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Myelin Essay

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Myelin is a fatty sheath that coats nerve cells. It consists of about 70% lipids. In the central nervous system, it is made of oligodendrocytes. One oligodendrocyte can myelinate many axons. In the peripheral nervous system, myelin is made of a Schwann cell. One Schwann cell can myelinate only one axon. Oligodendrocytes and Schwann cells form myelin by wrapping around the axon.
The myelin sheath is a good insulator. It also creates low capacitance. This means that fewer ions are needed to charge and discharge the membrane of the axon. Myelin also clusters ions channels between myelin sheaths. These clusters are called nodes of Ranvier.
Myelin allows the action potential of myelinated axons to travel further than unmyelinated axons with the same diameter. Because the myelin sheath is a good insulator, within myelinated segments of the axon, there is a high resistance to ion flow in and out of the axon. As a result, there is little charge leakage within the myelinated segments of the axon. This allows for the action potential to travel longer distances. From an evolutionary perspective, this allowed for …show more content…

Within the myelinated segments of axon, charge flows passively and quickly from one node of Ranvier to another. The time consuming process of propagating an action potential occurs at the ions channels. Myelinated axons do not have ions channels spanning the entire axon. Instead, they are clustered only at the nodes of Ranvier. So, the time consuming propagation of action potentials is limited to small segments in the axon. This allows the action potential to move quickly. Therefore, a myelinated axon can conduct a faster action potential than an unmelinated axon with the same diameter. This allows for faster information integration and response in organisms with myelinated axons (compared to organisms with unmyelinated axons of the same

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