Key Difference – Myelinated vs Unmyelinated Axons
神经系统负责接收和分发体内各处的感觉信号。神经元是神经系统的构建块或基本细胞。神经元负责传输正确的信息或命令以纠正身体的位置。神经元具有三个主要成分:细胞体,dendrites, and an axon。树突接收电信号并移交给轴突。轴突将信号传输到下一个神经元。轴突用称为的电绝缘体层绝缘myelin sheath。Myelin sheath is composed of a fatty material called myelin. Myelin sheath is produced by special外周神经系统细胞称Schwann cells。Myelin is produced by Schwann cells, and myelin sheath is formed around the axon in a spiral fashion. Myelin sheath increases the speed of the signal transmission, but not all axons are myelinated. Based on the presence and absence of the myelin sheath around the axon, there are two types of neurons. They are myelinated neurons and unmyelinated neurons. Myelinated neurons possess myelinated axons, and unmyelinated neurons possess unmyelinated axons. The key difference between myelinated axon and unmyelinated axon is thatmyelinated axons have a myelin sheath while unmyelinated axons do not have a myelin sheath.
CONTENTS
1。概述和关键差异
2。什么是髓鞘的轴突
3。什么是无髓的轴突
4。并排比较 - 髓鞘形式与表格形式的无髓线轴突
5。Summary
什么是髓鞘的轴突?
轴突是神经细胞(神经元)的长薄突出。它导致电脉冲从神经元细胞体转移到化学突触。Axons are also known as nerve fibers. Nerve impulses are transmitted along the axons continually without changing its path. Cells of the peripheral nervous system support the transmission of the nerve impulses via neurons.
Schwann cells are one type of special glial cells that form myelin sheaths around the axons. Myelin sheath is an electrical insulating layer composed of myelin protein and lipids, including胆固醇,糖脂,以及磷脂。轴突被髓鞘覆盖的神经元称为髓鞘神经元。用髓鞘保护的轴突被称为髓鞘轴突。通常,较大的轴突被髓鞘覆盖,它们被称为髓纤维或髓质纤维。较厚的轴突具有较厚的髓磷脂和更长的节间。当轴突被髓载时,它们看起来白色。
髓鞘鞘从雪旺细胞中衍生而来,schwann细胞在轴突周围缠绕时会保持间隙。这些差距是无髓的。因此,髓鞘被这些间隙打断了,它们被称为Ranvier的节点。当轴突被髓载时,神经脉冲的传导沿着神经元更快,并且避免了传导过程中脉冲的损失。
什么是无髓的轴突?
当轴突未用髓磷脂鞘保护时,它们被称为不髓鞘轴突。通常,直径少于一微米的较薄轴突周围没有髓鞘。这些轴突或神经纤维也被称为非髓鞘或非纤维纤维。通过无髓线轴突传导神经冲动比髓鞘轴突慢。在传导过程中,也有可能失去冲动。
髓鞘和不髓鞘的轴突有什么区别?
Myelinated vs Unmyelinated Axons |
|
髓鞘轴突是神经元轴突,上面覆盖有髓鞘。 | 无髓线轴突是未被髓鞘覆盖的轴突。 |
Speed of Nerve Impulses | |
神经冲动的传导在髓鞘的轴突中更快。 | 神经冲动的传导在不髓鞘的轴突中较慢。 |
失去冲动 | |
在髓鞘的轴突中避免了冲动的损失。 | There is more chance of losing impulses. |
厚度 | |
骨髓轴突比不髓鞘的轴突厚。 | Unmyelinated axons are thinner than myelinated axons. |
Summary – Myelinated vs Unmyelinated Axons
一个神经元的轴突是一个细长的延伸。它extends from the soma of the neuron. Axons transmit electrical signals away from the neuron. In some neurons, axons are wrapped with special glial cells called Schwann cells. Schwann cells form an electrical insulating layer around the axon, which is known as myelin sheath and it increases the speed of the signal transmission. Some axons do not have myelin sheaths. They are known as unmyelinated axons. The axons which are covered with myelin sheath are known as myelinated axons. This is the difference between myelinated and unmyelinated axons.
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References:
1.”髓线。”维基百科。Wikimedia基金会,2017年7月13日。在这里可用。2017年7月19日。
2.莫雷尔,皮埃尔。“髓鞘。”基本神经化学:分子,细胞和医学方面。第六版。美国国家医学图书馆,1999年1月1日。在这里可用。2017年7月18日。
图片提供:
1. Ladyofhats的“完整的神经元细胞图EN” - 自己的作品。图像从图像重命名:完整的神经元细胞图.svg(公共域)通过下议院维基梅迪亚
2.“”Myelinated unmylinated neurons” By Nick Gorton –(CC BY-SA 3.0)通过下议院维基梅迪亚
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