The sensory receptors are classified according to the stimuli they get: mechanoreceptors are stimulated by pressure (e.g., touch or sound); chemoreceptors respond to chemical stimuli (olfactory, taste, pH, metabolite concentration, etc.); thermoreceptors are sensitive to temperature changes; photoreceptors are stimulated by light; nocireceptors send pain information; proprioceptors are sensitive to the spatial position of muscles and joints (they generate information for the equilibrium of the body).