Somatosensory Systems Sue Keirstead, Ph.D. Assistant Professor Dept. of Integrative Biology and Physiology Stem Cell Institute E-mail:
[email protected] Tel: 612 626 2290 Class 9: Somatosensory System (p. 292-306) 1. Describe the 3 main types of somatic sensations: 1. tactile: light touch, deep pressure, vibration, cold, hot, etc., 2. pain, 3. Proprioception. 2. List the types of sensory receptors that are found in the skin (Figure 9.11) and explain what determines the optimum type of stimulus that will activate each. 3. Describe the two different modality-specific ascending somatosensory pathways and note which modalities are carried in each (Figure 9.10 and 9.13). 4. Describe how it is possible for us to differentiate between stimuli of different modalities in the same body part (i.e. fingertip). Consider this at the level of 1) the sensory receptors and 2) the neurons onto which they synapse in the ascending sensory systems. 5. Explain how one might determine the location of a spinal cord injury based on the modality of sensation that is lost and the region of the body (both the side of the body and body part) where sensation is lost (Figure 9.18). 6. Describe how incoming sensory inputs from primary sensory axons can be modified at the level of the spinal cord and relate this to the mechanism of action of some common pain medications (Figure 9-18). 7. Describe the homunculus and explain the significance of the size of the region of the somatosensory cortex devoted to a particular body part. Cerebral cortex Interneuron Thalamus Interneuron 4 Integration of sensory Stimulus input in the CNS 1 Stimulation Sensory Axon of sensory of sensory receptor neuron receptor Graded potential Action potentials 2 Transduction 3 Generation of of the stimulus action potentials Copyright © 2016 by John Wiley & Sons, Inc.