrifugation, and pressing have enabled upconcentration of particular components of food, yielding flour, oils, juices and so on, and even separate fatty acids, amino acids, vitamins, and minerals. Inevitably, such large scale upconcentration changes the nutritional content of food, saving certain nutrients while removing others. Heating techniques may also reduce food's content of many heat-labile nutrients such as certain vitamins and phytochemicals, and possibly other yet to be discovered substances. Because of reduced nutritional value, processed foods are often 'enriched' or 'fortified' with some of the most critical nutrients (usually certain vitamins) that were lost during processing. Nonetheless, processed foods tend to have an inferior nutritional profile than do whole, fresh foods, regarding content of both sugar and high GI starches, potassium/sodium, vitamins, fibre, and of intact, unoxidized (essential) fatty acids. In addition, processed foods often contain potentially harmful substances such as oxidized fats and trans fatty acids. A dramatic example of the effect of food processing on a population's health is the history of epidemics of beri-beri in people subsisting on polished rice. Removing the outer layer of rice by polishing it removes with it the essential vitamin thiamin, causing beri-beri. Another example is the development of scurvy among infants in the late 1800's in the United States. It turned out that the vast majority of sufferers were being fed milk that had been heat-treated (as suggested by Pasteur) to control bacterial disease. Pasteurisation was effective against bacteria, but it destroyed the vitamin C. As mentioned, lifestyle- and obesity-related diseases are becoming increasingly prevalent all around the world. There is little doubt that the increasingly widespread application of some modern food processing technologies has contributed to this development. The food processing industry is a major part of modern economy, and as such it is influential in political decisions (e.g. nutritional recommendations, agricultural subsidising). In any known profit-driven economy, health considerations are hardly a priority; effective production of cheap foods with a long shelf-life is more the trend. In general, whole, fresh foods have a relatively short shelf-life and are less profitable to produce and sell than are more processed foods. Thus the consumer is left with the choice between more expensive but nutritionally superior whole, fresh foods, and cheap, usually nutritionally inferior processed foods. Because processed foods are often cheaper, more convenient (in both purchasing, storage, and preparation), and more available, the consumption of nutritionally inferior foods has been increasing throughout the world along with many nutrition-related health complications.

Policy advice and guidance on nutrition

Most Governments provide guidance on good nutrition, and some also impose mandatory labelling requirements upon processed food manufacturers to assist consumers in complying with such guidance. Current dietary guidelines in the United States are presented in the concept of a food pyramid. There is no apparent consisteny in science-based nutritional recommendations between countries, indicating the role of politics as well as cultural bias in research emphasis and interpretation.

Current issues and challenges

Challenging issues in modern nutrition include: 'Artificial' interventions in food production and supply:
- Should genetic engineering be used in the production of food crops and animals?
- Are the use of pesticides, and fertilizers damaging to the foods produced by use of these methods (see also organic farming)?
- Are the use of antibiotics and hormones in animal farming ethical and/or safe? Sociological issues:
- How do we minimise the current disparity in food availability between first and third world populations (see famine and poverty)?
- How can public advice agencies, policy making and food supply companies be coordinated to promote healthy eating and make wholesome foods more convenient and available?
- Do we need nutritional supplements in the form of pills, powders, liquids, etc.?
- How can the developed world promote good worldwide nutrition through minimising import tariffs and export subsidies on food transfers? Research Issues:
- How do different nutrients affect appetite and metabolism, and what are the molecular mechanisms?
- What yet to be discovered important roles do vitamins, minerals, and other nutrients play in metabolism and health?
- Are the current recommendations for intake of vitamins and minerals generally too low?
- How and why do different cell types respond differently to chronically elevated circulating levels of insulin, leptin, and other hormones?
- What does it take for insulin resistance to develop?
- What other molecular mechanisms may explain the link between nutrition and lifestyle-related diseases?
- What role does the intestinal bacterial flora play in digestion and health?
- How essential to proper digestion are the enzymes contained in food itself, which are usually destroyed in cooking (see Living foods diet)?
- What more can we discover through what has been called the phytochemical revolution?

References

- Shils et al. (2005) Modern Nutrition in Health and Disease, Lippincott Williams and Wilkins. ISBN: 0781741335.
- Bluher, Khan BP, Kahn CR, Extended longevity in mice lacking the insulin receptor in adipose tissue. Science 299(5606): 572-4, Jan 24, 2003.
- The Times newspaper, January 31 2004 Could vitamins help delay the onset of Alzheimer’s? by Jerome Burne.
- The Times newspaper February 28, 2004 Autism: I can see clearly now . . . by Simon Crompton
- The Times newspaper March 10, 2004 Work up an Amish appetite by Anne-Celine Jaeger
- Das M, Gabriely I, Barzilai N.Caloric restriction, body fat and aging in experimental models. Obes Rev. 2004 Feb;5(1):13-9.
- William Eaton et al Coeliac disease and schizophrenia British Medical Journal, February 21, 2004.
- Janssen I, Katzmarzyk PT, Ross R. Waist circumference and not body mass index explains obesity-related health risk. Am J Clin Nutr. 2004 Mar;79(3):379-84.
- J Mei, SSC Yeung et al "High dietary phytoestrogen intake and bone mineral density in postmenopausal women."Journal of Clinical Endocrinology and Metabolism, 2001, Vol 86, Iss 11
- Merritt JC "Metabolic syndrome: soybean foods and serum lipids."J Natl Med Assoc. 2004 Aug;96(8):1032-41.
- Sobczak S, et al Lower high-density lipoprotein cholesterol and increased omega-6 polyunsaturated fatty acids in first-degree relatives of bipolar patients Psychol Med. 2004 Jan;34(1):103-12.
- Walter C. Willett and Meir J. Stampfer,Rebuilding the Food Pyramid, Scientific American January 2003.
- Weindruch R, et al. The retardation of aging in mice by dietary restriction: longevity, cancer, immunity and lifetime energy intake. (Journal of Nutrition, 116(4), pages 641-54.,April, 1986.)

External links

- [http://www.unsystem.org/scn/ UN Standing Committee on Nutrition] - In English, French and Portuguese
- [http://www.nal.usda.gov/fnic/foodcomp/Bulletins/faq.html USDA Frequently asked questions]
- [http://outside.utsouthwestern.edu/chn/literature/index.htm Texas University: A review of current nutrition academic articles ]
- [http://www.nutritional-supplements-directory.com Nutrition and Nutritional Supplements Information]
- [http://www.nal.usda.gov/fnic/ Department of Agriculture's Food and Nutrition Information Center].
- [http://7nutrition.co.uk Nutrition Dictionary]
- [http://www.nismat.org/nutricor/healthydiet.html Nutrition advice for sports people from Nicholas Institute for Sports Medicine and Trauma]
- [http://www.code-interactive.com/evolution-diet/healthprofile.html Personalized Online Health Profile]
- [http://www.agr.gc.ca/misb/fb-ba/nutra/index_e.php/ Agriculture & Agri-Food Canada]
- [http://www.ifpri.org/ International Food Policy Research Institute]
- [http://www.foodfileonline.com/ Food File Online] Nutrition information for thousands of food products
- [http://www.iodinenetwork.net Network for Sustained Elimination of Iodine Deficiency]

Disclaimer

:Please remember that Wikipedia is offered for informational use only. The information is in most cases not reviewed by professionals. You are advised to contact your doctor for health-related decisions. Category:Health Category:Nutrition ja:栄養学

Suffix

Suffix has meanings in linguistics, nomenclature and computer science.

Linguistics

In linguistics, a suffix is an affix that follows the morphemes to which it can attach. Example: establish (verb) + -ment (suffix) —> establishment (noun). (See derivation and also the list of English suffixes.)

Nomenclature

- A suffix is a style at the end of a person's name which gives additional identifying information about the person. These may be academic, professional, honorary or social.
- In the United States, callsigns for broadcast stations may have a suffix of -FM, -AM, -TV, -LP, or -CA, if the root callsign is the same as another station's. The -HD and -DT suffixes for digital television have been dropped.

Computer science

A suffix of a string

T = t_1 t_2 \dots t_n

is a string

P = p_1 p_2 \dots p_m

such that

t_ \dots t_ = p_1 \dots p_

. T = BANANA |||| P = NANA

Polyphagy

:In biology, "polyphagia" is a type of phagy, referring to an animal that feeds on many kinds of food In medicine, polyphagia is a medical sign meaning excessive hunger and abnormally large (poly-) intake of solids by mouth. It is also known as "hyperphagia".

External links

- [http://www.wrongdiagnosis.com/sym/excessive_hunger.htm Diseases and conditions associated with Polyphagia]

Ophiophagy

Ophiophagy ("snake eating") is a specialized form of feeding or alimentary behavior of animals which hunt and eat snakes. There are ophiophagous mammals (such as the skunks and the mongooses), birds (such as snake eagles, the Secretary Bird, and some hawks), lizards (such as Crotaphtyus collaris), and even other snakes, such as the Central and South American mussuranas and the North American Common Kingsnake (Lampropeltis getula). There is even an entire genus of snakes named after this habit, Ophiophagus, with species such as the venomous King Cobra (Ophiophagus hannah).

Ophiophagy in myth and legend

King Cobra :The mythic associations of snakes are discussed at Serpent. A snake-eating bird of prey appears in a legend of the Mexica people, who gave rise to the Aztec empire, and it is represented in the Mexican flag: The Mexicas, guided by their god Huitzilopochtli, sought a place where the bird landed on a prickly pear cactus, devouring a snake. They found the sign on a island in Lake Texcoco, where they erected the city of Tenochtitlan ("Place of the Prickly Pear Cactus" – present-day Mexico City) in 1325. (In the Coat of Arms of Mexico this bird is depicted as a Golden Eagle, though it's often said to be a Crested Caracara^{[http://www.siti.com.mx/musave.dir/]}. It is also possible that the bird was a Laughing Falcon or Snake Hawk, a bird of prey which feeds almost exclusively on snakes.) The Mayans also had the legend of ophiophagy in their folklore and mythology. Guatemala may derive its name from the Nahuatl word coactlmoctl-lan, meaning "land of the snake-eating bird."^{[http://www.questconnect.org/ca_guatemala.htm]} Christian folklore associates snakes with evil (see serpent) and considers anything that destroys them good. An example for this tradition is Rudyard Kipling's short story "Rikki-Tikki-Tavi" (in The Jungle Book), in which Rikki-Tikki, a mongoose, defends a human family against a pair of evil cobras.

Practical use

In some regions, farmers keep ophiophagous animals as pets in order to keep their living environment clear of such snakes as cobras and pit vipers (including rattlesnakes and lanceheads) which annually claim a large number of deaths of domestic animals, such as cattle, and attacks on humans. An example is tamed mongoose in India. In the 1930s a Brazilian plan to breed and release large numbers of mussuranas for the control of pit vipers was tried but didn't work. The Butantan Institute, in São Paulo, which specializes in the production of antivenins, erected a statue of the mussurana Clelia clelia as its symbol and a tribute to its usefulness in combating venomous snake bites.

Immunity

Many ophiophagous animals seem to be immune to the venom of the usual snakes they prey and feed upon. The phenomenon has been studied in the mussurana by the Brazilian scientist Vital Brazil. They have antihemorrhagic and antineurotoxic antibodies in their blood. The Virginia Opossum (Didelphis virginiana) has been found to have the most resistance towards snake venom. This immunity is not acquired and has probably evolved as an adaptation to predation by venomous snakes in their habitat.

External links

- [http://panchatantra.org/the-brahmani-and-the-mongoose.html The Brahmani and the Mongoose].
- [http://www.fotw.us/flags/mx).html History of Mexico National Coat of Arms]. Category:Snakes

Hematophagy

Hematophagy is the habit of certain animals of feeding on blood (from the Greek words, haima, blood, and phagein, eat). Since blood is a fluid tissue rich in nutritious proteins and lipids and can be taken without enormous effort, hematophagy has evolved as a preferred form of feeding in many small animals, such as worms and arthropods. Some intestinal helminth worms, such as the Ascaris, feed on blood extracted from the capillaries of the gut and about 75% of all species of leeches (Hirudo medicinalis), a free-living worm, are hematophagous. Some fishes, such as lampreys, and mammals, especially the vampire bats, also practice hematophagy.

Mechanism and evolution of hematophagy

These hematophagous animals have evolved different specialized mouth parts and chemical agents for penetrating vascular structures in the skin of hosts, mostly of mammals, birds and fishes. This type of feeding is known as phlebotomy (from the Greek words, phleps, vein, and tomos, cutting). Once phlebotomy is performed (in most insects by a specialized fine hollow "needle" called proboscis which perforates skin and capillaries; in bats by sharp incisor teeth that act as a razor to cut the skin), blood is acquired either by sucking action directly from the vases, or from a pool of escaped blood, or by lapping (again, in bats). In order to overcome natural hemostasis (blood coagulation), vasoconstriction, inflammation and pain sensation in the host, biochemical solutions in the saliva for instance, for pre-injection, anesthesia and capillary dilation have evolved in different hematophagous species. In fact, new anticoagulant medicines have been developed on the basis of substances found in the saliva of several hematophagous species, such as leeches (hirudin). Hematophagy can be classified into obligatory and optional. Obligatory hematophagous animals will not feed on any other things except blood, such as Rhodnius prolixus (an assassin bug from South America). Many mosquitoes, such as Aedes aegypti may also feed on pollen, fruit juice and other biological fluids, too. Sometimes, only the female of the species is a hematophage (this is essential for egg production and reproduction). Hematophagy has apparently evolved independently in many disparate arthropod, annelid, nematode and mammalian taxa. For example Diptera (insects with two wings, such as flies) have nine families with hematophagous habits (more than half of the 17 hematophagous arthropod taxa). Circa 14,000 species of arthropods are hematophagous, even some genres that were not previously thought to be, such as moths of the Calyptra genre. Several complementary biological adaptations for locating the hosts (usually in the dark, as most hematophagous species are nocturnal and silent, in order to avoid detection and destruction by the host) have also evolved, such as special physical or chemical detectors (for sweat components, CO₂, heat, light, movement, etc.).
Medical importance
light] The phlebotomic action opens a channel for contamination of the host species with bacteria, viruses and blood-borne parasites contained in the hematophagous organism. Thus, many animal and human infectious diseases are transmitted by hematophagous species, such as the bubonic plague, Chagas disease, dengue fever, filariasis, leishmaniasis, Lyme disease, malaria, rabies, sleeping sickness, St. Louis encephalitis, tularemia, typhus, Rocky Mountain spotted fever, West Nile encephalitis and many others. Among the hematophagous insects of medical importance are the sandfly, blackfly, tsetse fly, bedbug, assassin bug, mosquito, tick, louse, mite, midge, leech, chigger, and flea. Recently, hematophagous organisms have been used by physicians for beneficial purposes (hirudotherapy). Some doctors now use leeches to prevent the clotting of blood on some wounds following surgery or trauma. The anticoagulants in the laboratory-raised leeches' saliva keeps fresh blood flowing to the site of an injury, actually preventing infection and increasing chances of full recovery. In a recent study, a genetically engineered drug called desmoteplase based on the saliva of Desmodus rotundus (the vampire bat) was shown to improve stroke patients
Human hematophagy
Drinking blood and manufacturing foodstuffs and delicacies with animal blood is also a feeding behavior in many societies. African Masai mainstay food, for instance is cow blood mixed with milk. Blood sausage is eaten in many places around the world. Some societies, such as the Moche, had ritual hematophagy, as well as the Scythes, a nomadic people of Russia, who had the habit of drinking the blood of the first enemy they would kill in battle. Some religious rituals underline the importance of metaphorical hematophagy, such as in the representation of blood of Jesus Christ by wine during Catholic mass. Satanic sects in the West have been reported to drink human blood from willing donors and psychiatric cases of hematophagy as a symptom also exist. Sucking one's own blood from a wound is also a behaviour commonly seen in humans. Finally, real or imagined, human vampirism has been a persistent object of literary and media attention, and tales of blood-thirsty Count Vlad, the supposed inspiration of the Dracula character, continue to be told.
See also

- Hirudotherapy
- Natural reservoir
- Tick-borne disease
- Transmission (medicine)
- Zoonosis
- Vampirism
References

- Scharfetter C, Hagenbuchner K. Blutdurst als Symptom. Ein seltsamer Fall von Bluttrinken. Psychiatr Neurol (Basel). 1967;154(5):288-310.'
- Ciprandi, A; Horn, F; Termignoni, C. Saliva of hematophagous animals: source of new anticoagulants. Rev. Bras. Hematol. Hemoter., 2003, vol.25, no.4, p.250-262 [http://www.scielo.br/scielo.php?pid=S1516-84842003000400012&script=sci_pdf&tlng=pt PDF full text]
- Markwardt F. Hirudin as alternative anticoagulant -- a historical review. Semin Thromb Hemost. 2002 Oct;28(5):405-14. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12420235&query_hl=2 Medline abstract]
- Ribeiro JM. Blood-feeding arthropods: live syringes or invertebrate pharmacologists? Infect Agents Dis. 1995 Sep;4(3):143-52. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8548192&query_hl=6 Medline abstract]
External links

- Galun, R. [http://www.bgu.ac.il/desert_ecology/ecology/Ziv%202003.htm#Galun Evolution of Hematophagy]
- Beaty, LC. [http://www.colostate.edu/Depts/Entomology/courses/en507/papers_1997/beaty.html Host-Seeking Behavior in Hematophagous Mosquitoes]
- [http://www.biopharm-leeches.com/ Biopharm]. Company specialised in providing medicinal leeches. Category:Behavior

Faeces

: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.

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

Geophagy

Geophagy is a practice of eating earthy substances such as clay, often to augment a mineral-deficient diet. While most often seen in rural or preindustrial societies among pregnant women, it also occurs among children and as a psychological eating disorder. Geophagy is a type of disorder known as pica. In parts of Africa and among some African-Americans, clay consumption may be correlated with pregnancy as women eat clay to eliminate nausea possibly because the clay coats the gastrointestinal tract and absorbs dangerous toxins. The clay may also provide critical calcium for fetal development. In the southeastern United States especially tasty earth (usually a chalky earth with a certain flavor) is sold in local stores or sent to friends and family who are no longer living near the source of this earth. Bentonite clay is available worldwide as a digestive aid, kaolin is also widely used as a digestive aid and as the base for some medicines. Geophagy was also practiced by Native Americans who would eat earth with acorns and potatoes to neutralize potentially harmful alkaloids. Clay was used in the production of acorn bread. Geophagy has also been observed in birds. Notably, South American macaws have been observed at clay licks in South America by scientist Charles Munn, whilst sulphur crested cockatoos have been observed ingesting clays in Papua New Guinea by Jared Diamond (Discover, 1998) as well as in the Blue Mountains of Australia by David W Cooper (Parrots Magazine, 2000)

References

- Wiley, Andrea S. "Geophagy." Encyclopedia of Food and Culture. Ed. Solomon H. Katz. Vol. 2. New York: Charles Scribner's Sons, 2003. 120-121.
- Wiley, Andrea S., and Solomon H. Katz. "Geophagy in Pregnancy: A Test of a Hypothesis." Current Anthropology 39, no. 4 (1998): 532–545.
- Lagercrantz, Sture. "Geophagical Customs in Africa and among the Negroes in America." Studia Ethnographica Upsaliensia 17 (1958): 24–81.

External link

- [http://www.uic.edu/classes/osci/osci590/8_2DirtasFood.htm Dirt as Food]
- [http://geography.about.com/cs/culturalgeography/a/geophagy.htm Eating Dirt] Category:Eating behaviors

Pica (disorder)

Pica is an appetite for non-foods (e.g., coal, soil, chalk) or an abnormal appetite for some things that may be considered foods, such as food ingredients (e.g., flour, raw potato, starch). In order for these actions to be considered pica, they must persist for more than 1 month, at an age where eating dirt, clay, etc. is considered developmentally inappropriate. The condition's name comes from the Latin word for the magpie, a bird which is reputed to eat almost anything. Pica is seen in all ages, particularly in pregnant women and small children, especially among children who are developmentally disabled where it is the most common eating disorder. It is much more common in developing countries and rural areas than elsewhere. In extreme forms, pica is regarded as a medical disorder. Pregnant women have been known to develop strong cravings for gritty substances like soil or flour. Some theorize that these women may be craving trace minerals lacking in their system. There is a lack of major studies and research in this field. Pica in children, while common, can be dangerous. Children eating painted plaster containing lead may suffer brain damage from lead poisoning. There is a similar risk from eating dirt near roads that existed prior to the phaseout of tetra-ethyl lead in gasoline or prior to the cessation of the use of contaminated oil (either used, or containing toxic PCBs) to settle dust. In addition to poisoning, there is also a much greater risk of gastro-intestinal obstruction or tearing in the stomach. This is also true in animals.

Examples

- Acuphagia (ingestion of sharp objects)
- Amylophagia (consumption of starch)
- Coniophagia (consumption of dust from Venetian blinds)
- Coprophagia (consumption of excrement)
- Geomelophagia (abnormal ingestion of raw potatoes)
- Geophagy (consumption of soil)
- Gooberphagia (pathological consumption of peanuts)
- Lithophagia (ingestion of stones)
- Mucophagy (consumption of mucus)
- Pagophagia (pathological consumption of ice)
- Trichophagia (consumption of hair or wool)
- Urine Therapy (consumption of urine, often for supposed medical and health benefits, though also a sexual fetish and possibly an appetite)
- Xylophagia (consumption of wood)

Reference

- [http://www.straightdope.com/classics/a5_090.html The Straight Dope: Is it crazy to eat clay?], Cecil Adams, 1995
- [http://www.emedicine.com/ped/topic1798.htm Eating Disorder: Pica]

External links

- [http://www.cnn.com/2004/HEALTH/02/18/coin.eater.ap/index.html Hundreds of coins found in patient's belly]
- [http://sprott.physics.wisc.edu/pickover/vomit.html The Woman Who Vomited Frogs] Category:Childhood psychiatric disorders Category:Eating behaviors

Dysphagia

Dysphagia is the medical term for the symptom of the sensation of difficulty in swallowing. There may be confusion regarding overlap with the term odynophagia, which describes painful swallowing. It occurs in all age groups, but especially in the elderly. The disorders can occur at any stage of the normal swallowing process, in which food and liquid move from the mouth, through the pharynx, into the esophagus and finally, into the stomach. The disorders are common in individuals with degenerative neurological disorders such as amyotrophic lateral sclerosis (ALS), postpolio syndrome, myasthenia gravis, multiple sclerosis and Parkinson's disease, and may be the first symptom of the disease. They may also occur after sudden neurological damage as in stroke, or head or spinal cord injury, or indicate other problems, such as the presence of cancer or heart problems. People with swallowing disorders may suffer from weight loss or dehydration and may be at risk for developing pneumonia. Some individuals notice that the disorders get worse at times of stress or excitement.

Causes

mechanical obstruction
- oesophageal web
- oesophageal ring
- oesophageal diverticulum
- peptic stricture (from gastroesophageal reflux disease)
- oesophageal malignancy local motility disorders
- achalasia
- oesophageal spasm
- scleroderma neurological disorders
- brainstem pathology (stroke, mass lesion)
- multiple sclerosis
- movement disorders (Parkinson's, Huntington's)

Treatment

Drug therapy, including botulinum toxin injection, may provide relief to some individuals with swallowing disorders. Surgery may also be needed in severely affected persons. Many individuals can be helped by changing their diets and learning new feeding techniques, for example, positioning the head and neck in a certain way to help in swallowing. While in many cases, swallowing disorders can be partially or completely corrected, in some cases they can be life-threatening and require aggressive interventions, such as feeding tubes. The prognosis for people with swallowing disorders that accompany other diseases depends upon the severity of those other diseases.

External links

- [http://www.nidcd.nih.gov/health/voice/dysph.asp NIH]
- [http://www.emedicine.com/pmr/topic194.htm eMedicine] Category:Symptoms ms:Penyakit Disfagia

Deglutition

Swallowing, known scientifically as deglutition, is the reflex in the human body that makes something pass from the mouth, through the esophagus. If this fails and the object goes through the trachea, then choking occurs if the airway is completely blocked, or pulmonary aspiration occurs if the object is drawn into the lungs. The mechanism for swallowing is co-ordinated by the swallowing centre in the medulla oblongata and pons. The reflex is initiated by touch receptors in the pharynx as a bolus of food is pushed to the back of the mouth by the tongue. Then:
- The soft palate is pulled upwards to stop food getting into the nasal cavity, and the palatopharyngeal folds on each side of the pharynx are brought close together, so that only boluses of an approximately small size can pass.
- The larynx is pulled upwards towards the flap-like epiglottis which passively shuts off its entrance and the vocal cords are pulled close together, narrowing the passageway between them.
- The respiratory centre of the medulla is directly inhibited by the swallowing centre for the very brief time that it takes to swallow. This is known as deglutition apnoea.
- The upper oesophageal sphincter relaxes to let food past, after which various striated constrictor muscles of the pharynx contract sequentially to push the bolus of food down into the esophagus. A failure of the reflex to swallow leads, in terminally ill patients, to a buildup of mucous or saliva in the throat and airways, producing a noise known as a death rattle.

Prefix

Prefix has meanings in linguistics, mathematics and computer science, and telecommunications.

Linguistics

In linguistics, a prefix is a type of affix that precedes the morphemes to which it can attach. Prefixes are bound morphemes (they cannot occur as independent words). While most languages employ both prefixes and suffixes, prefixes are crosslinguistically less common. Some languages employ mostly suffixes and almost no prefixes at all. The use of prefixes has been found to correlate statistically with other linguistic features, such as a verb-object word order and the use of prepositions. In the Indo-European languages, prefixes are mostly derivational morphemes (inflection is most often marked with suffixes).

Mathematics and computer science: Prefix operator

In the syntax of notations used in mathematics and computer science, prefix is used to describe an operator such as the usual addition sign + that is taken to bind to the variables succeeding them. See operator for more on the placement of operators.
- prefix : prefix notation Polish notation
- postfix : postfix notation reverse Polish notation
- infix : infix notation

Computer science: Strings

A prefix of a string

T = t_1 t_2 \dots t_n

is a string

P = p_1 p_2 \dots p_m

such that

t_1 \dots t_ = p_1 \dots p_

, where

m \leq n

. T = BANANA ||| P = BAN

Telephone prefixes

A telephone prefix is the first set of digits of telephone number; in the North American Numbering Plan countries (country code 1), it is the first three digits out of a seven-digit phone number. It shows which exchange the remaining numbers refer to. For example: abc-defg (with actual numbers) might refer to Anytown while cab-defg could refer to Anycity. Some places restrict certain prefixes to only fax numbers or for cell phones while in other places the prefixes are all jumbled up. Most (but not all) area codes reserve the prefix 555 for special uses (555-1212 is telephone information in most area codes.) For this reason, it is often used for phone numbers in television and movies. Failure to do so in the film Bruce Almighty resulted in someone's real phone number being used, eventually leading to a lawsuit. See also: area code

Phagocytosis

Phagocytosis (literally, "cell eating") is a form of endocytosis where large particles are enveloped by the cell membrane of a (usually larger) cell and internalized to form a phagosome, or "food vacuol