Electrotonus
The change in excitability of a nerve or muscle fiber due to a sustained electric current
Electrotonus refers to the changes in the excitability and conduction properties of nerve and muscle fibers when subjected to a sustained electric current. This phenomenon is crucial in understanding how nerves and muscles respond to electrical stimuli, which is fundamental in both physiological and clinical contexts.
Physiological Basis[edit | edit source]
Electrotonus occurs when a constant electric current is applied to a nerve or muscle fiber, leading to a change in the membrane potential. This change can either be a depolarization or a hyperpolarization, depending on the direction of the current flow.
- Anode Electrotonus: When the anode (positive electrode) is placed on a nerve fiber, it causes hyperpolarization of the membrane potential. This is because the positive charge repels the positive ions inside the cell, making the inside more negative.
- Cathode Electrotonus: Conversely, when the cathode (negative electrode) is applied, it causes depolarization. The negative charge attracts positive ions, making the inside of the cell less negative.
These changes in membrane potential affect the excitability of the nerve or muscle fiber. Depolarization generally increases excitability, while hyperpolarization decreases it.
Clinical Relevance[edit | edit source]
Electrotonus is an important concept in neurophysiology and has implications in various clinical settings. For instance, understanding electrotonus is essential in the application of transcutaneous electrical nerve stimulation (TENS) and other forms of electrical therapy used in pain management and rehabilitation.
In neurology, electrotonus can help explain certain pathological conditions where nerve excitability is altered, such as in multiple sclerosis or peripheral neuropathy.
Historical Context[edit | edit source]
The concept of electrotonus was first described in the 19th century by scientists studying the electrical properties of nerves. It laid the groundwork for the development of modern electrophysiology and our understanding of nerve conduction.
Also see[edit | edit source]
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