Unit 2 Flashcards
Neurophysiology
The study of the life processes of neurons
Ions
An atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons
Anions
A negatively charged ion, such as a protein or a chloride ion
Cations
A positively charged ion, such as a potassium or sodium ion
Resting Potential
The difference in electrical potential across the membrane of a neuron at rest
Ion Channel
A pore in the cell membrane that permits the passage of certain ions through the membrane when the channel is open
Selective Permeability
The property of a membrane that allows some substances to pass through, but not other
Diffusion
Spread of solute molecules from an area of high concentration to an area of low concentration through a solvent until a uniform solute concentration is achieved
Electrostatic Pressure
The propensity of charged molecules or ions to move toward areas with the opposite charge
Sodium-Potassium Pumps
The energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in
Equilibrium Potential
Movement of ions across the cell membrane is balanced
Electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in the opposite direction
Hyperpolarization
An increase in membrane potential, becoming more negative
Depolarization
A decrease in membrane potential, becoming more positive
Local Potential
Electrical potential initiated by stimulation at a specific site
Graded response that spreads passively across the cell membrane
Weaker with time and distance
All or none property
amplitude of the action potential is independent of stimulus size
Action Potential
Rapid reversal of the membrane potential that momentarily makes the inside of a neuron positive
Created by the sudden movement of Na+ ions into the axon
After Potential
change in membrane potential that may follow an action potential
Voltage-Gated Na+ Channel
Na+-selective channel that responds to changes in the voltage of the local membrane potential.
Mediates the action potential = Has recharge period
Absolute Refractory Phase
A brief period of complete insensitivity to stimuli
Relative Refractory Phase
Reduced sensitivity, only strong stimulation produces an action potential
Post-syn Potential
Local potential initiated by stimulation at a synapse
Spreads passively across the cell membrane, decreasing in strength with time and distance
Excitatory Postsynaptic Potential (EPSP)
Depolarizing potential in a neuron normally caused by synaptic excitation
Increases the probability that the postsynaptic neuron will fire an action potential
Inhibitory Postsynaptic Potential (IPSP)
Hyperpolarizing potential in a neuron
Decreases the probability that the postsynaptic neuron will fire an action potential
Spatial Summination
The postsynaptic potentials that reach the axon hillock
Temporal Summination
The summation of postsynaptic potentials that reach the axon hillock at different times. The closer in time the potentials occur, the greater the summation.
Synaptic Delay
The brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential.
Agonist
A substance that mimics or boosts the actions of a transmitter or other signaling molecule
Antagonist
A substance that blocks or attenuates the actions of a transmitter or other signaling molecule
Degredation
The chemical breakdown of a neurotransmitter into inactive metabolites
Reuptake
The reabsorption of molecules of neurotransmitter by the neurons that released them, thereby ending the signaling activity of the transmitter molecules
Axo-dendritic Synapse
A synapse at which a presynaptic axon terminal synapses onto a dendrite of the postsynaptic neuron, either via a dendritic spine or directly onto the dendrite itself.
-Axon terminal synapses onto dendrite
Axo-somatic synapses
A synapse at which a presynaptic axon terminal synapses onto the cell body (soma) of the postsynaptic neuron.
-Axon terminal synapses onto cell body (soma)
Axo-axonic Synapses
A synapse at which a presynaptic axon terminal synapses onto the axon terminal of another neuron
-Axon terminal synapses onto axon terminal
Dendo-denritic synapses
A synapse at which a synaptic connection forms between the dendrites of two neurons
Epilepsy
major, sudden changes in the electrophysiological state of the brain that are referred to as seizures
Seizure
Abnormally synchronous electrical activity in the brain
widespread synchronization of electrical activity: broad stretches of the brain start firing in simultaneous waves
Tonic-Clonic Seizures (AKA grand mal seizure)
seizure in which neurons fire in high-frequency bursts, usually accompanied by involuntary rhythmic contractions of the body
Simple Partial Seizures (Petit mal seizure or 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
Complex Partial Seizures
A type of seizure that doesn’t involve the entire brain and therefore can cause a wide variety of symptoms
Transporters
A specialized membrane component that returns transmitter molecules to the presynaptic neuron for reuse
Ionotropic receptor- Ligand-gated ion channel
A receptor protein containing an ion channel that opens when the receptor is bound by an agonist.
Excitatory Synapse
Synapse when active, causes a local depolarization that increases the likelihood the neuron will fire an action potential
Inhibitory Synapse
Synapse when active, causes a local hyperpolarization that decreases the likelihood the neuron will fire an action potential
Metabotropic Receptors
When activated, use a second-messenger system to open nearby ion channels or to produce other cellular effects
Amino Acid Transmitters
A neurotransmitter that is itself an amino acid.
-GABA
Peptide Neurotransmitters
Also called neuropeptide. A neurotransmitter consisting of a short chain of amino acids
Amine Neurotransmitters
A neurotransmitter based on modifications of a single amino acid nucleus.
-Acetylcholine, serotonin, and dopamine
Glutamate
An amino acid transmitter, the most common excitatory transmitter
GABA
Amino acid transmitter, the main inhibitory transmitter in the mammalian nervous system.
-Xanax (alprazolam) and Ativan (lorazepam)—potently activate GABAA receptors and are widely used to treat anxiety and panic attacks, as well as to aid muscle relaxation, sleep induction, ect