Chapter 1.c Concept Review: Refractory Periods

Question 1

what happens to myocardial cells once they enter phase 0, depolarization?

Answer 1

cells become refractory to conduction of incoming impulses

Question 2

refractory states are defined by what?

Answer 2

strength of impulse required for myocardial cell to generate and propagate an action potential

Question 3

during which phases are myocardial cells unable to propagate an action potential in response to a stimulus, REGARDLESS of strength of stimulus?

Answer 3

effective refractory period: phases 0, 2, and part of 3

Question 4

during which phase, before the cell has returned to its resting membrane potential of -90 mV, can myocardial cells respond to a STRONGER than normal stimulus?

Answer 4

relative refractory period: during phase 3 of repolarization

Question 5

define supranormal period

Answer 5

SMALLER than normal impulse can elicit normal action potential

Question 6

define reenterant circuit

Answer 6

consists of two separate pathways that differ in refractory period duration