Organ system

An organ system is a group of organs that work together as a biological system to perform one or more functions. Each organ does a particular job in the body, and is made up of distinct tissues.
Organ systems and their functions.
There are 11 distinct organ systems in human beings, which form the basis of anatomy. Other animals have similar organ systems although simpler animals may have fewer organs in an organ system or even fewer organ systems Plants too have organs such as flowers and leaves, and these are grouped into organ systems as well
Notes.
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.