Question

Read the following statements about the nervous system and mark the CORRECT option.

$\left(a\right)$ Synaptic cleft of neurons secretes adrenaline.

$\left(b\right)$ Myelinated nerve fibers in PNS are enveloped with Schwann cell.

$\left(c\right)$ Non-myelinated nerve fiber in PNS is enclosed by a Schwann cell that does not form the myelin sheath.

$\left(d\right)$ Spinal cord and cranial nerves are made of non-myelinated nerve fibers.

Of the four statements,

• A. a, b are correct, but c and d are incorrect
• B. a, b and c are correct, but d is incorrect
• C. c, d are correct, but a and b are incorrect
• D. b, c are correct but a and d are incorrect

Answer 1

Answer: (D)

PNS consists of myelinated and non-myelinated nerve fibers. In PNS the myelin nerves are made up of Schwann cells that secrete the sheath. Non-myleinated neurons also show presence of Schwann cells but they do not secrete Myelin sheath. The most common neurotransmitter is acetylcholine, which often is the messenger between axons and muscles. Spinal cord and cranial nerves are made up of myelinated fibres.