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Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
Biopotentials are generated as a result of the electrochemical activity of the cells that are the components of the nervous, muscular and granular tissue. The electrical activity of the cell is generated via in and out ion movement (K+, Na+ and Cl−) through the cell membrane (Van Drongelen, 2010). Generally, the potentials are in two states (active and resting potential). The active potential is generated when cells are stimulated. The membrane potential when the cell is inactive is the resting potential. At resting state, the potassium ion is more permeable in the cell membrane when compared to the sodium and potassium ion concentrations is higher in the interior of the cell when compared to the exterior of the cell. The diffusion gradient of potassium ion arises toward the exterior of the cell that creates more negative ions in the interior of the cell. At steady or depolarization state, the diffusion gradient of potassium ion is in equilibrium and balanced by the electric field with the polarization voltages of −70 mV (Thakor, 2015; Webster, 1984). If the cells are electrically stimulated, the diffusion gradient of potassium ion increases and diffuse toward the interior of the cells that creates more potential. If the active potentials reach +40 mV, the permeability of the potassium ion decreases and the sodium ion increases causing resting potential. This cycle produces the several cellular potentials called as action potentials (Yazıcıoğlu et al., 2009; Thakor, 2015).
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Published in Mara Cercignani, Nicholas G. Dowell, Paul S. Tofts, Quantitative MRI of the Brain: Principles of Physical Measurement, 2018
Wieland A. Worthoff, Aliaksandra Shymanskaya, Chang-Hoon Choi, Jörg Felder, Ana-Maria Oros-Peusquens, N. Jon Shah
As 23Na is the second most abundant element in living organisms and is a part of the sodium–potassium exchange across cell membranes; it requires energy in the form of ATP for the maintenance of a constant concentration gradient across the membrane. The intracellular concentration of 23Na is low (10–15 mmol/L), while the extracellular concentration is about 140 mmol/L (Modo and Bulte, 2011). A resting potential, responsible for signal transmission in nerves and muscles, is generated by ions in the intra- and extracellular space. As intracellular sodium concentration is much lower than the extracellular concentration, changes in the intracellular concentration can be masked by the changes in extracellular concentration, even though intracellular volume is larger than extracellular volume.
Biopotentials and Electrophysiology Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
The origins of these biopotentials can be traced to the electric activity at the cellular level [2]. The electric potential across a cell membrane is the result of different ionic concentrations that exist inside and outside the cell. The electrochemical concentration gradient across a semipermeable membrane results in the Nernst potential. The cell membrane separates high concentrations of potassium ion and low concentrations of sodium ions (along with other ions such as calcium in less significant proportions) inside a cell and just the opposite outside a cell. This difference in ionic concentration across the cell membrane produces the resting potential [3]. Some of the cells in the body are excitable and produce what is called an action potential, which results from a rapid flux of ions across the cell membrane in response to an electric stimulation or transient change in the electric gradient of the cell [4]. The electric excitation of cells generates currents in the surrounding volume conductor manifesting itself as potentials on the body.
Electrochemical evaluation of ion substituted-hydroxyapatite on HeLa cells plasma membrane potential
Published in Cogent Engineering, 2019
Bernard Owusu Asimeng, Elvis Kwason Tiburu, Elsie Effah Kaufmann, Lily Paemka, Claude Fiifi Hayford, Samuel Essien-Baidoo, Obed Korshie Dzikunu, Prince Atsu Anani
It is reported that disrupting the plasma membrane potential of cancer cells may trigger apoptosis (Zhang, Chen, Gueydan, & Han, 2017). Generally, cell plasma membranes generate potential (membrane potential) because of the imbalance of charges between the intracellular and extracellular environment. This arises from the presence of different ion channels which allow distinct ions such as Na+, K+, Ca2+ and Cl− access through the voltage-gates of the ion channels based on their specific size. Because of the difference in the number of ions within the cytoplasm and the extracellular medium, a voltage difference (electrochemical gradient) is always evolving. A normal cell tries to balance the ion concentration across the plasma membrane to achieve a resting potential through polarization. At resting potential, the cytoplasm becomes more negative. That is, more Na+ are sent outside and K+ are kept inside the cytoplasm (polarization). Typically, normal cells generate stimuli through polarization, for example, during muscle contraction (Lodish, Berk Arnold, Lawrence, & Baltimore David, 2000). On the contrary, cancer cells generate stimuli through plasma membrane depolarization (more Na+ are taken up by the cell and the cytoplasm becomes less negative). Depolarization generates strong stimuli that communicate faster, causing rapid proliferation (Yang & Brackenbury, 2013).
Mechanism of peripheral nerve modulation and recent applications
Published in International Journal of Optomechatronics, 2021
Heejae Shin, Minseok Kang, Sanghoon Lee
The most important role in generating action potentials inside neurons is the membrane permeability of membrane proteins such as ion channels and sodium-potassium pumps. The membrane permeability causes the concentration gradients of ions across the membrane between the inside of the cell (cytoplasm) and the outside of the cell, creating a membrane potential. In general, only the potential difference caused by Na+ and K+, which has the most influence on this, are considered. The voltage across the membrane in the absence of any stimulus is called the resting potential which has a value of about −70 mV.[13–15]