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Discussion on various A&P questions

1. How does the myelin sheath affect the speed of an action potential? What about the diameter of the nerve fiber?

2. Describe the structure of a synapse.

3. Describe the general functions of the hypothalamus.

4. What is the difference between static and dynamic equilibrium?

5. Identify the hormones produced by each of the cell types in the pancreatic islets.

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1. How does the myelin sheath affect the speed of an action potential? What about the diameter of the nerve fiber?

The myelin sheath, a fatty substance that surrounds and envelops most neurons (white matter in the brain and spinal cord are myelinated neurons, as well as most neurons in peripheral nerves) is actually made up of the cell membranes of cells that wrap themselves around the axons of the neurons (oligodendrites in the CNS and Schwann cells in the PNS).
When the myelin sheath is not present the action potential will move along an axon like a wave. But when the axon is myelinated, the action potential "hops" along the axon from gap to gap (nodes of Ranvier) between the myelin. This is called saltatory conduction. It also increases the electrical resistance of the neuron cell membrane, thus keeping the action potential from "bleeding ...

Solution Summary

In this solution, I discuss the following questions:

1. How does the myelin sheath affect the speed of an action potential? What about the diameter of the nerve fiber?
2. Describe the structure of a synapse.
3. Describe the general functions of the hypothalamus.
4. What is the difference between static and dynamic equilibrium?
5. Identify the hormones produced by each of the cell types in the pancreatic islets.

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