Sejthártyának

Sejthártyának, also known as the cell membrane or plasma membrane, is a biological membrane that surrounds the cytoplasm of a cell. It is primarily composed of a phospholipid bilayer with embedded proteins. This structure is selectively permeable, meaning it controls the passage of substances into and out of the cell. The phospholipid bilayer forms a barrier that prevents water-soluble molecules from freely crossing, while the embedded proteins act as channels, carriers, and pumps to facilitate the transport of specific ions and molecules.

The cell membrane plays a crucial role in maintaining cell integrity and regulating the internal environment. It separates the cell's internal contents from the external surroundings, protecting the cell from mechanical stress and osmotic changes. Furthermore, the membrane is involved in various cellular processes, including cell signaling, cell adhesion, and the generation of electrical potentials. Receptors on the cell surface bind to signaling molecules, initiating intracellular responses. Proteins within the membrane also allow cells to attach to each other and to the extracellular matrix, forming tissues. The unequal distribution of ions across the cell membrane creates an electrochemical gradient that is essential for nerve impulse transmission and muscle contraction. The fluidity of the membrane, due to the movement of its components, allows for dynamic changes and interactions.