The harmones of the adrenal cortex are called cortin or adrenocorticoides e. Outer space within the Solar System is called interplanetary space , which passes over into interstellar space at what is known as the heliopause. Since the urinogenital system comprises two closely associated urinary excretory and the genital reproductive system, it is collectively called as the urinogenital system. These effects can also be manifested as severe headache or nausea, and can lead to reduced judgment, dizziness, irritability, fatigue, impaired memory function, deficits in perception and coordination, reaction time, or sleepiness; and, b Narcotic effects observed in animal studies may include lethargy, lack of coordination righting reflex, narcosis, and ataxia. Whatever little energy required during this period is obtained from the fat-bodies and from the stored glycogen of the liver, which had been stored in sufficient quantity earlier.
Although natural wonders are celebrated in the Psalms and the Book of Job , wilderness portrayals in art became more prevalent in the s, especially in the works of the Romantic movement. British artists John Constable and J. Turner turned their attention to capturing the beauty of the natural world in their paintings.
Before that, paintings had been primarily of religious scenes or of human beings. William Wordsworth 's poetry described the wonder of the natural world, which had formerly been viewed as a threatening place. Increasingly the valuing of nature became an aspect of Western culture. A common classical idea of beautiful art involves the word mimesis , the imitation of nature. Also in the realm of ideas about beauty in nature is that the perfect is implied through perfect mathematical forms and more generally by patterns in nature.
As David Rothenburg writes, "The beautiful is the root of science and the goal of art, the highest possibility that humanity can ever hope to see". Some fields of science see nature as matter in motion, obeying certain laws of nature which science seeks to understand. Matter is commonly defined as the substance of which physical objects are composed. It constitutes the observable universe. The visible components of the universe are now believed to compose only 4. The remainder is believed to consist of The behavior of matter and energy throughout the observable universe appears to follow well-defined physical laws.
These laws have been employed to produce cosmological models that successfully explain the structure and the evolution of the universe we can observe. The mathematical expressions of the laws of physics employ a set of twenty physical constants  that appear to be static across the observable universe. Outer space, also simply called space , refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace and terrestrial locations.
There is no discrete boundary between the Earth's atmosphere and space, as the atmosphere gradually attenuates with increasing altitude. Outer space within the Solar System is called interplanetary space , which passes over into interstellar space at what is known as the heliopause. Outer space is sparsely filled with several dozen types of organic molecules discovered to date by microwave spectroscopy , blackbody radiation left over from the big bang and the origin of the universe, and cosmic rays , which include ionized atomic nuclei and various subatomic particles.
There is also some gas, plasma and dust , and small meteors. Additionally, there are signs of human life in outer space today, such as material left over from previous manned and unmanned launches which are a potential hazard to spacecraft. Some of this debris re-enters the atmosphere periodically. Although the Earth is the only body within the solar system known to support life, evidence suggests that in the distant past the planet Mars possessed bodies of liquid water on the surface.
At present though, most of the water remaining on Mars is frozen. If life exists at all on Mars, it is most likely to be located underground where liquid water can still exist. Conditions on the other terrestrial planets, Mercury and Venus , appear to be too harsh to support life as we know it. But it has been conjectured that Europa , the fourth-largest moon of Jupiter , may possess a sub-surface ocean of liquid water and could potentially host life.
Astronomers have started to discover extrasolar Earth analogs — planets that lie in the habitable zone of space surrounding a star , and therefore could possibly host life as we know it.
From Wikipedia, the free encyclopedia. For other uses, see Nature disambiguation. For other uses, see Natural disambiguation. Hopetoun Falls , Australia. Bachalpsee in the Swiss Alps. Lightning strikes during the eruption of the Galunggung volcano , West Java , in Human timeline and Life timeline. Earth and Earth science. History of the Earth and Evolution. Atmosphere of Earth , Climate , and Weather. Human timeline and Nature timeline. Life , Biology , and Biosphere. Life timeline and Nature timeline.
Outer space , Universe , and Extraterrestrial life. Retrieved September 23, Generally, these senses match rather well the current senses in which the English word nature is used, as confirmed by Guthrie, W.
The word is dealt with thoroughly in Liddell and Scott's Greek Lexicon. For later but still very early Greek uses of the term, see earlier note. Retrieved September 20, Retrieved September 21, Retrieved January 6, Retrieved January 7, Archived from the original on January 23, American Institute of Physics.
The Age of the Earth. Archived from the original on September 28, Retrieved May 24, Palaeobotanical records and forest simulations". Vegetation History and Archaeobotany. Retrieved on November 3, Problems, Connections and Solutions. Quarterly Journal of the Royal Meteorological Society. Retrieved May 14, CIA — The world fact book. Retrieved December 20, Retrieved June 25, Definitions that precisely distinguish lakes, ponds, swamps, and even rivers and other bodies of nonoceanic water are not well established.
It may be said, however, that rivers and streams are relatively fast moving; marshes and swamps contain relatively large quantities of grasses, trees, or shrubs; and ponds are relatively small in comparison to lakes. Geologically defined, lakes are temporary bodies of water.
Retrieved September 6, Geological Survey — faqs , No. Introduction to the Ecosystem Concept". Fundamentals of Physical Geography 2nd Edition. Retrieved September 28, Fundamentals of Physical Geography 2nd edition. Archived from the original PDF on December 4, California Academy of Sciences. Archived from the original on February 8, International Development Research Centre. Archived from the original on November 13, The total biomass of all kinds on earth is estimated to be in excess of 6.
By these calculations, the portion of total biomass accounted for by humans would be very roughly 0. University of Hamburg Department of Biology. Species Diversity and Biodiversity". Extinction Web Page Class Notes. Archived from the original on September 9, Retrieved September 26, Land Use History of North America. Archived from the original on September 23, Website based on the contents of the book: Perspectives on the land use history of North America: Geological Survey, Biological Resources Division.
Retrieved September 27, More Support for Biocomplexity as a Research Paradigm". Global environment outlook 3: Archived from the original on February 25, Evidence of Archean life: Retrieved July 7, Journal of the Atmospheric Sciences. Status and Trends of the Nation's Biological Resources.
Chloride secretion increases in cystic fibrosis. Recycling of various nutrients takes place in colon. Examples include fermentation of carbohydrates, short chain fatty acids, and urea cycling. The appendix is attached to the inferior surface of the cecum, and contains a small amount of mucosa-associated lymphoid tissue which gives the appendix an undetermined role in immunity.
However, the appendix is known to be important in fetal life as it contains endocrine cells that release biogenic amines and peptide hormones important for homeostasis during early growth and development.
At this point some electrolytes like sodium , magnesium , and chloride are left as well as indigestible parts of ingested food e. As the chyme moves through the large intestine, most of the remaining water is removed, while the chyme is mixed with mucus and bacteria known as gut flora , and becomes feces.
The ascending colon receives fecal material as a liquid. The muscles of the colon then move the watery waste material forward and slowly absorb all the excess water, causing the stools to gradually solidify as they move along into the descending colon.
The bacteria break down some of the fiber for their own nourishment and create acetate , propionate , and butyrate as waste products, which in turn are used by the cell lining of the colon for nourishment. The large intestine  produces no digestive enzymes — chemical digestion is completed in the small intestine before the chyme reaches the large intestine. The pH in the colon varies between 5. Water absorption at the colon typically proceeds against a transmucosal osmotic pressure gradient.
The standing gradient osmosis is the reabsorption of water against the osmotic gradient in the intestines. Cells occupying the intestinal lining pump sodium ions into the intercellular space, raising the osmolarity of the intercellular fluid. This hypertonic fluid creates an osmotic pressure that drives water into the lateral intercellular spaces by osmosis via tight junctions and adjacent cells, which then in turn moves across the basement membrane and into the capillaries , while more sodium ions are pumped again into the intercellular fluid.
This allows the large intestine to absorb water despite the blood in capillaries being hypotonic compared to the fluid within the intestinal lumen. The large intestine houses over species of bacteria that perform a variety of functions, as well as fungi , protozoa , and archaea. Species diversity varies by geography and diet. This mass of mostly symbiotic microbes has recently been called the latest human organ to be "discovered" or in other words, the "forgotten organ".
The large intestine absorbs some of the products formed by the bacteria inhabiting this region. Undigested polysaccharides fiber are metabolized to short-chain fatty acids by bacteria in the large intestine and absorbed by passive diffusion. The bicarbonate that the large intestine secretes helps to neutralize the increased acidity resulting from the formation of these fatty acids. These bacteria also produce large amounts of vitamins , especially vitamin K and biotin a B vitamin , for absorption into the blood.
Although this source of vitamins, in general, provides only a small part of the daily requirement, it makes a significant contribution when dietary vitamin intake is low. An individual who depends on absorption of vitamins formed by bacteria in the large intestine may become vitamin-deficient if treated with antibiotics that inhibit the vitamin producing species of bacteria as well as the intended disease-causing bacteria.
Other bacterial products include gas flatus , which is a mixture of nitrogen and carbon dioxide , with small amounts of the gases hydrogen , methane , and hydrogen sulfide. Bacterial fermentation of undigested polysaccharides produces these. Some of the fecal odor is due to indoles , metabolized from the amino acid tryptophan. The normal flora is also essential in the development of certain tissues, including the cecum and lymphatics. They are also involved in the production of cross-reactive antibodies.
These are antibodies produced by the immune system against the normal flora, that are also effective against related pathogens, thereby preventing infection or invasion. The two most prevalent phyla of the colon are firmicutes and bacteroides.
The ratio between the two seems to vary widely as reported by the Human Microbiome Project. Bifidobacteria are also abundant, and are often described as 'friendly bacteria'. A mucus layer protects the large intestine from attacks from colonic commensal bacteria. Colonoscopy is the endoscopic examination of the large intestine and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus.
It can provide a visual diagnosis e. Colonoscopy can remove polyps as small as one millimetre or less. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are precancerous or not. It takes 15 years or less for a polyp to turn cancerous.
Colonoscopy is similar to sigmoidoscopy —the difference being related to which parts of the colon each can examine. A sigmoidoscopy is often used as a screening procedure for a full colonoscopy, often done in conjunction with a fecal occult blood test FOBT. Virtual colonoscopy , which uses 2D and 3D imagery reconstructed from computed tomography CT scans or from nuclear magnetic resonance MR scans, is also possible, as a totally non-invasive medical test, although it is not standard and still under investigation regarding its diagnostic abilities.
If a growth or polyp is detected using CT colonography, a standard colonoscopy would still need to be performed. Additionally, surgeons have lately been using the term pouchoscopy to refer to a colonoscopy of the ileo-anal pouch. The large intestine is truly distinct only in tetrapods , in which it is almost always separated from the small intestine by an ileocaecal valve.
In most vertebrates, however, it is a relatively short structure running directly to the anus, although noticeably wider than the small intestine. Although the caecum is present in most amniotes , only in mammals does the remainder of the large intestine develop into a true colon. In some small mammals, the colon is straight, as it is in other tetrapods, but, in the majority of mammalian species, it is divided into ascending and descending portions; a distinct transverse colon is typically present only in primates.
However, the taeniae coli and accompanying haustra are not found in either carnivorans or ruminants. The rectum of mammals other than monotremes is derived from the cloaca of other vertebrates, and is, therefore, not truly homologous with the "rectum" found in these species.
In fish, there is no true large intestine, but simply a short rectum connecting the end of the digestive part of the gut to the cloaca. In sharks , this includes a rectal gland that secretes salt to help the animal maintain osmotic balance with the seawater.
The gland somewhat resembles a caecum in structure, but is not a homologous structure. From Wikipedia, the free encyclopedia. Redirected from Colon anatomy.
Large intestine Front of abdomen , showing the large intestine, with the stomach and small intestine in gray outline. Front of abdomen, showing surface markings for liver red , and the stomach and large intestine blue. Ferns reawakened What is Evolution? Evolution in the above links is based on current scientific evidence. Beagle as naturalist, I was much struck with certain facts in the distribution of the organic beings inhabiting South America, and in the geographical relations of the present to the past inhabitants of that continent.
See 72, image results for dinosaurs. Zoom Dinosaurs - EnchantedLearning. Try this search facility - just click on the first letter of what you need information on. Periodic Chart of the Elements with correlation to their health aspects - http: Taxonomy Detailed information and examples and links to database searches are found on our Microscopy Page Paragraph 3. All life forms are composed of basic chemical elements. Atomic elements prefer to exist as molecules. Earth life thrives on water. Life is built up from some very common materials.
There is one substance though that is more complicated and vital to life. A Dutch biochemist, named Mulder, first used the word "protein" in He got the word form a Greek word meaning "holding first place. Although proteins are complicated they consist the elements of carbon, hydrogen, oxygen, nitrogen and sulphur. Some parts of the human body contain more than other parts but it exists is some amount in all parts of the body and it is vital for life to exist.
There is no living organism that does not contain protein. Viruses for example contain a complicated type of protein called nucleoprotein. When proteins are exposed to an acid the protein breaks apart into smaller molecules. These smaller molecules are called amino-acids. Millions of different proteins can be formed from the combinations of different amino-acid molecules.
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