Misplaced Pages

#834165

34-604: (Redirected from Dendritic ) [REDACTED] Look up dendrite  or dendritic in Wiktionary, the free dictionary. Dendrite derives from the Greek word "dendron" meaning ( lit. "tree-like"), and may refer to: Biology [ edit ] Dendrite , a branched projection of a neuron Dendrite (non-neuronal) , branching projections of certain skin cells and immune cells Physical [ edit ] Dendrite (metal) ,

68-570: A brand of contact cement from India and South Asia See also [ edit ] Dendroid (disambiguation) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Dendrite . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Dendrite_(disambiguation)&oldid=1120675115 " Category : Disambiguation pages Hidden categories: Short description

102-535: A characteristic tree-like structure of crystals growing as molten metal freezes Dendrite (mathematics) , a locally connected continuum that contains no simple closed curves Dendrite (crystal) , a crystal that develops with a typical multi-branching tree-like form Dendrimer , a repetitively branched molecule Software [ edit ] Dendrite (matrix) , a server for the matrix protocol written in Go Brand [ edit ] Dendrite (adhesive) ,

136-577: A chemical signal. When an action potential arrives at an axon terminal (A), the neurotransmitter is released and diffuses across the synaptic cleft. If the postsynaptic cell (B) is also a neuron , neurotransmitter receptors generate a small electrical current that changes the postsynaptic potential . If the postsynaptic cell (B) is a muscle cell ( neuromuscular junction ), it contracts. Axon terminals are specialized to release neurotransmitters very rapidly by exocytosis . Neurotransmitter molecules are packaged into synaptic vesicles that cluster beneath

170-519: A cone away from cell body, see pyramidal cells ), or fanned (where dendrites radiate like a flat fan as in Purkinje cells ). The structure and branching of a neuron's dendrites, as well as the availability and variation of voltage-gated ion conductance , strongly influences how the neuron integrates the input from other neurons. This integration is both temporal, involving the summation of stimuli that arrive in rapid succession, as well as spatial, entailing

204-535: A constant radius and can be very long. Typically, axons transmit electrochemical signals and dendrites receive the electrochemical signals, although some types of neurons in certain species lack specialized axons and transmit signals via their dendrites. Dendrites provide an enlarged surface area to receive signals from axon terminals of other neurons. The dendrite of a large pyramidal cell receives signals from about 30,000 presynaptic neurons. Excitatory synapses terminate on dendritic spines , tiny protrusions from

238-503: A dendrite. There are also dendrodendritic synapses , signaling from one dendrite to another. An autapse is a synapse in which the axon of one neuron transmits signals to its own dendrite. The general structure of the dendrite is used to classify neurons into multipolar , bipolar and unipolar types. Multipolar neurons are composed of one axon and many dendritic trees. Pyramidal cells are multipolar cortical neurons with pyramid-shaped cell bodies and large dendrites that extend towards

272-444: A nerve fiber, is a long, slender projection of a nerve cell that conducts electrical impulses called action potentials away from the neuron's cell body to transmit those impulses to other neurons, muscle cells, or glands. Most presynaptic terminals in the central nervous system are formed along the axons ( en passant boutons ), not at their ends (terminal boutons). Functionally, the axon terminal converts an electrical signal into

306-414: A nervous system were made in the late 1930s by Kenneth S. Cole and Howard J. Curtis. Swiss Rüdolf Albert von Kölliker and German Robert Remak were the first to identify and characterize the axonal initial segment . Alan Hodgkin and Andrew Huxley also employed the squid giant axon (1939) and by 1952 they had obtained a full quantitative description of the ionic basis of the action potential, leading to

340-447: A part or in all directions from a cell body, see cerebellar granule cells ), laminar (where dendrites can either radiate planarly, offset from cell body by one or more stems, or multi-planarly, see retinal horizontal cells , retinal ganglion cells , retinal amacrine cells respectively), cylindrical (where dendrites radiate in all directions in a cylinder, disk-like fashion, see pallidal neurons ), conical (dendrites radiate like

374-408: A particular location on a dendrite transmit this electrical signal through a system of converging dendrite segments of different diameters, lengths, and electrical properties. Based on passive cable theory one can track how changes in a neuron's dendritic morphology impact the membrane voltage at the cell body, and thus how variation in dendrite architectures affects the overall output characteristics of

SECTION 10

#1733105964835

408-712: A presynaptic to a postsynaptic cell (and maturation of excitatory synaptic inputs) eventually can change the course of synapse formation at dendritic and axonal arbors. This synapse formation is required for the development of neuronal structure in the functioning brain. A balance between metabolic costs of dendritic elaboration and the need to cover the receptive field presumably determine the size and shape of dendrites. A complex array of extracellular and intracellular cues modulates dendrite development including transcription factors, receptor-ligand interactions, various signaling pathways, local translational machinery, cytoskeletal elements, Golgi outposts and endosomes. These contribute to

442-453: A train of back-propagating action potentials can induce a calcium action potential (a dendritic spike ) at dendritic initiation zones. Dendrites themselves appear to be capable of plastic changes during the adult life of animals, including invertebrates. Neuronal dendrites have various compartments known as functional units that are able to compute incoming stimuli. These functional units are involved in processing input and are composed of

476-596: Is different from Wikidata All article disambiguation pages All disambiguation pages dendrite Dendrites play a critical role in integrating these synaptic inputs and in determining the extent to which action potentials are produced by the neuron. Dendrites are one of two types of cytoplasmic processes that extrude from the cell body of a neuron , the other type being an axon . Axons can be distinguished from dendrites by several features including shape, length, and function. Dendrites often taper off in shape and are shorter, while axons tend to maintain

510-421: Is sufficient to receive as many as 100,000 inputs to a single neuron. The term dendrites was first used in 1889 by Wilhelm His to describe the number of smaller "protoplasmic processes" that were attached to a nerve cell . German anatomist Otto Friedrich Karl Deiters is generally credited with the discovery of the axon by distinguishing it from the dendrites. Some of the first intracellular recordings in

544-442: The presynaptic membrane , releasing their content into the synaptic cleft within 180 μs of calcium entry. When receptors in the postsynaptic membrane bind this neurotransmitter and open ion channels , information is transmitted between neurons (A) and neurons (B). To generate an action potential in the postsynaptic neuron, many excitatory synapses must be active at the same time. Historically, calcium-sensitive dyes were

578-475: The Nodes of Ranvier. Santiago Ramón y Cajal, a Spanish anatomist, proposed that axons were the output components of neurons. He also proposed that neurons were discrete cells that communicated with each other via specialized junctions, or spaces, between cells, now known as a synapse. Ramón y Cajal improved a silver staining process known as Golgi's method, which had been developed by his rival, Camillo Golgi . During

612-445: The aggregation of excitatory and inhibitory inputs from separate branches. Dendrites were once thought to merely convey electrical stimulation passively. This passive transmission means that voltage changes measured at the cell body are the result of activation of distal synapses propagating the electric signal towards the cell body without the aid of voltage-gated ion channels . Passive cable theory describes how voltage changes at

646-479: The axon terminal membrane on the presynaptic side (A) of a synapse. Some of these vesicles are docked , i.e., connected to the membrane by several specialized proteins, such as the SNARE complex . The incoming action potential activates voltage-gated calcium channels , leading to an influx of calcium ions into the axon terminal. The SNARE complex reacts to these calcium ions. It forces the vesicle's membrane to fuse with

680-462: The dendrite with a high density of neurotransmitter receptors . Most inhibitory synapses directly contact the dendritic shaft. Synaptic activity causes local changes in the electrical potential across the plasma membrane of the dendrite. This change in membrane potential will passively spread along the dendrite, but becomes weaker with distance without an action potential . To generate an action potential, many excitatory synapses have to be active at

714-468: The dendritic structure can change as a result of physiological conditions induced by hormones during periods such as pregnancy, lactation, and following the estrous cycle. This is particularly visible in pyramidal cells of the CA1 region of the hippocampus, where the density of dendrites can vary up to 30%. Recent experimental observations suggest that adaptation is performed in the neuronal dendritic trees, where

SECTION 20

#1733105964835

748-466: The development of dendrites, several factors can influence differentiation. These include modulation of sensory input, environmental pollutants, body temperature, and drug use. For example, rats raised in dark environments were found to have a reduced number of spines in pyramidal cells located in the primary visual cortex and a marked change in distribution of dendrite branching in layer 4 stellate cells. Experiments done in vitro and in vivo have shown that

782-413: The first tool to quantify the calcium influx into synaptic terminals and to investigate the mechanisms of short-term plasticity . The process of exocytosis can be visualized with pH-sensitive fluorescent proteins ( Synapto-pHluorin ): Before release, vesicles are acidic, and the fluorescence is quenched. Upon release, they are neutralized, generating a brief flash of green fluorescence. Another possibility

816-572: The formulation of the Hodgkin–Huxley model . Hodgkin and Huxley were awarded jointly the Nobel Prize for this work in 1963. The formulas detailing axonal conductance were extended to vertebrates in the Frankenhaeuser–Huxley equations. Louis-Antoine Ranvier was the first to describe the gaps or nodes found on axons and for this contribution these axonal features are now commonly referred to as

850-472: The function of the neuron. Malformation of dendrites is also tightly correlated to impaired nervous system function. Branching morphologies may assume an adendritic structure (not having a branching structure, or not tree-like), or a tree-like radiation structure. Tree-like arborization patterns can be spindled (where two dendrites radiate from opposite poles of a cell body with few branches, see bipolar neurons ), spherical (where dendrites radiate in

884-427: The motor protein includes KIF5, dynein, LIS1. Dendritic arborization has been found to be induced in cerebellum Purkinje cells by substance P . Important secretory and endocytic pathways controlling the dendritic development include DAR3 /SAR1, DAR2/Sec23, DAR6/Rab1 etc. All these molecules interplay with each other in controlling dendritic morphogenesis including the acquisition of type specific dendritic arborization,

918-430: The neuron. Action potentials initiated at the axon hillock propagate back into the dendritic arbor. These back-propagating action potentials depolarize the dendritic membrane and provide a crucial signal for synapse modulation and long-term potentiation . Back-propagation is not completely passive, but modulated by the presence of dendritic voltage-gated potassium channels . Furthermore, in certain types of neurons,

952-663: The organization of the dendrites on individual cell bodies and the placement of these dendrites in the neuronal circuitry. For example, it was shown that β-actin zipcode binding protein 1 (ZBP1) contributes to proper dendritic branching. Other important transcription factors involved in the morphology of dendrites include CUT, Abrupt, Collier, Spineless, ACJ6/drifter, CREST, NEUROD1, CREB, NEUROG2 etc. Secreted proteins and cell surface receptors include neurotrophins and tyrosine kinase receptors, BMP7, Wnt/dishevelled, EPHB 1–3, Semaphorin/plexin-neuropilin, slit-robo, netrin-frazzled, reelin. Rac, CDC42 and RhoA serve as cytoskeletal regulators, and

986-506: The presence of afferents and input activity per se can modulate the patterns in which dendrites differentiate. Little is known about the process by which dendrites orient themselves in vivo and are compelled to create the intricate branching pattern unique to each specific neuronal class. One theory on the mechanism of dendritic arbor development is the Synaptotropic Hypothesis. The synaptotropic hypothesis proposes that input from

1020-459: The regulation of dendrite size and the organization of dendrites emanating from different neurons. Dendritic arborization, also known as dendritic branching, is a multi-step biological process by which neurons form new dendritic trees and branches to create new synapses. Dendrites in many organisms assume different morphological patterns of branching. The morphology of dendrites such as branch density and grouping patterns are highly correlated to

1054-482: The same time, leading to strong depolarization of the dendrite and the cell body ( soma ). The action potential, which typically starts at the axon hillock , propagates down the length of the axon to the axon terminals where it triggers the release of neurotransmitters, but also backwards into the dendrite (retrograde propagation), providing an important signal for spike-timing-dependent plasticity (STDP). Most synapses are axodendritic, involving an axon signaling to

Dendrite (disambiguation) - Misplaced Pages Continue

1088-536: The subdomains of dendrites such as spines, branches, or groupings of branches. Therefore, plasticity that leads to changes in the dendrite structure will affect communication and processing in the cell. During development, dendrite morphology is shaped by intrinsic programs within the cell's genome and extrinsic factors such as signals from other cells. But in adult life, extrinsic signals become more influential and cause more significant changes in dendrite structure compared to intrinsic signals during development. In females,

1122-495: The surface of the cortex ( apical dendrite ). Bipolar neurons have two main dendrites at opposing ends of the cell body. Many inhibitory neurons have this morphology. Unipolar neurons, typical for insects, have a stalk that extends from the cell body that separates into two branches with one containing the dendrites and the other with the terminal buttons. In vertebrates, sensory neurons detecting touch or temperature are unipolar. Dendritic branching can be extensive and in some cases

1156-432: The timescale of adaptation was observed to be as low as several seconds. Certain machine learning architectures based on dendritic trees have been shown to simplify the learning algorithm without affecting performance. Axon terminal Axon terminals (also called terminal boutons , synaptic boutons , end-feet , or presynaptic terminals ) are distal terminations of the branches of an axon . An axon, also called

#834165