Moderate

Which of the following statements is correct for the the node of Ranvier of the nerve?

Correct answer: B. Myelin sheath is discontinuous

  • A. Neurolemma is discontinuous
  • B. Myelin sheath is discontinuous
  • C. Both neurilemma and myelin sheath are discontinuous.
  • D. It is covered by the myelin sheath

Explanation

At the level of the node of Ranvier, the myelin sheath is discontinuous but not the neurilemma lining. Actually, the myelin sheath is an integral part of the Schwann cell - which forms a continuous neurilemmal covering. Each Schwann cell wraps around the neurite to form concentric layers of the plasma membrane. But at the level of the junction between two Schwann cells, myelin cannot be formed and thus a gap appears.

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About Coordination and Control

Coordination depends on receptors, neurons, synapses and nerve impulses, with reflex actions traced through the reflex arc and the roles of major brain regions. Chemical coordination covers endocrine glands and hormones, including how hormones regulate growth, metabolism, reproduction and internal balance, unlike rapid nervous control.

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