The circulatory system is a network consisting of blood, blood vessels, and the heart. This network supplies tissues in the body with oxygen and other nutrients, transports hormones, and removes unnecessary waste products. The thoracic cavity lodges the heart covered with pericardium in the center and lungs with pleura on each side. The midline, narrow space with structures in between the two pleural sacs is called mediastinum. The blood vascular system consists of the heart and blood vessels through which blood circulates. This chapter describes mediastinum, pericardium, heart, coronary vessels, arteries of the body, and veins of the body. Pericardium is a fibroserous sac which invests and protects the heart and the roots of the great vessels. Heart is a hollow, conical, muscular organ situated in middle mediastinum covered by pericardium. In this chapter, long essay type and short essay type questions are also provided.