Neurons in the CNS may be classifie

Neurons in the CNS may be classified into two major types: (1) projection neurons and (2) local circuit neurons. Projection neurons have long axons coursing from one region of the central nervous system to another. Local circuit neurons have axons passing and interacting with neurons in the immediate vicinity.
There are three types of synapses: Fig. 3.8(A) neuromuscular junction (NMJ); Fig. 3.8(B) asymmetric central synapse (Gray type 1) and Fig. 3.8(C) symmetric central synapse (gray type 2). The asymmetric and symmetric synapses of the CNS collectively are called central synapses. Three features are common to both central synapses and NMJs. All originate developmentally as unspecialized contacts between growth cones and the targets cells (Chap. 6). Both types of synapse are functional at birth, but undergo postnatal alterations. Their ultrastructural and functional roles are essentially similar. They contain pretransmitterladen vesicles in their presynaptic terminals. Each synapse is capped by glial (astrocyte) or Schwann cell processes. A synaptic cleft separates neurons from each another at a synapse.
Several significant differences do exist between these synaptic types. The quantity and distribution of the synapses on the target cells (neurons or muscle cells) are critical. Each postsynaptic neuron is the target and recipient of multiple small synaptic inputs from other neurons that converge on its dendrites and cell body. In contrast, each postsynaptic striated muscle cell is the target and recipient of a single massive input from only one NMJ of a motor neuron. The synapses are markedly different between the two synaptic types. The NMJs are characterized by having a basal lamina located within the synaptic cleft that
extends as a continuum to envelop both the nerve terminal and the Schwann cell (Figs. 2.5 and 3.9). In contrast, the central neuron’s synaptic cleft does not have a basal lamina, but might have a slight amount of extracellular matrix. These differences suggest that the functional roles of cell adhesion molecules associated with the matrix of the extracellular clefts differ in these synaptic types. In the NMJs, such molecules as laminins, integrins, and others mediate the cell membrane–matrix interactions. In central synapses, where the extracellular space lacks a basal lamina, cellto- cell adhesion molecules are mediated by cadherins and others.
The central synapses, functionally designated as excitatory or inhibitory synapses, differ morphologically by the relative thickness between their presynaptic and postsynaptic membranes. The asymmetric synapse has a postsynaptic membrane that is thicker than the presynaptic membrane; functionally, this is usually an excitatory synapse (Gray’s type 1; Fig. 3.8). The symmetric synapse with its
presynaptic and postsynaptic membranes essentially equal in thickness is functionally usually inhibitory Gray’s type 2.
The target cells functionally express the nature of the multiple inputs to the central synapses, as contrasted to the solitary input to a muscle cell. The multisynaptic inputs to CNS neurons are essential for the critical role of processing excitatory and inhibitory synaptic inputs. The unitary synaptic input to the NMJ of each voluntary muscle cell acts as a “failsafe” synapse that ensures a muscle contraction, but lacks the critical qualities of the integrated multisynaptic synaptic inputs that is characteristic of the innervation of each CNS neuron.

Hasil (Bahasa Indonesia) 1:

Neuron dalam SSP barangkali bisa digolongkan menjadi dua jenis utama: (1) proyeksi neuron dan neuron sirkuit (2) lokal. Neuron proyeksi memiliki panjang Akson mengalir dari satu wilayah sistem saraf pusat yang lain. Sirkuit lokal neuron memiliki Akson lewat dan berinteraksi dengan neuron di sekitarnya. Ada tiga jenis sinapsis: gambar 3.8(A) neuromuscular junction (NMJ); Gambar 3.8(B) asimetris pusat sinaps (abu-abu tipe 1) dan gambar 3.8(C) simetris pusat sinaps (abu-abu tipe 2). Sinapsis simetrik dan asimetrik pada SSP secara kolektif disebut sinapsis pusat. Tiga fitur umum untuk sinapsis tengah dan NMJs. Semua berasal perkembangannya sebagai terspesialisasi berkembang kontak antara pertumbuhan kerucut dan sel target (Bab 6). Kedua jenis sinaps fungsional saat lahir, tetapi menjalani perubahan setelah melahirkan. Peran mereka ultra dan fungsional pada dasarnya serupa. Mereka berisi vesikel pretransmitterladen di terminal presinaps mereka. Setiap sinaps dibatasi oleh glial (sehingga) atau sel Schwann proses. Sumbing sinaptik memisahkan neuron dari satu sama lain di sinaps. Several significant differences do exist between these synaptic types. The quantity and distribution of the synapses on the target cells (neurons or muscle cells) are critical. Each postsynaptic neuron is the target and recipient of multiple small synaptic inputs from other neurons that converge on its dendrites and cell body. In contrast, each postsynaptic striated muscle cell is the target and recipient of a single massive input from only one NMJ of a motor neuron. The synapses are markedly different between the two synaptic types. The NMJs are characterized by having a basal lamina located within the synaptic cleft thatextends as a continuum to envelop both the nerve terminal and the Schwann cell (Figs. 2.5 and 3.9). In contrast, the central neuron’s synaptic cleft does not have a basal lamina, but might have a slight amount of extracellular matrix. These differences suggest that the functional roles of cell adhesion molecules associated with the matrix of the extracellular clefts differ in these synaptic types. In the NMJs, such molecules as laminins, integrins, and others mediate the cell membrane–matrix interactions. In central synapses, where the extracellular space lacks a basal lamina, cellto- cell adhesion molecules are mediated by cadherins and others. The central synapses, functionally designated as excitatory or inhibitory synapses, differ morphologically by the relative thickness between their presynaptic and postsynaptic membranes. The asymmetric synapse has a postsynaptic membrane that is thicker than the presynaptic membrane; functionally, this is usually an excitatory synapse (Gray’s type 1; Fig. 3.8). The symmetric synapse with itspresynaptic and postsynaptic membranes essentially equal in thickness is functionally usually inhibitory Gray’s type 2. The target cells functionally express the nature of the multiple inputs to the central synapses, as contrasted to the solitary input to a muscle cell. The multisynaptic inputs to CNS neurons are essential for the critical role of processing excitatory and inhibitory synaptic inputs. The unitary synaptic input to the NMJ of each voluntary muscle cell acts as a “failsafe” synapse that ensures a muscle contraction, but lacks the critical qualities of the integrated multisynaptic synaptic inputs that is characteristic of the innervation of each CNS neuron.

Hasil (Bahasa Indonesia) 2:

Neuron di SSP dapat diklasifikasikan menjadi dua jenis utama: (1) neuron proyeksi dan (2) neuron sirkuit lokal. Neuron proyeksi memiliki akson panjang mengalir dari satu daerah dari sistem saraf pusat yang lain. . Neuron sirkuit lokal memiliki akson lewat dan berinteraksi dengan neuron di sekitar segera
Ada tiga jenis sinapsis: Gambar. 3.8 (A) neuromuscular junction (NMJ); Gambar. 3.8 (B) sinaps pusat asimetris (Gray tipe 1) dan Gambar. 3.8 (C) sinaps pusat simetris (abu-abu tipe 2). Sinapsis asimetris dan simetris dari SSP secara kolektif disebut sinapsis pusat. Tiga fitur yang umum untuk kedua sinapsis pusat dan NMJs. Semua berasal kontak perkembangan sebagai terspesialisasi antara kerucut pertumbuhan dan sel-sel target (Bab. 6). Kedua jenis sinaps fungsional saat lahir, tetapi menjalani perubahan postnatal. Peran ultrastructural dan fungsional mereka pada dasarnya sama. Mereka mengandung vesikel pretransmitterladen di terminal presynaptic mereka. Setiap sinaps dibatasi oleh glial (astrosit) atau proses sel Schwann. Sebuah celah sinaptik memisahkan neuron dari masing-masing lain pada sinaps.
Beberapa perbedaan yang signifikan memang ada antara jenis sinaptik. Kuantitas dan distribusi sinapsis pada sel target (neuron atau sel otot) sangat penting. Setiap neuron postsinaptik adalah target dan penerima beberapa input sinaptik kecil dari neuron lain yang berkumpul di dendrit dan sel tubuh. Sebaliknya, setiap sel otot lurik postsinaptik adalah target dan penerima input besar tunggal dari satu NMJ dari neuron motorik. Sinapsis yang sangat berbeda antara kedua jenis sinaptik. The NMJs ditandai dengan memiliki lamina basal yang terletak di dalam celah sinaptik yang
meluas sebagai kontinum untuk menyelimuti kedua terminal saraf dan sel Schwann (Gambar. 2.5 dan 3.9). Sebaliknya, celah sinaptik neuron sentral tidak memiliki lamina basal, tetapi mungkin memiliki jumlah sedikit matriks ekstraselular. Perbedaan ini menunjukkan bahwa peran fungsional molekul adhesi sel yang terkait dengan matriks ekstraselular celah berbeda dalam jenis ini sinaptik. Dalam NMJs, molekul seperti Laminin, integrin, dan lain-lain memediasi interaksi sel membran-matrix. Dalam sinapsis pusat, di mana ruang ekstraselular tidak memiliki lamina basal, molekul adhesi sel cellto- dimediasi oleh cadherin dan lain-lain.
The sinapsis pusat, fungsional ditunjuk sebagai sinapsis rangsang atau penghambatan, berbeda morfologi dengan ketebalan relatif antara membran presinaptik dan postsinaptik mereka. Asimetris sinaps memiliki membran pascasinaps yang lebih tebal dari membran presinaptik; fungsional, ini biasanya merupakan sinaps rangsang (Gray tipe 1;. Gambar 3.8). Sinaps simetris dengan yang
membran presinaptik dan postsinaptik pada dasarnya sama dalam ketebalan fungsional biasanya penghambatan tipe 2. Gray
Sel target fungsional mengungkapkan sifat dari beberapa input ke sinapsis pusat, sebagai kontras dengan input soliter ke sel otot. Input multisynaptic ke neuron SSP sangat penting untuk peran penting pengolahan rangsang dan input sinaptik penghambatan. Input sinaptik kesatuan dengan NMJ setiap sukarela bertindak sel otot sebagai "failsafe" sinaps yang menjamin kontraksi otot, tetapi tidak memiliki kualitas penting dari input sinaptik multisynaptic terpadu yang merupakan karakteristik dari persarafan dari setiap neuron SSP.