What is a system?

SYSTEM 

  Is an essamble of parts and the relationships between them, which together constitue a whole.

 System composition :

• storages: matter and energy 
• flows: inputs and outputs
• processes: tranfer and transfromation 
• feed back mechanisms: positive feedback and negative feedback

Types of systems: 

• Open system: Exchanges both  energy and matter
• Closed system: Exchanges energy but not matter
• Isolated system: Neither matter or energy crosses

Digestive system is an open system. 

                                                            A fishbowl is a closed system