Neuroscience I Flashcards
a highly specialized cell found in nervous systems of animals that communicates with other cells by electrical or chemical signals
neurons
a structure found in the peripheral nervous system that is composed of multiple myelinated axons bound by connective tissue; carries information to or from the central nervous system
nerves
the brain and spinal cord
central nervous system (CNS)
all nerves and ganglia outside the brain and spinal cord
peripheral nervous system (PNS)
a part of a neuron that contains the cell nucleus and other organelles
cell body
a treelike extension of the plasma membrane of a neuron that receives electrical signals from other neurons
dendrites
an extension of the plasma membrane of a neuron that is involved in sending signals to neighboring cells
axon
the part of an axon closest to the cell body; typically where an action potential begins
axon hillock
the end of an axon, which conveys electrical or chemical messages to other cells
axon terminals
cells that surround the neurons; a major class of cells in nervous system that perform various functions
glia
exposed area along the axons of myelinated neurons that contain many voltage-gated Na+ channels and are the sites of regeneration of action potentials
nodes of Ranvier
the glial cells that form myelin on axons that travel outside the brain and spinal cord
Schwann cells
glial cells that produce the myelin sheath around neurons in the central nervous system
oligodendrocytes
in the nervous system, an insulating layer made up of specialized glial cells wrapped around certain axons
myelin sheath
a neuron that detects or senses information from the outside world, such as light, sound, touch, and heat; also detect internal body conditions such as blood pressure and blood temperature
sensory neurons
a neuron that sends signals away from the central nervous system and elicits some type of response from a gland, muscle, or other structure
motor neurons
a type of neuron that forms interconnections between other neurons
interneuron
a simple circuit that allows an organism to respond rapidly to inputs from sensory neurons and consists of only a few neurons
reflex arc
the difference between the electric charges along the inside and outside surfaces of a cell membrane
membrane potential
the differences in charges across the plasma membrane in an unstimulated neuron
resting membrane potential
a dual gradient across a membrane having both electrical and chemical components; determines what directions the ions will move
electrochemical gradient
the membrane potential at which the flow of an ion across a membrane is at equilibrium, with no net movement in either direction
equilibrium potential
the change in the membrane potential that occurs when a cell membrane becomes less polarized, less negative inside the cell relative to the extracellular fluid
depolarization
the change in the membrane potential that occurs when the cell membrane becomes more polarized than it is at rest
hyperpolarization
ion channels that will open and close in response to changes in voltage across a cell membrane
voltage-gated ion channels
a type of cell surface receptor that binds a ligand and functions as an ion channels; ligand binding either opens or closes a channel
ligand-gated ion channels
the membrane potential, typically around -55 to -50 mV, that is sufficient to trigger an action potential in an electrically excitable cell such as a neuron
threshold potential
a string of amino acids that juts out from a channel protein into the cytosol and can swing into the channel pore to block the movements of ions through the channel
inactivation gate
the period during an action potential when the inactivation gate of the voltage-gated Na+ channel is closed; during this time, it is impossible to generate another action potential
absolute refractory period
the period near the end of an action potential when voltage-gated K+ channels are still open; during this time a new action potential can be generated if a stimulus is sufficiently strong to raise the membrane potential to the threshold
relative refractory period
a junction where an axon terminal meets another neuron, a muscle cell, or a gland cell and through which an electrical or chemical signal passes
synapse
the extracellular space between a neuron and a receiving cell
synaptic cleft
the neuron that sends an electrical or chemical signal to another cell
presynaptic cell
the cell that receives the electrical or chemical signal
postsynaptic cell
a synapse in which a chemical called a neurotransmitter is released from an axon terminal and acts as a signal from the presynaptic to the postsynaptic cells
chemical synapse
the response to an excitatory neurotransmitter that depolarizes the postsynaptic membrane; the depolarization brings the membrane potential closer to the threshold potential that would trigger an action potential
excitatory postsynaptic potential (EPSP)
the response to an inhibitory neurotransmitter that hyperpolarizes the postsynaptic membrane; this hyperpolarization reduces the likelihood of an action potential occurring
inhibitory postsynaptic potential (IPSP)
the process that occurs when multiple excitatory postsynaptic potentials are generated at one time at synapses along different regions of the dendrites and/or cell body and their depolarizations and hyperpolarizations sum together to initiate action potential
spatial summation
the process that occurs when two or more postsynaptic potentials arrive at the same location on a dendrite or cell body in quick succession and their depolarizations and hyperpolarizations sum together to initiate an action potential
temporal summation
the contact point between an axon terminal of a motor neuron and a skeletal or cardiac muscle fiber
neuromuscular juction
one of two types of postsynaptic membrane receptors; consists of a ligand-gated ion channel that opens in response to the binding of a neurotransmitter
iontropic receptor
a G-protien coupled receptor that initiates a signaling pathway in response to a neurotransmitter
metabotropic receptor
