Final answer:
Sensitization increases the rate of nociceptor firing and lowers their excitation threshold, leading to enhanced pain perception when a painful stimulus is repeatedly applied.
Step-by-step explanation:
Sensitization, synonymous with an increased response to painful stimuli, occurs when a painful stimulus is applied over time. The rate of nociceptor firing will increase and the excitation threshold of the nociceptor membrane becomes lowered. This phenomenon is due to the fact that nociceptors, which are sensory receptors responsible for the sensation of pain, can become more sensitive when repeatedly stimulated by painful sensations. Activation of nociceptors may occur due to mechanical, thermal, or chemical stimuli. When tissues are stressed or damaged, they release chemicals that can sensitise these receptors, leading to an increased sensation of pain. This pain perception does not occur until the nociceptive signals are processed in the brain, with axons carrying this information projecting primarily to the thalamus and to other brain areas such as the hypothalamus, which modulates autonomic functions.