# Bioap4580 Problem Set 7 Key

Topics: Action potential, Heart, Sinoatrial node Pages: 3 (834 words) Published: March 11, 2013
BIOAP 458, 2012 Name: _______________________ Raw Score: ________/ 102, ________% PROBLEM SET 7 Cardiac Electrophysiology 1) (8 pts.) Match the most appropriate pairs _F__ AV node (atrioventricular node) _E__ gap junctions _G__ action potential generated by ventricular myocytes _H__ functions as the pacemaker of the whole heart _D__ calcium _C__ Bachmann’s bundle _A__ Bundle of His _B__ action potential generated by pacemakers

Prof. Beyenbach VRT 8014

A. ventricular conduction system that distributes the action potential arriving at the AV node B. slow response action potential C. mediates the atrial action potential from right to left atrium. D. primary mediator of excitation-contraction coupling E. eliminate the need for synaptic transmission in ventricular cardiomyocutes F. electrical connection between right atrium and right ventricle G. fast response action potential H. sinoatrial node

2) (6pts.) Find the most appropriate match describing the function of the fast inward Na+ channel. _B__ channel is closed and at rest _A_ channel is open and conducting _C_ channel is closed and unresponsive (refractory) A. both m and h gates are open B. h gate is open and m gate is closed C. both m and h gates are closed

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3) (12 pts.) a) (4 pts.) Draw the action potential of a pacemaker cell (slow response) as a function of time (solid line), identify the phases 0 through 4 and indicate the ionic currents dominating these four phases

b) (8 pts.) Complete the table to indicate the dominant ion and inward or outward current Phase 0 2 3 4 Dominant ion Ca Ca K K, Na, leak Inward/outward current inward current reduced inward current outward current K, reduced outward K current Na, funny inward current Leak, increased leak current

4) (14 pts) Find the appropriate match D_ shortly before the P wave A_ between P and Q B_ QRS complex C_ increased P-R interval G_ T-wave F_ not life threatening E_ occasional P without QRS A. cardiac impulse travels from SA node...