A membrane is a thin, flexible sheet or layer of tissue or material that serves as a selective barrier or boundary, separating different substances or compartments within a system. It can be composed of various materials, including biological tissues such as skin or cellular structures, as well as synthetic materials like polymers or plastics.
In biological organisms, membranes play a crucial role in regulating the movement of substances, such as ions or molecules, between different regions of the body. They can control the passage of specific substances based on their size, charge, or other properties, enabling processes like osmosis, diffusion, or active transport.
In cellular biology, the cell membrane, also known as the plasma membrane, is a critical structure that encloses the cell and defines its boundary. It controls the entry and exit of various molecules, maintaining the internal environment necessary for cellular function and protecting the cell from the external environment.
Membranes can also be found in various organs or structures within organisms, such as the respiratory membrane in the lungs for gas exchange, the blood-brain barrier that protects the brain from harmful substances, or the mucous membranes that line body cavities and protect underlying tissues.
Outside of biology, membranes have numerous applications in different fields, including filtration systems, chemical separation processes, waterproofing materials, and in electronics, for example, in capacitors or batteries.
Overall, membranes serve as vital interfaces that regulate the flow and exchange of substances, both within biological systems and in various technological contexts, making them essential for many processes and functionalities.
