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26 Cards in this Set
- Front
- Back
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what are the relative intracellular/extracellular ion concentrations or the following ions:
K+ Na+ Cl- Ca++ proteins |
K+ → (↑)intracellular; (↓)extracellular
Na+ → (↓)intracellular; (↑)extracellular Cl- → (↓)intracellular; (↑)extracellular Ca++ → (↓)intracellular; (↑)extracellular proteins → (↑)intracellular; (↓)extracellular |
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what does the Nernst equation describe:
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the membrane potential established by a concentration difference for a single ion across a semipermeable membrane
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what is membrane potential
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the electrical potential difference (voltage) across a cell's plasma membrane.
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what is the resting membrane potential of a cell (in terms of relative charge):
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there is excess negative charge inside the cell compared to outside
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Membrane Conductance can be thought of as what:
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a measure of permeability
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if you (↑)conductance → effect: (polarization/flux)
K+ Cl- Na+ Ca++ |
(↑)conductance → effect
K+ hyperpolarize, efflux Cl- hyperpolarize, influx Na+ DEPOLARIZE, INFLUX Ca++ DEPOLARIZE, INFLUX |
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where do you find cardiac fast response action potentials: (x2)
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(1) atrial and ventricular myocytes
(2) conducting fibers of the Purkinje system |
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where do you find cardiac slow response action potentials: (x2)
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(1) sinoatrial node
(2) atrioventricular node |
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what are the type of action potentials depicted:
identify each phase: |
(see figure)
RRP = relative refractory period |
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what are the phases of the cardiac action potential and what is going on in each phase:
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Phase 0 fast upstroke of depolarization
Phase 1 rapid partial repolarization Phase 2 plateau depolarization Phase 3 repolarization to resting membrane potential Phase 4 resting membrane potential |
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what is the resting membrane potential in the cardiac cell:
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-90 mV
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how do the cardiac action potential phases differ in the slow from the fast responses: (x4)
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(1) no phase 1
(2) lower amplitude (3) phase 2 is less flat (less of a plateau) (4) relative refractory period extends into a larger fraction of the resting potential |
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how long is the duration of the ventricular muscle action potential and therefore its effective refractory period:
What is the consequence of this phenomenon with regards to cardiac cells: |
approximately as long as the mechanical event
tetany will not occur because very difficult to achieve summation → due to long effective refractory period |
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what is effective refractory period:
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During a cardiac cycle, once an action potential is initiated, there is a period of time that a new action potential cannot be initiated
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identify the effective refractory period:
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(see figure)
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what are the different types of potassium channels in cardiac muscle: (x4)
(what type of stimulus do they respond to) |
voltage regulated
and those that respond to: neurotransmitter hormone intracelular metabolsim (such as [ATP]) |
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During phase 4 there is an (efflux/influx) of potassium through a voltage-gated channel which tends to ___ the cell, referred to as the what:
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efflux
hyperpolarize inwardly rectifying K+ current (iK1) |
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for other electrically excitable cells, ___ concentration has a large effect on resting membrane potential
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extracellular potassium
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as the extracellular K+(↑), what happens to:
resting membrane potential: |
decreases
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why does the [K+] have more of an effect on membrane potential than [Na+]:
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K+ has a higher conductance than Na+
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Extracellular sodium concentration has almost no effect on ___ but has a large effect on the ___
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resting membrane potential
action potential amplitude |
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the cardiac cell resting potential is about ___
the threshold is about ___ |
-90 mV
-65 mV |
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The upstroke, phase 0, occurs when sufficient ___ channels are opened
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fast sodium
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what type of channels are responsible for the phase 0 rapid depolarization:
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Na+ channels
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what are the fast sodium channel activation gates:
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m gates
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what are the fast sodium channel inactivation gates:
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h gates
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