Bio 100 Exam 4

Bio 100 Exam 4 - Class 10: 6/2 Lecture 10 (contd) Squid...

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Class 10: 6/2 Lecture 10 (cont’d) Squid – long nerve fibers The Nervous System 3 Major Parts - Sensory Receptors o Point at which information comes in from the outside o Eye = light, ears = pressure - Eye then sends information into the brain sensory input -- comes in through peripheral nervous system - Central nervous system -- Brain and spinal cord take that information and integrate it: puts it into sense for the organism - Once its integrated, the person sends out further signals ( motor output signals ) to the legs, for example, to do what the brain says to do Central Nervous system: - Integration - Brain and spinal cord Peripheral Nervous system: - Controls sensory input and motor output - All the nerves that come off the spinal cord and out of the brain Structure of a motor neuron - Structure of a nerve cell - Cell body, with spiderlike legs called dendrites that pick up signals - Signal passes down through the dendrites down the body of the cell and out to axon - Myelin sheath allows for a faster signal jump across Schwann cell : make myelin (a fatty molecule) - Myelin acts like an insulator At end, have synaptic knobs , which transfers signals to next cell jump across Resting potential – when it is not firing, lots of positive charge inside, not so many outside Difference in charge = gradient The action potential – signal opening up channels and allowing sodium to rush into cell 1. Resting state: no net ion flow across the membrane; voltage gated Na+ and K+ channels closed across the membrane; resting potential is maintained 2. Na+ channels open, K+ channels are closed; threshold potential is reached and action potential is triggered 3. Na+ channels close and inactivate. K+ channels open, and K+ rushes out
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4. The K+ channels close relatively slowly, causing a brief undershoot 5. Return to resting state Electrically gated channel : triggered by sodium rushing into axon (change in charge) - So then the sodiums rush in through a channel, and then they change the electrical systems next to them, which causes an electrical spike, etc. on and on and on down the length of the axon - **Think about dominos Neuro transmitters - Carried around in vesicles in the synapse (synaptic knob) - Chemicals that trigger action potential and cause next neuron to fire, or prevent it from firing - When the electrical signal gets to the end of the nerve, the vesicles dump their neurons into the synaptic cleft - Neurotransmitter binds to the receptor and the ions rush into the cell, causing the electrical signal in the dendrite - That’s how you have a signal that goes down the length of one neuron (*domino), and once you get to the end of the neuron, you have signals being passed from one neuron to the next, and then that neuron passes the signal along Lots of inputs coming in that determine whether to fire or not Constantly receiving inhibitory and excitatory signals Billions of signals coming into the brain very complicated!! Reason we don’t have instantaneous reflexes is because of the nerves
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This note was uploaded on 01/27/2012 for the course BIOL 100-31 taught by Professor J.campanella during the Summer '11 term at Montclair.

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Bio 100 Exam 4 - Class 10: 6/2 Lecture 10 (contd) Squid...

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