NRSG 421 - ECGs Exam Questions And Correct Answers
automaticity - ANSWER the ability of cardiac pacemaker cells to spontaneously initiate
an electrical impulse (Usually done by the SA node)
Na, K, Ca - ANSWER Normal concentrations of these electrolytes are important in
maintaining automaticity
increased - ANSWER ____________________ automaticity can cause dysrhythmias
excitability - ANSWER ability of cardiac cells to respond to an electrical impulse
generated by pacemaker cells or other stimuli
depolarization - ANSWER this is the process where the cells electrically become excited
repolarization - ANSWER this is when cells return to the resting state
excitability - ANSWER the responsiveness of cardiac muscle cells by responding to an
outside stimulus. Can be chemical, drugs, low K/Ca, mechanical or electrical.
sodium enters cell - ANSWER what electrolyte is involved in depolarization?
potassium exits cell and calcium enters - ANSWER what electrolyte is involved in
repolarization?
calcium enters cell - ANSWER what electrolyte is involved in cardiac muscle
contraction?
, absolute refractory - ANSWER cell will not respond to further stimulation
relative refractory - ANSWER - vulnerable period
- some cardiac cells have repolarized and can be stimulated to respond to a stronger
than normal stimulus
bentricular depolarization and early repolarization - ANSWER When does the absolute
refractory period occur?
ventricular repolarization - ANSWER When does the relative refractory period occur?
protective mechanism - ANSWER The absolute refractory period is a __________________
_________________ that prevents the cell from responding to any type of stimulus
regardless of strength.
relative refractive period-ANSWER During this phase the cells can respond to a
stimulus, but it has to be very strong. A strong stimulus can cause a response because
some of the cells are depolarized and some of the cells are repolarized-a cell that is
repolarized is ready to receive another stimulus
super normal or vulnerable period-ANSWER During this phase a minimal stimulus can
cause a response.
repolarization- ANSWER The vulnerable period exists during the last phase of
____________________
R on T phenomenon- ANSWER A stimulus that occurs during the super normal or
vulnerable period is called _____________________.
conductivity- ANSWER the ability of the cardiac cells to transmit the electrical impulse
to adjacent cardiac cells (all cardiac cells possess this characteristic)
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