Term
| Where does the ventricular action potential occur? |
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Definition
| Bundle of His and Purkinje fibers |
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Term
What happens at each phase?
[image] |
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Definition
Phase 0= voltage gated Na+ channels open
Phase 1=Na+ channels close. K+ channels open, K+ efflux.
Phase 2= Ca2+ influx balances K+ efflux. Ca2+ influx triggers Ca2+ release from SR and myocyte contraction.
Phase 3= massive K+ efflux due to opening of SLOW K+ channels and close of Ca2+ channels.
Phase 4= K+ permeability
(ventricular action potential) |
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Term
What happens at each phase?
[image] |
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Definition
Phase 0= opening of Ca2+ channels.
Phase 3= inactivation of Ca2+ channels and opening of K+ channels for K+ efflux.
Phase 4= slow spontaneous depolarization due to If Na+ channels.
(pacemaker AP) |
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Term
What does the PR interval represent?
[image] |
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Definition
| conduction delay through AV node |
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Term
What does the T wave represent?
[image] |
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Definition
| ventricular repolarization |
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Term
| What is the speed of the 3 cardiac pacemakers in order of fastest to slowest? |
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Definition
| SA>AV> bundle of His/Purkinje/Ventricles |
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Term
| Where depolarization and repolarization of the ventricles begins |
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Definition
| Begins on the left side of the interventricular septum |
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Term
| What is Torsades de pointes? |
|
Definition
| weird ventricular tachycardia that can progress to ventricular fibrillation and is associated with/caused by long QT intervals |
|
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Term
| irregularly irregular heart rate= |
|
Definition
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Term
| How to distinguish Afib on an ECG |
|
Definition
| no discrete P waves and unevenly spaced QRS complexes |
|
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Term
| 3 drugs used to treat Afib |
|
Definition
β-blocker
Ca2+ channel blocker
Digoxin
(also use Warfarin) |
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Term
| Describe atrial flutter on ECG |
|
Definition
| back-to-back atrial depolarizations with a "saw-tooth" appearance |
|
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Term
| 4 drugs used to treat atrial flutter |
|
Definition
class IA, IC, or III antiarrhhythmics
β-blocker |
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Term
| Describe a first degree AV block |
|
Definition
| asymptomatic prolonged PR interval |
|
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Term
| Describe a Mobitz type I 2nd degree AV block |
|
Definition
| progressive lengthening of PR interval until a beat is "dropped" (P wave not followed by a QRS) |
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Term
| Describe a Mobitz type II 2nd degree AV block |
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Definition
| Often 2 P waves to 1 QRS response. No lengthening of PR interval. |
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Term
Describe a 3rd degree (complete) AV block
Give 1 possible cause |
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Definition
Atria and ventricles beat independently. Atrial rate is fater than ventricular rate.
Can be caused by Lyme disease. |
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Term
When is atrial natriuretic peptide released?
What does it do? (3) |
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Definition
Released by atria in response to increased blood volume and atrial pressure.
1. causes generalized vascular relaxation
2. constricts efferent renal arterioles
3. dilates afferent renal arterioles (promotes diuresis) |
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