The property of a membrane that allows certain substances to pass while restricting the passage of others, based on factors such as molecular size, charge, and lipid solubility.
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Passive Transport
The movement of molecules across a membrane without the input of energy, primarily through diffusion from an area of high concentration to an area of low concentration.
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Active Transport
The movement of molecules across a membrane that requires the expenditure of energy, usually in the form of ATP, to transport molecules against their concentration gradient.
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Endocytosis
The process by which cells engulf substances from the extracellular environment by forming vesicles.
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Exocytosis
The process by which vesicles fuse with the cell membrane, releasing their contents into the extracellular space.
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Membrane Potential
The voltage difference across the cell membrane, usually maintained by ion concentration gradients, and important for various cellular functions.
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Transporters
Integral membrane proteins that facilitate the movement of specific molecules across the membrane, either through active or passive mechanisms.
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Ion Channels
Specialized membrane proteins that allow the selective passage of ions across the cell membrane, playing a crucial role in maintaining the electrical properties of membranes.
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Resting Membrane Potential
The electrical potential difference across the cell membrane when the cell is at rest, typically around -70 millivolts (mV), primarily determined by the differential distribution of ions across the membrane.
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Action Potentials
Rapid and transient changes in the membrane potential that allow for long-range communication in excitable cells such as neurons and muscle cells.
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Synaptic Transmission
The process by which neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, leading to changes in the postsynaptic membrane potential.
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Endocytosis
bulk transport
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Pinocytosis
ingestion of liquid material
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Phagocytosis
Ingestion of solid complex materials
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Conductance
It refers to the ability of an ion channel to allow the flow of ions.
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Permeability
It is the measure of the ease with which ions can pass through a channel.
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Ion Selectivity
Ion channels exhibit selectivity for specific ions based on their size, charge, and hydration.
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Synaptic transmission
It involves the release of neurotransmitters from the presynaptic neuron, which then bind to receptors on the postsynaptic neuron.
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Depolarization
It refers to a change in the membrane potential towards a more positive value, typically caused by the influx of positively charged ions.
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Repolarization
It is the process of returning the membrane potential back to its resting state after depolarization.