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Encyclopedia > Cilium
SEM micrograph of the cilia projecting from respiratory epithelium in the lungs
SEM micrograph of the cilia projecting from respiratory epithelium in the lungs

A cilium (plural cilia) is an organelle found in eukaryotic cells. Cilia are thin, tail-like projections extending approximately 5–10 micrometers outwards from the cell body.
There are two types of cilia: motile cilia, which constantly beat in a single direction, and non-motile cilia, which typically serve as sensory organelles. Along with flagella, they make up a group of organelles known as undulipodia. Image File history File links Emblem-important. ... Psyllium or Ispaghula is the common name used for several members of the plant genus Plantago whose seeds are used commercially for the production of mucilage. ... Image File history File links Size of this preview: 585 × 599 pixelsFull resolution (1024 × 1049 pixel, file size: 375 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 585 × 599 pixelsFull resolution (1024 × 1049 pixel, file size: 375 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Sem may refer to: Sem or Shem; (Hebrew) One of the sons of Noah in the Bible. ... Respiratory epithelium is another name for ciliated pseudostratified columnar epithelium with goblet cells. ... Schematic of typical animal cell, showing subcellular components. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... A flagellum (plural, flagella) is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about. ... Diagram of a cross-section of the axoneme microtubule array present in all undulipodia An undulipodium is an intracellular projection of a eukaryotic cell containing a microtubule array. ...

Contents

Types and distribution

Cilia are rare in plants, occurring most notably in cycads. Protozoans (ciliates) possess motile cilia exclusively and use them for either locomotion or to simply move liquid over their surface. Some ciliates bear groups of cilia that are fused together into large mobile projections called cirri (singular, cirrus). Families Cycadaceae cycas family Stangeriaceae stangeria family Zamiaceae zamia family Leaves and male cone of Cycas revoluta Cycads are an ancient group of seed plants characterized by a large crown of compound leaves and a stout trunk. ... Protozoa (in Greek protos = first and zoon = animal) are single-celled creatures with nuclei that show some characteristics usually associated with animals, most notably mobility and heterotrophy. ... Classes Karyorelictea Heterotrichea Spirotrichea Litostomatea Phyllopharyngea Nassophorea Colpodea Prostomatea Oligohymenophorea Plagiopylea See text for subclasses. ...


Larger eukaryotes, such as mammals, have motile cilia as well. Motile cilia are rarely found alone, usually present on a cell's surface in large numbers and beating in coordinated waves. In humans, for example, motile cilia are found in the lining of the trachea (windpipe), where they sweep mucus and dirt out of the lungs. In female mammals, the beating of cilia in the Fallopian tubes moves the ovum from the ovary to the uterus. This article is about modern humans. ... Windpipe redirects here. ... For other uses, see Female (disambiguation). ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... // For ovary as part of plants see ovary (plants) An ovary is an egg-producing reproductive organ found in female organisms. ... This article is about female reproductive anatomy. ...



In contrast to motile cilia, non-motile cilia usually occur one per cell. The outer segment of the rod photoreceptor cell in the human eye is connected to its cell body with a specialized non-motile cilium. The dendritic knob of the olfactory neuron, where the odorant receptors are located, is also carrying non-motile cilia (about 10 cilia / dendritic knobs). Aside from these specialized examples, almost all mammalian cells have a single non-motile "primary cilium". Though the primary cilium has historically been ignored by scientists, recent findings regarding its physiological roles in chemical sensation, signal transduction, and control of cell growth, have led scientists to re-evaluate its importance. This article is about cellular photoreceptors. ... Olfaction, the sense of smell, is the detection of chemicals dissolved in air (or, by animals that breathe water, in water). ...


Assembly and maintenance

Cross-section of two motile cilia, showing the "9+2" structure

To grow a cilium, the building blocks of the cilia such as tubulins and other partially assembled axonemal proteins are added to the ciliary tips which point away from the cell body. In most species bi-directional motility called intraciliary/intraflagellar transport or IFT plays an essential role to move these building materials from the cell body to the assembly site. IFT also carries the disassembled material to be recycled from the ciliary tip back to the cell body. By regulating the equilibrium between these two IFT proceses, the length of cilia can be maintained dynamically. Image File history File links Size of this preview: 744 × 599 pixelsFull resolution (1560 × 1257 pixel, file size: 724 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 744 × 599 pixelsFull resolution (1560 × 1257 pixel, file size: 724 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Microtubules are protein structures found within cells. ... Intraflagellar transport (IFT) refers to the cellular process essential for the formation and maintainance of eukaryotic cilia and flagella. ... Intraflagellar Transport (IFT) refers to the cellular process essential for the formation and maintenance of eukaryotic cilia and flagella. ...


Exceptions where IFT is not present include Plasmodium falciparum which is one of the species of Plasmodium that cause malaria in humans. In this parasite, cilia assemble in the cytoplasm.[1] Binomial name Welch, 1897 Plasmodium falciparum is a protozoan parasite, one of the species of Plasmodium that cause malaria in humans. ... Species Plasmodium achiotense Plasmodium achromaticum Plasmodium acuminatum Plasmodium adunyinkai Plasmodium aegyptensis Plasmodium aeuminatum Plasmodium agamae Plasmodium anasum Plasmodium anomaluri Plasmodium arachniformis Plasmodium ashfordi Plasmodium atheruri Plasmodium aurulentum Plasmodium australis Plasmodium attenuatum Plasmodium azurophilum Plasmodium balli Plasmodium bambusicolai Plasmodium basilisci Plasmodium beebei Plasmodium beltrani Plasmodium berghei Plasmodium bertii Plasmodium bigueti Plasmodium... Malaria is a vector-borne infectious disease caused by protozoan parasites. ...


Cilium-related disease

Ciliary defects can lead to several human diseases. Genetic mutations compromising the proper functioning of cilia can cause chronic disorders such as primary ciliary dyskinesia (PCD). In addition, a defect of the primary cilium in the renal tube cells can lead to polycystic kidney disease (PKD). In another genetic disorder called Bardet-Biedl syndrome (BBS), the mutant gene products are the components in the basal body and cilia. Primary ciliary dyskinesia (PCD), also known as immotile ciliary syndrome, is a rare autosomal recessive genetic disorder caused by a defect in the action of the tiny hairs (cilia) lining the respiratory tract. ... Polycystic kidney disease (PKD) is a progressive, genetic disorder of the kidneys. ... The Bardet-Biedl syndrome is a a syndrome characterized mainly by obesity, pigmentary retinopathy, polydactyly, mental retardation, hypogonadism, and renal failure in fatal cases. ...


Lack of functional cilia in mammalian Fallopian tubes can cause ectopic pregnancy. A fertilized ovum may not reach the uterus if the cilia are unable to move it there. In such a case, the ovum will implant in the Fallopian tubes, causing a tubal pregnancy, the most common form of ectopic pregnancy. Female internal reproductive anatomy The Fallopian tubes or oviducts are two very fine tubes leading from the ovaries of female mammals into the uterus. ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... This article is about female reproductive anatomy. ... An ectopic pregnancy is one in which the fertilized ovum is implanted in any tissue other than the uterine wall. ...


References

  1. ^ http://www.pandasthumb.org/archives/2007/06/of_cilia_and_si.html

External Links


  Results from FactBites:
 
Cilium (227 words)
A cilium (plural cilia) is a fine projection from a eukaryotic cell that constantly beats in one direction.
The internal structure of a cilium is identical to that of a eukaryotic flagellum, and the terms are often used interchangeably.
A cilium has an outer membrane that surrounds a matrix which contains nine microtubules around a central core with two additional microtubules.
Interactive Fly, Drosophila (2164 words)
This probably reflects a general defect in cilium assembly, since both the proximal and the distal parts of the organelle are disorganized -- that is, both rootlet apparatus and axonemal structures are absent from scolopidia in Rfx mutant antennae as observed by electron microscopy.
Cilium defects are associated with dendrite morphogenesis defects such as incorrect positioning in the wing, swollen shape in the femur and the wing.
The cilium defect could be responsible for incorrect dendrite positioning by disrupting close interactions between the cilium and structures of the sheath and the hair cell.
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