UNIT 14 I Introduction to the Nervous System 299 Multiple sclerosis is an autoim
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UNIT 14 I Introduction to the Nervous System 299 Multiple sclerosis is an autoimmune disease that affects the brain and spinal cord. It causes dam- age to the myelin surrounding nerve fibers as well as to the nerve fibers themselves. The damaged myelin forms scar tissue (a process called sclerosis), which gives the disease its name. How does this disease affect nerve impulse conduction? Why? 7. 8. Does each description apply to an astrocyte (A) or to a satellite cell (S) or to both cell types (A and S)? a. Maintains proper ionic environment _- b. Anchors capillaries to neurons -c. Found in central nervous system Does each description apply to a hormone (H) or to a neurotransmitter (N) or to both a hormone and a neurotransmitter (H and N)? 9. a. Function as chemical messengers b. Released into the bloodstream c. Produced by endocrine glands Does each description apply to a bipolar neuron (B) or to a unipolar neuron (U) or to both neuron types (B and U)? 10. a. Classified as a sensory neuron b. Consists of one dendrite and one axon c. Found in the retina and olfactory mucosa Does each description apply to a graded potential (G) or to an action potential (A) or to both potential types (G and A)? 11. a. Classified as an electrical event b. Can vary in intensity c. Classified as an all-or-none eventExplanation / Answer
7. Myelin sheaths are essential to maintain saltatory conduction of impulses. It decreases the loss of the electrical impulse traveling through the axon. Multiple sclerosis is a de-myelinating disease, which means that it causes nerves to not conduct the same impulse as effectively, or in the case of longer nerves, the signal might be completely most. The inflammatory component of this disease causes re-myelination to fail as well.
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