The correct sequence of components in a spinal reflex arc is

  • A. effector, motor neurone, spinal cord, sensory neurone, receptor
  • B. receptor, motor neurone, spinal cord, sensory neurone, effector
  • C. receptor, sensory neurone, interneurone in the spinal cord, motor neurone, effector
  • D. sensory neurone, receptor, effector, motor neurone, spinal cord

Explanation

The stimulus is detected by the receptor, carried into the spinal cord by the sensory neurone through the dorsal root, passed to a relay neurone and then out along the motor neurone through the ventral root to the muscle or gland that responds. Sensory always means towards the central nervous system and motor always means away from it, which is enough to rule out the reversed options.

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