Sensory receptors are selective, i.e., they respond vigorously to one particular kind of stimulus and weakly or not at all to others. In terms of simplicity or complexity, simple receptors are associated with general senses, and complex receptors are associated with special senses. The receptors for these sensations are located in the skin, in connective tissue under the skin, in mucous membranes, and at the ends of the gastrointestinal tract. Pressure sensations generally result from stimulation of tactile receptors in deeper tissues and are longer lasting and have less variation in intensity than touch sensations, and in addition pressure is a sustained sensation that is felt over a larger area than touch. Like corpuscles of touch, lamellated corpuscles adapt rapidly.
Vibration sensations result from rapidly repetitive sensory signals from tactile receptors.
Itch and tickle receptors are free nerve endings. Pain is a vital sensation because it provides us with information about tissue-damaging stimuli and with signs which may be used for diagnosis of disease or injury. The pain may also be felt in a surface area far from the stimulated organ in a phenomenon known as referred pain. B. Proprioceptive Sensations 1. Receptors located in skeletal muscles, in tendons, in and around joints, and in the internal ear convey nerve impulses related to muscle tone, movement of body parts, and body position.