Lecture

Conservation and separation of charges

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Description

This lecture explains the principle of conservation of charge in a neuron's compartmental model, illustrating how charges move intracellularly and exit elsewhere. It also delves into the complexities of interpreting extracellular signals, highlighting the impact of synaptic inputs on the extracellular potential and the challenges posed by thousands of independently activated synaptic inputs. The lecture further explores the phenomenon of the extracellular action potential, demonstrating how the amplitude of signals falls with distance from the dipole and is influenced by the strength and separation of current sources. It concludes by discussing factors that enable neurons to effectively separate charges, such as low intracellular resistance and high membrane resistance, emphasizing the intricate relationship between a neuron's morphology, synaptic inputs, and extracellular signals.

In MOOC

Simulating a hippocampus micro-circuit

Official source

Ontological neighbourhood

Biology

Cell biology: Neurotransmission

Related concepts (24)

Synapse

In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Synapses are essential to the transmission of nervous impulses from one neuron to another. Neurons are specialized to pass signals to individual target cells, and synapses are the means by which they do so. At a synapse, the plasma membrane of the signal-passing neuron (the presynaptic neuron) comes into close apposition with the membrane of the target (postsynaptic) cell.

Membrane potential

Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. That is, there is a difference in the energy required for electric charges to move from the internal to exterior cellular environments and vice versa, as long as there is no acquisition of kinetic energy or the production of radiation. The concentration gradients of the charges directly determine this energy requirement.

Synaptic vesicle

In a neuron, synaptic vesicles (or neurotransmitter vesicles) store various neurotransmitters that are released at the synapse. The release is regulated by a voltage-dependent calcium channel. Vesicles are essential for propagating nerve impulses between neurons and are constantly recreated by the cell. The area in the axon that holds groups of vesicles is an axon terminal or "terminal bouton". Up to 130 vesicles can be released per bouton over a ten-minute period of stimulation at 0.2 Hz.

Cell signaling

In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellular life in prokaryotes and eukaryotes. Signals that originate from outside a cell (or extracellular signals) can be physical agents like mechanical pressure, voltage, temperature, light, or chemical signals (e.g., small molecules, peptides, or gas).

Resting potential

A relatively static membrane potential which is usually referred to as the ground value for trans-membrane voltage. The relatively static membrane potential of quiescent cells is called the resting membrane potential (or resting voltage), as opposed to the specific dynamic electrochemical phenomena called action potential and graded membrane potential. Apart from the latter two, which occur in excitable cells (neurons, muscles, and some secretory cells in glands), membrane voltage in the majority of non-excitable cells can also undergo changes in response to environmental or intracellular stimuli.

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