The closed circulatory system means that the blood flow is in the vascular system. The blood in circulatory system flows in arteries and the veins. Nearly all vertebrates have closed circulatory system. The blood in the closed circulatory system does not bath the organs, but gets nutrition by the vascular system. The heart in closed circulatory system is chambered and blood is sent in to vascular system with high pressure to reach the extremities of the body. Even the blood volume in the closed circulatory system is lower then the open circulatory system.
The pulmonary circulation and the systemic circulation are the two types of the circulatory system involved in the closed circulatory system. The deoxygenated blood is carried from heart to the lungs for its oxygenation; the pulmonary circulation carries this out. The oxygenated blood is sent to rest of the organs of the body. This is done by the systemic circulation. The blood reaches the tissues through the network of capillaries. The blood is returned back to the heart by the venous system. The blood pressure in the venous system is lower compared to the pressure in the arterial system.
There is great ability for oxygen deliveries in the closed circulatory system. Also the ultra filtration of the blood is the process present in only in the closed circulatory system.
Also in the closed circulatory system the lymphatic system is separately working
One most important advantage is the system and pulmonary circulation maintains their pressure respectively.