Action potentials - picture questions Flashcards
What is repsonsible for Phase 0?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/731/958/q_image_thumb.jpg?1659517718)
Voltage-gated Na channels open (Na influx)
What is repsonsible for Phase 1?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/732/297/q_image_thumb.jpg?1659517720)
Voltage-gated K channels begin to open (K+ efflux)
What is responsible for Phase 2?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/732/480/q_image_thumb.jpg?1659517720)
Ca2+ influx through voltage gated Ca2+ channels — Balances K efflux
Ca2+ triggers Ca2+ release from sarcoplasmic reticulum & myocyte contraction
What is responsible for phase 3?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/732/720/q_image_thumb.jpg?1659517721)
Massive K efflux due to opening of voltage-gated slow K channels & closure of voltage-gated Ca channels
What is reponsible for Phase 4?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/732/842/q_image_thumb.jpg?1659517721)
Resting potential: high K permeability thru K channels
What classes of antiarrhythmics affect ventricular APs?
Class I: Na+channel blockers
Class III: K+ channel blockers
What class of antiarrythmic drug is this and what are 3 examples?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/733/314/q_image_thumb.png?1659517721)
Class Ia
Quinidine, Procainamide, Disopyramide
What class of antiarrythmic drug is this? What are two examples?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/734/175/q_image_thumb.jpg?1659517724)
Class IB
Lidocaine, Mexiletine
What class of antiarrythmic drug is this? What are two examples?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/734/331/q_image_thumb.jpg?1659517724)
Class IC
Flecainide & Propafenone
Which of the class I is best post-MI? Which is contraindicated?
Class IB: Lidocaine, Mexiletine
**Preferentially affect ischemic or depolarized Purkinje/ventricular tissue
**Class IC: Flecainide, Propafenone **
Proarrhythmic
What side effect is noted with quinidine?
Cinchonism: Headache and tinnitus
What side effect is noted with procainamide?
Reversible SLE-like syndrome
What side effect is noted with Disopyramide?
Heart failure
What effect do K+ channel blockers have on the ventricular AP?
↑ AP duration
↑ Effective Refractory Period (ERP)
↑ QT interval
What are examples of the class of drugs that have this effect?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/137/737/619/q_image_thumb.png?1659517726)
Class III: K+ blockers
“AIDS”
Amiodarone
Ibutilide
Dofetilide
Sotalol