Large intestine


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William Wordsworth 's poetry described the wonder of the natural world, which had formerly been viewed as a threatening place. Increase in carbon dioxide and temperature also affects the sinus venosus and thereby it increases the rate of heart beat. Pinus wood tangential sec. The outer layer is non-sensory pigmented cuboidal epithelium, which lies very close with the choroid. Moreover, classification shall be considered where there is a significant toxic effect in the offspring, e. There are present many horizontal and some bundles of vertical connective tissue fibres. Archived from the original on September 23,

Systems Biology in Toxicology and Environmental Health

Essay on Frogs

Some common proteins are: Difference Patterson Tutorial; PR Enzymes control body chemistry. The enzymes of the human body work by means of surface catalysis http: That is the surface of the enzyme enables other molecules to react in a manner they would not without the surface of the enzyme present.

The enzyme being the catalyst is not changed in any manner from the action of the protein. The human body contains only a small quantity of enzymes but even this small quantity is sufficient. They are important to many functions including food digestion. For an explanation of what an enzyme is click here http: Some, however such as egg cells of birds, can be seen with the naked eye.

Others, like nerve cells, may be very small in some of their dimensions, but extremely long; a single human nerve cell may be as much as 3 or 4 feet long, and an elephant's nerve cell may be even longer.

To say that cells are generally small is not saying much, however, because even among microscopic cells there is a wide range in size. Biologists took it for granted that cells are bounded by a membrane - the plasma membrane, as it is often called. Cell image from http: The cell membrane is not simply an envelope giving mechanical strength and shape and some protection to the cell, though these functions are important. It regulates the traffic in materials between the precisely ordered interior of the cell and essentially unfavorable and potentially disruptive outer environment.

Usually portions of the cell flow around the material, enclosing it within a chamber. When the engulfed material is liquid or consists of very small particles, the process is often termed pinocytosis.

Cell Biology Links - Click on the links below for detailed information. Everything you need to know about Protonema. Moss gametophytes and sporophytes Moss capsule Moss antheridia Moss archegonia Marchantia thallus Marchantia archegonia Marchantia antheridia. Ligustrum Leaf Cross Section. Evergreen ligustrum often called privet shrubs and trees thrive throughout the state of Florida. They are widely used as landscape shrubs, hedges, and specimen trees.

Many species and cultivars are available with a diversity of leaf colors, leaf forms, and growth habits. All selections are tolerant of heavy pruning, which makes them suited for clipped hedges. Because of a rapid growth rate, many require pruning to maintain them within bounds.

The white flowers are attractive during late spring and early summer. However, the pungent odor may be objectionable.

The nucleus plays the central role in cellular reproduction, the process whereby a single cell undergoes cell division and forms two new cells. The nucleus directs the metabolic activities of the living cell and guides the life of the cell as long as it lives. They are composed of nucleic acid and protein.

The chromosomes bear, apparently in linear arrangement, the basic units of heredity, called genes. They are the code units of the transmission of bits of information from parent to offspring, and for the determination of the enzymes that so precisely regulate the myriad interdependent chemical reactions of life. Genes and Chromosomes - Biology: DNA in a Nutshell! DNA - From the Beginning. Primer on Molecular Genetics from the U. Up to 3 fragments may be cloned at a time can you replicate that in the lab?

Each fragment may be inverted relative to its original orientation. Genetic elements contained in the cloned fragments are transferred to the cloned DNA. We found an excellent Genetics tutorial: You will have to register to view it but it is free.

A virus can multiply only inside a host cell, whose genetic mechanisms it subverts for its own reproduction. Both the structure of the virus and its mode of replication differ widely between viruses. The usual outcome of a viral infection is the lysis destruction of the infected cell, with the release of viral particles. Some viruses, however, can instead become integrated into the host chromosome, where their genes are replicated along with those of the host cell.

Because viruses sometimes carry host DNA sequences from one species to another, they make possible an occasional mixing of different gene pools during their evolution. Virulent viruses usually kill the cells they infect. Other viruses, although also often able to kill cells, frequently have a more subtle effect.

These viruses are called temperate. Virus infected bacteria which appear un-infected but have the hereditary ability to produce phage, are called lysogenic. Upon infection, genes promoting both lytic growth and lysogenic integration are expressed. Which pathway succeeds is determined by the competing action of these early gene products and by the influence of host factors.

The lambda phage is a well studied temperate phage which can grow in synchrony with its host E. The lytic cycle is that part of the life cycle of a temperate phage in which it multiplies rapidly, destroying its host and releasing many copies into the medium. The pathway genes in the lambda immunity region are: The lambda system provides one of the best studied examples of a genetic switch.

Two back-to-back promoters in the region of cI and cro control the genetic switch. When cI is present it activates its own synthesis and blocks transcription of cro. When cI is inactivated, transcription of cro can occur, resulting in the lytic cycle. The cI protein combines with the operator, Or. Polymerase are enzymes producing a polynucleotide sequence, complementary to a pre-existing template polynucleotide. Polymerization is the combination of several molecules to form a more complex molecule, usually by addition or a condensation process.

It is sometimes a reversible process. Biology I Reference Sites. Gram Negative Stain - Red or pinkish. Why does it stain this way? The color differences are sometimes subtle so learn to recognize the differences! When, as the result of my first communications on the fermentations in , it appeared that the ferments, properly so-called, are living beings, that the germs of microscopic organisms abound in the surface of all objects, in th air and in water; that the theory of spontaneous generation is chimerical; Book Directory Computational Molecular Biology: An Integration of Chemistry Click on the names in the List below for detailed information.

It is known for its nitrogen fixing abilities, and they form symbiotic relationships with certain plants, such as the mosquito fern. They are one of four genera of cyanobacteria that produce neurotoxins , which are harmful to local wildlife, as well as farm animals and pets.

Joint-Legs Phylum Arthropoda M Those That Sting - Visit the Oregon Coast Aquarium's virtual jellyfish exhibit to learn about the jellyfish's biology, life cycle, relatives and even see live pictures on the JellyCam.

Also has two classroom activities, one K-4 and the other Introduction to the Ctenophora - Information on ctenophores "comb jellies" with links to cnidarian and jellyfish information. Invasion of the jellyfish. Sea Stars - Information on its description, habitat, diet, breeding, etc. Confocal Image Gallery - Marchantia Sporophyte. Deuterostomia - Lophotrochozoans vs. Metabolic Pathways Wall Chart. You can access the individual images by clicking in a reduced image of an entire section of the wall chart use the linkS below.

Stem Cells; Scientific Progress and A Global Resource Scientific American: Science and the Citizen: If you enjoy caring for people and are intrigued by a job where you will constantly learn and interact with people, than learn more about online medical assisting degrees.

As a medical assistant, you will work closely with a physician and perform clinical tasks as well as work on administrative tasks. Human Anatomy Online - InnerBody. What is zoology anyway? The study of animals. The branch of biology that studies and classifies animals and animal life. It is a branch of biology that is concerned with the scientific study of animals, including their biology, distribution, and identification and including the study of animals - mammals, birds, reptiles, amphibians, fish, insects, spiders, and mollusks including mussels.

The science and history of the animal kingdom, including its king, the House Fly Musca maledicta. The father of Zoology was Aristotle, as is universally conceded, but the name of its mother has not come down to us. Two of the science's most illustrious expounders were Buffon and Oliver Goldsmith, from both of whom we learn L'Histoire generale des animaux and A History of Animated Nature that the domestic cow sheds its horn every two years.

The outer surface is divided into several gradually migrating tectonic plates. The interior remains active, with a thick layer of plastic mantle and an iron-filled core that generates a magnetic field. This iron core is composed of a solid inner phase, and a fluid outer phase. Convective motion in the core generates electric currents through dynamo action, and these, in turn, generate the geomagnetic field.

The atmospheric conditions have been significantly altered from the original conditions by the presence of life-forms, [7] which create an ecological balance that stabilizes the surface conditions. Despite the wide regional variations in climate by latitude and other geographic factors, the long-term average global climate is quite stable during interglacial periods, [8] and variations of a degree or two of average global temperature have historically had major effects on the ecological balance, and on the actual geography of the Earth.

Geology is the science and study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition, structure , physical properties , dynamics, and history of Earth materials , and the processes by which they are formed, moved, and changed.

The field is a major academic discipline , and is also important for mineral and hydrocarbon extraction, knowledge about and mitigation of natural hazards , some Geotechnical engineering fields, and understanding past climates and environments.

The geology of an area evolves through time as rock units are deposited and inserted and deformational processes change their shapes and locations. Rock units are first emplaced either by deposition onto the surface or intrude into the overlying rock. Deposition can occur when sediments settle onto the surface of the Earth and later lithify into sedimentary rock , or when as volcanic material such as volcanic ash or lava flows, blanket the surface.

Igneous intrusions such as batholiths , laccoliths , dikes , and sills , push upwards into the overlying rock, and crystallize as they intrude. Deformation typically occurs as a result of horizontal shortening, horizontal extension , or side-to-side strike-slip motion.

These structural regimes broadly relate to convergent boundaries , divergent boundaries , and transform boundaries , respectively, between tectonic plates. Earth is estimated to have formed 4. Initially molten, the outer layer of the Earth cooled, resulting in the solid crust. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor , most or all of which came from ice delivered by comets , produced the oceans and other water sources.

Continents formed, then broke up and reformed as the surface of Earth reshaped over hundreds of millions of years, occasionally combining to make a supercontinent. During the Neoproterozoic era, freezing temperatures covered much of the Earth in glaciers and ice sheets. Since the Cambrian explosion there have been five distinctly identifiable mass extinctions.

Several million years ago, a species of small African ape gained the ability to stand upright. The present era is classified as part of a mass extinction event , the Holocene extinction event, the fastest ever to have occurred. The Earth's atmosphere is a key factor in sustaining the ecosystem.

The thin layer of gases that envelops the Earth is held in place by gravity. Air is mostly nitrogen , oxygen , water vapor , with much smaller amounts of carbon dioxide, argon, etc. The atmospheric pressure declines steadily with altitude. The ozone layer plays an important role in depleting the amount of ultraviolet UV radiation that reaches the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.

Terrestrial weather occurs almost exclusively in the lower part of the atmosphere , and serves as a convective system for redistributing heat. These currents help to moderate the differences in temperature between winter and summer in the temperate zones. Also, without the redistributions of heat energy by the ocean currents and atmosphere, the tropics would be much hotter, and the polar regions much colder.

Weather can have both beneficial and harmful effects. Extremes in weather, such as tornadoes or hurricanes and cyclones , can expend large amounts of energy along their paths, and produce devastation.

Surface vegetation has evolved a dependence on the seasonal variation of the weather, and sudden changes lasting only a few years can have a dramatic effect, both on the vegetation and on the animals which depend on its growth for their food. Climate is a measure of the long-term trends in the weather.

Various factors are known to influence the climate , including ocean currents, surface albedo , greenhouse gases , variations in the solar luminosity, and changes to the Earth's orbit. Based on historical records, the Earth is known to have undergone drastic climate changes in the past, including ice ages.

The climate of a region depends on a number of factors, especially latitude. A latitudinal band of the surface with similar climatic attributes forms a climate region. There are a number of such regions, ranging from the tropical climate at the equator to the polar climate in the northern and southern extremes. Weather is also influenced by the seasons, which result from the Earth 's axis being tilted relative to its orbital plane. Thus, at any given time during the summer or winter, one part of the Earth is more directly exposed to the rays of the sun.

This exposure alternates as the Earth revolves in its orbit. At any given time, regardless of season, the northern and southern hemispheres experience opposite seasons. Weather is a chaotic system that is readily modified by small changes to the environment , so accurate weather forecasting is limited to only a few days.

Water is a chemical substance that is composed of hydrogen and oxygen and is vital for all known forms of life. Additionally, a minute amount of the Earth's water is contained within biological bodies and manufactured products. An ocean is a major body of saline water , and a principal component of the hydrosphere. More than half of this area is over 3, meters 9, feet deep. Average oceanic salinity is around 35 parts per thousand ppt 3. Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean.

The major oceanic divisions are defined in part by the continents , various archipelagos , and other criteria: Smaller regions of the oceans are called seas, gulfs , bays and other names. There are also salt lakes , which are smaller bodies of landlocked saltwater that are not interconnected with the World Ocean. A lake from Latin lacus is a terrain feature or physical feature , a body of liquid on the surface of a world that is localized to the bottom of basin another type of landform or terrain feature; that is, it is not global and moves slowly if it moves at all.

On Earth, a body of water is considered a lake when it is inland, not part of the ocean, is larger and deeper than a pond, and is fed by a river. It is not known if Titan's lakes are fed by rivers, though Titan's surface is carved by numerous river beds. Natural lakes on Earth are generally found in mountainous areas, rift zones , and areas with ongoing or recent glaciation.

Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world, there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them. A pond is a body of standing water , either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding, and solar ponds designed to store thermal energy.

Ponds and lakes are distinguished from streams via current speed. While currents in streams are easily observed, ponds and lakes possess thermally driven micro-currents and moderate wind driven currents. These features distinguish a pond from many other aquatic terrain features, such as stream pools and tide pools. A river is a natural watercourse , [37] usually freshwater , flowing toward an ocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water.

Small rivers may also be called by several other names, including stream, creek, brook, rivulet, and rill; there is no general rule that defines what can be called a river. Many names for small rivers are specific to geographic location; one example is Burn in Scotland and North-east England.

Sometimes a river is said to be larger than a creek, but this is not always the case, due to vagueness in the language.

Water within a river is generally collected from precipitation through surface runoff , groundwater recharge, springs , and the release of stored water in natural ice and snowpacks i. A stream is a flowing body of water with a current , confined within a bed and stream banks. In the United States, a stream is classified as a watercourse less than 60 feet 18 metres wide. Streams are important as conduits in the water cycle , instruments in groundwater recharge , and they serve as corridors for fish and wildlife migration.

The biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction , streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity.

The study of streams and waterways in general involves many branches of inter-disciplinary natural science and engineering, including hydrology , fluvial geomorphology , aquatic ecology , fish biology , riparian ecology , and others. Ecosystems are composed of a variety of abiotic and biotic components that function in an interrelated way. Variations of these factors will initiate dynamic modifications to the ecosystem.

Some of the more important components are: Central to the ecosystem concept is the idea that living organisms interact with every other element in their local environment.

Eugene Odum, a founder of ecology, stated: A smaller unit of size is called a microecosystem. For example, a microsystem can be a stone and all the life under it. A macroecosystem might involve a whole ecoregion , with its drainage basin.

Wilderness is generally defined as areas that have not been significantly modified by human activity. Wilderness areas can be found in preserves, estates, farms, conservation preserves, ranches, national forests , national parks , and even in urban areas along rivers, gulches, or otherwise undeveloped areas.

Wilderness areas and protected parks are considered important for the survival of certain species , ecological studies, conservation , and solitude. Some nature writers believe wilderness areas are vital for the human spirit and creativity, [45] and some ecologists consider wilderness areas to be an integral part of the Earth's self-sustaining natural ecosystem the biosphere.

They may also preserve historic genetic traits and that they provide habitat for wild flora and fauna that may be difficult or impossible to recreate in zoos , arboretums , or laboratories. Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization , metabolism , growth , adaptation , response to stimuli , and reproduction. Properties common to terrestrial organisms plants, animals, fungi , protists , archaea , and bacteria are that they are cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, and reproduce.

An entity with these properties is generally considered life. However, not every definition of life considers all of these properties to be essential. Human-made analogs of life may also be considered to be life. From the broadest geophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere rocks , hydrosphere water , and atmosphere air.

Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence. The origin of life on Earth is not well understood, but it is known to have occurred at least 3. The odour is modified by the ingestion of certain foods or drugs. The mixed sample of normal urine in 24 hours has a pH 6. Individual samples vary from 4.

The urine is acid in high protein intake because excess phosphate and sulfate are formed in the catabolism of protein. The urine becomes alkaline on standing due to the conversion of urea to ammonia and loss of CO 2 to air. The acidity of urine is increased after strenuous muscular exercise elimination of lactic acid , by ingestion of ammonium salts of strong acids. An alkaline urine may be produced by ingestion of sufficient NaHCO 3.

There is a high ammonia output in the urine in uncontrolled diabetes mellitus in which renal function is unimpaired. Creatinine is formed from creatine. It is excreted in relatively constant amounts regardless of diet. It is the end product of the oxidation of purines in the body. It is not only formed from dietary nucleoprotein but also from the breakdown of cellular nucleoprotein in the body.

Pure uric acid is colourless. The specificity of the analysis of uric acid is increased by treatment with uricase, the enzyme from hog kidney which converts uric acid to allantoin. It is the partial oxidative products of uric acid. Small quantities of the allantoin are excreted in human urine. It is proportionate to the ingested protein with a ratio of 5: Normally, mg of indican are excreted and the amount increases in constipation.

Phosphates of food are not completely absorbed. Some phosphate is also derived from cellular breakdown. Marked increase of phosphate excretion is also observed in hyperparathyroidism and decrease in hypoparathyroidism and in infectious diseases. Sodium content varies with intake. Urine potassium increases when the intake is increased or in excessive tissue catabolism. The excretion of potassium is affected by alkalosis. The pregnancy test is also performed by the urinary sex hormones.

The traces of protein mg present in normal urine cannot be detected by the ordinary simple tests. Pathologically, several proteins, such as serum albumin, serum globulin, hemoglobin, mucus, proteose, Bence-Jones proteins are found in urine.

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