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Encyclopedia > Phagocytic

Phagocytosis (literally "cell-eating") is a form of endocytosis wherein large particles are enveloped by the cell membrane of a (usually larger) cell and internalized to form a phagosome, or "food vacuole." Endocytosis is a process whereby cells absorb material (molecules or other cells) from outside by engulfing it with their cell membranes. ... Drawing of a cell membrane A component of every biological cell, the selectively permeable cell membrane (or plasma membrane or plasmalemma) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... Cells in culture, stained for keratin (red) and DNA (green). ... In cell biology, a vacuole formed around a particle absorbed by phagocytosis. ...

In animals, phagocytosis is performed by specialized cells called phagocytes, which serve to remove foreign bodies and thus fight infection. In vertebrates, these include larger macrophages and smaller granulocytes, types of blood cells. Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytosed. Virulent bacteria may need to be coated in antibodies before they can be consumed. Certain pathogenic bacteria, such as those of leprosy and tuberculosis, once internalized by phagocytosis, are resistant to killing by the phagocytes that have ingested them. Anything that impedes or prevents the action of phagocyctes is termed antiphagocytic. Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... A phagocyte is a cell that ingests (and destroys) foreign matter, such as microorganisms or debris via a process known as phagocytosis, in which these cells ingest and kill offending cells by cellular digestion. ... Macrophages (Greek: big eaters) are cells found in tissues that are responsible for phagocytosis of pathogens, dead cells and cellular debris. ... Granulocytes are a category of white blood cells, characterised by the fact that all types have differently staining granules in their cytoplasm on light microscopy. ... Schematic of antibody binding to an antigen An antibody is a protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ... For the malady found in the Hebrew Bible, see the article Tzaraath. ... Tuberculosis (commonly shortened to TB) is an infection caused by the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system (meningitis), lymphatic system, circulatory system (Miliary tuberculosis), genitourinary system, bones and joints. ...

Received wisdom dictates that macrophages and neutrophils represent professional phagocytes, but this merely reflects the greater amount of research performed on these cell types. A great body of evidence continues to mount showing that resident, neighbouring cells in a tissue will phagocytize their apoptotic neighbours, thus maintaining tissue homeostasis. This clearance can, depending on the location, facilitate greater clearance than that achieved by resident macrophages. Apoptosis In biology, apoptosis (from the Greek words apo = from and ptosis = falling, commonly pronounced ap-a-tow-sis[1]) is one of the main types of programmed cell death (PCD). ...

The most important facet of phagocytosis is its control of inflammation. Depending on the phagocytosed particle, phagocytosis can induce inflammation or, as is the case with apoptotic cells, induce resolution of inflammation. Phagocytosis is also involved in immune tolerance, which prevents inflammation against normal components of the body.

In many protists, phagocytosis is used as a means of feeding, providing part or all of their nourishment. This is called phagotrophic nutrition, as distinguished from osmotrophic nutrition, which takes place by absorption. In some, such as amoebae, phagocytosis takes place by surrounding the target object with pseudopods, as in animal phagocytes. In other protozoa, for instance, ciliates, there is a specialized groove or chamber in the cell where phagocytosis takes place, called the cytostome or mouth. The resulting phagosome may be merged with lysosomes containing digestive enzymes, forming a phagolysosome. The food particles will then be digested, and the released nutrients diffused or transported into the cytosol to use in other metabolic processes. Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Dinoflagellata Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies Protists (pronounced /prəʊˌtɪst/) are a heterogeneous group of living things, comprising those eukaryotes that are neither animals, plants... Amoeba (also spelled ameba) is a genus of protozoa that moves by means of temporary projections called pseudopods, and is well-known as a representative unicellular organism. ... Pseudopods or pseudopodia (false feet) are temporary projections of eukaryotic cells. ... Classes & Subclasses Class Karyorelictea Class Heterotrichea (e. ... A cytostome or cell mouth is a part of a cell specialized for phagocytosis, usually in the form of a microtubule-supported funnel or groove. ... In cell biology, a vacuole formed around a particle absorbed by phagocytosis. ... Lysosomes contain digestive enzymes (acid hydrolases) to digest macromolecules. ... Ribbon diagram of the catalytically perfect enzyme TIM. An enzyme is a protein that catalyzes, or speeds up, a chemical reaction. ... ÃThe cytosol (as opposed fatty cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ...

See also

  Results from FactBites:
Phagocyte - Wikipedia, the free encyclopedia (201 words)
A phagocyte is a cell that ingests and destroys foreign matter such as microorganisms or debris via a process known as phagocytosis, in which these cells ingest and kill offending cells by a process analogous to cellular digestion, usually using lysosomes which carry potent enzymes that digests cell components such as other lipids or proteins.
These phagocytes are extremely useful as an initial immune system response to tissue damage.
They are also involved in cell death, usually programmed cell death through apoptosis, in which the phagocytes are responsible for cleaning up the debris and effectively "recycling" the dead cell parts.
Immune system - Wikipedia, the free encyclopedia (5202 words)
To phagocytose a particle or pathogen, a phagocyte extends portions of its plasma membrane, wrapping the membrane around the particle until the entire particle is enveloped (i.e.
Phagocytes generally patrol the body searching for pathogens, but are also able to react to a group of highly specialized molecular signals, called cytokines, produced by other cells.
Dendritic cells (DC) are phagocytic cells that are present in tissues that are in contact with the external environment, mainly the skin (where they are often called Langerhans cells) and the inner lining of the nose, lungs, stomach and intestines.
  More results at FactBites »



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