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

Clostridium tetani produces a potent toxin which causes constant constriction of muscles. Which of the following cells of the nervous system are targeted by this toxin?

  1. Pyramidal cells

  2. Renshaw cells

  3. Purkinje cells

  4. Basket cells
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Renshaw cells are targetted by the toxin of Clostridium tetani. When wounds are contaminated with Clostridium tetani, the toxin travels to the spinal cord where it inhibits the release of glycine, an inhibitory neurotransmitter, from Renshaw cells. As a result, alpha motor neurons become hyperactive and muscles constantly contract.

Multiple choice

Myelin sheath provides insulation to the axon that allows electrical signals to propagate more efficiently. Which of the following cells produce myelin sheath in neurons of CNS?

  1. Astrocytes

  2. Oligodendrocytes

  3. Schwann cells

  4. Enteric glial cells
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oligodendrocytes are the glial cells that coat axons in the central nervous system (CNS) with their cell membrane, forming a specialised membrane differentiation called myelin, to produce the so-called myelin sheath. Myelin sheath provides insulation to neuron and allows electrical signals to propagate more efficiently.

Multiple choice

Which of the following statements is false?

  1. Slit sense organs enable spiders to detect ground vibrations produced by approaching prey.

  2. Among arthropods, the greatest visual acuity is found in the predaceous mantis shrimp.

  3. The sensory nerve endings are lodged in cuticular hair.

  4. The arthropod nervous system consists of a dorsal brain and a ventral, ganglionated longitudinal nerve cord.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is false. Slit sense organs enable spiders to detect web vibrations produced by trapped insects and they permit scorpions to detect ground vibrations produced by approaching prey.

Multiple choice

After successfully escaping by running from a fierce tiger that was running directly towards Raman, he paused to catch his breath and collect his wits. The physical symptoms he will be experiencing now are controlled by

  1. parasympathetic nervous system

  2. sympathetic nervous system

  3. central nervous system

  4. peripheral nervous system

  5. Enteric nervous system
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When the stress subsides, the parasympathetic nervous system of the body produces opposite effects of sympathetic nervous system. It conserves energy as it calms an individual by decreasing heartbeat, lowering blood sugar and so forth.

Multiple choice

Regarding the innervation of the human heart, which among the following statements 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 effect of autonomic nervous system on coronary artery and blood flow is a 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

During rest, the vagal tone is dominant. There is continuous parasympathetic activity that has a negative chronotropic character.

Multiple choice

The acetylcholine receptor at the nerve-muscle junction is an example of

  1. intracellular receptor

  2. tyrosine kinase-linked receptor

  3. G protein-coupled receptor

  4. ion channel receptor

  5. receptors with intrinsic enzymatic activity
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The acetylcholine receptor at the nerve- muscle junction is an example of ion-channel receptors. The binding of ligand changes the conformation of the receptor that allows flow of specific ions through it. The ion movement thus alters the electric potential across the membrane.

Multiple choice

The conduction of electric impulse from a nerve cell to a muscle cell occurs via

  1. autocrine signaling

  2. endocrine signaling

  3. cell-to-cell signaling

  4. paracrine signaling

  5. signaling by plasma membrane-bound proteins
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The conduction of an electric impulse from one nerve cell to a muscle cell either to inhibit or induce the muscle contraction happens via paracrine signaling, where in the signaling molecules secreted by a cell affect the target cells that are in close proximity to the cell that secretes them.

Multiple choice

In which of the following disorders, the immune system of the body itself attacks the optic nerves and spinal cord of the body?

  1. Myositis

  2. Neuromyelitis optica

  3. Neuromyotonia

  4. Cicatricial pemphigoid

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Neuromyelitis optica is an autoimmune, inflammatory disorder in which a person's own immune system attacks the optic nerves and spinal cord. This produces an inflammation of the optic nerve (optic neuritis) and the spinal cord (myelitis).