Biology

Nervous System and Neurons

1,164 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 among the following statements regarding sympathetic nervous system is INCORRECT?

  1. Sympathetic nerves originate inside the vertebral column.

  2. Sympathetic nervous system is responsible for up- and down-regulating in many homeostatic mechanisms of the body.

  3. Sympathetic nervous system mobilises the body in a fight-or-flight response.

  4. Sympathetic nervous system stimulation causes vasodilation of most blood vessels in the body.

  5. Sympathetic nervous system stimulates gut motility, and urinary system output and function.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sympathetic nervous system stimulation causes vasoconstriction of most blood vessels, including those of the skeletal muscle.

Multiple choice

In a neuron, the ion channels are located at

  1. axolemma

  2. axon terminals

  3. axon hillock

  4. axoplasm

  5. nodes of Ranvier
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The axolemma is the cell membrane surrounding an axon. It is responsible for maintaining the membrane potential of the neuron, and it contains ion channels through which ions can flow.

Multiple choice

Which among the following is a mixed nerve?

  1. Spinal nerve

  2. Cranial nerve

  3. Efferent nerve

  4. Motor nerve

  5. Sensory nerve
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. There are 31 pairs of spinal nerves, one on each side of the human vertebral column.

Multiple choice

The unit cell of the nervous system is

  1. axons

  2. dendrites

  3. neuron

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

The neuron (nerve cell) is the fundamental structural and functional unit of the nervous system. Axons and dendrites are parts of a neuron, not independent units. Neuralgia is a condition involving nerve pain.

Multiple choice

The unit structure of gap junctions is named as connexin. What is not true about it?

  1. An aspect of connexins is that they have a relatively short half life of only a few hours.

  2. Connexins are also called as gap junctions.

  3. Connexins contain only single termini.

  4. The connexin gene family is diverse, with twenty-one identified members in the sequenced human genome.

  5. It is in the ER that connexins are properly folded, yielding two extracellular loops.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Connexins are four-pass transmembrane proteins with both C and N cytoplasmic termini.

Multiple choice

Goose pimples are innervated by _______.

  1. central nervous system

  2. peripheral nervous system

  3. sympathetic nervous system

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Goose pimples (piloerection) are controlled by the sympathetic nervous system, which is part of the autonomic nervous system. This involuntary response causes arrector pili muscles to contract, forming goose bumps.

Multiple choice

Neuron consists of a

  1. nerve cell with cytoplasm and nucleus

  2. nerve cell with short fibres called axon

  3. nerve cell with long part as axon and short branches called dendrites

  4. nerve cell with nerve endings

  5. nerve cell without nucleus
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Complete parts of a Neuron

Multiple choice

ATP is required in the

  1. establishment of the resting potential

  2. initiation of the nerve impulse

  3. repolarization of the neural membrane

  4. depolarization of the neural membrane
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Na+/K+ ATPase pump actively transports 3 Na+ out and 2 K+ in against their concentration gradients, using ATP to establish the resting membrane potential (~-70mV). Depolarization and repolarization are passive ion flows down gradients once the resting potential is established.

Multiple choice

Directions: For this question, select the best of the answer choices given.

Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord. Antibodies that deactivate those inhibitors have now been developed. Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.
Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above?

  1. Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.

  2. Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors.

  3. Nerves in the brain are similar to nerves in the spinal cord in their ability to regenerate themselves naturally.

  4. Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants.

  5. Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A is correct because if inhibiting nerve growth is merely a by-product of the inhibitors' main function, then deactivating them could interfere with essential biological processes, casting doubt on whether nerve repair will become routine. B is irrelevant because chemical similarity between stimulants and antibodies does not impact the argument. C discusses brain nerves, not spinal cord nerves, so it is out of scope. D refers to nerves outside the spinal cord, which does not help explain why spinal nerve repair specifically would fail. E discusses a practical delivery issue rather than a fundamental biological barrier, so it is less damaging to the conclusion.

Multiple choice

In mammals, the deep peroneal nerve provides sensory innervation to

  1. tibialis anterior

  2. tibialiis posterior

  3. peroneus brevis

  4. peroneus longus
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The tibialis anterior muscle in humans is percepted from the L4-S1 roots, particularly the L5 and to a lesser extent L4 root through the sciatic and ultimately the deep peroneal nerves.

Multiple choice

In humans, the greater splanchnic nerve frequently synapses in the

  1. superior mesenteric ganglion

  2. celiac ganglion

  3. aorticorenal ganglion

  4. inferior mesenteric ganglion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Celiac ganglion is the largest group of sympathetic prevertebral ganglia on the upper part of the abdominal aorta on either side of the celiac artery, containing the sympathetic neurons. The axons of the greater and least splanchnic nerves synapse on the postganglionic neurons located in the celiac ganglion.