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Nicholas Boileau Despreaux
11/10/2018 Title: Anat & Phys 11/16/06 Objectives: To learn about the nervous system. Class Topics Nervous System Review "Honor is like an island, rugged and without a beach; once we have left it, we can never return." Nicholas Boileau Despreaux Saturday, November 10, :53 PM
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Class Assignments Read 240-270 11/16/06 Nervous system test 11/20/06
11/10/2018 Class Assignments What By When Read /16/06 Nervous system test 11/20/06 Due this class period Due next class period Due in the future
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11/10/2018 Review
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Animations Action potential Channel gating
11/10/2018 Animations Action potential Channel gating
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11/10/2018 Saltatory Conduction Movement of action potential along myelinated fibers Impulse moves from node of Ranvier to node of Ranvier Moves much faster due to the fact that the impulse jumps over the myelinated areas Can jump up to 3 mm sections 130 m per second compared to 10 m per second for unmyelinated
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Problems Speed = Distance/time
11/10/2018 Problems Speed = Distance/time Myelinated fibers can carry an action potential 150 m/s Unmyelinated fibers can carry an action potential 10 m/s How long does it take for an action potential to travel from the toe to the brain of a 1.8 m individual for each fiber?
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11/10/2018 All-none-response If a stimulus causes an action potential it will be sent the length of the neuron at maximum speed threshold stimulus minimum stimulus needed to send an action potential Summation a series of subthreshold stimuli that eventually add up to a stimulus
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Anatomy of a synapse Presynaptic neuron Postsynaptic neuron
11/10/2018 Anatomy of a synapse Presynaptic neuron Synaptic end bulb Synaptic vesicles Contain neurotransmitters Chemicals released to relay impulse Postsynaptic neuron Concave surface Synaptic cleft Space between the two neurons
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Physiology of a synapse
11/10/2018 Physiology of a synapse Nerve impulse enters synaptic end bulb Ca2+ ions enter bulb from outside Synaptic vesicles fuse with cell membrane Exocytosis of neurotransmitters Chemicals diffuse between cells Contact postsynaptic neuron (receptor protein) Can excite neuron or inhibit neuron Depends on what neurotransmitter is released Excited neurons open Na+ ion channels Neurotransmitter is immediately inactivated By enzymes (ex. acetylcholinesterase)
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Neurotransmitters Acetylcholine (Ach) Dopamine
11/10/2018 Neurotransmitters Acetylcholine (Ach) neuromuscular junction prominent in PNS Dopamine brain processes that control movement, emotional response, and ability to experience pleasure and pain. Norepinephrine & Epinephrine also called adrenaline sympathetic branch of autonomic system
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Neurotransmitters Serotonin Melatonin Endorphins found in brain
11/10/2018 Neurotransmitters Serotonin found in brain Melatonin brain - used in sleep Endorphins inhibit the transfer of pain impulses opiates bond to same receptors morphine, heroin, codeine
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Neurotransmitter actions
11/10/2018 Neurotransmitter actions Inhibitory hyperpolarizes the cell membrane below resting potential unable to conduct an action potential Excitatory depolarizes the cell membrane action potential is sent to next neuron
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Good Links http://www.zerobio.com/central/actionpotential.htm
11/10/2018 Good Links
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