Flashcards
281 - Pacemaker action potential (add)
Cards in this deck (10)
- 1Pacemaker action potential occurs in what nodes?SA and AV nodes.
- 2Describe Phase 0upstroke—opening of voltage-gated Ca2+ channels. Fast voltage-gated Na+ channels are permanently inactivated because of the less negative resting potential of these cells. Results in a slow
conduction velocity that is used by the AV node to prolong transmission from the atria to ventricles. - 3Describe Phase 1Phase 1 is absent
- 4Describe Phase 2Phase 2 is absent
- 5Describe Phase 3inactivation of the Ca2+ channels and increased activation of K+ channels ---> increased K+ efflux.
- 6Describe Phase 4slow spontaneous diastolic depolarization due to If (“funny current”). If channels responsible for a slow, mixed Na+/K+ inward current; different from INa in phase 0 of ventricular action potential. Accounts for automaticity of SA and AV nodes. The slope of phase 4 in the SA node determines HR. ACh/adenosine decreases the rate of diastolic depolarization and decreases HR, while
catecholamines increases depolarization and increases HR. Sympathetic stimulation increases the chance that If channelsare open and thus increases HR. - 7In Phase 4, slow spontaneous ___________ ____________ due to If (“funny current”)Slow spontaneous diastolic depolarization due to If (“funny current”)
- 8In Phase 4, ___________ decreases the rate of diastolic depolarization and decreases HR, while ___________ increases depolarization and increases HR.ACh/adenosine decreases the rate of diastolic depolarization and decreases HR, while catecholamines increases depolarization and increases HR.
- 9In Phase 4, The________ of phase 4 in the SA node determines _________The slope of phase 4 in the SA node determines HR
- 10In Phase 4, Sympathetic stimulation increases the chance that If channels are open and thus _________ _________Sympathetic stimulation increases the chance that If channels are open and thus increases HR.
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- User has deleted their subject information Flashcards on 281 - Pacemaker action potential (add), created by Deleted user on 30/05/2017.
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- Deleted user · May 2017
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- May 30, 2017
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- Created by Victoria Wright · May 30, 2017
- Copied by Victoria Wright · May 30, 2017
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