Introduction to Nerve Impulse MCQ - Practice Questions with Answers

Nerve Impulse

• All the nerve fibres carry information in the form of the nerve impulse.
• The nerve impulse is the sum total of physical and chemical disturbances created by a stimulus (electrical, chemical or mechanical) in a neuron or nerve fibre which results in the movement of a wave along the nerve fibre.
• The nerve fibre or axon is like a cylinder. 
• The interior of the axon is filled with axoplasm (i.e., the cytoplasm of the nerve cell) 
• The exterior of the axon is covered with a thin membrane, the axon membrane or axolemma.
• Axolemma is selectively permeable for simple organic and inorganic molecules 
• The axon is immersed in the extracellular fluid (ECF).
• Through axolemma movement of solute takes place between the axoplasm and ECF.
• Generally, the solutes in ECF and axoplasm are in ionic form.

Membrane or Ionic Theory of Nerve Impulse:

• It was proposed by Hodgkin and Huxley in the 1930s.
• This theory suggests that the electrical events in the nerve fibres are governed by differential permeability of the axolemma to sodium and potassium ions. 
• The differential permeability is regulated by the electric field across the membrane. 
• As per this theory, the conduction of nerve impulse can be categorised into two phases:

                       - Resting membrane potential of nerve
                       - Action membrane potential of nerve