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Concept
An action potential is a rapid, temporary change in the electrical membrane potential of a neuron or muscle cell, allowing it to transmit signals over long distances. This process involves the sequential opening and closing of voltage-gated ion channels, resulting in depolarization and repolarization of the cell membrane.
Concept
Resting potential is the electrical potential difference across the membrane of a neuron when it is not actively transmitting a signal, typically around -70mV. It is maintained by the sodium-potassium pump and selective membrane permeability, setting the stage for action potentials to occur when the neuron is stimulated.
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Depolarization is the process by which a cell's membrane potential becomes less negative, typically leading to the generation of an action potential in neurons and muscle cells. This change in electrical charge is crucial for the transmission of signals in the nervous system and the contraction of muscles.
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Repolarization is the process by which a cell's membrane potential returns to its resting state after depolarization, crucial for the proper functioning of excitable cells such as neurons and cardiac cells. This process involves the closing of sodium channels and the opening of potassium channels, allowing potassium ions to flow out of the cell, restoring the negative membrane potential.
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Hyperpolarization is a change in a cell's membrane potential that makes it more negative, moving further away from the threshold needed to trigger an action potential. This process is crucial for regulating neuronal excitability and signal transmission in the nervous system.
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Threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential in excitable cells, such as neurons and muscle cells. It acts as a gatekeeper, ensuring that only significant stimuli trigger a response, thus maintaining the fidelity of signal transmission in the nervous system.
Concept
Ion channels are specialized proteins embedded in cell membranes that regulate the flow of ions across the membrane, crucial for a variety of physiological processes including nerve impulse transmission and muscle contraction. They can be gated by voltage, ligands, or mechanical forces, allowing cells to respond dynamically to changes in their environment.
Concept
The sodium-potassium pump is a vital membrane protein that maintains cellular homeostasis by actively transporting three sodium ions out of the cell and two potassium ions into the cell against their concentration gradients. This process is crucial for maintaining the resting membrane potential and enabling nerve impulse transmission, muscle contraction, and various cellular functions.
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Synaptic transmission is the process by which neurons communicate with each other through the release and reception of neurotransmitters across a synapse. This fundamental mechanism underlies all neural activity and is essential for brain function, including learning, memory, and behavior.
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Neurotransmitters are chemical messengers that transmit signals across synapses from one neuron to another, playing a crucial role in shaping everyday life and functions by influencing mood, sleep, and cognitive abilities. They are essential for proper brain function and are involved in a wide range of physiological processes and mental health conditions.
Concept
The All-or-None Principle states that once a threshold stimulus is reached, an action potential is triggered and propagates along the neuron without decrement. This principle ensures that the signal is transmitted in a consistent and reliable manner, independent of the strength of the stimulus, as long as it is above the threshold.
Concept
The refractory period is a brief time after an action potential during which a neuron is unable to fire another action potential, ensuring unidirectional propagation of nerve impulses. It is divided into the absolute refractory period, where no new action potential can be initiated, and the relative refractory period, where a stronger-than-usual stimulus is needed to elicit a response.
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