AP BIOLOGY

Detailed explanation-1: -Specialized peripheral sensory neurons known as nociceptors alert us to potentially damaging stimuli at the skin by detecting extremes in temperature and pressure and injury-related chemicals, and transducing these stimuli into long-ranging electrical signals that are relayed to higher brain centers.

Detailed explanation-2: -Nociceptors can be activated by three types of stimulus within the target tissue-temperature (thermal), mechanical (e.g stretch/strain) and chemical (e.g. pH change as a result of local inflammatory process).

Detailed explanation-3: -Nociceptors are sensory receptors that detect signals from damaged tissue or the threat of damage and indirectly also respond to chemicals released from the damaged tissue. Nociceptors are free (bare) nerve endings found in the skin (Figure 6.2), muscle, joints, bone and viscera.

Detailed explanation-4: -Stimulation of the nociceptors by tissue damage results in action potentials in the peripheral nerve fibers. The action potentials pass via the neuron cell bodies in the dorsal root ganglion of the spinal cord to the axons, which synapse with motor neurons in the spinal cord.

Detailed explanation-5: -An important property of nociceptors is that they sensitize (that is, their excitability can be increased). Sensitization, which typically develops as a consequence of tissue insult and inflammation, is defined as a reduction in the threshold and an increase in the magnitude of a response to noxious stimulation10.