Jharkhand PSC Prelim Exam 2006 Solved Paper

(3) Heart development refers begins with the formation of two endocardial tubes which merge to form the tubular heart, also called the primitive heart tube, that loops and separates into the four chambers and paired arterial trunks that form the adult heart. The heart is the first functional organ in vertebrate embryos and in the human,beats spontaneously by week 4 of development.