Tag: nervous system

Questions Related to nervous system

Which of the following is not considered to be a tissue?

zoology nervous system neural tissue structure of neuron nervous tissues

  1. cartilage

  2. Blood

  3. Lung

  4. Cardiac muscle

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Correct Option: C
Explanation:

Cartilage is supportive non-living soft connective tissue

Blood is fluid connective tissue
Cardiac muscle is a tissue made of cardiac cells
So, the correct option is 'Lung', which is an organ made of multiple tissue

The largest number of cell bodies of neurons in our body is found in:

zoology nervous system neural tissue structure of neuron nervous tissues

  1. brain

  2. tongue

  3. kidneys

  4. stomach

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Correct Option: A
Explanation:

The largest number of cell bodies of neurons in our body is found in the brain, the human brain has approximately 86 billion neurons.

So, the correct option is 'brain'.

Reflex arc is formed by 

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

  1. Receptor - brain - muscles

  2. Muscles - spinal cord - receptor

  3. Receptor - spinal cord - muscles

  4. Muscle - brain - receptor

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Correct Option: C
Explanation:

The reflex arc is a simple nervous pathway and consists of the sensory receptor, afferent neuron, centre, efferent neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to the spinal cord (sensory pathway). Reflex arc starts with sensory receptors, not with muscles. 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 which. The brain is not the part of reflex arc. Thus, the correct answer is option C.

The sequence of a reflex arc is

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

  1. Receptor $\rightarrow$ Sensory neuron $\rightarrow$ Motor neuron $\rightarrow$ Effector $\rightarrow$ Response

  2. Effector $\rightarrow$ Sensory neuron $\rightarrow$ Motor neuron $\rightarrow$ Receptor $\rightarrow$ Response

  3. Effector $\rightarrow$ Motor Neuron $\rightarrow$ Interneuron $\rightarrow$ Receptor $\rightarrow$ Response

  4. Receptor $\rightarrow$ Motor neuron $\rightarrow$ Sensory neuron $\rightarrow$ Effector $\rightarrow$ Response

Show answer
Correct Option: A
Explanation:

Reflex arc transmits the sensory information from receptor to effector via spinal cord. It consists of sensory receptor, afferent (sensory) neuron, centre, efferent (motor) neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to spinal cord (sensory pathway). Detection of environmental stimulus by receptors forms the first step of reflex arc. 

Sensory neurons receive the information from receptors while motor neurons transmit the nerve impulses from CNS to effectors (muscles and glands). 
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). The effector organs respond according to the information carried by motor pathway.
Therefore, the correct answer is option A.

All are examples of cranial reflexes but not

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

  1. Salivation

  2. Scratching

  3. Blushing

  4. Sneezing

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Correct Option: B
Explanation:

Reflex arc consists of sensory receptor, afferent neuron, centre, efferent neuron and effector organ. The reflexes that involve sensory and motor nerve fibres of cranial nerves and control the head region are known as cranial reflexes. Since, cranial reflexes involve head, eyes, nose, mouth, swallowing and facial expression, they produce the vital and involuntary responses. Spinal reflexes are the one in which spinal cord serves as centre without involvement of brain. They control the voluntary responses of other body parts via spinal cord. Salivation in response to sight/smell/thought of food, blushing and sneezing are involuntary actions, which involve mouth, facial expression and nose, and thus are categorized under cranial reflexes. Scratching is a voluntary response to itch stimulus in which brain is not involved and thus is a spinal reflex. 

Therefore, the correct answer is option B.

The reflex arcs in which one or more interneurons connect the afferent and efferent signals are

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

  1. Autonomic reflex

  2. Somatic reflex

  3. Monosynaptic reflex

  4. Polysynaptic reflex

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Correct Option: D
Explanation:

  • Monosynaptic reflex is a type of reflex in which the reflex arc consists of only two neurons, one sensory neuron, and one motor neuron. Monosynaptic refers to the presence of a single chemical synapse. 
  • By contrast, in polysynaptic reflex arcs, more than one relay neurons connect the sensory and motor neuron. 
  • Polysynaptic reflex or spinal reflex or withdrawal reflex protects the body from the damaging stimulus. It is located in the spinal cord. 

Therefore, the correct answer is option D.

Reflex arc is controlled by?

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

  1. Brain

  2. Vertebral column

  3. Autonomous nervous system

  4. Peripheral nervous system

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Correct Option: A

Simple two neuron reflex arc involves

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

  1. Sensory neuron

  2. Spinal cord

  3. Effector neuron

  4. All of the above

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Correct Option: D
Explanation:

Reflex arc transmits the sensory information from receptor to effector via the spinal cord. It consists of the sensory receptor, afferent neuron, centre, 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). 

Route of reflex arc is

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

  1. Effectors, grey matter, motor fibres, sensory fibres and receptors

  2. Receptors, sensory fibres, grey matter and motor fibres

  3. Receptors, sensory fibres, grey matter, motor fibres and effectors

  4. Sensory fibres, grey matter, motor fibres, receptors and effectors

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Correct Option: C
During reflex the sensory neurons do not pass directly to the brain.
biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

  1. True

  2. False

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Correct Option: B
Explanation:

The path taken by the nerve impulses in a reflex is called as a reflex arc. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This characteristic allows reflex actions to occur relatively quickly by activating spinal motor neurons without the delay of routing signals through the brain, although the brain will receive sensory input while the reflex action occurs. 

Therefore, the correct answer is option A.