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PGY 412: Exam 1
Electrical transmission uses ___ _______ across the membrane to generate electrical potentials
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ion channels
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In chemical transmission, 2 neurons are not directly connected.. one neuron releases ________ _________ at the terminal which act on the next neuron through receptors to initiate an electrical signal
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chemical messengers
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ion channels are usually _______, meaning when they are open, ion movement is along the concentration gradient.
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passive
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ion channels can be _____ ______, meaning they open when the membrane reaches a given potential
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voltage gated
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Na+/K+ ATPase pump use ___ to move ions _____ their concentration gradients
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ATP, against
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ion channels that open when ligand bind to the receptor on the surface:
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ligand gated
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Intracellular Na+ and Cl- is ______, while extracellular K+ is _____.
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high, low
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A means of calculating the equilibrium potential of a given ion across the membrane
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nernst equation
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resting membrane potential:
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-70 mv
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Resting membrane potential is primarily driven by the flux of __ out of the cell down its concentration gradient through ____ __ channels
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K+, leak K+
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The Na+/K+ ATPase pump maintains the negative membrane potential by actively pumping __ out of he cell and __ into the cell against their concentration gradients
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Na+, K+
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Moving the membrane potential from negative toward zero
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depolarization
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The polarization of the membrane from zero to a positive
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overshoot
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Going back to the negative resting membrane potential
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repolarization
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Going more negative than the resting membrane potential
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hyperpolarization
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First step of action potential (rise)
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Na+ channels open, Na+ enters cell
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Second step of action potential (top of peak)
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K+ channels open, K+ begins to leave cell, Na+ channels close
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Third step of action potential (fall)
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K+ channels close
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Last step of action potential (leveling out)
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Excess K+ outside diffuses away
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Sodium channels open and inactivate very _____
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rapidly
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Potassium channels open and close _____
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slowly
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A period of time during which a second stimulus cannot induce a new action potential
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absolute refractory period (Na+ channels cannot re-open)
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A period of time after the absolute potential can be induced but requires a stronger stimuli
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relative refractory period (some, but not all Na+ channels have returned to their resting state)
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Saltatory conduction - action potentials only occur at ______ __ _______
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nodes of Ranvier
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Saltatory conduction - implies jumping of AP, but it doesn't actually jump it _______ __ ____ ____
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regenerates at each node
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Saltatory conduction means ________ __________ is much faster than an unmyelinated axon.
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signal propagation
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Synaptic transmission involves... (3)
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neurotransmitter molecules, synapse, receptor
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This type of signal allows information from many different sources to influence a cell's activity
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convergence
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This type of signal allows one cell to influence multiple pathways
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divergence
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The ________ terminal contains synaptic vesicles, which hold the neurotransmitter.
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presynaptic
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The ________ ______ is a 10-20nm space between the cells
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synaptic cleft
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The __________ _______ is populated with receptors, which allow the initiation of the new action potential in the receiving cell
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postsynaptic density
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Synaptic transmission - _____ ______ triggers release of neurotransmitters
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action potential
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Activation of the postsynaptic cell involves _ proteins
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G (metabotropic)
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The binding of a ligand (the neurotransmitter) to the receptor opens the ion channel
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ionotropic
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The binding of a ligand to the receptor activates a SECOND MESSENGER protein, a G protein, which can either directly activate an ion channel or activate an intracellular signaling cascade which will activate an ion channel
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metabotropic
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(ionotropic vs. metabotropic) Bottom line: most of the time, _____ ______ opens ion channels
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receptor activation
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Negative interior of cell, means that it is ____polarized
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hyper
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Positive interior of cell, means that it is ____polarized
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de
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EXCITATORY SYNAPSES usually involve the opening of __ or __ channels
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Na+ or Ca2+
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INHIBITORY SYNAPSES usually involve the opening of __ or _ channels
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Cl- or K+
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A change in membrane potential relative to resting potential is known as a _______ _________
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graded potential
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The potential changes in the membrane that occur at an excitatory synapse (depolarize - Na+ channels)
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excitatory postsynaptic potentials (EPSP)
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The potential changes that occur at an inhibitory synapse (hyperpolarize - Cl- channels)
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inhibitory postsynaptic potentials (IPSP)
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Synaptic integration - temporal means
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time
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Synaptic integration - spatial means
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2 different synapses fired
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Neurotransmitters are all VERY DIVERSE, YET ALL CLASSIFIED AS NEUROTRANSMITTERS. Ok?
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Ok
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Ach is inhibitory or excitatory?
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excitatory
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Glutamate is inhibitory or excitatory?
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excitatory
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GABA is inhibitory or excitatory?
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inhibitory
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