11892095
| Questão | Responda |
| Electrical potential across a semipermeable membrane is established by ________. | Differences in ion concentrations across the membrane. |
| Aside from the concentrations of the ions, what are the two factors affecting the electrical potential? | 1. Temperature 2. charge of ion |
| What is the cell potential if all sodium pumps are made permeable? | +64 mV (peak of AP curve) |
| What is the cell potential if all postassium pumps are made permeable? | -85.6 mV (bottom of AP curve) |
| T/F: Action potential is established by the ion pumps. | F. It is a dynamic change in permeability of the cell membrane. |
| T/F: Sodium channels are voltage sensitive. | T. |
| T/F: Potassium channels respond faster than sodium channels. | F. They are slower. |
| Why is the cell's resting potential close to that of the reversal potential of potassium? | Because the sodium channels are mostly closed while potassium channels are mostly open at rest. |
| What causes the initial increase in voltage of the cell? | presynaptic input. |
| The refractory period is due to the inactivation of ________ channels. | Sodium |
| At the end of the axon, ______ influx is stimulated and vesicles containing _______are released. | Ca2+ influx. Vesicles with neurotransmitters. |
| T/F: Synaptic strength refers to the firing rate of a given neuron. | F. It measures how the presynaptic cell can change the soma voltage of its postsynaptic cell. |
| How is synaptic strength quantified? | By post-synaptic potentials. (in mV) |
| What are the two types of postsynaptic potentials? | 1. excitatory postsynaptic potential 2. inhibitory postsynaptic potential |
| What are the two types of summation of EPSP? | 1. temporal (multiple APs in a train) 2. spacial (multiple APs at different locations) |
| List 5 factors that affect synaptic strength | 1. number of connections (spatial summation) 2. size of postsynaptic soma 3. number of vesicles released per presynaptic action potential 4. number of postsynaptic receptors. |
| Order of recruitement of motor units? | Small and fatigue-resistance --> large and more fatigable |
| Why are larger post-synaptic neurons activated later? | There is more channels to allow charge to dissipate before building up past the threshold. |
| T/F: synaptic strength is remarkably stable under regular use conditions unless special situation occurs. | T. |
| Habituation is the | Reduction in postsynaptic response to the same stimulation over time. |
| Sensitization is the | Increase in postsynaptic response due to external reasons. |
| During the famous Aplysia study, the gill withdrawal response _________ overtime when no tail shock was given. | Reduced. |
| During the famous Aplysia study, the gill withdrawal response _________ when 1 tail shock was given during a single stimulation. | Increased drastically and remained relatively higher |
| The more tail shocks given, the more lasting the increase in gill withdrawal remained. | T. |
| Rank the effect on gill withdrawal due to the following stimulations: 1. 4 single tail shocks 2. no shocks 3. 4 trains of tail shock 4. 4 trains/ day for 4 days. | 4 trains/ day for 4 days > 4 trains > 4 single shocks > no shocks |
| Which neuron is activated during a tail-shock? | Facilitatory interneuron. |
| How does a SINGLE tail shock enhance the gill withdrawal? | 1. Activation of facilitatory interneuron 2. release of serotonin 3. serotonin combines with receptors on the sensory neuron 4. cAMP and protein-kinase A are acivated 5. inhibition of K+ channels 6. K+ cannot flow in at the end of AP 7. the AP stays around longer 8. more glutmate released to motor neuron 9. stronger response |
| How does long-term changes occur in sensitization? | genetic expression changes. |
| T/F: The CA1 cells stimulate the CA3 schaffer collateral cells. | F. CA3 stimulate CA1. |
| The EPSP after tetanus is (higher/lower) than that before tetanus. | Higher |
| T/F: The EPSP of pathway 2 is not affected by tetanus in pathway 1. | T. |
| The EPSP can last for up to a year. | T. |
| Can paring of presynaptic spikes with postsynaptic depolarization give LTP? | Yes. |
| What is responsible for the quick LTP? | 1. NMDA receptors become unblocked from Mg2+. 2. Ca2+ influx into the postsynaptic cell. 3. Increase in Ca2+ influx results in a cascade of reaction that results in the addition of AMPA receptors. 4. increased reaction to the same stimuli. |
| T/F: LTP at one site can only stimulate addition of AMPA at the same site. | F. It can also signal addition of AMPA at other locations. |
| T/F: LTP may cause the formation of new synapses. | T. |
| What is the cause of LTD? | Repeated low-frequency stimulation. |
| AMPA receptors are internalized in LTD. | T. |
| Spike-time dependent plasticity suggests that | LTP and LTD are determined by the relative timing of the pre and post-synaptic spike. |
| If pre- and post-synaptic activities occur at the same time, result is more likely ____________ | LTP. |
| If post-synaptic happens right before pre-synaptic cell, there is _________. | more likelihood of LTD. |
| If pre-synaptic happens right before post-synaptic activity, then there is ________. | more likely LTP. |
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