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19 Cards in this Set
- Front
- Back
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neuron
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nerve cells that transfer information in the body
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glia
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supporting cells of the nervous system
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peripheral nervous system
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- sensory neurons (afferent neurons - going toward CNS).
- effector neurons (efferent neurons - motor neurons. going away from CNS). |
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central nervous system
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- consists of just brain and spinal cord
- interneurons. - integration. |
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neuron structure and function
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- dendrites - receive signals from stimuli.
- cell body - generic cell. - axon hillock - neuronal integration. neurons decide whether to fire. - axon - neural potential. responsible for flow of information. |
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how do neurons move along information?
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- as electrical charges by changing membrane potentials.
- membrane potentials change by integral membrane proteins that pump ions. - resting potentials and action potentials. |
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membrane potentials
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- sodium potassium ATPase ion pumps.
- pump 2 positives in, 3 positives out. - inside of cell is negative, potassium rich - outside of cell is positive, sodium rich - electrochemical gradient. |
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gated ion channels
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- ligand-gated ion channels - open or close by virtue of a CHEMICAL BINDING to the channel.
- voltage-gated ion channels - open or close by virtue of CHANGES in the MEMBRANE POTENTIAL. |
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hyperpolarization
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- large potential difference.
- positive ions move out, negative ions move in. - farther from the threshold. becomes more negative. |
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depolarization
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- sodium ions move to the interior.
- membrane potential closer to the threshold. becomes more positive. |
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action potentials
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- the signals conducted by axons when a threshold is breached.
- strong depolarizations lead to spike on the graph. - calls for response within the body. |
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steps of action potential
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1. resting state - Na channels and K channels closed. NA/K ATPase is open. inside (-), outside (+)
2. depolarization - Na channels slowly open. K channels close. NA/K ATPase still pumping. inside becoming more (+) 3. rising action potential - all Na channels open. K channels closed. 4. falling action potential - Na channels closing. K channels opening. 5. hyperpolarizing event - undershoot. |
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action potentials move _________ along the neuron (especially the axon).
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- UNIDIRECTIONALLY.
- think of "the wave" - starts with Na+ in. - undershoot prevents backwards movement of action potential. |
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factors influencing action potential speed
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- axon diameter - wider are faster.
- insulation of the axon - myelin sheath. saltatory conduction. |
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myelin sheath
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- made in: schwann cells (PNS) or oligodendrocytes (CNS)
- ions move between gaps of myelin - called nodes of ranvier. |
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synapse communication
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- electrical synapses - direct flow of electrical current through gap junctions.
- chemical synapses - release of chemicals (called neurotransmitters) by the presynaptic cell that binds to receptors on the postsynaptic cell. |
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chemical synapse
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- action potential comes to synaptic terminals.
- calcium channels open - vesicles with neurotransmitter fuse with presynaptic membrane. - neurotransmitter binds to ligand-gated ion channel receptor on postsynaptic membrane - ions rush in or out. |
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neurotransmitter causing depolarization and hyperpolarization
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- depolarization - excitatory postsynaptic potential (EPSP)
- hyperpolarization - inhibitory postsynaptic potential (IPSP) |
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summation
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postsynaptic potentials (in the receiving cell) are summed together
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