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
