更改

树突（源于希腊语 δνδρν déndron，树的意思），是神经细胞的分枝状的原生质延伸，对其他神经细胞传递的电化学刺激传播到该细胞的胞体。电刺激信号由上游神经元（通常通过其轴突）经树突分支各处的突触传递到树突上。树突在整合这些突触输入以及决定神经元动作电位发生起着关键作用<ref name="urbanska" />。树突分枝形成，是个多步骤的生物过程，藉此神经元形成新的树突分支和分叉，以创建新突触<ref name="urbanska" />。树突的形态如分支密度和分组模式与神经元的功能密切相关。树突畸形也与神经系统功能损伤有很高关联。与树突畸形有关的疾病包括自闭症、抑郁症、精神分裂症、唐氏综合症和焦虑症。

树突（源于希腊语 δνδρν déndron，树的意思），是神经细胞的分枝状的原生质延伸，可接收其他神经细胞传递的电化学刺激，并传播到该细胞的胞体。电刺激信号由上游神经元（通常通过其轴突）经树突分支各处的突触传递到树突上。树突在整合这些突触输入以及决定神经元动作电位发放起着关键作用<ref name="urbanska" />。树突分枝形成，是个多步骤的生物过程，藉此神经元形成新的树突分支和分叉，以创建新突触<ref name="urbanska" />。树突的形态如分支密度和分组模式与神经元的功能密切相关。树突畸形也与神经系统功能损伤高度相关。与树突畸形有关的疾病包括自闭症、抑郁症、精神分裂症、唐氏综合症和焦虑症。

[[File:1920px-Neuron Hand-tuned.svg.png|thumb|Structure of a typical neuron|链接=Special:FilePath/1920px-Neuron Hand-tuned.svg.png]]

[[File:1920px-Neuron Hand-tuned.svg.png|thumb|Structure of a typical neuron|链接=Special:FilePath/1920px-Neuron Hand-tuned.svg.png]]

Certain classes of dendrites contain small projections referred to as dendritic spines that increase receptive properties of dendrites to isolate signal specificity. Increased neural activity and the establishment of long-term potentiation at dendritic spines change the sizes, shape, and conduction. This ability for dendritic growth is thought to play a role in learning and memory formation. There can be as many as 15,000 spines per cell, each of which serves as a postsynaptic process for individual presynaptic axons. Dendritic branching can be extensive and in some cases is sufficient to receive as many as 100,000 inputs to a single neuron. Dendrites are one of two types of protoplasmic protrusions 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 a constant radius and be relatively long. Typically, axons transmit electrochemical signals and dendrites receive the electrochemical signals, although some types of neurons in certain species lack axons and simply transmit signals via their dendrites. Dendrites provide an enlarged surface area to receive signals from the terminal buttons of other axons, and the axon also commonly divides at its far end into many branches (telodendria) each of which ends in a nerve terminal, allowing a chemical signal to pass simultaneously to many target cells.

[[File:Dendrites of neural tissue.jpg|thumb|The green arrow shows the dendrites emanating from soma|链接=Special:FilePath/Dendrites_of_neural_tissue.jpg]]

某些类型的树突具有称为树突棘的小突起，其增强树突的信号接收特性，通过隔离增强信号的特异性。树突棘的神经活动增强和长时程增强会改变其大小、形状和传导性能。这种树突生长能力被认为在学习和记忆形成中起着重要作用。每个细胞可以有多达 15,000 个树突棘，每个树突棘都可以作为单个突触前轴突的突触后突起<ref>{{cite journal|last=Koch|first=C.|author2=Zador, A.|title=The Function of Dendritic Spines: Devices Subserving Biochemical Rather Than Electrical Compartmentalization|journal=The Journal of Neuroscience|date=February 1993|volume=13|issue=2|pages=413–422|pmid=8426220|pmc=6576662|doi=10.1523/JNEUROSCI.13-02-00413.1993}}</ref>。树突分支可以非常庞大，有的可以为单个神经元接收多达 100,000 个输入<ref name="Alberts 2009">{{cite book|last=Alberts|first=Bruce|title=Essential Cell Biology|date=2009|publisher=Garland Science|location=New York|isbn=978-0-8153-4129-1|edition=3rd}}</ref>。树突是从神经元胞体延伸出来的两种原生质突起之一，另一种是轴突。轴突与树突可以通过几个特征来区分，包括形状、长度和功能。树突有逐渐变细的形状，更短，而轴突一般粗细不变，相对较长。通常，轴突传递电化学信号，而树突接收电化学信号，尽管某些种类的神经元没有轴突，仅仅通过树突传递信号<ref name="Yau" /> 。树突提供了扩大的表面区域来接收来自其他轴突末梢的信号，轴突也通常在其远端形成许多分支（终树突），每个分支形成一个神经末梢，允许一种化学信号同时传递给许多目标细胞<ref name="Alberts 2009" /> 。电化学信号，通常在树突部位，刺激神经元，并引起神经元质膜电位的变化。这种膜电位的变化会在整个树突进行被动扩布，但随着距离的增加而变弱，不会产生动作电位。动作电位沿着神经元树突的细胞膜传递电活动到胞体，然后沿着轴突传递到轴突末梢，在那里触发神经递质释放到突触间隙<ref name="Alberts 2009" />。然而，有树突的突触也可以是轴树突触，即从轴突向树突传递信号，也可以是树树突触，即树突之间传递信号<ref name="Carlson 2013">{{cite book|last=Carlson|first=Neil R.|title=Physiology of Behavior|date=2013|publisher=Pearson|location=Boston|isbn=978-0-205-23939-9|edition=11th}}</ref>。自突触是神经元的轴突将信号传递给自身树突的突触。

Typically, when an electrochemical signal stimulates a neuron, it occurs at a dendrite and causes changes in the electrical potential across the neuron's plasma membrane. This change in the membrane potential will passively spread across the dendrite but becomes weaker with distance without an action potential. An action potential propagates the electrical activity along the membrane of the neuron's dendrites to the cell body and then afferently down the length of the axon to the axon terminal, where it triggers the release of neurotransmitters into the synaptic cleft. However, synapses involving dendrites can also be axodendritic, involving an axon signaling to a dendrite, or dendrodendritic, involving signaling between dendrites. An autapse is a synapse in which the axon of one neuron transmits signals to its own dendrites.[[File:Dendrites of neural tissue.jpg|thumb|The green arrow shows the dendrites emanating from soma|链接=Special:FilePath/Dendrites_of_neural_tissue.jpg]]

There are three main types of neurons; multipolar, bipolar, and unipolar. Multipolar neurons, such as the one shown in the image, are composed of one axon and many dendritic trees. Pyramidal cells are multipolar cortical neurons with pyramid shaped cell bodies and large dendrites called [[apical dendrite]]s that extend to the surface of the cortex. Bipolar neurons have one axon and one dendritic tree at opposing ends of the cell body. Unipolar neurons 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. Unipolar dendrites are used to detect sensory stimuli such as touch or temperature.<ref name="Carlson 2013" /><ref name=":5">{{cite book|last=Pinel|first=John P.J.|title=Biopsychology|date=2011|publisher=Allyn & Bacon|location=Boston|isbn=978-0-205-83256-9|edition=8th}}</ref><ref name=":6">{{Cite journal | last1 = Jan | first1 = Y. N. | last2 = Jan | first2 = L. Y. | doi = 10.1038/nrn2836 | title = Branching out: Mechanisms of dendritic arborization | journal = Nature Reviews Neuroscience | volume = 11 | issue = 5 | pages = 316–328 | year = 2010 | pmid = 20404840 | pmc =3079328 }}</ref>

某些类型的树突具有称为树突棘的小突起，增加树突的信号接收特性，通过隔离增强信号的特异性。树突棘的神经活动增强和长时程增强会改变其大小、形状和传导性能。这种树突生长能力被认为在学习和记忆形成中起着重要作用。每个细胞可以有多达 15,000 个树突棘，每个都可以作为单个突触前轴突的突触后突起<ref>{{cite journal|last=Koch|first=C.|author2=Zador, A.|title=The Function of Dendritic Spines: Devices Subserving Biochemical Rather Than Electrical Compartmentalization|journal=The Journal of Neuroscience|date=February 1993|volume=13|issue=2|pages=413–422|pmid=8426220|pmc=6576662|doi=10.1523/JNEUROSCI.13-02-00413.1993}}</ref>。树突分支可以非常庞大，足以为单个神经元接收多达 100,000 个输入<ref name="Alberts 2009">{{cite book|last=Alberts|first=Bruce|title=Essential Cell Biology|date=2009|publisher=Garland Science|location=New York|isbn=978-0-8153-4129-1|edition=3rd}}</ref>。树突是从神经元细胞体延伸出来的两种原生质突起之一，另一种是轴突。轴突与树突可以通过几个特征来区分，包括形状、长度和功能。树突有逐渐变细的形状，更短，而轴突倾向于保持恒定的半径，相对较长。通常，轴突传递电化学信号，树突接收电化学信号，尽管某些种类的神经元没有轴突，仅仅通过树突传递信号<ref name="Yau" /> 。树突提供了扩大的表面区域来接收来自其他轴突末端的信号，轴突也通常在其远端形成许多分支（终树突），每个分支形成一个神经末梢，允许一种化学信号同时传递给许多目标细胞<ref name="Alberts 2009" /> 。当电化学信号，通常在树突部位，刺激神经元，并引起神经元质膜电位的变化。这种膜电位的变化会在整个树突进行被动扩布，但随着距离的增加而变弱，不会产生动作电位。动作电位沿着神经元树突的细胞膜传递电活动到胞体，然后沿着轴突传递到轴突末梢，在那里触发神经递质的释放到突触间隙<ref name="Alberts 2009" />。然而，包含树突的突触也可以是轴树突触，即从轴突向树突传递信号，也可以是树树突触，即树突之间传递信号<ref name="Carlson 2013">{{cite book|last=Carlson|first=Neil R.|title=Physiology of Behavior|date=2013|publisher=Pearson|location=Boston|isbn=978-0-205-23939-9|edition=11th}}</ref>。自突触是一种神经元的轴突将信号传递给自身树突的突触。

There are three main types of neurons; multipolar, bipolar, and unipolar. Multipolar neurons, such as the one shown in the image, are composed of one axon and many dendritic trees. Pyramidal cells are multipolar cortical neurons with pyramid shaped cell bodies and large dendrites called [[apical dendrite]]s that extend to the surface of the cortex. Bipolar neurons have one axon and one dendritic tree at opposing ends of the cell body. Unipolar neurons 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. Unipolar dendrites are used to detect sensory stimuli such as touch or temperature.<ref name="Carlson 2013" /><ref>{{cite book|last=Pinel|first=John P.J.|title=Biopsychology|date=2011|publisher=Allyn & Bacon|location=Boston|isbn=978-0-205-83256-9|edition=8th}}</ref><ref>{{Cite journal | last1 = Jan | first1 = Y. N. | last2 = Jan | first2 = L. Y. | doi = 10.1038/nrn2836 | title = Branching out: Mechanisms of dendritic arborization | journal = Nature Reviews Neuroscience | volume = 11 | issue = 5 | pages = 316–328 | year = 2010 | pmid = 20404840 | pmc =3079328 }}</ref>

神经元有三种主要类型：多极、双极和单极。多极神经元，如图所示，由一个轴突和许多树突组成。锥体细胞是多极的皮层神经元，具有锥形的胞体和延伸到皮层表面的称为顶树突的大树突。双极神经元在胞体相对的两端分别有一个轴突和一个树突树。单极神经元有一根柄从细胞体延伸出来，分成两个分支，一个分支包含树突，另一个分支包含末梢。单极树突被用来检测感觉刺激，如触摸或温度<ref name="Carlson 2013" /><ref name=":5" /><ref name=":6" />。

 

 

==历史==

==历史==

The term ''dendrites'' was first used in 1889 by [[Wilhelm His, Sr.|Wilhelm His]] to describe the number of smaller "protoplasmic processes" that were attached to a [[Neuron|nerve cell]].<ref>{{Cite book|title=Origins of neuroscience : a history of explorations into brain function|last=Finger|first=Stanley|publisher=Oxford University Press|year=1994|isbn=9780195146943|pages=44|oclc=27151391|quote=The nerve cell with its uninterrupted processes was described by Otto Friedrich Karl Deiters (1834-1863) in a work that was completed by Max Schultze (1825-1874) in 1865, two years after Deiters died of typhoid fever. This work portrayed the cell body with a single chief "axis cylinder" and a number of smaller "protoplasmic processes" (see figure 3.19). The latter would become known as "dendrites", a term coined by Wilhelm His (1831-1904) in 1889.}}</ref> German anatomist [[Otto Friedrich Karl Deiters]] is generally credited with the discovery of the axon by distinguishing it from the dendrites.

The term ''dendrites'' was first used in 1889 by [[Wilhelm His, Sr.|Wilhelm His]] to describe the number of smaller "protoplasmic processes" that were attached to a [[Neuron|nerve cell]].<ref>{{Cite book|title=Origins of neuroscience : a history of explorations into brain function|last=Finger|first=Stanley|publisher=Oxford University Press|year=1994|isbn=9780195146943|pages=44|oclc=27151391|quote=The nerve cell with its uninterrupted processes was described by Otto Friedrich Karl Deiters (1834-1863) in a work that was completed by Max Schultze (1825-1874) in 1865, two years after Deiters died of typhoid fever. This work portrayed the cell body with a single chief "axis cylinder" and a number of smaller "protoplasmic processes" (see figure 3.19). The latter would become known as "dendrites", a term coined by Wilhelm His (1831-1904) in 1889.}}</ref> German anatomist [[Otto Friedrich Karl Deiters]] is generally credited with the discovery of the axon by distinguishing it from the dendrites.

树突（''dendrite''）这一术语最早是在 1889 年被 [[Wilhelm His, Sr.|Wilhelm His]] 用来描述神经细胞相连的较小的“原生质突起”的数量。德国解剖学家 [[Otto Friedrich Karl Deiters]] 被认为发现了轴突，是他首先将轴突与树突区分开。

树突（''dendrite''）这一术语最早是在 1889 年被 [[Wilhelm His, Sr.|Wilhelm His]] 用来描述神经细胞相连的较小的“原生质突起”的数量。德国解剖学家 [[Otto Friedrich Karl Deiters]] 被认为发现了轴突，是他首先将轴突与树突区分开。

==Electrical properties 电性质==

==Electrical properties 电性质==

The structure and branching of a neuron's dendrites, as well as the availability and variation of [[voltage-gated ion channel|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 the aggregation of excitatory and inhibitory inputs from separate branches.<ref name=":3">{{cite book|last=Kandel|first=Eric R.|title=Principles of neural science.|date=2003|publisher=McGrawHill|location=Cambridge|isbn=0-8385-7701-6|edition=4th|url-access=registration|url=https://archive.org/details/isbn_9780838577011}}</ref>

The structure and branching of a neuron's dendrites, as well as the availability and variation of [[voltage-gated ion channel|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 the aggregation of excitatory and inhibitory inputs from separate branches.<ref name=":3">{{cite book|last=Kandel|first=Eric R.|title=Principles of neural science.|date=2003|publisher=McGrawHill|location=Cambridge|isbn=0-8385-7701-6|edition=4th|url-access=registration|url=https://archive.org/details/isbn_9780838577011}}</ref>

神经元树突的结构和分支模式，以及电压门控离子通道的表达与种类，强烈地影响着神经元如何整合来自其他神经元的输入。这种整合既包含时间整合，即快速连续到达的刺激的总和，也包含空间整合，即来自不同分支的兴奋性和抑制性输入的聚合<ref name=":3" />。

神经元树突的结构和分支模式，以及电压门控离子通道的表达与种类，强烈地影响着神经元如何整合来自其他神经元的输入。这种整合既包含时间整合，即快速连续到达的刺激的总和，也包含空间整合，即来自不同分支的兴奋性和抑制性输入的聚合<ref name=":3" />。

Dendrites themselves appear to be capable of [[synaptic plasticity|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 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, 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%.<ref name=Tavosanis />

Dendrites themselves appear to be capable of [[synaptic plasticity|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 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, 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%.<ref name=Tavosanis />

树突在动物包括无脊椎动物的成年生命阶段似乎能够发生可塑性变化。神经元树突有许多被称为功能单元的区域，它们能够对传入的刺激进行计算。这些功能单元参与处理的输入，由树突的子域，如树突棘、分支或分支组组成。因此，引起树突结构变化的可塑性将影响细胞的通信和处理。在发育过程中，树突形态是由细胞基因组编码的内在程序和（来自其他细胞的信号）外在因子塑造的。但在成年阶段，相比于发育阶段，外源信号相比于内源信号，对树突结构的影响更为显著。在女性，树突结构可以因激素诱导的生理状态如怀孕、哺乳、动情周期期间而改变。这在海马 CA1 区的锥体细胞中尤其明显，起树突密度的变化可达30% <ref name="Tavosanis" />。

树突在动物包括无脊椎动物的成年生命阶段似乎能够发生可塑性变化。神经元树突有许多被称为功能单元的区域，它们能够对传入的刺激进行计算。这些功能单元参与处理的输入，由树突的子域，如树突棘、分支或分支组组成。因此，引起树突结构变化的可塑性将影响细胞的通信和处理。在发育过程中，树突形态是由细胞基因组编码的内在程序和（来自其他细胞的信号）外在因子塑造的。但在成年阶段，相比于发育阶段，外源信号相比于内源信号，对树突结构的影响更为显著。在女性，树突结构可以因激素诱导的生理状态如怀孕、哺乳、动情周期期间而改变。这在海马 CA1 区的锥体细胞中尤其明显，其树突密度的变化可达30% <ref name="Tavosanis" />。

==Notes==

==Notes==

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[[Category:Neurohistology]]

[[Category:Neurohistology]]

[[Category:Neuroplasticity]]

[[Category:Neuroplasticity]]

[[Category:待整理页面]]

[[Category:待整理页面]]