| |
 |
UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2025-07-06 14:35 |
 |
|
|
|
Conference: Bucharest University Faculty of Physics 2025 Meeting
Section: Biophysics; Medical Physics
Title:
Teaching Biophysics IV. Biophysical Approach of membrane action potential propagation
Authors:
Aurel I. POPESCU and Claudia G. CHILOM
Affiliation:
University of Bucharest, Faculty of Physics, Department of Electricity, Solid-State Physics and Biophysics
E-mail
prof.aurel.popescu@gmail.com
Keywords:
Neuron, axon, synapse, synaptic vesicles, ionic channels, ionic pump, action potential, chemical synapses, neurotrasnsmitters, electrical synapses, action potential propagation
Abstract:
This work describes the generation and propagation of the action potential along a neuron as well as the chain of interconnected neurons through chemical and electrical synapses. At the level of dendrites, soma, axon, and axonal ramifications, the AP propagation is of electric type, being mediated by ionic currents. The soma membrane depolarization due to affluent signals sent by dendrites are summed up in space and time. If the degree of depolarization is beyond a threshold, then at the level of axonal hillock, a train of action potentials is generated which are propagating, without decrement, along the axon, reaching the presynaptic membranes and producing the fusion of vesicles, filled with neurotransmitters, with the presynaptic membrane. The liberated neurotransmitters are passively diffusing in the synaptic cleft, reaching the specific receptors embedded in the postsynaptic membrane. The interaction of neurotransmitters with their specific receptors opens or closes different ionic channels, depolarizing (in the case of excitatory synapses) or hyperpolarizing the postsynaptic membrane (in the case of inhibitory synapses). If the value of depolarization is beyond a critical threshold, a train of action potentials is downstream delivered to the next neuron and so on. The chain of neurons assuring action potential propagation could be affected by different anomalies at the level of ionic channels axon, synapses etc. engendering many neural disorders (e.g., channelopathies, synaptopathies). Therefore, the profound understanding of the action potential propagation present great medical importance.
|
|
|
|