Which of the following statement is correct for node of Ranvier of nerve
The correct option is (B) : Myelin sheath is discontinuous
Because of the Ranvier nodes, the myelin sheath is disjointed. Nodes of Ranvier, a recurring opening in the myelin sheath that surrounds the axon of certain neurons, help nerve impulses to travel more quickly. A phenomenon called as saltatory conduction allows impulses to move from node to node because nodes of Ranvier periodically interrupt the insulation. The outermost nucleated cytoplasmic layer of Schwann cells, also known as neurolemmocytes, that encircles the neuron's axon is known as the neurolemma.
S.No. | Cranial nerves | Arises from ... | Ends in ... |
---|---|---|---|
I. | Olfactory nerves | Olfactory epithelium of nasal chambers | Temporal lobes of cerebrum |
II. | Optic nerves | Retina of eyes | Cerebellum |
III. | Auditory nerves | Internal ears | Cerebrum |
IV. | Pathetic nerves | Floor of mid brain | Superior oblique muscle of eye ball |
Table 1: List of Cranial Nerves: Their Origins and End Points
A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is :
Predict the major product $ P $ in the following sequence of reactions:
(i) HBr, benzoyl peroxide
(ii) KCN
(iii) Na(Hg), $C_{2}H_{5}OH$
AB is a part of an electrical circuit (see figure). The potential difference \(V_A - V_B\), at the instant when current \(i = 2\) A and is increasing at a rate of 1 amp/second is:
The human nervous system is responsible for controlling and coordinating all the activities of the human body.
The Central Nervous System (CNS) comprises the brain and spinal cord.
The Peripheral Nervous System (PNS) comprises sensory/motor neurons and ganglion.