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Difficulty: MediumHuman Anatomy and Body Systems

When a person accidentally touches a hot stove, a somatic reflex arc coordinates an immediate withdrawal response before conscious perception occurs. Arrange the anatomical components of this neural pathway in the correct sequence, from the initial detection of the stimulus to the physical motor response.

  1. 1A sensory receptor in the skin detects the intense heat stimulus.
  2. 2An afferent (sensory) neuron carries the nerve impulse toward the spinal cord.
  3. 3An interneuron within the spinal cord gray matter integrates and transfers the signal.
  4. 4An efferent (motor) neuron transmits the action potential away from the central nervous system.
  5. 5An effector muscle contracts to pull the hand away from the heat source.

Answer

Sensory receptor in skin →\rightarrow Afferent (sensory) neuron →\rightarrow Interneuron in spinal cord →\rightarrow Efferent (motor) neuron →\rightarrow Effector skeletal muscle
A somatic reflex follows a direct anatomical sequence: peripheral sensory receptors detect the stimulus, afferent neurons carry the signal to the spinal cord, interneurons integrate the impulse within the gray matter, efferent neurons conduct the response command outward, and effector skeletal muscles contract to perform the withdrawal movement.

Step-by-Step Solution

1
Identify the initial receptor activation.
The sensory receptor in the skin detects the thermal stimulus and generates an action potential.
All somatic reflex pathways begin at a peripheral sensory receptor responding to an environmental trigger.
2
Trace the inward neural transmission to the central nervous system.
The afferent (sensory) neuron carries the impulse into the spinal cord.
Afferent pathways conduct impulses from peripheral tissues toward the central nervous system.
3
Identify the integration step in the central nervous system.
An interneuron in the spinal cord gray matter relays the signal directly to a motor neuron.
In polysynaptic reflexes, interneurons serve as the internal processing link between sensory inputs and motor outputs.
4
Trace the outward transmission from the central nervous system.
The efferent (motor) neuron propagates the motor command toward the periphery.
Efferent pathways carry motor commands away from the central nervous system toward target organs.
5
Identify the terminal physical action.
The effector skeletal muscle contracts, pulling the limb away.
The effector organ executes the physical response stimulated by the motor neuron.

Key Concept

Sequential neural pathway of a somatic reflex arc in the human nervous system
Estimated Time:1m 0s
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Topics

Human Anatomy and Body Systems

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