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21 Cards in this Set
- Front
- Back
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Ca efflux across the cell membrane (sarcolemma) must ______ __________ Ca influx (I-Ca).
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Exactly equal
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Altered [Ca]i modulates Ca ______ until influx and efflux are again in balance creating a new steady state.
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Influx
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The primary means of Ca efflux is the _________.
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NCX
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The NCX uses energy in the ______ gradient to _______ Ca during diastole.
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Na; extrude
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The NCX produces ____ Na in --> ___ Ca out.
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3; 1
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The _______ is a high capacity, low affinity transporter.
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NCX
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The NCX moves a lot of Ca but cannot get [Ca]i to ___________.
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Very low levels
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The ___________ pump directly extrudes Ca from the cell using energy of splitting ATP.
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Sarcolemmal
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Sarcolemmal CA-ATPase works when the [Ca]i is _____, and pumps a ___________ amount of Ca.
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Low; small
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Mitochondria can also accumulate _____.
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Ca
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Mitochondrial Ca uptake is ______ and requires _______ cytoplasmic Ca levels.
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Slow; high
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Mitochondrial uptake ________ ________ have a physiological role in contraction.
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Does not
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Mitochondrial Ca uptake plays an important role in regulating mitochondrial ________________.
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ATP production
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Intracellular organelles can transiently affect [Ca]i but cannot maintain ______ ______ Ca constant in the face of a mismatch btwn sarcolemmal Ca efflux and influx.
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Steady-state
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Action potential duration can influence ________ _____.
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Contractile force
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Reduction of APD to less than 150 msec results in contractions with ____ _____.
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Decreased force
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Decreasing APD ______ Ca entry via I-Ca.
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Reduces
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Reduced I-Ca provides a _____ trigger for Ca release from the SR.
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Smaller
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Reduced I-Ca provides a ____ Ca influx and therefore ____ Ca is available to fill SR Ca stores.
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Smaller; less
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A ____ duration action potential is really critical for cardiac contraction.
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Long
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If you decrease the APD to what would look like a skeletal muscle AP, there would ___ __ _____ time for cardiac muscle to contract b/c there would not be enough time for ____ _____.
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Not be enough; Ca influx (occurs during plateau)
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