Session 2 Homework Assignment: Definitions
Define/Identify each of the following terms:
1. ) Depolarization:
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Change in the cardiac cell’s electrical charge from negative to positive that is
accomplished by sodium and potassium ions changing place
Causes a wave of electrical charge to course from cell to cell, resulting in a
discharge of electricity.
2.) Repolarization:
-​ Return of the cardiac cell to its electrically negative charge
-​ Accomplished by way of the sodium-potassium pump, an active transport
system
3.) Absolute Refractory: No stimulus can cause depolarization
4.) Relative Refractory: Strong stimulus can cause depolarization
5.) Supernormal Refractory: Even a weak stimulus can cause depolarization
6.) P wave: Atrial depolarization
7.) QRS complex: Ventricular depolarization
8.) T wave: Ventricular depolarization
9.) U wave: Late ventricular repolarization. Not usually seen.
10.) P-R segment: Flat line between P wave and QRS complex.
11.) S-T segment: Flat line between QRS complex and T wave
12.) Isoelectric line: The flat line between the T wave of one beat and the P wave of the next
beat.
13.) Automaticity: Ability to create an impulse without outside stimulation.
14.) Conductivity: Ability to conduct an impulse to neighboring cells
15.) Excitability: Ability to depolarize
16.) Contractility:Ability to contract. This is a “mechanical” characteristic
17.) Identify which of the following are electrical and which are mechanical (4 points):
a.) Automaticity- electrical
b.) Conductivity- electrical
c.) Contractility- mechanical
d.) Excitability- electrical