Neurophysiology Flashcards
(101 cards)
1
Q
Neurophysiology
A
The study of electrical and chemical processes in neurons
2
Q
Ion
A
An atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons
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Q
Anion
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A negatively charged ion, such as a protein or chloride ion
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Cation
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A positively charged ion, such as a potassium or sodium ion
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Q
Intracellular Fluid
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CYTOPLASM - The watery solution found within cells
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Q
Extracellular Fluid
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The fluid in the spaces between cells (interstitial fluid) and in the vascular system
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Q
Cell Membrane
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The lipid bilayer that ensheathes a cell
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Q
Lipid Bilayer
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The structure of the neuronal cell membrane, which consists of two layers of lipid molecules. Various specialized proteins, such as ion channels and receptors, are embedded within the membrane
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Q
Micro-electrode
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An especially small electrode used to record electrical potentials from living cells
10
Q
Resting Membrane Potential
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A difference in electrical potential across the membrane of a nerve cell during an inactive period
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Q
Millivolt (mV)
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A thousandth of a volt
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Negative Polarity
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A negative electrical-potential difference relative to a reference electrode
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Ion Channel
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A pore in the cell membrane that permits the passage of certain ions through the membrane when the channel is open
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Q
Potassium Ion (K+)
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A potassium atom that carries a positive charge because it has lost one electron
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Q
Selective Permeability
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The property of a membrane that allows some substances to pass through, but not others
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Q
Diffusion
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The spontaneous spread of molecules of one substance among molecules of another substance until a uniform concentration is achieved
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Concentration Gradient
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Variation of the concentration of a substance within a region
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Sodium-Potassium Pump
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The energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in
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Q
Sodium Ion (NA+)
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A sodium atom that carries a positive charge because it has lost one electron
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Q
Equilibrium
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Here, the state in which the of ions crossing a membrane in one direction is matched by the number crossing in the opposite direction
21
Q
Electrostatic Pressure
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The propensity of charged molecules or ions to move toward areas with the opposite charge
22
Q
Nernst Equation
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An equation predicting the equilibrium potential for a given ion based on the concentrations of the ion on opposite sides of a permeable membrane
23
Q
Equilibrium Potential
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The voltage across a permeable membrane that exactly counteracts the movement of ions from the side with the high concentration to the side with a low concentration
24
Q
Goldman Equation
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An equation predicting the potential difference across a membrane based on the concentrations of ions on the opposite sides of the membrane, as well as its relative permeability to each ion
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Calcium Ion (Ca^2+)
A calcium atom that carries a DOUBLE positive charge because it has lost two electrons
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Action Potential
The propagated electrical message of a neuron that travels along the axon to the presynaptic axon terminals
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Hyper-polarization
An increase the membrane potential (the interior of the neuron becomes even more negative)
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Depolarization
A reduction in membrane potential (the interior of the neuron becomes less negative)
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Local Potential
An electrical potential that is initiated by stimulation at a specific site, which is a graded response that spreads passively across the cell membrane, decreasing in strength with time and distance
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Threshold
The stimulus intensity that is just adequate to trigger an action potential
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All-Or-None Property
The fact that the amplitude of the action potential is independent of the magnitude of the stimulus
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Afterpotential
The positive or negative change in membrane potential that may follow an action potential
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Voltage-Gated Na+ Channel
A Na+ selective channel that opens or closes in response to changes in the voltage of the local membrane potential; it mediates the action potential
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Refractory
Referring to transiently inactivated or exhausted axonal membrane
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Absolute Refractory Phase
A period of reduced sensitivity during which only strong stimulation produces an action potential
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Axon Hillock
A cone-shaped area from which the axon originates out of the cell body. Functionally, the integration zone of the neuron
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Conduction Velocity
The speed at which an action potential is propagated along the length of an axon (or section of peripheral nerve)
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Node of Ranvier
A gap between successive segments of the myelin sheath where the axon membrane is exposed
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Saltatory Conduction
The form of conduction that is characteristic of myelinated axons, in which the action potential jumps from one node of Ranvier to the next
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Channelopathy
A genetic abnormality of ion channels, causing a variety of symptoms
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Tetrodototoxin (TTX)
A toxin from puffer fish ovaries that blocks the voltage-gated sodium channel, preventing action potential conduction
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Saxitoxin (STX)
An animal toxin that blocks sodium channels when applied to the outer surface of the cell membrane
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Batrachotoxin
A toxin, secreted by poison arrow frogs, that selectively interferes with Na+ channels
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Neurotransmitter
The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons.
Also called synaptic transmitter, chemical transmitter, or simply transmitter
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Postsynaptic Potential
A local potential that is initiated by stimulation at a synapse, can vary in amplitude, and spreads passively across the cell membrane, decreasing in strength with time and distance
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Excitatory Postsynaptic Potential (EPSP)
A depolarizing potential in the postsynaptic neuron that is caused by excitatory connections.
EPSPs increase the probability that the postsynaptic neuron will fire an action potential
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Synaptic Delay
The brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential
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Inhibitory Postsynaptic Potential (IPSP)
A hyper-polarizing potential in the postsynaptic neuron that is caused by inhibitory connections.
IPSPs decrease the probability that the postsynaptic neuron will fire an action potential
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Chloride Ion (Cl-)
A chlorine atom that carries a negative charge because it has gained one electron
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Spatial Summation
The summation at the axon hillock of postsynaptic potentials from across the cell body. If this summation reaches threshold, an action potential is triggered
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Temporal Summation
The summation of postsynaptic potential that reach the axon hillock at different times. The closer in time the potentials occur, the more complete the summation
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Exocytosis
The process by which a synaptic vesicle fuses with the presynaptic terminal membrane to release neurotransmitter into the synaptic cleft
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v-SNARE
Specialized protein anchored to vesicles to aid their fusing to the presynaptic membrane to release neurotransmitter
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t-SNARE
Specialized protein anchored to the presynaptic "target" membrane to bind v-SNAREs to dock vesicles, making them ready for release
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Synaptotagmin
A specialized protein that responds to calcium ions to trigger vesicular exocytosis
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Botulinum Toxin
A toxin that cleaves SNAREs, disabling neurotransmitter release
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Tetanus Toxin
A toxin that cleaves SNAREs, disabling neurotransmitter release
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Ligand
A substance that binds to receptor molecules, such as those at the surface of the cell
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Acetylcholine (ACh)
A neurotransmitter produced and released by parasympathetic post-ganglionic neurons, by motor neurons, and by neurons throughout the brain
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Receptor Molecule
A protein that binds and reacts to molecules of a neurotransmitter or hormone.
Also called a receptor
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Endogenous Ligand
Any substances that is produced within the body and selectively binds to the type of receptor that is under study
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Exogenous Ligand
Any substance that originates outside the body and selectively binds to the type of receptor that is under study
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Curare
An alkaloid neurotoxin that causes paralysis by blocking acetylcholine receptors in the muscle
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Bungarotoxin
A neurotoxin from the venom of the banded krait that selectively blocks acetylcholine receptors
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Agonist
A molecule, usually a drug, that binds a receptor molecule and initiates a response like that of another molecule, usually a neurotransmitter
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Antagonist
A molecule, usually a drug, that interferes with or prevents the action of a transmitter
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Up-Regulation
A compensatory increase in receptor availability at the synapses of a neuron
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Down-Regulation
A compensatory reduction in receptor availability at the synapses of a neuron
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Ionotropic Receptor
A receptor protein that includes an ion channel that is opened when the receptor is bound by an agonist
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Ligand-Gated Ion Channel
An ion channel that opens or closes in response to the presence of a particular chemical
Also called a chemically gated ion channel
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Metabotropic Receptor
A receptor protein that does not contain an ion channel but may, when activated, use a G protein system to alter the functioning of the postsynaptic cell
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G Proteins
A class of proteins that reside next to the intracellular portion of a receptor and that are activated when the receptor binds an appropriate ligand on the extracellular surface
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Second Messenger
A slow-acting substance in the postsynaptic cell that amplifies the effects of synaptic activity and signals synaptic activity within the postsynaptic cell
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Degradation
The chemical break-down of a neurotransmitter into inactive metabolites
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Reuptake
The process by which released synaptic transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping presynaptic activity
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Transporter
Specialized receptor in the presynaptic membrane that recognizes transmitter molecules and returns them to the presynaptic neuron for reuse
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Autoreceptor
A receptor for a synaptic transmitter that is located in the presynaptic membrane, telling the axon terminal how much transmitter has been released
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Axo-Dendritic
Referring to a synapse in which a presynaptic axon terminal synapses onto a dendrite of the postsynaptic neuron
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Axo-Somatic
Referring to a synapse in which a presynaptic axon terminal synapses onto the cell body (soma) of the postsynaptic neuron
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Axo-Axonic
Referring to a synapse in which a presynaptic axon terminal synapses onto another axon's terminal
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Retrograde Synapse
A synapse in which a signal (usually a gas neurotransmitter) flows from the postsynaptic neuron to the presynaptic neuron, thus counter to the usual direction of synaptic communication
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Dendro-Dendritic
Referring to a synapse in which a synaptic connection forms between the dendrites of two neurons
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Ectopic Transmission
Cell-cell communication based on the release of neurotransmitter in regions outside traditional synapses
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Varicosity
The axonal swelling from which neurotransmitter diffuses in a nondirected synapse
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Non-Directed Synapse
A type of synapse in which the presynaptic and postsynaptic cells are not in close apposition; instead, neurotransmitter is released by axonal varicosities and diffuses away to affect wide regions of tissue
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Neural Chain
A simple kind of neural circuit in which neurons are attached linearly, end to end
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Knee-Jerk Reflex
A variant of the stretch reflex in which stretching a tendon below the knee leads to an upward kick of the leg
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Convergence
The phenomenon of neural connections in which many cells send signals to a single cell
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Divergence
The phenomenon of neural connections in which one cell sends signals to many other cells
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Electroencephalogram (EEG)
A recording of gross electrical activity of the brain recorded from electrodes placed on the scalp
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Epilepsy
A brain disorder marker by major sudden changes in the electrophysiological state of the brain referred to as seizures
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Seizure
An epileptic episode
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Tonic-Clonic Seizure
Also called grand mal seizure
A type of generalized epileptic seizure in which nerve cells fire high-frequency bursts
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Simple Partial Seizure
Also called absence attack
A seizure that is characterized by a spike-and-wave EEG and often involves a loss of awareness and inability to recall events surrounding the seizure
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Complex Partial Seizure
In epilepsy, a type of seizure that is characterized by a spike-and-wave EEG and often involves a loss of awareness and inability to recall events surrounding the seizure
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Aura
In epilepsy, the unusual sensations or premonition that may precede the beginning of a seizure
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Kindling
A method of experimentally inducing an epileptic seizure by repeatedly stimulating the brain region
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Event-Related Potential (ERP)
EVOKED POTENTIAL
Averaged EEG recordings measures brain responses to repeated presentations of a stimulus
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Optogenetics
The use of genetic tools to induce neurons to become sensitive to light, such that experimenters can excite or inhibit a cell by exposing it to light
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Channelrhodopsin
A protein that, in response to light of the proper wavelength, opens a channel to admit sodium ions which results in excitation of the neuron
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Halorhodopsin
A protein that, in response to light of the proper wavelength, opens a channel to admit chloride ions, which results in inhibition of neurons
