Exam 2 Flashcards
element or atom that has gained or lost an electron
ION
any chemical that carries electrical charge when dissolved in water
ELECTROLYTE
material where positively or negatively charged ions can move freely toward each other
CONDUCTOR
material where oppositely charged ions can not move toward each other
INSULATOR
form of potential energy created by difference between amounts of electrical charge
ELECTROCHEMICAL POTENTIAL
membrane potential when membrane is resting and not actively conducting an electrical impulse
RESTING POTENTIAL
change in the membrane potential whose magnitude is proportional to the strength of the stimulus
GRADED POTENTIAL
rapidly moving wave of electrical charge that moves along the membrane of an active excitable cell
ACTION POTENTIAL
channels whose molecular conformation responds to the changes in electrical potential across the membrane
VOLTAGE-GATED CHANNELS
a stimulus strong enough to initiate an action potential by triggering opening of the activation gate
THRESHOLD STIMULUS
a stimulus not strong enough to initiate an action potential by triggering opening of the activation gate
SUBTHRESHOLD STIMULUS
rapid increase in concentration of Na+ in cell because of opening of the activation gate of the voltage-gated Na+ channel
DEPOLARIZATION
process of regaining Vrest after depolarization
REPOLARIZATION
undershooting of the Vrest due to excess K+ ions flowing out of the cell
HYPERPOLARIZATION
brief space in time in which an excitable membrane is resistant to further stimulation
REFRACTORY PERIOD
short period during and immediately after depolarization where a neuron or myofiber will not respond again to any stimulus, no matter how strong
ABSOLUTE REFRACTORY PERIOD
period following absolute refractory period where neuron or myofiber will only respond to a strong stimulus
RELATIVE REFRACTORY PERIOD
spread of an action potential along the membrane of an excitable cell
PROPAGATION
used in unmyelinated axons and muscle cells
CONTINUOUS PROPAGATION
used in myelinated axons
SALTATORY PROPAGATION
a segmented wrapping around the axon formed by Schwann’s cells in the PNS and oligodendria in the CNS
MYELIN
unmyelinated areas of a myelinated axon found between myelin sheaths
NODES OF RANVIER
groups of neurons that influence each other’s activity by communicating at neuronal synapses
NEURONAL PATHWAYS
site or junction where electrical signals are transmitted from one cell to another
SYNAPSE
found between successive neurons in a neuronal pathway
NEURONAL SYNAPSES
found between somatic alpha-motor neurons and myofibers of skeletal muscles
NEUROMUSCULAR JUNCTIONS
found between autonomic motor neurons and autonomic effectors including smooth muscle and glandular cells
NEUROEFFECTOR JUNCTIONS
neuron that carries impulse INTO the synapse
PRESYNAPTIC NEURON
neuron that carries impulse AWAY FROM the synapse
POSTSYNAPTIC NEURON
physical space separating two cells
SYNAPTIC CLEFT
extracellular signal molecule released by neurons that diffuse across the synaptic cleft to stimulate or inhibit activity
NEUROTRANSMITTERS (NT)
membrane proteins found on the postsynaptic neuron that bind a specific NT and generate a response in the postsynaptic cell
NEUROTRANSMITTER RECEPTORS
depolarizing graded potential that brings postsynaptic neuron closer to the threshold for creating action potentials
EXCITATORY POSTSYNAPTIC POTENTIAL (EPSP)
hyperpolarizing graded potential the moves a postsynaptic neuron further away from the threshold for creating action potentials
INHIBITORY POSTSYNAPTIC POTENTIAL (IPSP)
process of integrating the input from multiple synapses
SUMMATION
effect produced by the simultaneous release of neurotransmitters from more than one synaptic knobs on a single postsynaptic neuron
SPATIAL SUMMATION
effect produced by stimulation of NT release from the same presynaptic knob in rapid succession on a postsynaptic neuron
TEMPORAL SUMMATION
membrane potential of a postsynaptic neuron is held nearer to threshold then normal but not yet above
FACILITATION
pathways in which a signal entering into a section of a neuronal pathway excites a greater number of signals leaving that section
DIVERGENT PATHWAYS
pathways in which signals from multiple input fibers come together to excite a single output fiber
CONVERGENT PATHWAYS
