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

The floor of mouth and suprahyoid muscles are supplied by

  1. lingual nerve

  2. inferior alveolar nerve

  3. maxillary nerve

  4. facial nerve
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Branches of inferior alveolar nerve: Mylohyoid branch: supplies mylohyoid muscle and anterior belly of digastrics branches supplying lower teeth and gums Mental nerve: supplies skin of chin along with the skin and mucous membrane of the lower lip

Multiple choice

The infrahyoid muscles are supplied by

  1. vagus nerve

  2. cervical plexus

  3. branchial plexus

  4. supraclavicular nerve
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The cervical plexus is formed by the ventral rami of the upper four cervical nerves and supplies some neck muscles and the diaphragm and areas of skin on the head, neck and chest.

Multiple choice

Infraorbital nerve exits through

  1. foramen ovale

  2. foramen spinosum

  3. foramen magnum

  4. inferior orbital fissure
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The inferior orbital fissure connects the orbit with the pterygopalatine and infratemporal fossae. It transmits the infraorbital and zygomatic branches of the maxillary nerve and accompanying vessels, orbital rami from the pterygopalatine ganglion and a connection between the inferior ophthalmic vein and pterygoid venous plexus.

Multiple choice

Afferent component of corneal reflex is mediated by

  1. vagus nerve

  2. facial nerve

  3. trigeminal nerve

  4. glossopharyngeal nerve
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Afferent fibres of cornea pass through trigeminal nerve while efferent come by facial nerve.

  1. The afferent component of corneal reflex is mediated through the ophthalmic branch of the trigeminal nerve (V nerve).
  2. The efferent component is mediated through the facial nerve (VII nerve).
Multiple choice

Mylohyoid nerve is a branch of

  1. main trunk of mandibular nerve

  2. ophthalmic nerve

  3. maxillary nerve

  4. inferior alveolar nerve
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The mylohyoid nerve branches from the inferior alveolar nerve (a branch of the mandibular nerve, the third part of the trigeminal nerve) just before it enters the mandibular foramen. It descends in a groove on the deep surface of the ramus of the mandible, and reaching the under surface of the mylohyoid muscle, it supplies both the mylohyoid and the anterior belly of the digastrics muscle.

Multiple choice

The following statements concerning chorda tympani nerve are true, except that it

  1. carries secretomotor fibres to submandibular gland

  2. joins lingual nerve infratemporal fossa

  3. is a branch of facial nerve

  4. contains postganglionic parasympathetic fibres
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It contains efferent preganglionic parasympathetic (secretomotor) fibres which enter the submandibular ganglion, from which postganglionic fibres are relayed to submandibular and sublingual glands.

Multiple choice

Ptosis is due to the damage of

  1. occulomotor nerve

  2. abducens nerve

  3. trochlear nerve

  4. facial nerve
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lesions of the sympathetic supply result in the drooping of the upper eyelid (ptosis), as seen in Horner’s syndrome.

Multiple choice

The membrane potential in a nerve cell during resting stage denotes ______.

  1. both sides negative

  2. negative inside the cell with respect to outside

  3. positive inside the cell with respect to outside

  4. both sides positive
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Membrane potentials across cell membranes are a function of the electrolyte concentrations in the intracellular and extracellular solutions and of the selective permeabilities of the ions. Membrane potential in a nerve cell during resting stage is -60 mV, which means interior of the cell is negative with respect to the exterior. During depolarisation of nerve cells, the inside becomes positive due to the influx of Na+ ions.

Multiple choice

A person entering an empty room suddenly finds a snake right in front of him on opening the door. Which one of the following is likely to happen in his neuro-hormonal control system?

  1. SNS is activated releasing epinephrine and norepinephrine from adrenal medulla.

  2. Neurotransmitters diffuse rapidly across the cleft and transmit a nerve impulse.

  3. Hypothalamus activates the parasympathetic division of brain.

  4. Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal cortex.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Epinephrine and norepinephrine are secreted by adrenal medulla in response to stress of any kind and during emergency situations. Hence, they are also called emergency hormones of flight or fight.

Multiple choice

Find the odd one out.

  1. GABA

  2. Acetylcholine

  3. Histidine

  4. Glutamate
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Histidine is the only amino acid that does not act as neurotransmitter.

Multiple choice

The resting membrane potential of neuron is maintained by which of the following? A. Differences in K+ and Na+ ion concentrations B. Sodium efflux and Potassium influx C. Higher permeability to sodium ions D. Sodium-potassium pumps that help to maintain the proper distribution of sodium and potassium

  1. A, D

  2. A, C

  3. B, C

  4. C, D
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The resting membrane potential is maintained by differences in both ion concentrations and electron gradient, which is established by the proper distribution of sodium and potassium through sodium-potassium ion channel.

Multiple choice

Which of the following statements regarding the innervation of the human heart is false?

  1. Afferent fibres carrying pain sensation run to the spinal cord.

  2. During rest, the vagal tone is recessive.

  3. Postganglionic fibres descend to the heart and form two plexuses.

  4. The effects of autonomic nervous system on coronary artery and blood flow are reciprocal.

  5. Preganglionic sympathetic fibres ascend from the upper five thoracic segments of the spinal cord.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is incorrect as during rest, the vagal tone is dominant.