Final answer:
Nociceptors are pain receptors found throughout many parts of the body but are not present in the brain, which does not perceive pain the same way other body parts do. Nociception refers to the process of painful stimuli being encoded and processed, which becomes pain perception when it reaches the brain.
Step-by-step explanation:
Nociceptors are specialized sensory receptors responsible for the sensation of pain and are activated by potentially damaging stimuli. While nociceptors are found throughout the body, including in the lungs, kidneys, and heart, they are not found in the brain. This organ does not contain nociceptors, and thus, does not feel pain in the same way that other body parts do. Nociceptors play a role in nociception which is the neural processes of encoding and processing painful stimuli. However, nociception is different from pain perception, which only occurs when signals from nociceptors reach the brain areas like the thalamus and the somatosensory cortex.