There are 11 distinct organ systems in human beings, which form the basis of human anatomy and physiology. The 11 organ systems include the respiratory system, digestive and excretory system, circulatory system, urinary system, integumentary system, skeletal system, muscular system, endocrine system, lymphatic system, nervous system, and reproductive systems. There are other systems in the body that are not organ systems. For example, the Immune system protects the organism from infection, but it is not an organ system as it is not composed of organs. Some organs are in more than one system. For example, the nose is in both the respiratory system and also is a sensory organ in the nervous system. The testes and ovary are both part of the reproductive systems and endocrine systems.
