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Mucus
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is a viscous colloid containing inorganic salts, antimicrobial enzymes (such as lysozymes), immunoglobulins (especially IgA), and glycoproteins such as lactoferrin and mucins, which are produced by goblet cells in the mucous membranes and submucosal glands. Mucus serves to protect epithelial cells in the linings of the respiratory, digestive, and urogenital systems, and structures in the visual and auditory systems from pathogenic fungi, bacteria and viruses. Most of the mucus in the body is produced in the gastrointestinal tract. Amphibians, fish, snails, slugs, and some other invertebrates also produce external mucus from their epidermis as protection against pathogens, and to help in movement and is also produced in fish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mucus Cells
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is a viscous colloid containing inorganic salts, antimicrobial enzymes (such as lysozymes), immunoglobulins (especially IgA), and glycoproteins such as lactoferrin and mucins, which are produced by goblet cells in the mucous membranes and submucosal glands. Mucus serves to protect epithelial cells in the linings of the respiratory, digestive, and urogenital systems, and structures in the visual and auditory systems from pathogenic fungi, bacteria and viruses. Most of the mucus in the body is produced in the gastrointestinal tract. Amphibians, fish, snails, slugs, and some other invertebrates also produce external mucus from their epidermis as protection against pathogens, and to help in movement and is also produced in fish to line t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goblet Cell
Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 5AC. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their secretions, when under stress. The term '' goblet'' refers to the cell's goblet-like shape. The apical portion is shaped like a cup, as it is distended by abundant mucus laden granules; its basal portion lacks these granules and is shaped like a stem. The goblet cell is highly polarized with the nucleus and other organelles concentrated at the base of the cell and secretory granules containing mucin, at the apical surface. The apical plasma membrane projects short microvilli to give an increased surface area for secretion. Goblet cells are typically found in the respiratory, reproductive and gastrointestinal tracts and are surrounded by other columnar cells. Biased differentiation of airway basal cells in the respiratory epithelium, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slugs
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semislugs (this is in contrast to the common name ''snail'', which applies to gastropods that have a coiled shell large enough that they can fully retract their soft parts into it). Various taxonomic families of land slugs form part of several quite different evolutionary lineages, which also include snails. Thus, the various families of slugs are not closely related, despite a superficial similarity in the overall body form. The shell-less condition has arisen many times independently as an example of convergent evolution, and thus the category "slug" is polyphyletic. Taxonomy Of the six orders of Pulmonata, two – the Onchidiacea and Soleolifera – solely comprise slugs. A third family, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submucosal Glands
Submucosal glands can refer to various racemose exocrine glands of the mucous type. These glands secrete mucus to facilitate the movement of particles along the body's various tubes, such as the throat and intestines. The mucosa is the lining of the tubes, like a kind of ''skin''. ''Submucosal'' means that the actual gland resides in the connecting tissue below the mucosa. The submucosa is the tissue that connects the mucosa to the muscle outside the tube. The glands themselves are quite complex. The mucus factory is at the bottom, in the submucosa, it is composed of many little sacs (acini) where the mucus originates. Each sac (acinus) has one end that can open and close (dilate) to allow the mucus out. The acini empty into little tubes (tubules) that lead to a reservoir (collecting duct) that has a portal through the ''skin'' (mucosa) that can open and close allowing the mucus into the main tube. The submucosal glands are a companion to goblet cells which also produce mucus, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Snail
A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial gastropod mollusks that have shells (those without shells are known as slugs). However, it is not always easy to say which species are terrestrial, because some are more or less amphibious between land and fresh water, and others are relatively amphibious between land and salt water. Land snails are a polyphyletic group comprising at least ten independent evolutionary transitions to terrestrial life (the last common ancestor of all gastropods was marine). The majority of land snails are pulmonates that have a lung and breathe air. Most of the non-pulmonate land snails belong to lineages in the Caenogastropoda, and tend to have a gill and an operculum. The largest clade of land snails is the Cyclophoroidea, with more than 7,000 species. Many of these operculate land snails live in habitats or microhabita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digestion
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. Mechanical digestion takes place in the mouth through mastication and in the small intestine through segmentation contractions. In chemical digestion, enzymes break down food into the small molecules the body can use. In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, but some species have developed behavioural adaptations to bypass this. The young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin. They are superficially similar to reptiles like lizards but, along with mammals and birds, reptiles are amniotes and do not require water bodies in which to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators; in recent decades there has been a dramatic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mucous Membrane
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is mostly of endodermal origin and is continuous with the skin at body openings such as the eyes, eyelids, ears, inside the nose, inside the mouth, lips, the genital areas, the urethral opening and the anus. Some mucous membranes secrete mucus, a thick protective fluid. The function of the membrane is to stop pathogens and dirt from entering the body and to prevent bodily tissues from becoming dehydrated. Structure The mucosa is composed of one or more layers of epithelial cells that secrete mucus, and an underlying lamina propria of loose connective tissue. The type of cells and type of mucus secreted vary from organ to organ and each can differ along a given tract. Mucous membranes line the digestive, respiratory and reproductive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mucin
Mucins () are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most gel-like secretions, serving functions from lubrication to cell signalling to forming chemical barriers. They often take an inhibitory role. Some mucins are associated with controlling mineralization, including nacre formation in mollusks, calcification in echinoderms and bone formation in vertebrates. They bind to pathogens as part of the immune system. Overexpression of the mucin proteins, especially MUC1, is associated with many types of cancer. Although some mucins are membrane-bound due to the presence of a hydrophobic membrane-spanning domain that favors retention in the plasma membrane, most mucins are secreted as principal components of mucus by mucous membranes or are secreted to become a component of saliva. Genes Human mucins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Respiratory System
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary history. In land animals the respiratory surface is internalized as linings of the lungs. Gas exchange in the lungs occurs in millions of small air sacs; in mammals and reptiles these are called alveoli, and in birds they are known as atria. These microscopic air sacs have a very rich blood supply, thus bringing the air into close contact with the blood. These air sacs communicate with the external environment via a system of airways, or hollow tubes, of which the largest is the trachea, which branches in the middle of the chest into the two main bronchi. These enter the lungs where they branch into progressively narrower secondary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serous
In physiology, serous fluid or serosal fluid (originating from the Medieval Latin word ''serosus'', from Latin ''serum'') is any of various body fluids resembling serum, that are typically pale yellow or transparent and of a benign nature. The fluid fills the inside of body cavities. Serous fluid originates from serous glands, with secretions enriched with proteins and water. Serous fluid may also originate from mixed glands, which contain both mucous and serous cells. A common trait of serous fluids is their role in assisting digestion, excretion, and respiration. In medical fields, especially cytopathology, serous fluid is a synonym for effusion fluids from various body cavities. Examples of effusion fluid are pleural effusion and pericardial effusion. There are many causes of effusions which include involvement of the cavity by cancer. Cancer in a serous cavity is called a serous carcinoma. Cytopathology evaluation is recommended to evaluate the causes of effusions in these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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