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52 Cards in this Set
- Front
- Back
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What is the integrative function of the nervous system?
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sending and processing of information to the right areas of the brain
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What is facilitation?
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transmission of certain neurotransmitters through a synapse makes it easier for the same reaction to occur again (think in terms of memory, if you see the same sentence many times you will read it faster each time)
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Theoretically, the spinal cord is able to function as a unit with out the brain. What does the brain really control?
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coordination of the information and responses. the spinal cord can sense and create reflexes without the brain
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Most subconscious control comes from what part of the brain?
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lower brain/subcortical
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Wakefullness is controlled by what level of the brain?
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subcortical/lower level
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Most electrical synapses are found in the form of ...
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gap junctions
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Chemical synapses use what to send the message?
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neurotransmitters
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One-way conductance is characteristic of what type of synapse? (chemical or electric)
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chemical/neurotransmitters
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Once the action potential reaches the end of the axon (pre-synaptic terminal), how is neurotransmitter released?
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action potential releases opens calcium channels and calcium flows into the terminal. calcium binds to release sites and leads to exocytosis of neurotransmitter
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What is the ionophore component of the receptor protein?
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on the post-synaptic receptors, the ionophore protein goes through the post synaptic membrane; can be ion channel or activate 2nd messenger
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Cation channels usually have what effect on the neurons?
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excitatory; help depolarize the neuron
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Anion channels usually have what effect on the neurons?
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inhibitory; increase polarization (decrease resting potential) so neuron firing is less likely
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The ionophore protein on the post-synaptic membrane can dissociate G-protein alpha to perform what functions?
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activate enzymes, gene transcription, open channels, cAMP production
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Acetyl CoA + Choline =
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acetylcholine
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Acetyl CoA + Choline = acetylcholine by using what enzyme?
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choline acetyltransferase
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Cholinesterase breaks acetylcholine into ...
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acetate and choline; choline re-enters presynaptic cleft and is recycled
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What happens to choline once Ach is degraded in the cleft by cholinesterase?
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re-enters the pre-synaptc neuron to be recycled
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What neurons of the autonomic nervous system use Ach?
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all preganglionics, and parasympathetic post-ganglionics (sympathetic post-ganglionics use epinephrine)
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Dopamine is usually (excitatory or inhibitory)?
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inhibitory
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GABA is usually (excitatory or inhibitory)
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inhibitory
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Glutamate is usually (excitatory or inhibitory)
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excitatory
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Serotonin is usually (excitatory or inhibitory)
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inhibitory
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Why is storage of nitric oxide in the presynaptic terminal unique form most neurotransmitters?
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it is not stored, but made immediately when the action potential reaches the terminal. then it diffuses out, doesn't use vesicles
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Most neurotransmitters are made in the pre-synaptic terminal of a neuron. Where are neuropeptides made?
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by ribosomes in the cell body (soma)
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What is axonal streaming?
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process of getting packaged neuropeptides form the soma to the terminal; slow
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Are neuropeptides stronger or weaker than small-molecule neurotransmitters?
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much stronger. they are made all the way in the soma and take a long time to reach the terminal. therefore they are found in small quantities in the terminal, so they must compensate by having a strong, long-lasting effect
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In a normal functioning neuron, sodium is found at a higher concentration (inside or outside) the neuron body?
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outside
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In a normal functioning neuron, calcium is found at a higher concentration (inside or outside) the neuron body?
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outside
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In a normal functioning neuron, potassium if found at a higher concentration (inside or outside) the neuron body?
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inside
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What is a Nernst potential?
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a force that exactly opposes ion movement
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Nernst equation
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EMF = 61 x log(inside/outside)
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If the concentration of sodium is 142 outside the cell and 14 inside the cell, the force needed to prevent sodium from having net movement is...
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61 x log(14/142) = 61 x 1.04 = +61mV
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The Nernst equation tell us...
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the potential (mV) at which there will be no net movement of an ions. for example, if the Nernst potential for sodium is 61 and the membrane potential is at -61, no net sodium will enter/exit
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Why is there little resistance to the electrical current in the soma?
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the diameter is so large
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Why is it important that there is little resistance to electrical conductivity in the soma?
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all the intracellular fluid should be the same resting potential; little resistance = quick movement of ions = uniform potential in soma
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What does an excitatory neurotransmitter do in the cleft to activate the postsynaptic neuron?
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increase the permeability to Na+ so it can depolarize
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What does an inhibitory neurotransmitter do in the cleft to inactivate the postsynaptic neuron?
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increase the permeability to Cl- so it is harder to depolarize
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GABA works as what type of inhibitory neurotransmitter?
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presynaptic; is open Cl- channels in the presynaptic neuron so the potential is lowered (further from the threshold) before it reached the synapse
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What is spatial summation?
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multiple neurons releasing the same neurotransmitter to a cleft leads to a quicker repsonse
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What is temporal summation?
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one neuron may fire/release neurotransmitter in quick succession to create a faster depolarization of the post-synaptic neuron
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What is neuronal facilitation (not related to memory)?
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some excitatory neurons can raise the resting potential close to the threshold but not at it yet. this allows for a very easily action potential to start with a small stimulus. it is just setting it up to go
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Why don't dendrites usually transmit action potentials?
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they don't have gated ion channels and have high thresholds; they transmit currents
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Where on a dendrite should an excitatory signal be received for the strongest result? (tips of the dendrite or closer to the soma)
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closer to the soma; the thin dendrites are permeable to ions. so if the signal for excitation is received on the tips, it may weaken as ions diffuse out of the dendrite
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What is decremental conduction?
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excitatory signal decreases as it travels from the tip of a dendrite towards the soma; due to thin membrane and ions diffusing out
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When would a neuron fire continuously?
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if the resting potential is above the threshold
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In a patient with seizures, why is it likely that the seizures will stop on their own?
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neuronal fatigue; they lose excitability as the levels of neurotransmitter are depleted and receptors are inactivated
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Acidosis has what effect on neuronal excitability?
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decreased excitability
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Alkalosis has what effect on neuronal excitability?
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increased excitability
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Hypoxia has what effect on neuronal excitability?
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decreased excitability
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Caffeine has what effect on neuronal excitability?
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increases excitability
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How does strychnine increase excitability of neurons?
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inhibits the natural inhibitory responses, making the excitatory signals overwhelming
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How do most anesthetics suppress neuron firing?
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increase threshold for excitation
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