18-neurophysiology (study guide) PDF

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Dr. Michael Lague Study Guide with Answers...

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BIOL 1270: ANATOMY & PHYSIOLOGY STUDY GUIDE: Neurophysiology 1) Membrane Potential (MP) a) What is the average resting MP of a neuron (in mV)? -70 b) What does the negative sign of this value indicate? c) Why is this value negative? Relate your answer to the relative numbers of Na+ and K+ leakage channels. Understand in which direction these ions diffuse across the membrane. d) What keeps Na+ and K+ ions from reaching equilibrium across the cell membrane? In other words, what maintains the concentration gradient of these ions? 2) Graded Potential a) What is a graded potential? Where on a neuron is it typically generated? b) How does a graded potential spread from the stimulus site? In other words, how does a change in MP at the stimulus site cause a change in MP at neighboring sites? c) Why do graded potentials operate only over short distances? 3) Action Potential (AP) a) What is an action potential? Where on a neuron is it typically generated and propagated? b) What does the AP curve look like? What do the different parts of the curve correspond to? c) What is depolarization? repolarization? hyperpolarization? d) What is the initial stimulus for an AP (at the axon hillock)? e) Understand what is happening with the Na+ and K+ voltage-gated ion channels during each of the three phases noted in 3c. What is the sequence of events? f) In what way is the depolarization phase characterized by a positive feedback mechanism? 4) Propagation of an AP a) How does an AP propagate down an unmyelinated fiber? What keeps the AP from going backwards (i.e., in the direction from which it came)? b) How does an AP propagate down a myelinated fiber? c) Where along a myelinated axon membrane are the voltage-gated ion channels concentrated? d) How does myelination affect the speed of transmission of the AP? Why? 5) The Synapse a) What is a synapse? b) What’s the difference between a presynaptic neuron and a postsynaptic neuron? c) Understand the 5 basic steps (discussed in class) involved in a chemical synapse. How does an AP at the axon terminals cause the release of a neurotransmitter? How are voltagegated Ca2+ channels involved? What is a synaptic cleft? What is the effect of the binding of neurotransmitter to a postsynaptic membrane? d) How does an excitatory synapse differ from an inhibitory synapse with respect to: - the name of the graded potential it causes - the particular ion channels involved (on the postsynaptic membrane) - whether it involves depolarization or hyperpolarization of the postsynaptic membrane e) Does the graded potential caused by an excitatory synapse always induce an AP? f) Why does the graded potential caused by an inhibitory synapse inhibit AP generation? 6) In what way can neurotransmitters be classified with respect to their effect? With respect to effect, does it matter what kind of receptor type the neurotransmitter interacts with? 7) In what ways can normal synaptic transmission be disrupted?...