Receptors and the Type of Stimulus
1) Mechanoreceptors : sensitive to mechanical stimuli such as deformation, stretching, bending of cells. They provide sensations of touch, pressure, vibration, proprioception, hearing/equilibrium, stretch of blood vessels and internal organs.
2) Thermoreceptors : detect changes in temperature
3) Nociceptors : respond to painful stimuli resulting from physical and/or chemical damage to tissue.
4) Photoreceptors : detect light that strikes the retina of the eye.
5) Chemoreceptors : detect chemicals in the mouth (taste), nose (smell), and body fluids.
6) Osmoreceptors : detect the osmotic pressure of body fluid.
Adaptation of Sensory Receptors
Most receptors exhibit Adaptation . With adaptation, the generator potential or receptor potential decreases in amplitude during maintained constant stimulus. This causes the frequency of nerve impulses in the neuron to decrease. Because of adaptation, the perception of a sensation may fade or disappear even though the stimuli persist (example: stepping into a hot shower).
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