Biological Systems MCAT Practice Exam

What does the gate control theory suggest about the spine's function concerning pain signals?

1. It amplifies all pain signals.

2. It completely blocks all pain signals.

3. It contains a gate that blocks or allows pain signals.

4. It only transmits pain signals during injury.

The correct answer is: It contains a gate that blocks or allows pain signals.

The gate control theory of pain asserts that the spinal cord acts as a "gate" that modulates the transmission of pain signals to the brain. According to this theory, there are mechanisms in the spinal cord that determine whether pain signals from the body will be transmitted to the brain or inhibited. When non-painful stimuli (such as light touch or vibration) are detected alongside painful stimuli, these non-painful signals can activate inhibitory interneurons in the spinal cord. This activation can "close the gate" on the painful signals, thereby reducing the perception of pain. Conversely, when there is a significant presence of painful stimuli, these signals can "open the gate," allowing more pain signals to be transmitted to the brain. This theory illustrates the complexity of pain perception and highlights how factors beyond the physical injury itself can influence the experience of pain. By understanding this gate mechanism, treatments for pain can focus on either closing the gate to reduce pain perception or alleviating the pain itself through various means.