PS271 Lecture Notes - Dorsal Root Ganglion, Dorsal Root Of Spinal Nerve, Agnosia
Document Summary
There are two major types of skin: hairy and glabrous (hairless). Skin has an outer layer, the epidermis, and an inner layer, the dermis. Skin performs an essential protective function, and it prevents the evaporation of body fluids into the dry environment we live in. Most of the sensory receptors in the somatic sensory system are mechanoreceptors, which are sensitive to physical distortion such as bending or stretching. Pressure in the heart and blood vessels. Stretching of the digestive organs and urinary bladder force against the teeth. Each mechanoreceptor contains unmyelinated axon branches which have mechanosensitive ion channels whose gating depends on stretching or changes in tension of the surrounding membrane. The largest and best studied receptor is the pacinian corpuscle which lies deep in the dermis. Ruffini"s endings are found in both hairy and glabrous skin (slightly smaller than the pacinian corpuscles). Meissner"s corpuscles are located in the ridges of glabrous skin.