I found chapter 14 on the cutaneous senses to be very interesting. The skin contains receptors that respond to touch, pressure, and temperature. The relationships between receptors and the cutaneous sensations are not completely understood. Meissner's corpuscles are sensitive to touch and Pacinian corpuscles to deep pressure. Ruffini endings transmit information about warmth and Krause's bulbs about cold. Information is transmitted from the receptors to nerve fibers that are routed through the spinal cord to the brainstem. From there they are transmitted to an area of cortex in the parietal lobe. Skin senses also undergo various kinds of sensory adaptation. For example, a hot tub can be initially so hot that it is intolerable, but after awhile one can sit in it without discomfort.
The part that I found most interesting about the cutaneous senses was pain.
Pain receptors are mostly free nerve endings in the skin. Information is transmitted by two types of pathways to the brain by way of the thalamus.
· The fast pathway (myelinated) detects localized pain and sends that information rapidly to the cortex.
· The slow pathway (unmyelinated) carries less-localized, longer-acting pain information (such as that concerning chronic aches).