Describe the difference between myelinated and unmyelinated nerve fibers (Be Specific). Why is the speed of signal conduction faster in myelinated fibers?

Because the long axons of neurons look like electrical wires, and both neurons and electrical wires conduct electricity, it is tempting to equate the two. Compare and contrast the functioning of axons and electrical wires in terms of their structure and the nature of the electrical signals they conduct. Please include references.

Assume that two nerves fibers have the same diameter, but one is myelinated and the other is unmyelinated. The conduction of an action potential is most energy-efficient along which type of fiber?

View the University of Michigan WebScope (http://openstaxcollege.org/l/nervefiber) to see an electron micrograph of a cross-section of a myelinated nerve fiber. The axon contains microtubules and neurofilaments that are bounded by a plasma membrane known as the axolemma. Outside the plasma membrane of the axon is the myelin sheath, which is composed of the tightly wrapped plasma membrane of a Schwann cell. What aspects of the cells in this image react with the stain to make them a deep, dark, black color, such as the multiple layers that are the myelin sheath?

Identify and label the following structures on the neuron model figure below: cell body, dendrites, neuron nucleus, neurolemma, axon hillock, nucleus of Schwann cell, Nissl bodies, myelin sheath, axon, node of Ranvier, axon terminals (of neurons synapsing with model neuron), endoneurium (refer to Figure 10.6). 3) 11

Discuss the concept of myelination and the purpose of the myelin sheath

Describe the resting potential for neurons. How is this potential established? Describe the development of the action potential. How does this come about, and what is the function of this phenomenon? Include a diagram of the various stages of the action potential, showing the changes in voltage that occur throughout this phenomenon

Draw a typical action potential (correctly label axis) and explain in words the roles of ion channels in generating the different phases of the action potential. (Extra credit: How would opening voltage gated calcium channels upon depolarization affect the shape of the action potential if they have a relatively slow inactivation rate?)

Unmyelinated axons conduct action potentials without decrement, but when myelinated axons lose myelin in demyelinating diseases such as multiple sclerosis, conduction of action potentials is blocked. Why?

1) A 100-um diameter nerve axon has the following properties: rm = 2.5 x 104 ohm x cm, ri = 1 x 105 ohm/cm, r0 = 0, cm = 3 x 10-8 F/cm. The permeability to Cl- is very high and Cl- ions are at resting potential Vm. A steady inward current is injected into the axon resulting in a Vm of -110 mV at the site of current injection. If the Vm 3 mm from the site of injection is -94.5 mV, what is the resting Vm?