Exercise 22: Reflex Physiology
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Transcript of Exercise 22: Reflex Physiology
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Exercise 22: Exercise 22: Reflex Reflex
PhysiologyPhysiology
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WHAT is a REFLEX?WHAT is a REFLEX? Rapid, predictable, unlearned, Rapid, predictable, unlearned, involuntaryinvoluntary motormotor response to a response to a stimulusstimulus
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REFLEX ARCREFLEX ARC Chain of events in neural pathwayChain of events in neural pathway Sensory to motorSensory to motor
Receptor Receptor Sensory neuron Sensory neuron Integration Center in CNS Integration Center in CNS Response through Motor neuron Response through Motor neuron EffectorEffector
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Reflexes: 5 StepsReflexes: 5 Steps
1.1. Arrival of a stimulus, activation Arrival of a stimulus, activation of receptorof receptor
2.2. Activation of sensory neuronActivation of sensory neuron3.3. Information processing: Information processing:
integration centerintegration center4.4. Activation of motor neuronActivation of motor neuron5.5. Response by an effector Response by an effector
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Know the steps & the diagram!!
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Somatic vs. AutonomicSomatic vs. Autonomic Somatic ReflexesSomatic Reflexes
Conscious control—skeletal musclesConscious control—skeletal muscles Autonomic ReflexesAutonomic Reflexes
Not conscious—smooth, cardiac, Not conscious—smooth, cardiac, glandsglands
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Somatic: Patellar Reflex = Somatic: Patellar Reflex = stretch reflexstretch reflex
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Tap tendonTap tendonStimulates muscle Stimulates muscle Reflex contraction of Reflex contraction of the stretched musclethe stretched muscle
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(Flexor reflex) Crossed-extensor reflex
Flexor reflex + extension reflex of Flexor reflex + extension reflex of opposite limbopposite limb
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Plantar ReflexPlantar Reflex Longitudinal stroking of sole of Longitudinal stroking of sole of
footfoot Tibial nerveTibial nerve Normal response: curling of toesNormal response: curling of toes
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Babinski’s Sign Babinski’s Sign (positive Babinski reflex)(positive Babinski reflex)
Same stimulus—but response is Same stimulus—but response is fanning of toesfanning of toes
Seen in infants; disappears if Seen in infants; disappears if descending motor pathways descending motor pathways develop properly—if seen in develop properly—if seen in adult, often a CNS injuryadult, often a CNS injury
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AUTONOMIC REFLEXESAUTONOMIC REFLEXES Pupillary reflexPupillary reflex
Receptor: retina Receptor: retina optic nerve optic nerve brain/s cord brain/s cord oculomotor nerve oculomotor nerve
Smooth muscle controls irisSmooth muscle controls iris Dilation = biggerDilation = bigger Constriction = smallerConstriction = smaller
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AUTONOMIC REFLEXESAUTONOMIC REFLEXES Salivary reflexSalivary reflex
Salivary glands are effectorsSalivary glands are effectors