PHGY 209 Lecture Notes - Lecture 18: Retinal Pigment Epithelium, Fovea Centralis, Vitreous Body

• School: McGill University
• Department: Physiology
• Course: PHGY 209
• Professor: Alvin Shrier

Document Summary

Bilateral loss of touch and proprioception from the bellybutton down to the toes. Bilateral loss of pain and temperature in a thin strip at the level of the lower chest. Answer: central canal because this is where pain and temperature cross. Answer: left hemisection of spinal cord at lower thoracic level (brown-sequard) Visceral and somatic pain afferents commonly synapse on the same neurons in the spinal cord. Branches and nuclei into the brain stem go down the spinal cord. The descending axons synapse on the pain afferent setter entering the spinal cord. The synapses are inhibitory block the pain entering the spinal cord = analgesia. The pain afferent release substance p on the second order neurons. Descending axons presynaptically inhibit the pain afferent from releasing the substance p by opiate neurotransmitters binding to the receptors on the presynaptic part of the afferent to stop the release of substance p. Morphine is an opiate neurotransmitter - reduces pain.