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50 Cards in this Set
- Front
- Back
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Classification of Nueral Reflexes |
1) Efferent divison that controls the effector - Somatic motor neurons control the skeletal muscles - Autonomic neurons control smooth muscle, cardiac muscle, glands and adipose tissue |
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Classification of Nueral Reflexes |
2) Integrating region within the central nervous system - spinal reflexes do not require input from the brain - cranial reflexes are integrated within the brain |
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Classification of Nueral Reflexes |
3) Time at which the reflex develops - innate (born) reflexes are genetically determined - learned (conditioned) reflexes are acquired through experiences |
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Classification of Nueral Reflexes |
4) The number of nuerons in the reflex pathway - monosynaptic reflexes have only two neurons: one afferent and one efferent. ONLY somatic motor reflexes are monosynaptic - polysynaptic reflexes include one or more interneurons between the afferent and efferent neurons. ALL autonomic reflexes are polysynaptic because they have three neurons: one afferent and two efferent |
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Autonomic Reflexes |
- aka visceral reflexes - involve internal organs of the body - urination and defecation: spinal reflexes that do not need input from the brain - integrated in the brain primarily in the hypothalamus, thalamus, and brainstem - conversion of emotional stimulus into visceral responses - polysynaptic reflexes |
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Brain stem and Autonomic Reflexes |
- contains integrating centers for salvating, vomitting, sneexing, couging, swallowing, and gagging |
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Limbic System |
- site of primitive drives such as sex, fear, rage, aggresion, and hunger - called the visceral brain - emotionally driven reflexes - emotion linked autonomic reflexes: urination, defecation, blushing, blanching, piloerection |
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Tonic Activity |
- continous stream of action potential that creates ongoing activity in the effector |
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Skeletal Muslce Reflex |
- efferent nuerons respond in two ways: if contraction is appropriate, CNS activates somatic motor nuerons in the muslce fibers or if a muslce needs to be relaxed, sensory input activates inhibitory interneurons in the CNS - relaxation of skeletal muscle results form the absence of excitatory input by the somatic motor neurons |
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Skeletal Muslce Reflexes Components |
1) Sensory receptors aka: proprioceptors - located in skeletal muscles, joint capsules and ligaments - monitor the position of our limbs in space, our movement, and effort we exert in lifting objects - input from proprioceptors go to the CNS through sensory neurons |
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Skeletal Muscle Reflexes Components |
3) the central nervous system integrates the input signal using networks and pathways of excitatory and inhibitory interneurons - some sensory information may be integrated in the cerebral cortex and become perception, and some reflexes can be modulated by conscious input |
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Skeletal Muscle Reflexes Components |
3) Somatic motor nuerons carry the output signal - alpha motor neurons: somatic motor neurons that innervate skeletal muscle contractile fibers |
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Skeletal Muscle Reflexes Components |
4) The effectors are contractile skeletal muscle fibers aka: extrafusal msucle fibers - action potential in alpha motor neurons cause extrafusal fibers to contract |
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Muslce Spindle |
- sends information about muscle stretch to the CNS - buried among the extrafusal fibers of the muscle |
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Gamma Motor Nuerons |
- innervate intrafusal fibers - control contraction of intrafusal fibers |
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Golgi Tendon Organ |
- consist of sensory nerve ending interwoven amoung collagen fibers |
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Proprioceptors Types |
- muslce spindles - Golgi tendon organs - joint receptors |
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Joint Receptors |
- found in the capusles and ligaments around joints in the body - stimulated by mechanical distortion that accompanies changes in the relative positioning of bones linked by flexible joints - sensory information from the joint receptors are integrated primarily in the cerebellum |
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Muscle Spinders |
- are stretch receptors that send information to the spinal cord and brain about muslce length and changes in muscle length - each muscle spindle consists of connective tissue capsule that encloses a group of small muscle fibers known as Intrafusal fibers |
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Intrafusal Fibers |
- group of muslce fibers that are enclsoed by a connective tissue capsule - many intrafusal fibers make a muscle spindle - modified so that the ends are contractile but the central region lack myofibrils |
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Gamma Motor Neurons |
- innervate the contractile ends of intrafusal fibers |
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Muslce Tone |
- level of tension when a muslce is at rest |
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Stretch Reflex |
- reflex contraction of the msulce which prevents damage form overs stretching |
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Alpha-gamma Cactivation |
- excitation of gamma motor neurons and alpha motor neurons at the same time - keeps the spindles stretched when the muscle contracts |
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Golgi Tendon Organ |
- found at the junction of tendons and muslce fibers - respond primarily to muscle tension created during an isometric contraction and are relatively insensitive to muscle stretch - the reflex of golgi tendon cause relaxation - afferent input from activation of the golgi tendon organ excites inhibitory interneurons in the spinal cord causing contraction - important inhibition to alpha motor neurons |
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Myotatic Unit |
- the collection of pathways controlling a single joint |
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Monosynaptic Stretch Reflex |
- the simpliest reflex in a myotatic unit - involves two neurons: the sensory neuron from the muscle spindle and somatic motor neuron to the muscle - ex: patellar reflex |
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Reciprocal Inhibition |
- the antagonist muscles must relax |
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Flexion Reflexes |
- polysynpatic reflex pathways that cause an arm or leg to be pulled away form a noxious stimulus - the signal diverges into activating multiple excitatory interneurons - activate either alpha motor neurons or inhibitory interneurons that activate antagonistic muscle groups |
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Cross Extensor Reflex |
- postural reflex that helps maintain balance when one foots is lifted form the ground - extensors contract in the supporting left leg and relax in the withdrawing of the right leg |
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Classifying Movement |
- reflex, voluntary, and rhythmic |
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Reflex Movement |
- the least complex and are integrated primarly in the spinal cord - sensory input that initiates reflex movements such as the input from muscle spindles and golgi tendons organs, goes to the brain and participates in the coordination of voluntary movements and postural reflexes |
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Postural Reflexes |
- helps us maintain body position as we stand or move through space - reflexes are integrated in the brain stem - require continuous sensory input from visual and vestibular sensory system and from the muscles themselves |
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Proprioception |
- muslce, tendon, and joint receptors provide information about the position of various body parts relative to one another |
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Voluntary Movements |
- most complex type of movement - require integration at the cerebral cortex and they can be initiated at will without external stimuli - |
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Muslce Memory |
- the ability of the unconscious brain to reproduce voluntary, learned movements and positions |
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Rhythmic Movments |
- walking or running, - combination of reflex movements and voluntary movements - initiated and terminated by input from the cerebral cortex - central pattern generators maintain spontaneous repetitive activity |
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Central Pattern Generators |
- networks of CNS interneuorns that maintain the spontaneous repetive activity |
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Feedfoward Reflexes |
- allow the body to prepare for a voluntary movement and feedback mechanisms are used to create a smooth continous motion |
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Levels of nervous system that control movement |
1) the spinal cord - which integrates spinal reflexes and contains central pattern generators |
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Levels of nervous system that control movement |
2) the brain stem and cerebellum - which control postural reflexes and hand and eye movement |
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Levels of nervous system that control movement |
3) the cerebral cortex and basal ganglia - responsible for voluntary movements |
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look at the table on page |
454 |
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Control of Voluntary Movements Steps |
1) decision making and planning 2) initaiting the movement 3) executing the movement |
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Volunatary Movements |
- require coordination between the cerebral cortex, cerebellum, and basal ganglia |
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Corticospinal Tract |
- a group of interneurons controlling voluntary movement that run form the motor cortex to the spinal cord where they synpse directly onto somatic motor neurons - cross to the opposite side of the body in the medulla forming pyramids |
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Feedfoward Postural Reflexes |
- adjust the body position - shifting weight slightly in anticipation of the changes about to occur |
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Basal Ganglia |
- play a orle in cognitive function in cognitive funtion and memtory as well as the coordination of movement |
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Parkison's Disease |
- progressive nuerolical disorder charactericized by abnormal movemetns, speech difficulties, and cognitive changes - symptoms are associated with the loss of neurons that release the neurotransmitter dopamine |
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Treatments for Parkinson's Disease |
- administrating drugs designed to enhance dopamine activity int he brain - drug treatments include dopamine agonists and inhibitors of enzymes that breakdown dopamine - severe cases: selected parts of the brain may be destroyed to reduce tremors and rigidity |
