PSL300H1 Lecture Notes - Lecture 25: Lamellar Corpuscle, Postcentral Gyrus, Spinal Nerve
Document Summary
Skin receptors are in the dermis or deep epidermis. Some receptors are free nerve endings (detect mechanical stimuli, temp, and chemicals) The rest are encapsulated (sheathed in connective tissue) and are mechanoreceptors. A lot of them are purely phasic respond briefly to change in stimuli"s and then shortly after, they will return to base line. Given a sustained, constant stimulus, the nerve end"s membrane depolarizes but then returns to a baseline in ~3 ms. It registers changes, not steady levels: humans won"t perceive much unless the stimulation is changing. At the bottom of the epidermis are saucer-shaped merkel disks. They are very sensitive to deformation of the skin (like poking) and are more tonic than phasic (they send a sustained message as long as the deformation [stimulus] persists) At the top of the dermis there are egg-shaped meissner corpuscles. They are mainly in the tongue and hairless skin erogenous zones, palms, fingertips (which have 5000/cm2 at 10.
