lecture 3 Flashcards
voltage-gated ion channels
proteins in the cell membrane that open or close in response to changes in the voltage across the membrane
Na+ channels
a type of voltage-gated ion channel that allow sodium ions to flow into the cell in response to a change in the membrane’s electrical potential
initial depolarization
the first phase in the process of generating an action potential
K+ channels
ion channels that open or close in response to changes in the membrane potential, allowing potassium ions (K⁺) to move in or out of the cell
patch clamp technique
a method used to measure the electrical properties of individual ion channels or small regions of a cell’s membrane
action potential
a rapid change in membrane potential that spreads along axons
all-or-none law
a neuron either fires a full-strength action potential or not at all, depending on whether the signal reaches a certain threshold
depolarization
a reduction in charge difference, occuring when Na+ ions flow into the neuron
hyperpolarization
an increase in charge difference, where the membrane potential becomes more negative
Absolute refractory period
the time during and just after an action potential when a neuron cannot fire another action potential, no matter how strong the stimulus is
relative refractory period
the period of time after an action potential during which a neuron can fire another action potential, but only if the incoming stimulus is stronger than usual.
propagation of the action potential
the process by which an electrical signal travels along the axon of a neuron
saltatory conduction
the process by which action potentials travel more quickly along myelinated axons
increasing current
the rate of action potential generation increases
graded potential
temporary changes in the membrane voltage
EPSP
a temporary increase in the postsynaptic membrane’s potential that makes the neuron more likely to fire an action potential
IPSP
potentials which decrease the likelihood of reaching the action potential threshold
ionotropic receptors
ligand-gated ion channels that open efficiently in response to neurotransmitter binding
metabotropic receptors
G-protein coupled receptors that modulate ion channel activity through second messengers
spatial summation
if two potentials arrive at the axon hillock at the same moment they are summed spatially across the cell body
temporal summation
occurs when multiple EPSP’s are generated from a single presynaptic neuron in quick follow-up
topical anesthesia
applied on slimy membranes to numb local areas
infiltration anesthesia
injected into tissue leading to localized numbness
spinal anesthesia
administered into cerebrospinal fluid to provide broader numbness effects
