Chapter 17 Flashcards
What are the three parts of an action potential?
- Resting when the membrane is polarized (+ on the outside and - on the inside)
- Depolarization (+ on the inside and - on the outside)
- Repolarization
What are the major charge carriers in cardiac muscle cells?
Sodium, Potassium, Calcium
What are the 5 phases of an action potential? What is happening in each?
0: rapid depolarization, Na+ in
1: early repolarization, K+, Cl- out
2: the plateau, Ca+ in, K+ out
3: rapid repolarization, K+ out
4: the resting membrane, K+
What is automaticity?
- Spontaneously initiate an action potential
- back up system for the health to start up an action potential
Explain SA node, AC node, and Purkinjes.
SA node: 60-100/ where rhythmic impulse is generated
AV node: 40-60/ impulse from atria is delayed
Purkinjes: 20-40/ conducts impulse to all parts of the ventricles
What is excitability?
Responding to an impulse and then generating its own action potential
What is conductivity?
To conduct impulses
What is remissibility?
Having a beat that is regular
Explain the pathway in the electrical system of the heart.
Sa node/ Bachmann’s bundle > internodal tracts > AV node > bundle of his > left & right bundle branch > perkinjes
Explain the Depolarization and repolarization of an ECG.
- SA node-> AV node = atrial depolarization
- atrial depolarization= P wave (induces atrial systole)
- AP spread through bundle of his, bundle branches, punkinjes =ventricular depolarization
- ventricular depolarization= QRS (induces ventricular systole)
- ventricular diastole is induced when AP passes out of ventricles
- ventricular repolarization = T wave
- purkinje repolarization= U wave
What does fibrillation mean?
Disorganized current flow
What is sinus bradycardia? Manifestations?
- <60
- Normal/ ischemia (restriction of blood supple, decreased oxygenation
- S&S of decreased perfusion
What is sinus tachycardia? Manifestations?
- > or equal to 100
- normal with exertion/ fever
- ischemia, hypoxemia
- increased myocardial workload, decreases coronary artery perfusion
What is sinus arrest? Manifestions?
- Heart stops and starts up again
- not common and not forever (short pause)
- ischemia
What is sick sinus arrest?
- sinus arrest occurs frequently
- may need a pacemaker