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| Three main parts of a neuron |
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Definition
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| Learning about structure allows us to learn about |
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| Every neuron has potentially several |
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| Main function of a neuron is to |
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| Info is recieved and integrated by ____ and goes down the _____ ______ to the _______. |
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Definition
soma, dendrites
myelin sheath
terminal |
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Term
| In spinal motor neurons, action potentials are initiated by the ___ which is located near the _____ |
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Definition
spike-initiating zones
axon hillock |
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Definition
| a chemical neurotransmitter is released to carry the signal to another cell |
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Definition
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| More complex the animal, the more |
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| The CNS contains most of an animals |
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Term
| A plasma membrane acts as a |
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Definition
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Term
| Plasma membrane separates |
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Definition
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Term
| Why do charges tend to line the membrane |
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Definition
| electrostatic interaction |
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Term
| When a microelectrode pierces a plasma membrane |
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Definition
| there is a shift in the recorded voltage |
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Term
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Definition
| movement of charged particles |
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Definition
| creating a concentration gradient |
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Term
| At electrochemical equilibrium, an electric potential difference exactly balances the |
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Definition
| chemical concentration gradient |
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Term
| If Cl was not permeable with a KCl solution |
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Definition
| only K would move of Cl which creates a current |
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Definition
| portion of cell that has nucleus "body" |
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Term
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Definition
| look like branches that form off soma plasma membrane. Portion of neuron associated with a particular function |
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Term
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Definition
| extensions from plasma membrane from soma. Distinguished by structure and function |
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Definition
| end of the axon, distinguished by function |
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Term
| Terminal buton is distinguished at |
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Definition
| potential for energy across every cellular membrane |
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Term
| If you have a high enough current |
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Definition
endocrine cell - releases hormones
neuron - fires signal |
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Term
| Unequal distribution of impermeable solutes: |
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Definition
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Term
| Differences in channel open states (K vs Na): |
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Definition
| more K channels and more are open than Na |
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Term
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Definition
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Term
| Extracellular fluid composition |
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Definition
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Term
| Cytosol fluid concentration |
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Definition
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Term
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Definition
| name of equation that describes the voltage we can predict from the movement of ions across a semi-permeable membrane. Can be referred to as an equilibrium potential, suggesting there is some sort of stored energy. |
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Term
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Definition
| cell is living, therefore the energy in the system is not 0 |
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Term
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Definition
| Electromotive force. An experimental term. It is due to the fact there is charge separation from K to Cl (from k movement), |
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Term
| In a living system, to decrease K permeability, does it require energy? |
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Definition
| Yes, it must close the channel. |
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Term
| Na/K pump contributes to Vrest in two ways: |
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Definition
1. Indirectly - maintaining high internal concentration of K
2. Directly - removing a small net amount of positive charge from the cell's interior |
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Term
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Definition
| diffusion of K through the membrane from inside the cell to outside, driven by the unequal concentrations of K and Na |
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Term
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Definition
| Large, quick, and short lived changes in membrane potential |
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Term
| Action potentials are a property of what kinds of cells? |
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Definition
| excitable (neurons and endocrine) |
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Term
| A more positive stimulus results in |
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Definition
| a more positive change in membrane potential |
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Term
| A neuron produces an action potential when |
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Definition
| Vmax reaches or exceeds the threshold potential |
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Term
| Two types of refractory periods |
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Definition
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Term
| Relative refractory period |
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Definition
| excitability is reduced so stronger stimuli are required to reach the threshold |
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Definition
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Term
| Strongly electric fish can produce currents up to |
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Definition
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Definition
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Term
| Mechanism of EOD (electric organ discharge) |
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Definition
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Term
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Definition
| controls the frequency of discharge from the electric organ |
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Term
| Signatures show evidence of |
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Definition
| speciation and convergence |
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Term
| Some neurons accommodate sustained stimulation. This is called |
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Definition
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Term
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Definition
| exhibit strong accommodation by producing one or two impulses at the beginning of the stimulus |
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Term
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Definition
| progressive lengthening of the inter-spike interval |
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Term
| Rising phase is correlated with the rise in |
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Definition
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Term
| Falling phase is correlated with the rise in |
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Definition
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Term
| Decrease in Na is caused by |
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Definition
| inactivation of Na channels |
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Term
| Decrease in K is caused by |
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Definition
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Term
| Are Na VGICs open all the time? |
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Definition
| No, but when they are they lat Na through |
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Term
| At resting, what voltage are we at? |
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Definition
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Term
| When stimulus is causing a positive shift in the membrane potential |
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Definition
| that creates a conformational change |
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Term
| • The Na moves down it’s electrochemical gradient from the outside to the inside of the cell when the channels open, which creates a |
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Definition
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Term
| What creates a positive shift in the membrane potential |
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Definition
| Moving the positive ion into the membrane |
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Term
| The door becomes activated by the _________ changes and closes, which cuts off the ___ flow. A ___ channel must open after this to create a ________ of the membrane. |
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Definition
positive
Na
repolarization
K |
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Term
| Three states a channel can have |
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Definition
Active, closed
Active, open
Inactive, closed |
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Term
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Definition
| can be closed during positive membrane potential. Numb to changes in the positive direction. Explains the absolute and relative refractory periods. |
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Term
| The structural conformation of the voltage-gated Na channel changes during |
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Definition
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Term
| In order to repolarize, must cause an increase in the _______ of the membrane. |
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Definition
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Term
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Definition
| positive feedback loop connecting membrane depolarization and Na conductance. It is responsible for the rising phase |
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Term
| The hodgekin cycle is initiated by a _________ of the membrane which is triggered from the _______ of the neuron and that is ________ of the VGICs. |
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Definition
depolarization
outside
independent |
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Term
| Under normal conditions, the positive feedback is interrupted by the ________ activation of ___ channels, which terminates the ________ phase. |
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Definition
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Term
| The hodgekin cycle can be stopped experimentally by voltage clamping the membrane, which |
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Definition
| prevents INA from changing Vm |
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Term
| Ion channels are selective |
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Definition
| allow some to pass through the membrane |
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Term
| Selectivity depends on the properties of the |
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Definition
-channel pore called the selectivity filter
-ease of dehydrating an ion - selectivity filter comes in direct contact to strip water from ions |
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Term
| K channel selectivity filter |
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Definition
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Term
| Na channel selectivity filter |
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Definition
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Term
| K channels are a complex of |
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Definition
| four monomeric a-subunits and four associated b-subunits |
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Term
| K channels. Four a-subunits span the ______ and are arranged around a _____ ______. B-subunits are located on the ________ face of the membrane, which affects |
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Definition
-membrane
-central pore
-cytoplasmic
-functional properties of a cell |
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Term
| In most K channels of eukaryotes, each monomer has: |
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Definition
- 6 membrane-spanning helices
-intra/extracellular segments that link the membrane-spanning regions |
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Term
| Membrane spanning helix S4 |
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Definition
| senses transmembrane voltage |
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Term
| A pH gated bacterial K channel consists of ___ monomers, each of which has ___ membrane spanning regions. |
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Definition
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Term
| S1 and S2 in ph bacterial K channels are homologous to ___ and __ in eukaryotes |
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Definition
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Term
| The selectivity filter consists of the sequences that link the two ______ _______ helices of each monomer, and it is so narrow at one point that it accommodates a K ion only if |
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Definition
-membrane spanning
-the water has been removed |
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Term
| The bacterial K channel is _____ shaped |
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Definition
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Term
| The voltage-gated Na channel look like |
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Definition
| 4 K channels linked together |
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Term
| Each Na channel contains a large _______ subunit that can form ________ _______ expressed by itself in Xenopus oocytes. |
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Definition
protein
functional channels |
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Term
| Two different kinds of subunits in voltage gated Na channel |
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Definition
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Term
| A protein of each channel contains |
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Definition
| -four homologous repeats of helical regions |
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Term
| Each set of 6 transmembrane helices in a VGNAC is homologous to |
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Definition
| a single voltage-gated K channel subunit |
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Term
| Voltage sensor in VGNAC is located |
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Definition
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Term
| Four homologous repeats in a Na channel are thought to associate with one another to form |
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Definition
| ion-conducting pore of a channel |
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Term
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Definition
-associate with a subunits and form the complete channel complex
-contribute to the physiological properties of the channel |
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Term
| A1 protein of VGCAC includes ___ sequential sets of __ transmembrane helices that are homologous to |
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Definition
4
6
transmembrane domains of VGNAC |
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