Question

Choose the correct answer from each of the four options given below:

A reflex arc in man is best described as the movement of stimuli from

• A. Receptor cell, sensory neuron, relaying neuron, effector’s muscles
• B. Receptor cell, efferent nerve, relaying neuron, muscles of the body
• C. Receptor cell, spinal cord, motor neuron, relaying neuron
• D. Receptor cell, synapse, motor neuron, relaying neuron.

Answer 1

The correct option is A

Receptor cell, sensory neuron, relaying neuron, effector’s muscles

The correct option is (A)

Explanation of correct option:

1. The complete method of reaction to peripheral nerve stimulation occurs involuntarily, while in this reaction, there is no involvement from the Central Nervous System. This is called a reflex motion.
2. Reflex motion is a spontaneous, automated, and involuntary mechanical reaction that's produced via way of means of stimulating unique actions.

Reflex arc Pathway:

1. The reflex pathway is shaped by at the very least one afferent neuron and one efferent neuron (receptor cell). These neurons are organized in a series.
2. The afferent neuron gets a sign from the sensory neuron and transmits the impulse through a dorsal nerve root into the Central Nervous System at the extent of the spinal cord.
3. The other neuron then carries the signal from the CNS to the effector. This way of terminating the reflex action is called the reflex arc.
4. Relaying neuron is those which communicates between sensory and motor neuron.
5. Sensory fibers transmit sensory impulses in the grey matter of the spinal cord.
6. They are now converted into motor impulses and reach the effector's muscles.
7. These muscles exhibit reflex actions for motor impulses received from motor neurons.

Explanation of incorrect option:

Option (B):

1. As for the movement of stimuli for the reflex arc in man, there should be an impulse from the sensory organ after the receptor cell stimulation.
2. The afferent nerve gets a signal from the sensory organ, not an efferent nerve.

Option (C):

1. To transmit the impulses into a CNS at the extent of the spinal cord.
2. First, there should be a signal from the sensory neuron.
3. Then comes the relaying neuron, which communicates between the sensory neuron to the motor neuron.

Option (D):

1. Synapses are the neuronal junction which is the site of transmission of nerve impulses between the neuron and muscle cell.
2. For this, first of all, sensory neuron should pass a signal to an afferent neuron.
3. And then relaying neurons plays an important role in the movement of muscles.

Final Answer:

A reflex arc in man is best described as the movement of stimuli from the Receptor cell > sensory neuron > relaying neuron > effector's muscles.