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 biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

In spite of the presence of complex neuron  networks, reflex arcs continue to be more efficient for quick responses.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The process of response to a peripheral nervous stimulation that occurs involuntarily, that I without conscious effort or thought and requires the involvement of a part of the central nervous system, is called a reflex action. These actions are very rapid, automatic, stereotyped behaviour or responses in which same kind of stimulus evokes a short-lived response. The stimulus is detected by sensory receptors present in the skin. These  initiate nerve impulses in the sensory or afferent neurons leading from them to the spinal cord. These impulses enter the spinal cord and initiate impulses in one or more interneurons. Interneurons initiate impulses in one or more motor or efferent neurons. The motor neurons then carry these impulses to the effectors or skeletal muscles in which response will be shown. This entire pathway from sensory receptor to sensory neuron to spinal cord (having interneurons) to motor neuron to effectors is called the reflex pathway or reflex arc.
So, the correct answer is 'True'.
Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Reflex arcs are formed in the 

  1. Brain

  2. Spinal cord

  3. Heart

  4. Eye
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The process of response to a peripheral nervous stimulation that occurs involuntarily, that I without conscious effort or thought and requires the involvement of a part of the central nervous system, is called a reflex action. These actions are very rapid, automatic, stereotyped behaviour or responses in which same kind of stimulus evokes a short-lived response. The stimulus is detected by sensory receptors present in the skin. These  initiate nerve impulses in the sensory or afferent neurons leading from them to the spinal cord. These impulses enter the spinal cord and initiate impulses in one or more interneurons. Interneurons initiate impulses in one or more motor or efferent neurons. The motor neurons then carry these impulses to the effectors or skeletal muscles in which response will be shown. This entire pathway from sensory receptor to sensory neuron to spinal cord (having interneurons) to motor neuron to effectors is called the reflex pathway or reflex arc. Therefore, reflex arc is formed in spinal cord.
So, the correct answer is 'Spinal cord'.
Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

The components of a reflex arc are

  1. Sensory neuron, receptor, motor neuron

  2. Receptor, sensory neuron, center, motor neuron

  3. Receptor, sensory neuron, center, motor neuron, effector organ

  4. Motor neuron, sensory neuron, center, effector organ
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A reflex arc is a simple nervous pathway and consists of the sensory/afferent neuron, center (spinal cord), motor/efferent neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to the spinal cord (sensory pathway). The interneurons of spinal cord integrate the incoming information and signal is relayed to motor/efferent neurons.  The motor pathway transmits the signal from motor neurons to the effector organs (muscles and glands etc). Thus, reflex arc transmits the information from receptor to effector via the spinal cord.

Therefore, the correct answer is option C.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Which one of the following reflex do not include innervation of brain?

  1. Spinal reflex

  2. Cranial reflex

  3. Afferent reflex

  4. Efferent reflex
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Spinal reflexes are responses to stimuli arising from the  spinal cord. These responses are quick usually to protect the body from a dangerous situation.

For example- the withdrawal of the hand on touching a hot object
So, the correct answer is 'spinal reflex'

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Which one of the following is the component of reflex arc?

  1. Sensory neuron

  2. Brain

  3. Motor neuron

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

A reflex arc is a simple nervous pathway and consists of a sensory/afferent neuron, center (spinal cord), motor/efferent neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to the spinal cord (sensory pathway). The interneurons of spinal cord integrate the incoming information and signal is relayed to motor/efferent neurons. The motor pathway transmits the signal from motor neurons to the effector organs (muscles and glands etc). Thus, reflex arc transmits the information from receptor to effector via the spinal cord. The brain is not the part of the reflex arc. 

Therefore, the correct answer is option D.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

What is the correct path of a reflex arc?

  1. $Sensory stimulus \rightarrow Dendrite \rightarrow Axon$
  2. $ Motor nerves \rightarrow Acetylcholine \rightarrow Adjustor neuron$
  3. $ Efferent nerves \rightarrow Connector nerves \rightarrow Motor nerves$
  4. $Afferent nerves \rightarrow Efferent nerves \rightarrow Connector nerves$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

The delay in transmission from the dorsal to the ventral root across the spinal cord for the reflex pathways 'A', 'B', 'D' and 'C' respectively is 0.5 ms,1.0 ms, 1.5 ms, and 2.0 ms.Identify the correct option: (Average synaptic delay =0.5 ms)

  1. A=monosynaptic , B=bisynaptic , C=trisynaptic

  2. A=monosynaptic , B= trisynaptic , D=bisynaptic

  3. A=monosynaptic , C=trisynap tic , D=quadrisynaptic

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

Monosynaptic transmission involves only two neurons, one sensory and one motor. In this, the signal is passed from one neuron to another neuron. In multisynaptic transmission, more than two neurons are involved. In this case, there is some delay in transmission of neural signal at the synapses. This is because more synapses are encountered in a reflex pathway and hence it takes more time to effect the reflex. In the given problem, it is given than average synaptic delay is 0.5 ms. Reflex pathway A is monsynaptic as it is taking 0.5 ms for transmission of signal. Reflex pathway B is disynaptic as it is taking 1.0 ms for signal transmission. This is because there are three neurons are involved. From sensory neuron each motor neuron takes 0.5 ms for transmission of signal. Reflex pathway for D is trisynaptic as it is having 1.5 ms of synaptic delay. Similarly, reflex pathway for C is quadrisynaptic as it is having 2.0 ms of synaptic delay. 

The correct answer is option D.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Reflex arc consists of 

  1. Motor nerve

  2. Sensory nerve

  3. Both sensory and motor nerves

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The primary components of the reflex arc are the sensory-nerve cells (or receptors), that receive stimulation, in turn connecting to other nerve cells, that activate muscle cells (or effectors), which perform the reflex action.

Multiple choice zoology locomotion and movement disorders of musculoskeletal system disorders of muscle and skeleton joints and movements

In Myasthenia gravis acetylcholine __________________.

  1. Receptors on motor end plate are reduced

  2. Secretion from nerve terminals is reduced

  3. Esterase activity is inhibited

  4. Secretion from nerve terminals is enhanced
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Myasthenia gravis is an autoimmune disease where antibodies block or destroy acetylcholine receptors at the neuromuscular junction. This prevents muscle contraction signals from being effectively received.

Multiple choice chemistry air and water pollution control smoke, dust and other air pollutants, acid rain air pollutants and its effects air and air pollution

 Which one of these is a neurotoxin that accumulates both in soft tissues and the bones, damaging the nervous system and causing brain disorders?

  1. Mg

  2. Na

  3. K

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

Lead is a neurotoxin that accumulates both in soft tissues and the bones, damaging the nervous system and causing brain disorders.

Multiple choice biology animal tissue types of neuron nervous tissue neural tissues

Which type of tissue forms spinal cord and brain?

  1. Muscular tissue

  2. Nervous tissue

  3. Epithelial tissue

  4. Connective tissue
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Spinal cord and brain control all activities of our body. Spinal cord possesses nerves, which carry messages between the brain and the body.
  •  The brain sends commands for the functioning of different organs of the body via nerves. 
  • Therefore, they are made of nervous tissue. Hence, option B is correct.  
Multiple choice biology animal tissue types of neuron nervous tissue neural tissues

Cell body of a nerve cell contains_____________.

  1. Nucleus

  2. Cytoplasm

  3. Kupffer cells

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cyton or cell body of a neuron possesses cytoplasm and nucleus. It contains many organelles, including granules called Nissl granules, which are composed largely of rough endoplasmic reticulum and free polyribosomes. Therefore, option D is correct. 

Multiple choice biology animal tissue types of neuron nervous tissue neural tissues

The nervous tissue, which contains densely packed cells are called as

  1. Neurons

  2. Nissl's granules

  3. Dendrons

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

  • The densely packed nerve cells present in the brain, spinal cord, and sense organs are called neurons. They are specialized for the conduction of nerve impulses and they are mainly of two types, sensory neurons, and motor neurons.

So, the correct option is 'Neurons'.

Multiple choice biology animal tissue types of neuron nervous tissue neural tissues

The neurons are specialised cells for

  1. Conduction of nerve impulses

  2. Conduction of food

  3. Immunity

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The neurons are specialized for the conduction of nerve impulses. Conduction of nerve impulses is aided by synapse. 
  • Synapse is a structure that allows a neuron to pass the electrical signal or chemical signal to another neuron. Therefore, option A is correct.