This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Cardiac output depends on all of the following except: September 2005 
Select and explain. 
A. Cardiac rate, B. Body surface area, C. Stroke volume, D. Cardiac contractility
B: Body surface area
Answer: B: Body surface area 
Explanation: Ans. B: Body surface area Cardiac Output (CO) = Stroke Volume x Hea Rate Normal SV is 70 mL and hence in a supine, resting man CO is 5.0 L/ min. (70 mLX 72 beats/min.) Cardiac Index (CI) = CO/ Body Surface Area (BSA) = SV x HR/BSA CI averages 3.2L