KNES462_d4 copy

Innervation interneurons generally inhibitory

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Unformatted text preview: ng so it stays relaxed this is called reciprocal innervation Interneurons • Generally inhibitory, constitute ~ 50% of the neurons in the CNS; • Release transmitter which hyperpolarizes postsynaptic cell and thus reduces the likelihood for firing. hyperpolarization makes cell more negative!!!! • In the spinal cord, these so-called spinal interneurons make contact with other spinal neurons, e.g., motoneurons or sympathetic neurons. • Two principles of inhibition: – feedforward: suppresses other competitive actions – feedback: limits the ability of the active neuron to excite the target muscle. 85 KNES 462 ©FK ‘08 KNES 462 Principles of inhibition feed forward inhibition is like the knee jerk Feed-forward inhibition Afferent innervation of extensor muscles feedback is like a brak on an active muscle it tells an active muscle to stop + + + Extensor/flexor Afferent innervation of extensor or flexor muscles Extensor + Afferent innervation of flexor muscles Feed-back inhibition + _ + _ + Flexor 86 KNES 462 ©FK ‘08 when the muscle is activly contracted it strtched the gto--resulting in muscle tension GTO tension regulation the harder you contract your biceps actively there is modulation by the spinal cord and brain acing on the internuero • Negative feedback regulation of muscle tension – Ib afferents from Golgi tendon organ synapse to inhibitory interneurons, which synapse to -MN 87 KNES 462 ©FK ‘08 KNES 462 Reflex: The Chain of Events Summary of the signaling sequence in a stretch reflex Action potential Graded receptor potential S Transmitter release Synaptic potential anglion Dorsal root g Muscle spindle Ia afferent 91 Action potential Ventral root Transmitter release C ganglion Motoneuron Muscle KNES...
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