Short answerModerate1 mark
4(b)
Mention the exact location of the following:
Myelin sheath
Topic: Location of the myelin sheath
Previous-year question practice database
Answer
Exam answer
It SURROUNDS THE AXON of a neuron.
Explanation
The myelin sheath is a fatty insulating covering around the axon, interrupted at intervals by gaps called the NODES OF RANVIER.
ITS FUNCTION: it INSULATES the fibre so that the impulse LEAPS from one node to the next rather than travelling along the whole length. That greatly SPEEDS transmission — which is why myelinated fibres conduct far faster than unmyelinated ones.
It is also why WHITE MATTER looks white: white matter consists of AXONS, and it is their myelin that gives the colour. GREY matter is made of CYTONS, which have no myelin.
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