Organ System

Like cells and tissues, organs seldom work alone. They "cooperate" with one another and form specific organ systems. Organ systems are the fourth level of organization in living things. An organ system is a group of organs working together to perform a specific function for the organism.

• Groups of two or more tissues that work together to perform a specific function for the organism.
• Examples - circulatory system, nervous system, skeletal system, etc.
• The Human body has 11 organ systems - circulatory, digestive, endocrine, excretory (urinary), immune(lymphatic), integumentary, muscular, nervous, reproductive, respiratory, and skeletal.