Definition of boundary of a system

In system theory, the border or limit of a system is a line (real and/or conceptual) that separates the system from its environment or suprasystem (See: environment of a system).

The boundary of a system defines what belongs to the system and what does not. What does not belong to the system can be part of its suprasystem or directly not be part of the system. It also allows you to know which components should be included as part of the system and which are not.

Establishing the limit of a system can be simple when there are real physical limits and it is very clear what the objective of the system to be studied is. For example, the human digestive system includes only the organs that process food.

When the objective of the study of the system has not been clearly defined, it can also be difficult to establish what its limits are.

Boundaries are more difficult to establish when dealing with a logical or conceptual system.

System boundaries also allow us to establish hierarchies between subsystems, systems, and supersystems.

Examples of boundaries or limits in systems

Here we have the human respiratory system, the dotted line sets a limit. If we want to define its limit we can simply mention which organs and components belong to this system: The respiratory system includes nostrils (used to bring air into the body), tubes (such as the trachea and bronchi) and the two lungs (where breathing occurs). gas exchange).

In this case our main system is the tree. To define its limits we must list its most important elements, especially those that can be seen: leaves, bark, branches and roots.

Relationship of the limit or boundary of the system and its environment

The boundary or boundary of the system is where the system exchanges data, energy, or matter with its environment. When a boundary is permeable or open, it means that the system itself is open. An open system allows data, energy and/or matter to be exchanged with the environment around it.

When the limit or frontier of the system is closed or impermeable, it means that the system itself is closed. There is no exchange of data, energy or matter with its environment.

Strictly speaking, there are no closed systems, with the exception of the Universe itself (if current theoretical physics is correct). All systems exchange something with their environment.

So conceptually a closed system can be one that exchanges an insignificant amount of energy, data or matter with its environment.