What system comprises the heart, lymphatic organs, and blood vessels?

The cardiovascular system is responsible for the circulation of blood throughout the body, which includes the heart as the central pump, blood vessels that transport blood, and lymphatic organs that are involved in fluid balance and immune functions. This system plays a crucial role in delivering oxygen and nutrients to tissues, removing waste products, and supporting overall homeostasis.

The heart pumps oxygenated blood through arteries and returns deoxygenated blood via veins, while the lymphatic components help to return excess tissue fluid to the bloodstream and maintain fluid balance. Together, these elements form a vital network that sustains life by ensuring that all cells receive adequate blood supply and are able to function effectively.

Other systems mentioned in the options, such as the respiratory, digestive, and nervous systems, have different functions. The respiratory system focuses on gas exchange, the digestive system is concerned with nutrient breakdown and absorption, and the nervous system is responsible for processing sensory information and coordinating responses throughout the body.