Term
| what 2 cells types compose the nervous system? |
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Definition
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Term
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Definition
| neuronal process which carries outgoing information |
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Term
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Definition
| neuronal process which receives incoming signals |
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Term
| what are the 3 classes of neurons according to function? |
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Definition
sensory (afferent)
interneurons
efferent |
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Term
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Definition
| neurons that lie entirely within the CNS |
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Term
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Definition
| enlarged regions along autonomic axons that store and release neurotransmitters |
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Term
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Definition
| runs from the spinal cord to the muscles |
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Term
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Definition
| mitochondria and membrane bound vesicles |
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Term
| at the distal end of an axon the electrical signal is translated into? |
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Definition
| a chemical message, by secretion of a neurotransmitter, neuromodulator or neurohormone |
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Term
| where do neurons that secrete neurotransmitters/modulators terminate |
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Definition
| near their target cells (other neurons, muscles, glands) |
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Term
| where do neurons that secrete neurohormones terminate? |
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Definition
| near blood vessels (so the hormone can get into the blood stream) |
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Term
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Definition
| the region where an axon terminal meets its target cell |
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Term
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Definition
| the process of moving proteins down the axon |
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Term
| at what rate does slow axonal transport move? |
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Definition
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Term
| how do materials move during slow axonal transport |
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Definition
| by axoplasmic(cytoplasmic) flow. via actin and myosin |
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Term
| what types of molecules are moved by slow axonal transport? |
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Definition
| neurofilaments and cytoskeletal proteins (molecules which are not consumed rapidly by the cell.) |
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Term
| at what rate does fast axonal transport move? |
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Definition
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Term
| how are molecules transported in fast axonal transport? |
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Definition
| via motor proteins that move along microtubule tracks. |
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Term
| fast axonal transport can move molecules in 2 directions, what do they transport in what direction. |
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Definition
forward (anterograde):vesicles & mitochondria to the axon terminal
backward (retrograde) old cellular components |
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Term
| the four types of CNS glial cells |
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Definition
| oligodendrocytes, microglia, ependymal cells, astrocytes |
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Term
| 2 types of PNS glial cells |
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Definition
| satellite cells, Schwann cells |
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Term
| what is the purpose of glial cells |
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Definition
| provide physical & chemical support to neurons |
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Term
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Definition
| insulate axons in the PNS by wrapping around them forming myelin |
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Term
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Definition
| insulate axons in the CNS by wrapping around them forming myelin |
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Term
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Definition
| an insulating substance composed of multiple layers of phospholipid membrane |
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Term
| each wrap of myelin = how many membrane layers? |
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Definition
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Term
| how are myelin membrane layers connected |
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Definition
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Term
| how many axons is 1 Schwann cell associated with |
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Definition
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Term
| how many axons is 1 oligodendrocyte associated with |
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Definition
|
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Term
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Definition
| gaps between the myelin insulated areas of axons |
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Term
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Definition
| form supportive capsules around nerve cell bodies in ganglia |
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Term
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Definition
| a cluster of nerve cell bodies located outside the CNS |
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Term
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Definition
| specialized immune cells which are permanently located in the CNS |
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Term
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Definition
| highly branched; contact neurons,blood vessels may transfer nutrients between the 2 |
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Term
| how do astrocytes help maintain homeostasis in the ECF around CNS neurons |
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Definition
| by taking up K+ and neurotransmitters from the ECF. |
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Term
| how do astrocytes communicate with each other? |
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Definition
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Term
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Definition
| create a selectively permeable epithelial layer that separates the fluid compartments of the CNS |
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Term
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Definition
| the epithelial layer created by ependymal cells |
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Term
| where are neural stem cells located |
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Definition
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Term
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Definition
| predicts membrane potential for a single ion |
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Term
| what 2 factors influence membrane potential? |
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Definition
concentration gradients
membrane permeability |
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Term
| (Nernst equation) E-ion = |
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Definition
| 61/z * log(ion-out/ion-in) |
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Term
| in the Nernst equation what is z |
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Definition
| electrical charge of the ion |
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Term
| in the Nernst equation what are ion-in and out |
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Definition
| ion concentrations inside and outside the cell |
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Term
| what is the resting membrane potential of neurons |
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Definition
|
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Term
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Definition
| predicts membrane potential using multiple ions |
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Term
| put the GHK equation into words |
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Definition
| resting membrane potential is determined by combined contributions of concentration gradient * permeability |
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Term
| the resting membrane potential of cells is determined by |
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Definition
K+ concentration gradient
permeability to K+, Na+, Cl- |
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Term
| to change the membrane potential by 100mV what has to happen |
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Definition
| 1 of every 100,000 K+ must enter or leave the cell (a significant change in membrane potential by the movement of only a few ions |
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Term
| how does a cell change its ion permeability |
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Definition
| by opening/closing existing channels in the membrane |
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Term
| slow method of changing a cells ion permeability |
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Definition
| inserting/removing channels into/from the membrane |
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Term
| the 4 types of ion channels in the neuron? |
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Definition
| Na+, Ca 2+, Cl-, K+ channels |
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Term
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Definition
| is the ease with which ions flow thru a channel |
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Term
| mechanically gated ion channels |
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Definition
| found in sensory neurons; open in response to physical forces such as stretching/pressure |
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Term
| chemically gated ion channels |
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Definition
| found in most neurons; open/close in response to chemicals (neurotransmitters, intracellular signal molecules |
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Term
| voltage gated ion channels |
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Definition
| respond to changes in the cells membrane potential |
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Term
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Definition
| are actually voltage gated channels that remain open in the voltage range of resting membrane potential |
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Term
| which channel opens faster Na+ or K+ |
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Definition
Na+ opens very rapidly
K+ is slower to open |
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Term
| 2 classes of electrical signals |
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Definition
graded potentials
action potentials |
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Term
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Definition
| variable strength signals; lose strength as they travel thru a cell; short distance communication |
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Term
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Definition
| large constant strength depolarizations; travel long distance thru a neuron w/o losing strength. |
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Term
| why are they called graded potentials |
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Definition
| their size is directly proportional to the strength of the triggering event. |
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Term
| where is the trigger zone in sensory neurons |
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Definition
| next to the receptor where the dendrite joins the axon |
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Term
| where is the trigger zone in efferent and interneurons |
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Definition
|
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Term
| what happens if a graded potential that reaches the trigger zone is strong enough to depolarize the membrane to threshold voltage? |
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Definition
| an action potential is initiated |
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Term
| why do graded potentials lose strength as they move thru the cytoplasm |
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Definition
current leak
cytoplasmic resistance |
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Term
| what happens if a graded potential that reaches the trigger zone is not strong enough to depolarize the membrane to threshold voltage? |
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Definition
| the graded potential dies out |
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Term
| depolarizing graded potentials are |
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Definition
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Term
| hyperpolarizing graded potentials are |
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Definition
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Term
| what is the value for the threshold |
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Definition
|
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Term
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Definition
| a potential that is below the threshold when it reaches the trigger zone |
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Term
| what 2 channels do action potentials require |
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Definition
| voltage gated K+ and Na+ channels |
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Term
| name the 3 phases of an action potential |
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Definition
| rising phase, falling phase, after-hyperpolarization phase |
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Term
| the rising phase of the action potential is due to |
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Definition
| a sudden temporary increase in the cells permeability to Na+ |
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Term
| the inside of a cell has what charge |
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Definition
| negative (due to all the proteins) |
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Term
| about how high does an action potential go |
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Definition
|
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Term
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Definition
| the portion of the action potential above 0 mV |
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Term
| what happens when the cell membrane potential becomes positive |
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Definition
| the electrical force driving Na+ disappears (since now both Na+ and the cell are positive) |
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Term
| in an action potential what opens first? second? |
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Definition
first Na+ channels
second K+ channels |
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Term
| the falling phase of the action potential is due to |
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Definition
|
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Term
| when do Na+ channels close |
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Definition
| at the peak of the action potential (+30 mV) |
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Term
| after-hyperpolarization phase |
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Definition
| the action potential hyperpolarizes past -70 mV, due to K+ channels not done closing yet |
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Term
| how many gates do Na+ channels in the axon have |
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Definition
|
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Term
| what are the 2 gates in axonal Na+ channels |
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Definition
| activation & inactivation gates |
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Term
| when a neuron is at resting membrane potential, the activation gate of the Na+ channel is |
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Definition
| closed (no Na+ moves thru the channel) |
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Term
| when a neuron is at resting membrane potential, the inactivation gate of the Na+ channel is |
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Definition
|
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Term
| when does the Na+ channels activation gate open? |
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Definition
| when the cell membrane near the channel depolarizes |
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Term
| when does the Na+ channels inactivation gate close? |
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Definition
| when the cell membrane near the channel depolarizes (it closes 0.5 msec after the activation gate opens) |
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Term
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Definition
| the period of time (2 msec) in which a second action potential cant be triggered after a first |
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Term
| what is happening during the refractory period |
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Definition
| the Na+ channel gates are resetting to their original positions |
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Term
| relative refractory period |
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Definition
| the period of time after absolute refractory period in which a strong than normal graded potential is needed to initiate an action potential |
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Term
| what is the cause of the relative refractory period |
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Definition
| most, but not all Na+ channel gates have reset to their original positions and K+ channels are still open |
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Term
| how does the neuron transmit info about the strength/duration of the stimulus that started the action potential? |
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Definition
| by frequency of action potential propagation (action potentials per second). |
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Term
| what happens to an action potential if you inhibit the Na-K pump of a neuron and then stimulate it over and over |
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Definition
| there is no immediate effect, but they diminish over time and eventually disappear |
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Term
| one action potential does not alter ion concentration gradients (true or false) |
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Definition
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Term
| action potentials are conducted from where to where |
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Definition
| trigger zone to axon terminal |
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Term
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Definition
| high speed movement of an action potential thru the axon |
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Term
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Definition
| the flow of electrical energy from one part of the cell to another in a process that constantly replenishes lost energy |
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Term
| if you place an electrode in the middle of an axon and depolarize the cell above threshold, which direction will the action potential travel? |
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Definition
| in both directions (towards the axon terminal and the cell body) |
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Term
| what are the physical parameters that influence the speed of action potential conduction in neurons |
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Definition
diameter of axon
resistance of axonal membrane to ion leakage out of cell |
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Term
| what physical parameters will increase action potential conduction in neurons |
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Definition
larger diameter axons
more leak resistant membrane |
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Term
| conduction is faster in myelinated or unmyelinated axons? |
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Definition
|
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Term
| what makes conduction more rapid in myelinated axons? |
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Definition
| channel opening slows conduction slightly and myelinated axons only have to open channels at Nodes of Ranvier |
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Term
| what is the most common demyelinating disease |
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Definition
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Term
| symptoms of multiple sclerosis |
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Definition
| fatigue, muscle weakness, difficulty walking, loss of vision |
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Term
| demyelinating diseases are |
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Definition
|
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Term
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Definition
| increase in blood K+ levels; will shift resting membrane potential closer to threshold, action potentials will fire in response to smaller graded action potentials |
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Term
|
Definition
| decrease in blood K+ levels; pushes resting membrane potential further from threshold |
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Term
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Definition
|
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Term
|
Definition
| pass electrical current from the cytoplasm of one cell to another thru gap junctions |
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Term
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Definition
| use neurotransmitters to carry info from 1 cell to the next |
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Term
| neurotransmitters are transported to the axon terminal by |
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Definition
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Term
| what is the signal for neurotransmitter release at the synapse |
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Definition
|
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Term
| what type of channels does the axon terminal membrane have |
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Definition
| voltage gated Ca2+ channels (they open in response to depolarization) |
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Term
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Definition
| synaptic vesicle doesnt fuse with presynaptic membrane, instead it creates a channel just large enuff for neurotransmitter to pass thru then pulls back |
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Term
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Definition
| at a synapse and elicit a rapid response |
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Term
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Definition
| at both synaptic and nonsynaptic sites and are slower acting |
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Term
| 7 classes of neurocrine molecules |
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Definition
| acetylcholine, purines, amines, amino acids, gases, lipids, peptides |
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Term
| the PNS secretes only 3 major neurocrines, what are they |
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Definition
acetylcholine and norepinephrien (neurotransmitters)
epinephrine (neurohormone) |
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Term
| where does the synthesis of acetylcholine take place |
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Definition
|
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Term
| neurons that secrete norepinephrine are called |
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Definition
|
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Term
| norepinephrine is the major neurotransmitter of |
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Definition
| peripheral autonomic sympathetic division |
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Term
| primary inhibitory neurotransmitter of the spinal cord |
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Definition
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Term
| ACh is rapidly broken down by |
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Definition
|
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Term
| dopamine, norepinephrine, epinephrine are all derived from |
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Definition
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Term
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Definition
|
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Term
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Definition
|
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Term
| neurotransmitter w/no receptor |
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Definition
|
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Term
| 2 classes of neurotransmitter membrane receptors |
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Definition
ligand gated ion channels
G protein coupled receptors |
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Term
| 2 main subtypes of cholinergic receptors |
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Definition
|
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Term
|
Definition
| monovalent cation channels (Na+, K+) found on skeletal muscle in CNS and PNS |
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Term
| muscarinic receptors in CNS and PNS |
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Definition
|
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Term
|
Definition
have alpha and beta subtypes
are linked to G proteins |
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Term
| if a synaptic potential is depolarizing it is called |
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Definition
| excitatory postsynaptic potential |
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Term
| if the synaptic potential is hyperpolarizing it is called |
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Definition
| inhibitory postsynaptic potential |
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Term
|
Definition
| neurotransmitters bind to receptor channels |
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Term
|
Definition
| neurotransmitters bind to G protein receptors |
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Term
|
Definition
| a single presynaptic neuron branches and targets multiple neurons |
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Term
|
Definition
| multiple presynaptic neurons target a smaller # of postsynaptic neurons |
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Term
|
Definition
| multiple subthreshold EPSPs sum to create a suprathreshold potential |
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Term
|
Definition
| summation that occurs from graded potentials overlapping in time. (ie: 2 potentials from the same presynapse) |
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Term
| what is a more precise means of control pre or postsynaptic modulation |
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Definition
|
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Term
| main excitatory neurotransmitter in the CNS |
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Definition
|
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Term
| what are the 2 types of receptors for glutamate |
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Definition
|
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Term
| disorders related to problems with synaptic transmission |
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Definition
| Parkinson's, schizophrenia, depression |
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Term
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Definition
| special tips on the axon of embryonic nerve cells that direct growth |
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