DATA Table 1 Baseline heart rate Minimum heart rate Maximum heart rate (bpm) (bpm) 79 60 Table 2 (bpm) 96 page 90 page up Pi P2 Pj P4 Ps P6 Correction Pre-squat Peak squat Correction post-squat Pre-standing Peak standing post- standing HR (bpm) 80 60 79 79 94 85 Time (s) 3631 33 23 28 43 Squatting P1 P3 82 This Time (s) Standing P6 page down onomic Re s to maintain a rate, amount of 'stem that is rece issues in the aor ing (see Figure 1 hich in turn acts Sudden increase "oreceptor senso oposite effect. sition and Above is a conceptual tracing of what may happen to your heart rate when you squat (P2) and then recover (P3-P4), before standing up (P4), and recover by P6. Your real tracing will be real data that is more challenging to read and may take some guessing as to what point your heart rate had recovered. DATA ANALYSIS 1. How much and in which direction (increase or decrease) did the heart rate change as a result of a. squatting? 25% b. standing? DECREME 17.5% INCREASE 2. How long did it take for the heart rate to stabilize after squatting? That is time between P2 and P3. P3-1 = x Tw page 91 3. What was the difference in heart rate between P2 and P3? 19 bpM 4. How long did it take for the heart rate to stabilize after standing? That is time between P5 and P6. 5. What was the difference in heart rate between P5 and P6? 6. Does recovery time from squatting equal the recovery time from standing? Which recovery takes longer? Explain. 7. Changing the heart rate is only one of a variety of homeostatic mechanisms that maintain a fairly constant blood pressure during changes in body position. The sympathetic nervous system helps by adjusting peripheral resistance in the arterial system. As this occurs the heart rate is able to normalize again. Compare the duration of the initial direction of heart rate change after standing to the recovery time. What does your data tell you about the relative speed of the change in peripheral vascular resistance as compared to that of the heart rate response? 8. Using your knowledge of heart rate response to a decrease in blood volume returning to the heart, suggest a way to evaluate (without the use of medical equipment) whether significant blood loss has occurred in an accident victim. 9. The majority of astronauts who are in a microgravity environment for several weeks will experience orthostatic hypotension and dizziness on return to Earth. What are possible mechanisms for this? (You will need to look this up) page 92