Cardiac AP Flashcards
Where is the fastest conduction in the heart found
His-Purkinje fibers (2-4 m/s)
Where is the slowest conduction through the heart
Through AV node, and then atria/ventricles
What are the fast K channels called
K(a)
What are the initial channels to open in an action potential
Na (m)
What are the slow K channels
K (b)
What are the leak K channels
K (c)
Phase 4 in SA node caused by action of what
Na (f) randomly depolarizing`
Phase 0 of SA node is due to
Opening of slow Ca channels and closing of K (b)
Phase 3 in SA node is caused by
Closing of Ca gates and opening of K(b)
Latent pacemakers are altered in what phase of the cycle
4 (random depolarization)
The speed of SA node velocity is correlated to the speed at which stage
0
What are the refractory periods in order of length
ARP->ERP->RRP->SNP
Chronotropic changes cause what phase to change
Phase 4
How does the parasympathetic slow heart rate
ACh from vagus goes to muscarinic receptors in SA and AV nodes
Decreases opening of Na(f) during phase 4
What causes valves to close
When pressure outside the area becomes greater than inside
What murmurs do we heart at S1
aortic or pulmonary regurg
OR
tricuspid or mitral stenosis
What murmurs do we heart at S2
aortic or pulmonic stenosis
OR
tricuspid or mitral regurg
What are systolic murmurs
AV regurg OR AP stenosis
What are diastolic murmurs
AV stenosis OR AP regurg
