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Read the given statements and select the...

Read the given statements and select the correct option.
(i)Synaptic cleft of neurons secreates adrenaline.
(ii)Myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon.
(iii)Non-myelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath.
(iv)Spinal and cranial nerves are made of non-myelinated nerve fibres.

A

I, II are correct, but III and IV are incorrect

B

I, II and III are correct but IV is incorrect

C

III and IV are correct, but I and II are incorrect

D

II and III are correct, but I and IV are incorrect

Text Solution

Verified by Experts

The correct Answer is:
D
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Which of the following statemetn are correct and incorret 1. Synaptic cleft of neurons secrate adrenaline 2. Myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon 3. Non- myrlineated nerve fibre is emclosed by a schwann cell that from a myelin sheath. 4. Spinal cord and cranial nerve are made of non-myelinated nerve fibres of the four statemets

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A neuron is a microscopic structure composed of three major parts, namely, cell body, dendrites and axon. There are two types of axons, namely, myelinated, and nonmyelinated. Which of the following is true for nerve ? i. The myelinated nerve fibres are enveloped with Schwann cells ii. Schwann cells form a myelin sheath around the axom iii. The gaps between two adjacent myelin sheaths are called nodes of Ranvier. iv.Myelinated nerve fibres are found in autonomous and the somatic neural systems v. Unmyelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath around the axon. vi. Unmyelinated nerve fibre is commonly found in spinal and cranial nerves