A test pilot was provided with a personal rocket backpack, intended to propel him up the side of a mountain. A range of body function monitors were supplied, so that these functions could be observed in real time on the ground. A parachute was also provided, designed to open automatically, so that he could land on the top of the mountain safely. During the first part of the flight, the rocket worked very effectively (perhaps too effectively), giving much more acceleration than was expected. The pilot fainted, but recovered as the rocket reached its maximum altitude. His body function monitors showed that just before he fainted, his BP fell and the blood volume in his legs increased. But as he recovered, the BP increased and the blood volume passing to his legs reduced.

1. Outline the most plausible explanation for the faint (he knew he had an automatically opening parachute, so you can assume he wasn’t terrified!). You will need to comment on changes in total peripheral resistance.
2. Give the most likely explanation for the recovery and BP increase.
3. At rest, the technician’s mean arterial blood pressure (BP) was 100mmHg and his cardiac output was 5L/min. What was the TPR?
4. During the walk up the mountain, the technician’s CO was 20L/min and his mean arterial blood pressure was 120mmHg.What was the TPR?
5. What are the factors that may affect blood flow to active muscles?
6. The test pilot’s reserve parachute opened just in time. What would the change in heart rate between that when his main parachute failed to open and his heart rate when the reserve parachute opened successfully? Why the change?