Study Questions Lab 2

Question 1

Exercise 1:

1. What electrical and mechanical events take place in the heart during the R wave?

Answer 1

1. Electrical: Atrial repolarization and ventricular depolarization
2. Mechanical: Ventricles are stimulated to pump blood out of the heart and into pulmonary and systemic circulation (ventricular contraction)

Question 2

Exercise 1:

2. What events take place in the CV system during the R and pulse waves?

Answer 2

• R-Wave: Ventricular contraction pushing blood to the rest of the body, also arteries vasoconstrict to help with blood propulsion.
• Pulse wave: The pulse of blood that is propelling through the rest of the body.

Question 3

Exercise 1:
3. The signal recorded on the Pulse channel is the rate of change of the BP entering the subject’s finger tip. When this signal is integrated, the waveform displayed on the Pulse Integral channel is similar to an arterial pressure curve. Is there a short plateau or dip during each cycle displayed on the Pulse Integral channel?

Answer 3

1. Short dip during each cycle displayed on the Pulse Integral channel. It represents the dicrotic notch, caused by the aortic valve closing. When pressure in the aorta is greater than pressure in the LV, the aortic valve closes suddenly, causing some blood to flow back towards the closed valve. This results in a drop in arterial pressure, or the dichrotic notch we observe.

Question 4

Exercise 1:

4. What event recorded on the Pulse channel corresponds to the dichrotic notch? What causes a dichrotic notch?

Answer 4

During each cycle displayed on the Pulse Integral Channel, there is a short
plateau/dip on the cure that represents the dichrotic notch. It corresponds to the closure of the aortic valve as the ventricles have now relaxed enough where the ventricular pressure is less than the aortic pressure

Question 5

Exercise 2:
5. How does the HR from the subject at rest at 0, 30, 60, 90, and 120 seconds after exercise (recovery) compared? If there is any variation btwn the rates for each time period? Is there a trend and what is it?

Answer 5

Subject’s HR is highest at t = 0 seconds at the beginning of the recovery period. This gradually declines over successive 30 seconds intervals up until 120s of recovery, where the HR is still higher than at rest prior to
exercise. There was a non-linear dec in HR as the values fluctuated from larger to smaller changes in HR btwn different time intervals.

Question 6

Exercise 2:

6. How does the avg P-R interval from rest and each time period in recovery compare? Do you see any variation or trend?

Answer 6

The P-R interval is largest at rest and smallest at recovery time of 0 seconds (aka during exercise the P-R interval reduces). It gradually increases getting closer to resting level as recovery time progresses.

Question 7

Exercise 2:

7. How does the avg Q-T interval from rest and each time period in recovery compare? Do you see any trend of variation?

Answer 7

The Q-T interval is largest at rest and smallest at recovery time of 0 seconds. It gradually increases getting closer to resting level as recovery time progresses; this is similar to the P-R interval.

Question 8

Exercise 2:

8. How does the avg T-P interval from rest and each time period in recovery compare? Do you see any trend of variation?

Answer 8

The T-P interval is largest at rest and smallest at recovery time of 0 seconds. It gradually increases getting closer to resting level as recovery time progresses; this is similar to the P-R and Q-T interval.

Question 9

Exercise 2:
9. How does the avg R-Pulse interval from rest and each time period in recovery compare? Do you see any trend of variation?

Answer 9

The R-Pulse interval is largest at rest and smallest at recovery time of 0 sec. It gradually increases getting closer to resting level as recovery time progresses; this is similar to the P-R, Q-T and T-P intervals.

Question 10

Exercise 2:
10. How does the R-wave ECG amplitude from rest and each time period in recovery compare? Do you see any trend of variation?

Answer 10

The R-wave ECG amplitude is largest at rest and smallest at the first recovery time of 0 seconds. It gradually increases getting closer to resting level as the recovery time progresses.

Question 11

Exercise 2:
11. How does the avg pulse wave amplitude from rest and each time period in recovery compare? Do you see any trend of variation?

Answer 11

The avg pulse wave amplitude is largest at rest and smallest at the first recovery time of 0 seconds. It gradually increases getting closer to resting level as the recovery time progresses.

Question 12

Exercise 2:

12. Is there any effect on the BF thru subject’s finger as the subject is performing leg exercises?

Answer 12

Blood flow increased due to the increased in HR (and thus CO) during exercise. Although pulse wave amplitude decreased, the amount of blood with respect to time increased during exercise.

Question 13

Exercise 3:

13. Did the LP values of the subject at rest go up or down as his or her HP values increased?

Answer 13

As the subjects LP values increased, their HP values decreased. Then as the subject’s LP values decreased, their HP values increased. Therefore LP and HP show to have an inverse relationship. This makes sense since LP is associated with sympathetic activity and HP is associated with vagal activity

Question 14

Exercise 3:
14. How do the HRV ratios from the 1st thru the 5th min of the rest period compare? Is ur subject more or less “stressed” as the rest period passes?

Answer 14

Stress tends to be associated with a high LP and low HP, thus an HRV ratio that is elevated (LP/HP) indicating there is more sympathetic influence on HR at rest.
In the first 3 minutes of the cycle, the subject alternated between a higher and lower ratio, but during the last 3 minutes of the cycle, the ratio decreased demonstrating that the subject become less stressed as time progressed.