Which of the following statements (s) regarding the cardiac system is/are correct ?
(i) Human heart is an ectodermal derivative
(ii) Mitral valve guards the opening between the right atrium and left ventricle
(iii) SAN is located on the left upper corner of the right atrium
(iv) Stroke volume `xx` Heart rate = Cardiac output.

Options

A. (i) only
B. (i) and (ii)
C. (ii) and (iii)
D. (iv) only

Answer

D

Explanation

During a cardiac cycle, each ventricle pumps out approximately 70 mL of blood which is called stroke volume. The stroke volume multiplied by the number of heart beats per minute (heart rate) gives the cardiac output. Therefore, Cardiac output = Stroke `xx` heart rate `= 70 xx 72 = 5040` mL per minute i.e., 5 litres per minute.