Week 1 - Afferent Sensory Neurons Efferent Motor neurons Glial cells(Schwann cells and Myelin Nodes of ranvier Interneurons connects sensory and

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1/14/08 – 1/18/08 Afferent – Sensory Neurons Efferent – Motor neurons Glial cells – (Schwann cells and Myelin ) Nodes of ranvier Interneurons – connects sensory and motor neurons Nervous System - Peripheral Nervous System - Central Nervous System o Composed of almost entirely of interneurons (almost exclusively) o Brain and the Spinal Cord Spinal Cord is the interface between the PNS and the CNS. The sensory neurons and the motor neurons of PNS enter into the spinal cord. Sometimes a sensory neuron will talk directly to motor neuron – however, if there is any kind of processing, interneurons are employed. Endocrine system: - Chemical - Slow - Undirected Information comes into sensory neuron and goes out – creates a motor response. - Reflex Arc – comes in many forms – does not go to the brain and needs no processing. - Cerebellar Pathway: Same sensory neurons can go through a secondary pathway called cerebellar pathway – using brainstem (which receives information from cranial neurons and the spinal cord – is part of an automated system – begin life with a blank cerebellum then train cerebellum how to respond to stimulus – i.e. walking is a trained cerebellar response. [99% of the time, you do not need to tell your legs to directly walk] – Drives motor functions. - Lemniscal pathway – still getting information from same sensory neurons, but processes it for a much higher function. – used in sharing information with another person. Summary: For every stimulus, generally there are these three different pathways of response. Note : Neuron that starts in the toes and progresses all the way up – 3 ½ feet long. – a nerve is a bundle of those axons. e.g. a whale could have a 24 feet long neuron (single cell) e.e.g. a giraffe – big neurons. Speed through neurons – 130-140 mph. – this is a major theme of the 1 st exam. Reflex Response Tests motor stimulus and muscle tone. – hitting patellar tendon and stretching muscles – hamstrings and quadriceps on side – muscle on the top is the extensor, muscle on the bottom is the flexor. Extensor thought it was being stretched – Top of calf, pulls thigh away– natural response is to make muscle shorter – (spindle body) – comes up through long dendrite and into spinal cord and synapses directly onto a motorneuron or an interneuron. Flexor – pulls the thigh closer to the body
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1/14/08 – 1/18/08 Dorsal Root Ganglia – What is this? Tell about the effects of different things done to it. Gray matter of body of the spinal cord Signal that comes out on ventral side comes back (motor neurons) Blue signal comes and says fire - Stimulus that results in an inhibition of a motor neuron Excitation vs. Inhibition – what happens at the synapses. Axons – are same everywhere – the diversity comes from the interface from a interface between
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This note was uploaded on 08/25/2008 for the course BIO 365R taught by Professor Draper during the Spring '08 term at University of Texas at Austin.

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Week 1 - Afferent Sensory Neurons Efferent Motor neurons Glial cells(Schwann cells and Myelin Nodes of ranvier Interneurons connects sensory and

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