exam 2 study - 1. The neuron's resting membrane potential...

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1. The neuron's resting membrane potential a) -70mV is the resting potential and is a result of ions in the neuron b)microelectrodes are used to record synapses c) in resting state neurons are said to be polarized d)ion channels transfer ions in and out of the neuron, causing synapses e) different ions are Cl-, K+, Na+, and A- proteins. Sodium-potassium pumps transfer 2 K+ in for 3 NA+ out f) Potassium (K+) and Proteins (A-) have a higher intracellular concentration. g)Sodium (Na+) and chloride (Cl-) have a higher extracellular concentration. h)Results in the interior of the neuron being -70 mV compared to the outside. i) transporters are mechanisms for transferring molecules through membranes 2. Generation and conduction of postsynaptic potentials a) synapse caused by change in polarization, depolarization (decrease) and hyperpolarization (increase) b)depolarization causes EPSPs, hyperpolarization causes IPSPs c) graded responses – amplitude proportional to intensity of signal d)decremental – amplitude decreases as synapse travels 3. Integration of postsynaptic potentials and generation of action potentials a) threshold of excitation ~ 65 mV is where polarization will result in an action potential. b)Action potentials change polarization from -70 to 50mV in 1millisecond. c) All-or-none responses, action potentials either occur entirely or not at all. d)Temporal summation is the tendency for simultaneous synapse pulses to combine and grow or cancel one other out. (EPSP positive, IPSP negative) 4. Conduction of action potentials a) The Ionic Basis of Action Potentials i . Voltage activated ion channels open or close in response to change of membrane potential ii .once threshold of excitation has been broken, sodium channels will open, Na+ ions rush in, K+ channels open shortly after, membrane potential climbs to 50mV. Sodium channels close, end rising phase. iii .Repolarization phase starts when sodium channels close, causing membrane potential to drop back to -70mV, then K channels close for hyperpolarization. b)Refractory periods i . Absolute refractory period – 1-2 milliseconds after initiating an AP in which another AP cannot be initiated. ii .Relative refractory period – the period in which, after applying higher than normal levels of stimulation, it is impossible for the neuron to fire again. c) Axonal conduction of action potentials
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exam 2 study - 1. The neuron's resting membrane potential...

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