Consider the following statements:

1.         Unlike mammals, the heart of fish has 2 chambers and that of reptile has 3 chambers. 2.         Epicardium, micocardium and endocardium are the three wall layers of human heart. 3.         Pericardial is the fluid present in the protective sac of the human heart.

Which of the statements given above are correct?

Statement 1: It is correct. In case of humans, other mammals and birds, the heart is divided into four chambers: upper left and right atria; and lower left and right ventricles. Fish, in contrast, have two chambers, an atrium and a ventricle, while reptiles have three chambers. Statement 2: It is incorrect. In a healthy heart, blood flows one way through the heart due to heart valves which prevent backflow. The heart is enclosed in a protective sac, the pericardium which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium. Statement 3: It is correct. Pericardial fluid is the serous fluid secreted by the serous layer of the pericardium into the pericardial cavity. The fluid is similar to the cerebrospinal fluid of the brain which also serves to cushion and allow some movement of the organ. Hence, the correct option is 2.