ANATOMY

Detailed explanation-1: -Histologically, the heart is mainly composed of cardiomyocytes and connective tissue.

Detailed explanation-2: -The 3 types of muscle tissue are cardiac, smooth, and skeletal. Cardiac muscle cells are located in the walls of the heart, appear striped (striated), and are under involuntary control.

Detailed explanation-3: -The heart wall consists of three layers: the endocardium, myocardium and epicardium.

Detailed explanation-4: -The pericardium is a two-layered connective tissue sac that encloses the heart. The fibrous pericardium is the outer layer, and the serous pericardium is the inner layer. The space between the two layers is the pericardial cavity, that contains serous fluid.

Detailed explanation-5: -The epicardium is a layer of epithelial cells covering the surface of the heart. The epicardium migrates to the surface of the heart from villous projections in the region of the sinus venosus in birds and from the septum transversum in mammals.