A myelinated neurone conducts impulses faster than an unmyelinated one because
Correct answer: A. the impulse jumps from one node of Ranvier to the next
- A. the impulse jumps from one node of Ranvier to the next
- B. myelin conducts electricity better than cytoplasm
- C. myelinated axons are always much thinner
- D. myelin increases the number of sodium channels along the whole axon
Explanation
Myelin is an insulator, so ions can cross the membrane only at the gaps between Schwann cells, and depolarisation therefore leaps from node to node in what is called saltatory conduction. This can raise conduction speed above 100 metres per second, against a few metres per second in an unmyelinated fibre of the same diameter. Loss of myelin in multiple sclerosis slows or blocks conduction.
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About Neurons and Nerve Impulse
Neurons receive and transmit information through dendrites, the cell body and axons. The topic explains resting potential, depolarization, repolarization, refractory periods and saltatory conduction, followed by synaptic transmission through neurotransmitters. An action potential is distinct from the graded potential produced at a receptor.
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