Flexi Says: Human organs are organized into organ systems. An organ system is a group of organs that work together to carry out a complex overall function. Each organ of the system does part of the larger job. The twelve important organ systems in the human body are: Cardiovascular, Lymphatic, Digestive, Endocrine, Integumentary, Muscular, Nervous, Reproductive, Respiratory, Skeletal, Urinary, Immune systems
