PSL300H1 Lecture Notes - Lecture 7: Lamellar Corpuscle, Somatosensory System, Dorsal Root Ganglion
Document Summary
There are 4 somatic senses: touch, temperature, proprioception, and nociception. Proprioception is awareness of the position of body parts relative to each other; e. g. even with your eyes closed you can sense how much your elbow is flexed. Nociception detects tissue damage or the threat of it, and is perceived as pain or itch. Somatic sensation below the chin: cell bodies in the dorsal root ganglia. The parts of these neurons that transduce touch, pressure etc, into electrical signals are in their nerve endings i. e. in the tips of their fibers, in the skin and viscera. There are a variety of receptors in the skin. Some receptors are free nerve endings; they detect mechanical stimuli, temperature, and chemicals. (very versatile) The rest are encapsulated i. e. sheathed in connective tissue. Skin largest organ; epidermis and thicker dermis underneath receptors are mainly in the dermis (not exactly at the surface) At the bottom of the epidermis are saucer-shaped merkel disks.
