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Do the amplitudes of each component wave of the ECG change between cardiac cycles? Why or why not?

Yes since your heart rate fluctuates based upon your activity level. Resting heart rate varies greatly from your active heart rate.

The P wave and the QRS complex represent depolarization of the atrial and ventricular muscle respectively. Why does the QRS complex have the larger amplitude?

The QRS complex correlates with the action needed to push blood back out away from the heart that requires higher pressure.

Heart rate was calculated based upon the peak-to-peak interval of the R waves. Was there variability between the beats? Would you expect the interval between beats to be identical? Why or why not?

Yes, there was variability. The person's level of activity (how relaxed they are) varies throughout time.

The range for a normal resting heart rate is 60 to 90 bpm. A trained athlete could have a resting heart rate of 45 to 60 bpm. Why might a very fit person have a slower heart rate than someone of average fitness?

A very fit person's heart has been trained for intense activity. Their resting heart rate is lower because a fit person has a larger stroke volume. his means that their heart pumps a larger volume of blood per second. They have a greatervolume of oxygen that is delivered to the body per heartbeat.

Are the amplitudes and durations of the various waves in different individuals similar or very different?

In some cases, they are very similar and in others, they are very different.

What variations in heart rate did you observe between individuals?

Depending on the individual and their body make-up, some peaks were higher than others.

Explain why ventricular contraction (systole) and the 'lub' sound occur immediately after the QRS complex.

the closure of valves (the atrioventricula (mitral and tricuspid) valves).

Explain why ventricular relaxation (diastole) and the 'dub' sound occur after the T wave.

After the T-wave, when the ventricles relax, the blood pressure drops below that in the artery and the semilunar valves (aortic and pulmonary) close, producing the "dub" sound.

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