Biology

Nervous System and Neurons

1,224 Questions

The nervous system and neurons section covers the structural and functional aspects of the human nervous system. Topics include nerve fibers, the myelin sheath, and sympathetic nervous system functions. This material is crucial for general science preparation in various competitive exams.

Neuron structureMyelin sheath productionSympathetic nervous systemCranial and spinal nervesParasympathetic functions

Nervous System and Neurons Questions

Multiple choice

Which nervous system enables a person to combat or escape?

  1. Parasympathetic nervous system

  2. Sympathetic nervous system

  3. Central nervous system

  4. Peripheral nervous system

  5. Synapse
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sympathetic nervous system acts as a combat or escape system. In case of emergencies, the sympathetic system prepares the body to either face the challenge or flee. While doing so, it increases the heartbeat, constricts the blood vessels, raises the blood pressure, slows or stops digestion, dilates the pupil and so on. 

Multiple choice

Which of the following statements regarding action potential across the muscle fibre is correct?

  1. The action potential propagates by activating voltage gated potassium channels along the axons of the neuron.

  2. An action potential originates in the PNS.

  3. The Na+ influx leads to a vesicle containing the neurotransmitter acetylcholine to fuse with the plasma membrane.

  4. The action potential propagates by muscle fibre's plexus of T-tubules.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The above statement is true. The action potential propagates by muscle fibre's plexus of T-tubules, depolarizing the inner portion of the muscle fibre.

Multiple choice

Which neural crest develops into neurons of some pharyngeal arches?

  1. Trunk neural crest

  2. Vagal and sacral neural crest

  3. Cranial neural crest

  4. Cardiac neural crest
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It gets transformed into melanocytes, cartilage, connective tissue and neurons of some pharyngeal arches. It also leads to the formation of some regions of the heart such as musculoconnective tissue of the large arteries.

Multiple choice

The velocity of an action potential propagation

  1. is independent of an axon diameter

  2. depends on the compactness of the myelin sheath surrounding the axon

  3. remains unaffected if the axon of a nerve cell losses myelin

  4. is the fastest in unmyelinated axons
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The above option is correct as the velocity of conduction action potential propagation is the fastest in large diameter myelinated axons.

Multiple choice

Which of the following can be excluded from the characteristics of action potential of a nerve cell?

  1. There is an unequal distribution of ions on both sides of a neuron in a brain.

  2. Nerve action potentials can be summated one with another.

  3. May vary considerably in amplitude.

  4. Becomes larger as stimulus strength increases.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is correct statement there is an unequal distribution of ions on the two sides of a nerve cell membrane and therefore, neurons can respond to stimuli and conduct impulses because a membrane potential is established across the cell membrane.

Multiple choice

In central nervous system

  1. white matter accomodates numerous nerve cell bodies

  2. the myelin fibres are created by Schwann cells

  3. neurons are conserved from changes in plasma composition

  4. the cerebrospinal fluid is an ultrafiltrate of blood plasma
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the central nervous system, the neurons are conserved from changes in plasma composition. The blood-brain barrier isolates central neurons from alterations to plasma composition.

Multiple choice

At the neuromuscular junction

  1. the muscle membrane possesses muscarinic receptors

  2. the motor nerve endings releases the norepinephrine

  3. curare initiates to prolongation of neuromuscular transmission

  4. the motor nerve endings releases acetylcholine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 The motor nerve endings secrete acetylcholine, which activates nicotinic receptors of the muscle fibre membrane.

Multiple choice

Neuroepithelial type of sensory receptors are present in which of the following systems?

  1. Visual

  2. Auditory

  3. Gustatory

  4. Olfactory
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A neuroepithelial receptor is a neuron with a soma situated near a sensory surface and an axon, which conveys sensory signals into the CNS to synapse on second order neurons. This is an evolutionarily primitive arrangement and the only example in man is the sensory neuron of the olfactory epithelium.