Kapitel 12 Flashcards
Traveling wave of electrical excitation caused by rapid - transient - self-propagating depolarization of the plasma membrane in a neuron or other excitable cell; also called a nerve impulse.
action potential
The movement of a solute across a membrane against its electrochemical gradient; requires an input of energy - such as that provided by ATP hydrolysis.
active transport
Long - thin extension that conducts electrical signals away from a nerve cell body toward remote target cells.
axon
An active transporter that uses energy supplied by ATP hydrolysis to actively expel Ca2+ from the cell cytosol.
Ca2+ pump
A protein that forms a hydrophilic pore across a membrane - through which selected small molecules or ions can passively diffuse.
channel
Active transporter that uses the movement of one solute down its electrochemical gradient to drive the uphill transport of another solute across the same membrane.
coupled pump
Short - branching structure that extends from the surface of a nerve cell and receives signals from other neurons.
dendrite
A shift in the membrane potential - making it less negative.
depolarization
Driving force that determines which way an ion will move across a membrane; consists of the combined influence of the ion’s concentration gradient and the membrane potential.
electrochemical gradient
Transmembrane protein that forms a pore across the lipid bilayer through which specific inorganic ions can diffuse down their electrochemical gradients.
ion channel
Ion channel permeable to K + that randomly flickers between an open and closed state; largely responsible for the resting membrane potential in animal cells.
K + leak channel
An ion channel that is stimulated to open by the binding of a small molecule such as a neurotransmitter.
ligand-gated channel
An ion channel that allows the passage of select ions across a membrane in response to a physical perturbation.
mechanically gated channel
Voltage difference across a membrane due to a slight excess of positive ions on one side and of negative ions on the other.
membrane potential
Any transmembrane protein that provides a passageway for the movement of select substances across a cell membrane.
membrane transport protein
Transporter found in the plasma membrane of most animal cells that actively pumps Na+ out of the cell and K+ in using the energy derived from ATP hydrolysis.
Na+ pump (sodium pump)
An equation that relates the concentrations of an inorganic ion on the two sides of a permeable membrane to the membrane potential at which there would be no net movement of the ion across the membrane.
Nernst equation
Structure at the end of an axon that signals to another neuron or target cell.
nerve terminal
An electrically excitable cell that integrates and transmits information as part of the nervous system; a nerve cell.
neuron
Small signaling molecule secreted by a nerve cell at a synapse to transmit information to a postsynaptic cell. Examples include acetylcholine - glutamate - GABA - and glycine.
neurotransmitter
Technique that uses light to control the activity of neurons into which light-gated ion channels have been artificially introduced.
optogenetics
Passive movement of water across a cell membrane from a region where the concentration of water is high (because the concentration of solutes is low) to a region where the concentration of water is low (and the concentration of solutes is high).
osmosis
The spontaneous movement of a solute down its concentration gradient across a cell membrane via a membrane transport protein - such as a channel or a transporter.
passive transport
Technique used to monitor the activity of ion channels in a membrane; involves the formation of a tight seal between the tip of a glass electrode and a small region of cell membrane - and manipulation of the membrane potential by varying the concentrations of ions in the electrode.
patch-clamp recording
A transporter that actively moves H+ across a cell membrane - thereby generating a gradient that can be used by the cell - for example - to import other solutes.
proton (H+) pump
Transporter that uses a source of energy - such as ATP hydrolysis or sunlight - to actively move a solute across a membrane against its electrochemical gradient.
pump
Voltage difference across the plasma membrane when a cell is not stimulated.
resting membrane potential
A transporter that transfers two different solutes across a cell membrane in the same direction.
symport
Specialized junction where a nerve cell communicates with another cell (such as a nerve cell - muscle cell - or gland cell) - usually via a neurotransmitter secreted by the nerve cell.
synapse
The ability of a synapse to adjust its strength for a prolonged period - either up or down - depending on its use; thought to play an important role in learning and memory.
synaptic plasticity
Small membrane-enclosed sac filled with neurotransmitter that releases its contents by exocytosis at a synapse.
synaptic vesicle
Transmembrane receptor protein or protein complex that opens in response to the binding of a neurotransmitter - allowing the passage of a specific inorganic ion; its activation can trigger an action potential in a postsynaptic cell.
transmitter-gated ion channel
Membrane transport protein that moves a solute across a cell membrane by undergoing a series of conformational changes.
transporter
Force exerted on a plant cell wall when water enters the cell by osmosis; keeps plant from wilting.
turgor pressure
Protein that selectively allows particular ions to cross a membrane in response to a change in membrane potential. Found mainly in electrically excitable cells such as nerve and muscle cells.
voltage-gated ion channel
Protein in the plasma membrane of electrically excitable cells that opens in response to membrane depolarization - allowing Na+ to enter the cell. It is responsible for action potentials in these cells.
voltage-gated Na+ channel
Type of coupled transporter that transfers two different ions or small molecules across a membrane in opposite directions - either simultaneously or in sequence.
antiport
See Na+ pump
sodium pump
Channel protein that permits the passage of selected ions - such as Na+ - across a membrane in response to changes in the membrane potential. Found primarily in electrically excitable cells such as nerve and muscle.
voltage-gated channel
