BIOS1171 Lecture 18: Lecture 18 Neural Mechanisms Underlying Reflexes
22 Aug 2018
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Contraction: automatic responses coordinated within spinal cord or brain stem, through interconnected sensory neurons, motor neurons & interneurons, produce simple & complex automatic behaviour. Involuntary does not require information from the brain - & is done at the level of the spc. Reflex arc: wiring of a single reflex, begins at receptor, ends at peripheral effector (can be far away) Spinal reflexes: range in increasing order of complexity, monosynaptic reflexes (stretch reflex, polysynaptic reflexes, intersegmental reflex arcs (many segments interact & produce highly variable motor responses segments coordinate the response) Muscle spindles: tone & contract the muscle: anulospiral endings: are primary sensory endings that depict stretch in the muscle and send signals to the cns. Intrafusal muscle fibres are all around the spindle & in the muscle: tendon organ tells the nervous system how much, spindle dendrites are wrapped around it tension is in the muscle contraction. Gamma efferents: axons of motor neurons, synapse back onto intrafusal fibres.
