Electrical Activitiy of the Heart Flashcards
Internodal Tracts
Anterior, posterior, and middle pseudopathways (really just fiber orientation) extending from SA node through atria
Bachman’s Bundle
Only true anatomical specialized pathway, b/w SA node in RA and LA
Reversal Potential
Overshoots beyond 0 bc Na faster than Cl
Low Resistance Syncytium Effect (from gap junctions)
Longitudinal propagation is favored
Main Functional Reason for Cardiac Plateau
Allows the mechanistic action of the heart to do shit without electrical interference
Upstroke and Conduction Velocity in Relation to RP
Lower RP at depol means those 2 go faster
Modulator Peptide
Attached to ion pore to control characteristics of ion flow for different cardiac tissues
Cortical Cytoskeleton
On inside, keeps channel oriented properly across membrane
Ito
Transient outward K+ channel to bring back down from overshoot
Ik-ATP
Ligand gated ion channel kept closed by ATP. Under disease state, ATP can be depleted and it will open causing rhythm problems
Voltage-Dependent Recovery of Excitability
Delaying repol increases RP, so its dependent on voltage and time is just another function of voltage
Purkinje Fiber vs. Ventricular Muscle Repol Time Course
Purk longer, but both shorten w/ increased HR
Main Difference b/w Endo and Epicardium Channel Activities
Epi has much stronger repol currents and thus faster repol, so that’s why repol appears to go in opposite direction from depol
AV Node Purpose, and 2/3 contributing physiological factors
For delay b/w A and V contraction.
Depol entirely mediated by slow Ca channels
Repol to Maximum Diastolic Potential (MDP), but this isn’t where strongest current is. Instead it’s later
So you have energy and thus time-dependent recovery of excitation rather than voltage-dependent
Decremental and Incremental Conduction
As you approach AV Node, increased branching causes increased SA. You lose RP and thus upstroke and conduction velocity. Then opposite happens leaving the AV node
