Question

Impulses travel very rapidly along nerves to the leg of a man. Which fact accounts for
the speed at which they travel?
(A) a nerve impulse is an all or none phenomenon
(B) the nerves contain myelinated fibres
(C) there is a high concentration of Nations inside the axons
(D) there is a potential difference across the axon membranes
tod?​

Answer 1

Answer:

B

Explanation:

myelinated neurons are present in periphral nervous systrm

Answer 2

Impulses travel very rapidly along the leg of a man because the nerves contain myelinated fibres.

• Impulses travel much more rapidly along the myelinated nerve.
• The nerves that possess the myelin sheath on the axon are known as a myelinated sheath.
• The myelin sheath acts as biological electrical insulation that provides resistance to the flow of the nerve impulse.
• The places on the axon where the myelin sheath is absent and where it does not provide any resistance are called nodes of Ranvier.
• The action potential jumps from one node to another as an electrical current.
• In myelinated nerve fibre, the nerve impulse travel as a continuous wave of depolarisation.
• Sodium ion channels open on the arrival of current impulse at one node creating another current that passes to another nose and so on.

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