Certified Rehabilitation Registered Nurse (CRRN) Practice Exam

According to the gate control theory, what blocks the transmission of nerve impulses?

1. Cells in the dorsal horn

2. Afferent nerve fibers

3. Endorphins released during pain

4. Peripheral nociceptors

The correct answer is: Cells in the dorsal horn

The gate control theory of pain proposes that the perception of pain is not solely a direct result of pain stimulus but is modulated by a "gate" mechanism in the spinal cord that can either allow or inhibit the transmission of nerve impulses to the brain. The "gate" referred to in this theory is located in the dorsal horn of the spinal cord. Cells in the dorsal horn, particularly the interneurons, play a critical role by receiving incoming nerve signals and determining whether they will be relayed to the brain. When these cells are activated, they can effectively inhibit the transmission of pain signals from peripheral nerves to the central nervous system, thereby "closing the gate" to pain. This mechanism helps explain why various stimuli, such as touch or non-painful sensations, can reduce the perception of pain when they occur simultaneously. In contrast, other options like afferent nerve fibers are responsible for transmitting pain signals rather than blocking them, endorphins act as natural pain relievers by attaching to opioid receptors, also promoting pain relief, while peripheral nociceptors detect harmful stimuli but do not inhibit the transmission of signals within the spinal cord. Thus, the correct answer underscores the importance of the dorsal horn's role in pain modulation according to the gate control