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Chapters 11c , 13 Integration and Reflexes neural integration • • • • • integration connects sensory neurons to motor neurons integration centers sensory input brain, spinal cord motor response appropriate reaction to change in conditions simplest = 1 synapse + 2 neurons neurons connect to neurons • • neuronal pools neurons with similar function circuits pattern of synaptic networks – diverging – converging – reverberating amplifying • eg. 1 sensory neuron to several brain areas • eg. CNS motor neuron to 1000’s skeletal muscles concentrates input • eg. several sensory neurons to 1 brain area • eg. different stimuli affect 1 motor neuron stimulates itself • eg. rhythmic output • eg. memory breathing neural processing • • • serial processing – – sensory neuron connects to one interneuron or motor neuron stimulus always causes same motor response parallel processing – – sensory neuron connects to several interneurons stimulus causes several responses many stimuli involve both reflexes • • • • • • direct connection of stimulus to response somatic reflex – – – sensory muscle, joint, skin motor skeletal muscle visceral reflex – – – sensory organs motor smooth, cardiac muscle spinal reflex function w/o brain centers learned reflex w/ higher brain centers endocrine reflex endocrine reflex path • • • • • • • control reflex path from stimulus to response stimulus = change in condition afferent signal stimulus - change in condition receptor endocrine gland integration endocrine gland efferent signal hormone effector organ , tissue response reflex arc • • • • • • 5 components : receptor sensation specific sensory neuron integration center synapse or interneuron motor neuron effector muscle, organ withdrawal (flexor) reflex • • • • • • • pain (danger) protective muscles flex receptors painful stimulus sensory neuron integration interneuron motor neuron effector eg. flexor muscles withdraw from stimulus heat, pain , touch, surprise, sound, light crossed extensor reflex • • • • • • • • contralateral extension receptors = reciprocal activation painful stimulus sensory neuron integration interneuron motor neuron effector contralateral extensors balance coordination muscle spindle • muscle tissue maintains “normal” length posture, balance prevent injury to muscle • intrafusal fibers noncontractile muscle fibers • – – sensory neurons stim by stretch motor (gamma) adjust length - contract extrafusal fibers – motor (alpha) skeletal muscle fibers contracts muscle stretch reflex • • • • • • • stretch muscle muscle contracts receptors muscle spindle stretched sensory neuron integration synapse motor neuron to muscle effector muscle (contracts) serial processing reciprocal inhibition • • • • • • • stretch muscle antagonists relax receptors muscle spindle stretched sensory neuron integration interneuron motor neuron to antagonists effector muscles relax parallel processing – also: sensory to brain DTR • • • deep tendon reflexes increase UMN lesion decrease LMN lesion Golgi tendon reflex • • • • • • • stretch tendon muscle relaxes prevents injury to tendon receptors tendon stretched sensory neuro integration interneuron motor neuron to muscle, synergists effector relax muscle , synergists – parallel contract antagonists visceral reflex • • • • • • receptors visceral or somatic stimuli sensory neuron integration interneurons motor neuron ANS effector organs, blood vessels eg. cough , sneeze swallow BP HR CO2 pupils brain , spinal cord CNS and visceral reflex – eg. BP • • • • • receptor blood vessel sensory neuron to spinal cord integration neuron up spinal cord neuron circuit in brain neuron down spinal cord 2 motor neurons from spinal cord effector smooth muscle – blood vessel cardiac muscle CNS as integration center • • • • connect “appropriate” motor responses to stimuli increased parallel pathways – – to/from several brain areas to several effectors brain spinal cord skeletal muscles several organs