electrocardiogram ( chapter 11) Flashcards
P wave
Atrial depolarization
QRS complex
ventricle depolarization before contraction
T wave
ventricle repolarization
Polarization
when the normally negative potential inside the fiber becomes slightly positive and the outside becomes slightly negative
Voltage and time calibration in Electrocardiograms
10 horizontal lines are 1 mv. Vertical lines are for time. Every 25 lines is a second
Q-R interval
time between beginning of p wave and beginning of QRS complex. This is the interval between the beginning of electrical excitation of the atria and beginning of the excitation of the ventricles. usually about .16 sec.
Q-T interval
contraction of the ventricle. Generally about .35 sec.
heart rate calculation
Rate is the reciprocal of time interval between 2 successive beats. Normal interval between 2 QRS complexes is .83 so 60/.83= 72 beats per min.
what is the last part of the heart that is depolarized?
outer wall of ventricles near the base of the heart
how does the current flow in the hear?
from negative to positive from the base to apex
what is a bipolar limb lead test?
when two electrodes are placed on different parts of the body and read on a meter.
lead 1
negative is on right arm. positive is on left arm.
lead 2
negative terminal is on right arm and positive is on left leg
lead 3
negative on left arm, positive on left leg
Einthovens triangle
an imaginary triangle that connects the 2 arms and the left leg. The points at which the two arms connect electrically with the fluids around the hear. The lower apex is the point at which the left leg connects with the fluids
