Jänniteherkkiä

Jänniteherkkiä is a Finnish term that translates to "voltage-sensitive" or "voltage-gated" in English. It describes a property of certain biological channels or proteins that change their conformation or function in response to changes in the electrical potential across a membrane. These voltage-sensitive structures are crucial for many physiological processes, particularly in excitable cells like neurons and muscle cells.

The most well-known examples are voltage-gated ion channels. These channels selectively allow specific ions, such as sodium, potassium, calcium, or chloride, to pass through the cell membrane. When the membrane potential reaches a certain threshold, the voltage sensor within the channel protein undergoes a conformational change. This change opens or closes the channel pore, thereby altering the flow of ions across the membrane. This ion flow is fundamental to generating and propagating electrical signals, such as action potentials, which are the basis of nerve impulses and muscle contractions.

Beyond ion channels, other cellular components can also exhibit voltage sensitivity. For instance, some receptors and enzymes might have their activity modulated by the electrical state of the cell membrane. The precise mechanisms by which voltage sensitivity is achieved vary, but they typically involve charged amino acid residues within the protein that are influenced by the electric field. Understanding jänniteherkkiä is essential for comprehending cell excitability, signal transduction, and the underlying mechanisms of various diseases.