PSIO 201 5th Edition Lecture 30 Outline of Last Lecture Spinal Cord Outline of Current Lecture I Muscle Reflexes II Classifications III Flexor Reflex IV Tendon Reflex V Stretched Reflex VI Crossed Reflex Current Lecture Objectives 1 Define reflex and list the five components of a reflex arc 2 Differentiate between ipsilateral and contralateral somatic and autonomic monosynaptic and polysynaptic reflexes 3 Diagram and describe the 4 representative reflex arcs discussed in lecture Definition reflex a rapid automatic response to a stimulus reflex arc the wiring of a particular reflex Innate Reflex inborn Learned Reflix reflex acquired through experience Components of a reflex arc Sensory receptor Sensory neuron Integrating center with or without interneuron Motor Neuron Effector Classification of Reflexes Monosynaptic vs Polysynaptic Somatic vs Visceral Cranial Vs Spinal Ipsilateral vs Contralateral Pathways of 4 Reflex Arcs 1 Stretch Reflex 2 Tendon Reflex 3 Flexor Reflex 4 Crossed extensor Reflex They are ALL SOMATIC and SPINAL Stretch Reflex purpose is to prevent injury from over stretching a muscle Results in contraction of the muscle that was stretched Stretch sensed by muscle spindle Monosynaptic ipsilateral spinal somatic reflex Anatomy of Muscle Spindle Sensory Nerve Efferent Nerve Fiber Muscle Spindle End plate on extrafusal plate Intrafusal muscle fiber Tendon Reflex purpose Is to prevent damage from development of too much tension in a muscle Result is inhibition of the muscle that is contracting Tension sensed by Golgi tendon Organ Polysynaptic Ipsilateral Spinal Somatic Reflex Flexor Reflex purpose is to protect body part from further injury results in flexion of affected limb pain sensed by nociceptors polysynaptic ipsilateral spinal somatic reflex Crossed Extensor Reflex purpose is to stabilize body position when a painful stimulus results in flexion of opposite limb Usually paired with flexor reflex Result is extension of opposite limb Pain sensed by nociceptors Polysynaptic contralateral spinal somatic relfex
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