Identify the labelled parts of the reflex arc and answer the following questions: 1.4.1 a) Which part detects the stimulus? b) Which part is the swelling on the dorsal root containing cell bodies of s

• A: Receptor (detects stimulus)
• B: Synapse/Interneuron region in the grey matter of the spinal cord
• C: Central canal of the spinal cord
• D: Dorsal root ganglion (contains cell bodies of sensory neurons)
• E: Motor neuron (efferent neuron)
• F: Effector (muscle)

• a) Part A is the structure that detects the stimulus.
  • Receptor
• b) Part D is the swelling on the dorsal root, which contains the cell bodies of sensory neurons.
  • Dorsal root ganglion

Cerebrospinal fluid (CSF) is found in the central canal of the spinal cord.

• C; Central canal

If a person can feel pain, it means the sensory pathway (from receptor A, through the sensory neuron and dorsal root ganglion D, into the spinal cord, and up to the brain) is intact. If they cannot respond to the stimulus, it means the motor pathway (from the spinal cord, along the motor neuron E, to the effector F) is damaged. Therefore, the motor neuron (E) is the damaged part preventing a response.

• E