False.
Pain receptors are free nerve endings- nociceptors- that are stimulated by the chemical released from damaged tissue.
These receptors alert us for possible danger but they don't display sensory adaptation. Sensory adaptation it's when the response to stimulus decreases even though the stimulus is the same, we just become unaware of it.
In pain sensations, that doesn't happen.
Diffusion because it requires no energy
Its only important because scientist need info to be able to find there conclusion.i hope this helps.