When depolarization occurs in the sarcoplasm of muscle cells, calcium ions (Ca2+) are released from the sarcoplasmic reticulum. This release triggers muscle contraction by allowing actin and myosin filaments to interact and generate force.
Sodium.A positive ion (cation) that enters the cell (influx) rapidly when the membrane threshold is reached and the voltage gated sodium channels open.This occurs during the rising phase of an action potential, i.e. membrane depolarization beyond the threshold for activation.
Depolarization involves a neuron's cell membrane potential becoming less negative, moving closer to zero. This occurs when positively charged ions flow into the cell, usually through ion channels, leading to an excitatory response in the neuron.
The ion that enters a neuron causing depolarization of the cell membrane is sodium (Na⁺). During an action potential, voltage-gated sodium channels open in response to a stimulus, allowing Na⁺ to flow into the neuron. This influx of positively charged sodium ions reduces the negative charge inside the cell, leading to depolarization. This change in membrane potential is crucial for the propagation of electrical signals along the neuron.
Depolarization of a neurotransmitter refers to the shift in the electrical charge of the neuron, making it more likely to generate an action potential. This can occur when a neurotransmitter binds to its receptor on the postsynaptic membrane, causing ion channels to open and allowing the influx of positively charged ions. This depolarization triggers a series of events that lead to the transmission of the nerve signal.
Self-propagated depolarization refers to the process by which an action potential triggers the opening of voltage-gated ion channels along the membrane, causing further depolarization in adjacent regions of the neuron. This process allows the action potential to travel down the length of the neuron, enabling rapid communication within the nervous system.
Calcium is transported out of the sarcoplasm by means of special ion pumps.
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The potassium ion is responsible for depolarization of hair cells in the spiral organ. When deflected, potassium channels open, leading to an influx of potassium ions into the cell and depolarization of the cell membrane.
Sodium.A positive ion (cation) that enters the cell (influx) rapidly when the membrane threshold is reached and the voltage gated sodium channels open.This occurs during the rising phase of an action potential, i.e. membrane depolarization beyond the threshold for activation.
The concentration of calcium ion is greater in the sarcoplasmic reticulum compared to the sarcoplasm of a resting muscle. This is because the sarcoplasmic reticulum stores and releases calcium ions during muscle contraction.
Voltage-gated sodium channels enable depolarization in excitable cells by allowing an influx of sodium ions, which leads to the rapid depolarization phase of an action potential.
Sodium ions are responsible for the rising phase of the action potential. This occurs when sodium channels open and sodium ions flow into the cell, causing depolarization.
Depolarization involves a neuron's cell membrane potential becoming less negative, moving closer to zero. This occurs when positively charged ions flow into the cell, usually through ion channels, leading to an excitatory response in the neuron.
The influx of sodium ions causes depolarization of the cell membrane, making the interior less negative. This depolarization can trigger the opening of voltage-gated ion channels, leading to the propagation of an action potential. Sodium-potassium pumps work to restore the original ion concentrations, repolarizing the cell.
Graded potentials can start as either depolarization or hyperpolarization, depending on the type of stimulus and the ion channels involved. Depolarization occurs when sodium channels open, allowing Na+ ions to flow into the cell, making the inside more positively charged. Conversely, hyperpolarization happens when potassium channels open, allowing K+ ions to exit, making the inside more negatively charged. Thus, graded potentials reflect changes in membrane potential that can vary in magnitude and direction.
The ion that enters a neuron causing depolarization of the cell membrane is sodium (Na⁺). During an action potential, voltage-gated sodium channels open in response to a stimulus, allowing Na⁺ to flow into the neuron. This influx of positively charged sodium ions reduces the negative charge inside the cell, leading to depolarization. This change in membrane potential is crucial for the propagation of electrical signals along the neuron.
Depolarization of a neurotransmitter refers to the shift in the electrical charge of the neuron, making it more likely to generate an action potential. This can occur when a neurotransmitter binds to its receptor on the postsynaptic membrane, causing ion channels to open and allowing the influx of positively charged ions. This depolarization triggers a series of events that lead to the transmission of the nerve signal.