Term
| What turns on the (If) channel? |
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Definition
| Repolarization of the membrane during the preceeding Action potential |
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Term
| What causes the upstroke in the sinoatrial node? |
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Definition
| Increase in calcium conductance, causing an inward calcium current |
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Term
| In the slow conducting action potential, which phases are missing? |
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Definition
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Term
| What is conduction volume? |
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Definition
| The time needed for the excitation to spread throughout cardiac tissue |
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Term
| Conduction velocity is highest in the AV node and slowest in the Purkinje system. |
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Definition
Both statements are false
- Fastest in purkinje system
- Slowest in AV node |
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Term
| Why is conduction velocity slowest in the AV node? |
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Definition
| Allows for ventricular filling before ventricular contraction |
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Term
| Structurally, what does the conduction velocity depend on? |
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Definition
- Number of gap junctions
- Fiber diamter |
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Term
| Physiologically, what determins the conduction velocity? |
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Definition
- How fast the change in voltage occurs (Phase 0) (dV/dt)
- APA (don't know what this is) |
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Term
| What three things determine the Electrical activity of the heart? |
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Definition
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Term
| What changes do Chronotropic effects have? |
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Definition
|
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Term
| What changes do dromotrophic effects have? |
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Definition
| Produce changes in conduction velocity |
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Term
| What areas of the heart have parasympathetic vagal innervation? |
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Definition
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Term
| What does the ST segment represent? |
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Definition
| The period when the ventricles are depolarized and contracting |
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Term
| What segments of the ECG are isoelectric portions without waves? |
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Definition
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Term
| Which intervals of the ECG can be used to measure heart rate? |
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Definition
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Term
| T/F In the heart, the first tissue to depolarize is the first to repolarize. |
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Definition
| False, the first tissue in the heart is the last to repolarize |
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Term
| What are Paroxysmal Tachycardias? |
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Definition
| Tachycardias which arise from an ectotopic focus. |
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Term
| How long can Paroxysmal Tachycardias last for? |
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Definition
- A few beats
- Many hours
- Days |
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Term
| Are paroxysmal tachycardias recurring? |
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Definition
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Term
| List three things that may cause a paroysmal tachycardia? |
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Definition
- rapid firig of an ectopic pacemaker
- triggered activity secondary to afterpotentials that reach threshold
- An impulse that circles a reentry loop repeatively |
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Term
| What are two examples of Supraventricular Tachycardias? |
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Definition
| Atrial flutter and Atrial Fibrilation |
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Term
| What does atrial flutter look like on an ECG? |
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Definition
| Numers rapid flutter waves. Ventricular rate may be regular or irregular depending on degree of block |
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Term
| What aspect of the ECG is missing in heart going through atrial fibrillation? |
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Definition
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Term
| In a second degree AV block, All QRS complexes are preceeded by a p-wave, but not all p-waves are follwed by a QRS complex |
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Definition
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Term
| What are the two types of second degree AV blocks? |
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Definition
- Mobitz I (Wenckebach)
- Mobitz II (Non-Wenckebach) |
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Term
| What does the ECG look like in a Mobitz I AV block? |
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Definition
| Pressive lengthening of the PR interval with intermittent dropped beats (QRS complexes) |
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Term
| What does the ECG look like in a Mobitz II AV block? |
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Definition
| Sudden drops of QRS complex without prior PR lengthening. |
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