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BB lecture 10-10 action potential

BB lecture 10-10 action potential - Chapter 48(pp.1015-1022...

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Chapter 48 (pp.1015-1022) Neurons - Cell communication by action potential Learning objectives: Be able to draw a typical vertebrate neuron and label its major features. Be able to diagram the phases of an action potential and explain the opening/closing sequences of the Na-channels and K-channels at each phase. Understand how a change in membrane permeability can affect membrane potential. Chapter 11 (pp.201-204) Cell communication – Signal transduction Explain the three stages of cell signaling: Reception, transduction, & response Terms to know include: depolarization, hyperpolarization, threshold, pre/post-synaptic cell, chemical synapse, saltatory conduction, graded potential, synaptic cleft. paracrine signaling, neurotransmitter, relay molecule,….
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Figure 48.5 Structure of a vertebrate neuron Dendrites Cell body Nucleus Axon hillock Axon Signal direction Synapse Myelin sheath Synaptic terminals Presynaptic cell Postsynaptic cell
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Fig. 48.12a,b The  resting potential  is negative (-70 to - 80 mV) inside the cell.   When the membrane potential becomes  more negative , it is called  hyperpolarization When the membrane potential becomes  less negative , it is called  depolarization .
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Figure 48.12 Graded potentials and an action potential in a neuron +50 0 –50 –100 +50 0 –50 –100 +50 0 –50 –100 Time (msec) Time (msec) Time (msec) 0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 6 Threshold Threshold Threshold Resting potential Resting potential Resting potential Hyperpolarizations Depolarizations Membrane potential (mV) Membrane potential (mV) Membrane potential (mV) Stimuli Stimuli Stronger depolarizing stimulus Action potential (a) Graded hyperpolarizations produced by two stimuli that increase membrane permeability to K + . The larger stimulus produces a larger hyperpolarization. (b) Graded depolarizations produced by two stimuli that increase membrane permeability to Na+. The larger stimulus produces a larger depolarization. (c) Action potential triggered by a depolarization that reaches the threshold.
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Hyperpolarization and depolarization Are both called graded potentials because the magnitude of the change in membrane potential varies with the strength of the stimulus
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The Resting Potential is … the membrane potential of a neuron that is not transmitting signals. An Action Potential results when a graded depolarization reaches a certain membrane voltage, the threshold. is a brief all-or-none depolarization of a neuron’s plasma membrane. is the type of signal that carries information along axons.
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Action potentials   are electrical  signals that have long-range  conduction:  1)   The  action  potential  is  self- propagating i.e.  it  maintains  its  intensity as it flows through the cell.
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