The rate at which a ventricle pumps blood is called the cardiac output, which ca
ID: 64477 • Letter: T
Question
The rate at which a ventricle pumps blood is called the cardiac output, which can be determined by this formula: Cardiac Output = Heart Rate X Stroke Volume. Imagine that a healthy man’s heart has a cardiac output of 5.53 L/min and it beats 72.0 times per min at resting conditions. Question 1. What is the stroke volume of this man’s ventricle at the resting conditions? Please round your answer to one tenth of a milliliter (mL), and please note 1 L = 1000 mL. Question 2. Suppose the man starts to exercise, and his sympathetic cardiac nerve gets activated, which shortens the duration of pacemaker potentials in the SA node by 0.1 second. Question 2a: How would this change his heart rate? Question 2b: What is his current cardiac output? Please round your answer to one hundredth of a liter per min (L/min).
Explanation / Answer
Q 1). Stroke volume = Cardiac output/ Number of beats per min = 5.53 L min-1/ 72 min-1 = 0.0768 L or 76.8 ml
Q 2a). .The normal cardiac cycle duration is 0.8 sec. Given that, duration of pacemaker potentials in the SA node by 0.1 second, means the duration of cardiac cycle is decreased by one sec, i.e. 0.7. Now, the number of beats per min = 85. 7 or approximately 86 beats per min. The heart rate is increased.
2b). considering the stroke volume remains same, The current cardiac output = 86 beats min-1* 76.8 ml = 6604.8 ml/ min.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.