BIOL 121 Lecture Notes - Lecture 6: Mechanoreceptor, Axon, Dermis
Document Summary
Somatosensory system is responsible for cutaneous sensation and : proprioception. The sense of limb position: kinesthesis. The somatosensory sense is unique due to the fact that receptors are not concentrated in one location. Most sensory receptors of the somatosensory system are mechanoreceptors - that are sensitive to physical distortion of skin, such as bending or stretching. They can be distinguished by their location in the skin and their distinctive structures. Merkel"s disks: disk shaped receptor near the boarder of the dermis and the epidermis. Meissner"s corpuscles: a stack of flattened cells in the dermis, just below the epidermis. Ruffini"s endings: many branched fibers within a cylindrical capsule. Pacininan corpuscles: largest, a layered, onion-like capsule that surrounds a nerve fiber deep in the dermis. Adaptation rate: all sensory receptors quickly respond to the presence of a stimulus - then become used to the presence of the stimulus (adapt to it, some receptors rapidly adapt while some are slower.
