Chapter 12 Flashcards
action potential
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.
active transport
The movement of a solute across a membrane against its
electrochemical gradient; requires an input of energy, such
as that provided by ATP hydrolysis.
antiport
Type of coupled transporter that transfers two different
ions or small molecules across a membrane in opposite
directions, either simultaneously or in sequence.
axon
Long, thin extension that conducts electrical signals away
from a nerve cell body toward remote target cells.
Ca2+ pump (or Ca2+ ATPase
An active transporter that uses energy supplied by ATP
hydrolysis to actively expel Ca2+ from the cell cytosol.
channel
A protein that forms a hydrophilic pore
across a membrane, through which
selected small molecules or ions can
passively diffuse.
dendrite
Short, branching structure that extends from the surface of
a nerve cell and receives signals from other neurons.
depolarization
A shift in the membrane potential, making it less negative
on the inside of the cell.
electrochemical gradient
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.
gradient-driven pump
A protein that uses energy stored in the electrochemical
gradient of ions to actively transport a solute across a
membrane.
H+ pump (or H+ ATPase
A protein or protein complex that uses energy supplied by
ATP hydrolysis, an ion gradient, or light to actively move
protons across a membrane.
ion channel
Transmembrane protein that forms a pore across the lipid
bilayer through which specific inorganic ions can diffuse
down their electrochemical gradients.
K+ leak 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.
ligand-gated channel
An ion channel that is stimulated to open by the binding of
a small molecule such as a neurotransmitter.
mechanically-gated channel
An ion channel that allows the passage of select ions across
a membrane in response to a physical perturbation.
membrane potential
Voltage difference across a membrane due to a slight
excess of positive ions on one side and of negative ions on
the other.
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 (or Na+-K+ ATPase
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
Nernst equation
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
nerve terminal
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.
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
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.
osmosis
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).
passive transport
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.
patch-clamp recording
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
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.
resting membrane potential
Voltage difference across the plasma membrane when a
cell is not stimulated
symport
A transporter that transfers two different solutes across a
cell membrane in the same direction.
synapse
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
synaptic vesicle
Small membrane-enclosed sac filled with neurotransmitter
that releases its contents by exocytosis at a synapse.
transmitter-gated ion channel
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.
transporter
Membrane transport protein that moves a solute across a
cell membrane by undergoing a series of conformational
changes.
voltage-gated channel
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 cells.
voltage-gated Na+ 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
