Question 2
An athlete competing in the steeplechase event (Figure 2) suffered a fall on the track, resulting in significant blood loss. Before the fall, his heart rate (HR) was 3 beats per second, and his stroke volume (SV) was 130 mL per beat. After the fall, due to the loss of blood, his stroke volume dropped to 80 mL per beat. In response, his body compensated by increasing his heart rate to 4 beats per second.
(a) Calculate the athlete's cardiac output (CO) before and after the fall. [2 marks]
Cardiac output measures how much blood the heart pumps per minute: $CO=HR\times SV$, where HR is in beats/min and SV is the volume pumped per heartbeat, in mL/beat.
(b) Despite the increased heart rate after the fall, the athlete felt lightheaded and weak. Why might this occur even though the heart rate has increased? [1.5 marks]
(c) One of the medical interventions that could be given to the athlete after the fall is intravenous (IV) fluid therapy. Explain how this therapy can stabilize the athlete's cardiac output and overall condition after significant blood loss. [1 mark]
(a) Calculate the athlete's cardiac output (CO) before and after the fall. [2 marks]
Cardiac output measures how much blood the heart pumps per minute: $CO=HR\times SV$, where HR is in beats/min and SV is the volume pumped per heartbeat, in mL/beat.
(b) Despite the increased heart rate after the fall, the athlete felt lightheaded and weak. Why might this occur even though the heart rate has increased? [1.5 marks]
(c) One of the medical interventions that could be given to the athlete after the fall is intravenous (IV) fluid therapy. Explain how this therapy can stabilize the athlete's cardiac output and overall condition after significant blood loss. [1 mark]