Physiology Nervous System lecture3

Arcs examples withdrawal reflex figure 920 3rd and

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Unformatted text preview: d and 4th editions) 1) stimulus - some kind of tissue damage burn, cut, pressure 2) events - 3) results - move (withdraw) body part from damaging stimulus limit degree, extent of injury muscle stretch reflex (figure 9.19, 3rd and 4th editions) 1) stimulus - sudden, sharp increase in muscle length 2) events dorsal root skeletal muscle sensory afferent spinal cord 3) results - ventral root contract stretched muscle motor efferent stretch receptor motor ending Spinal Pathways connections between different levels of CNS shorter pathways in spinal cord longer pathways between spinal cord and brain soem are axons of sensory afferent neurons most are axons of interneurons two major kinds of longer pathways ascending spinal pathways: brain spinal cord from ___________ to __________ action potentials traveling along axons in ascending pathways carry sensory information descending spinal pathways spinal cord from ___________ to __________ brain action potentials traveling along axons in descending pathways carry motor instructions organization of spinal pathways (figure 9.9, 3rd and 4th editions) precise location in white matter for each pathway particular origin and termination for each pathway specific functions of each pathway brain axon in long ascending pathway axon in long descending pathway spinal cord damage of long spinal pathways spinal cord needn't be severed, can be stretched, squeezed, or lacerated affects conduction of action potentials between brain and spinal cord examples of spinal cord injuries what might be lost and what often still functions? temporary condition after a serious spinal cord injury "spinal shock" flaccid apralysis permanent condition after a serious spinal cord injury spastic paralysis regeneration of damaged axons? good in PNS. pretty poor in CNS OBJECTIVES: NERVOUS SYSTEM 1) Explain the general pattern of central nervous system development. From what embryonic tissue does the nervous system develop? What is the neural plate? What is the neural groove? What is the neural tube? How are the neural plate, neural groove and neural tube related? What are some common problem in nervous system development? How common and how serious are these problems? What is the demonstrated value of folic acid? 2) Describe the functional organization of the spinal cord. Where is spinal gray matter found? Where is spinal white matter found? What is the difference between gray matter and white matter? How does sensory information enter the spinal cord? How do commands exit the spinal cord? What happens in between (in the spinal cord itself)? 3) Describe the workings of a spinal reflex. What is meant by a "reflex arc"? What is a withdrawal reflex? What is the stimulus? What is the response? What is the result? Why is it "useful"? What is a muscle stretch reflex? What is the stimulus? What is the response? What is the result? Why is it "useful"? What are two reasons is it so fast? Do reflexes vanish after spinal cord injuries? 4) Describe the way neural impulses pass between the brain and spinal cord. Axons of what neurons make up many of the pathways? Where are these pathways located? Are they well-organized or just jumbled together? What is the difference between ascending and descending spinal pathways? What kind of information do these pathways carry? What can happen to sensory and movement functions after damage to the cord? What sort of sensory and movement loss is experienced and where in relation to the point of spinal damage?...
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