AP 1 (11-4)
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AP 1 (11-4)
AP1 chapter 11.
Describe the process of repairing of a neuron.
1. Axon and myelin degenerate distal to injury
2. Schwann cells proliferate along original axon path. Macrophages move in and remove cellular debris
3. Axon grows along original path created by Schwann cells.
4. Schwann cells wrap around elongating axon
What does the term Wallerian degeneration?
nerve function that does not fully restore.
Only limited repair of injury can occur in the CNS due to what?
1. Many more axons involved.
2. Astrocytes produce scar tissue that can prevent axon growth.
3. Astrocytes release chemicals that block axon regrowth.
4. Lack of neurilemma
Neurons can be grouped by what?
on the basis of structural differences
by functional differences
Describe Anaxonic neurons.
-the cell processes look alike (dendrites vs. axons)
-Located in brain and special sense organs
-Functions are poorly understood
Describe bipolar neurons.
-found in the eyes, nose, and ears
-have a single axon and a single dendrite extending from opposite sides of the cell body
Describe unipolar neurons.
-found in ganglia outside the CNS
-have an axon and a dendrite arising from
Describe multipolar neurons.
-have many nerve fibers arising from their cell bodies and are commonly found in the brain and spinalcord
What are the four types of structural classifications?
What are the three types of functional classifications?
Describe sensory neurons.
-conduct impulses from peripheral receptors to the CNS and are usually unipolar, although some are bipolar neurons.
-multipolar neurons lying within the CNS that form links between other neurons.
Describe motor neurons.
-multipolar neurons that conduct impulses from the CNS to effectors.