The human flora is the microrganisms that constantly inhabit the human body. A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually The human body is the entire physical and mental structure of a Human Organism. They include bacteria, fungi and archaea. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ Some of these organisms are known to perform tasks that are useful for the human host, while the majority have no beneficial or harmful effect. Those that are expected to be present, and that under normal circumstances do not cause disease, are termed normal flora,^[1] or microbiota. An effort to better describe the microflora of humans has been initiated; see Human microbiome project. The gut flora are the Microorganisms that normally live in the Digestive tract and can perform a number of useful functions for their hosts The Human microbiome project (HMP is a National Institutes of Health initiative with the goal of identifying and characterizing the Microorganisms which are found

Bacterial flora

It is estimated that 500 to 100,000 species of bacteria live in the human body ^[2]. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. Bacterial cells are much smaller than human cells, and there are about ten times as many bacteria as human cells in the body (1000 trillion or 1 quadrillion (10¹⁵) versus 100 trillion (10¹⁴)). The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called ^[2] Though normal flora are found on all surfaces exposed to the environment (on the skin and eyes, in the mouth, nose, small intestine, and colon), the vast majority of bacteria live in the large intestine. In Biology the small Intestine is the part of the Gastrointestinal tract (gut between the Stomach and the Large intestine, and comprises The colon is a storage tube for solid wastes The main function of the colon appears to be extraction of Water and salts from Feces. The large intestine is the last part of the Digestive system: the final stage of the Alimentary canal in Vertebrate Animals Its function is to

Many of the bacteria in the digestive tract, collectively referred to as gut flora, are able to break down certain nutrients such as carbohydrates that humans otherwise could not digest. The gut flora are the Microorganisms that normally live in the Digestive tract and can perform a number of useful functions for their hosts Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Digestion is the breaking down of chemicals in the body into a form that can be absorbed The majority of these commensal bacteria are anaerobes, meaning they survive in an environment with no oxygen. In Ecology, commensalism is a kind of symbiotic relationship between two organisms where one benefits and the other is not significantly harmed or helped (like a bird An anaerobic organism is any Organism that does not require Oxygen for growth and may even die in its presence Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Bacteria of the normal flora can act as opportunistic pathogens at times of lowered immunity. An opportunistic infection is an infection caused by Pathogens that usually do not cause disease in a healthy Immune system. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor ^[1]

Escherichia coli (a. k. a. E. coli) is a bacterium that lives in the colon; it is an extensively studied model organism and probably the best understood bacterium of all. A model organism is a Species that is extensively studied to understand particular biological Phenomena, with the expectation that discoveries made ^[3] Certain mutated strains of these gut bacteria do cause disease; an example is E. coli O157:H7. Escherichia coli O157H7 is an Enterohemorrhagic strain of the bacterium Escherichia coli and a cause of Foodborne illness

A number of types of bacteria, such as Actinomyces viscosus and A. Actinomyces is a Genus of the Actinobacteria class of Bacteria. naeslundii, live in the mouth, where they are part of a sticky substance called plaque. Dental plaque is Biofilm (usually colorless that builds up on the Teeth. If this is not removed by brushing, it hardens into calculus (also called tartar). In Dentistry, calculus or tartar refers to calcified deposits on the teeth, formed by the continuous presence of Dental plaque. The same bacteria also secrete acids that dissolve tooth enamel, causing tooth decay. Tooth enamel is the hardest and most highly mineralized substance of the body and with Dentin, Cementum, and dental pulp is one of the four major Dental caries is a disease that damages Tooth structures resulting in what is commonly called tooth decay or cavities which are holes in the teeth

The vaginal microflora consist mostly of various lactobacillus species. Lactobacillus is a Genus of Gram-positive Facultative anaerobic or Microaerophilic Bacteria. It was long thought that the most common of these species was Lactobacillus acidophilus, but it has later been shown that the most common one is L. Lactobacillus acidophilus is one Species in the genus Lactobacillus. iners followed by L. crispatus. Other lactobacilli found in the vagina are L. delbruekii and L. gasseri. Disturbance of the vaginal flora can lead to bacterial vaginosis. Bacterial vaginosis (BV is the most common cause of vaginal infection ( Vaginitis)

Human bacterial flora and human health

Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells

Bacteria are vital for the maintenance of human health, but some pathogenic bacteria also pose a significant health threat by causing diseases. Salmonella enterica is a rod shaped Flagellated Gram-negative Bacterium, and a member of the Genus Salmonella The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Pathogenic bacteria are Bacteria that cause Infectious diseases. Large numbers of bacteria live on the skin and in the digestive tract. Their growth can be increased by warmth and sweat. Large populations of these organisms on humans are the cause of body odor and thought to play a part in acne. Body odor (spelled body odour outside the United States often abbreviated as B Acne vulgaris (commonly called acne) is a Skin disease caused by changes in the Pilosebaceous units (skin structures consisting of a Hair follicle There are more than 500 bacterial species present in the normal human gut and are generally beneficial: they synthesize vitamins such as folic acid, vitamin K and biotin, and they ferment complex indigestible carbohydrates. A vitamin is an Organic compound required as a Nutrient in tiny amounts by an Organism. Folic acid (also known as Vitamin M and Folacin) and Folate (the Anionic form are forms of the water-soluble Vitamin B9 Vitamin K (K from "Koagulations-Vitamin" in German Danish Swedish and Norwegian denotes a group of Lipophilic, Hydrophobic Vitamins that Vitamin H redirects here In medical slang "vitamin H" may also refer to Haloperidol. Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most ^[4][5] Other beneficial bacteria in the normal flora include Lactobacillus species, which convert lactose and other sugars to lactic acid in the gut. Lactobacillus is a Genus of Gram-positive Facultative anaerobic or Microaerophilic Bacteria. Lactose (also referred to as milk sugar) is a Sugar which is found most notably in Milk. ^[6] The presence of such bacterial colonies also inhibits the growth of potentially pathogenic bacteria (usually through competitive exclusion) and some beneficial bacteria are consequently sold as probiotic dietary supplements. In Community ecology, the competitive exclusion principle, sometimes referred to as Gause's Law of competitive exclusion or just Gause's Law Probiotics are Dietary supplements containing potentially beneficial Bacteria or Yeasts According to the currently adopted definition by FAO / ^[7]

Archaean flora

Archaea are present in the human gut, but in contrast to the enormous variety of bacteria in this organ, the number of archaeal species are much more limited. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have ^[8] The dominant group is the methanogens, particularly Methanobrevibacter smithii and Methanosphaera stadtmanae. Methanogens are Archaea that produce Methane as a Metabolic byproduct in Anoxic conditions In taxonomy, Methanobrevibacter is a genus of the Methanobacteriaceae. In taxonomy, Methanosphaera is a genus of the Methanobacteriaceae. ^[9] However, colonization by methanogens is variable and only about 50% of humans have easily-detectable populations or these organisms. ^[10]

Archaea and human health

As of 2007, no clear examples of archaeal pathogens are known,^[11][12] although a relationship has been proposed between the presence of some methanogens and human periodontal disease. A pathogen (from Greek πάθος pathos "suffering passion" and γἰγνομαι (γεν- gignomai (gen- "I give birth to" infectious ^[13]

Fungal flora

Fungi, particularly yeasts are present in the human gut. Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described The best studied of these are Candida species, due to their ability to become pathogenic in immunocompromised hosts. Candida is a Genus of Yeasts Many species of this genus are Endosymbionts In Medicine, immunodeficiency (or immune deficiency) is a state in which the Immune system 's ability to fight Infectious disease is compromised ^[14] Yeasts are also present on the skin, particularly Malassezia species, where they consume oils secreted from the sebaceous glands. Malassezia (formerly known as Pityrosporum) is a genus of related Fungi, classified as Yeasts naturally found on the skin surfaces of many The sebaceous glands are Glands found in the Skin of Mammals Locations and morphology A branched type of Acinar gland, these ^[15][16]

References

See also

• Microorganism
• Human microbiome project