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Bio Psyc: Chap 3
Neurophysiology
| Question | Answer |
|---|---|
| ion | an stom or molecule tha has acquired an electical charge by gaining or losing one or more electrons |
| anion | a negatively charged ion, such as a protein or choloride ion |
| cation | a positively charged ion, such as a potassium or sodium ion |
| intracelluar fluid | also called cytoplasm. The watery solution found within cells |
| extracelluar fluid | the fluid in the spaces between cells (interstial fluid) and in the vascular system. |
| cell membrane | teh lipid bilayer that ensheathes a cell. |
| microelcetrode | an especially small electrode used to record electrical potentials from living cells |
| resting membrane potential | a difference in electrical potential across teh membrane of a nerve cell during an inactive period. |
| millivolt (mV) | a thousandth of a volt |
| negative polarity | a negative electrical potential difference relative to a reference electrode. |
| lipid bilayer | the structure of the neuronal cell membrane, which consists of two layers of lipid molecules, within which float various specialized proteins, such as receptors. |
| ion channel | a pore in the cell membrane that permits the passage of certain ions through the membrane when the channels are open |
| gated | referring to teh property by which an ion channel may be opened or closed by factors such as chemicals, voltage changes or mechanical actions. |
| potassium ion (k+) | a potassium atom taht carries a positive charge because it has lost one electron. |
| selective permeability | the property of a membrane that allows some substances to pass through, but not others. |
| diffusion | the spontaneous spread of molecules of one substance among molecules of another substance until uniform concentration is achieved. |
| concetration gradient | variation of the concentration of a substance within a region. |
| electrostatic pressure | the propesity of charged molecules or ions to move, via diffusion, toward areas with the opposite charge. |
| equilibrium | in chemistry, the point at which all ongoing reactions are canceled or balanced by othersm resulting in a stable, balanced, or unchanging system. |
| Nernst equation | an equation used to calculate the equilibrium potential at a membrane. |
| sodium ion (Na+) | a sodium ion that carries a positive charge because it has lost one electron |
| sodium-potassium pump | the energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in. |
| action potential | the propagated electrical message of a neuron that travels along teh acon to the presynaptic axon terminals. |
| axon hillock | a cone-shaped area from which the axon orginates out of the cell body. Functionally, the integration zone of the neuron. |
| hyperpolarization | an increase in membrane potential (the interior of the neuron becomes even more negative). |
| depolarization | a reduction in membrane potential (the interior of the neuron becomes less negative). |
| graded response | a membrane electrical potential that spreads passively across the cell membrane, decreasing in strength with time and distance. |
| local potential | an electrical potential that is intiated by stimulation at a specific site and spreads passively across teh cell membrane, decreasing in strength with time and distance. |
| threshold | the stimulus intensity that is just adequate to trigger a nerve impulse at the axon hillock. |
| all-or-none property | the fact that the amplitude of the action potential is indedpendant of the magnitude of the stimulus. |
| afterpotential | teh positive or negative change in membrane potential that may follow an action potential. |
| voltage-gated Na+ channel | an Na+ selective channnel that opens or closes in response to changes in teh coltage of the local membrane potential; mediates the action potential. |
| refractory | transiently inactivated or exhauseted. |
| absolute refractory phase | a brief period of complete insensitivity to stimuli |
| relative refractory phase | a period of reduced sensitivity during which only strong stimulation produces an action potential. |
| conduction velocity | the speed at which an action potential is propagated along the length of an axon (or section of peripheral nerve). |
| node of Ranvier | a gap between successive segments of teh myelin sheath where the axon membrane is exposed. |
| saltatory conduction | the form of conduction that is characteristic of myelinated axons, in which the nerve impulse jumps from one node of Ranvier to the next. |
| neurotransmitter | also simply called transmitter. The chemical, released from the presynaptic axon terminal, that serves as the basis of communication between neurons. |
| postsynaptic potential | also called graded potential or local potential. An electrical potential that is intiated at a postsynaptic site that can vary in amplitude and spreads passively across the cell membrane, decreasing in strength with time and distance. |
| excitatory postsynaptic potential (EPSP) | a depolarizing potential in the psotsynaptic neuron that is caused by exctiatiry presynaptic impulses. EPSPs increas the probability that the postsynaptic neuron will fire an action potential. |
| synaptic delay | the brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential. |
| inhibitory postsynaptic potential (IPSP) | a hperpolarizing potential in teh postsynaptic neuron that is caused by inhibitory connections. IPSPs decrease the probability that the postsynaptic neuron will fire an action potential. |
| chloride ion (Cl-) | a chlorine atom that carries a negative charge because it has gained one electron. |
| spatial summation | the summation at the axon hillock of postsynaptic potentials from across the cell body. If this summations reaches threshold, an action potential is triggered. |
| temporal summation | the summation of postsynaptic potentials that reach the axon hillock at different times. The closer in time the potentials occur, the more complete the summation. |
| calcium ion (ca^2+) | a calcium atom that carries a double positive charge because it has lost two electrons. |
| ligand | a substance that binds to receptor molecules, such as those at the surface of the cell. |
| endogenous ligand | any substance, produced within the body, that selectively binds to the type of receptor that is under study. |
| exogenous ligand | any substance orginating from outside the body, that selectively binds to the type of receptor that is under study. |
| acetylcholine (ACh) | an amine transmitter that stimulates muscle contraction, but is also found throughout the brain. |
| receptor molecule | also called receptor. A protein that captures and reacts to molecules of the transmitter or hormone. |
| curare | an alkaloid neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle. |
| bungarotoxin | a meurotoxin, isolated from the venom of the banded krait, that selectively blocks acetylcholine receptors. |
| agonist | a molecule, usually a drug, that binds a receptor molecule and initiates a response like that of another molecule, usually a neurotransmitter. |
| antagonist | a molecule, usually a drug, that interfers with or prevents the action of a transmitter. |
| cholinergic | referring to cells that use acetylcholine as their synaptic transmitter. |
| up-regulation | a compensatory increase in receptor availability at the synapses of a neuron. |
| down-regulation | a compesatory reduction in receptor availabilty at the synapses of a neuron. |
| ionotropic receptor | a receptor protein that includes an ion channel that is opened when the receptor is bound by an appropriate ligand. |
| ligand-gated ion channel | an ion channel that opens or closes in response to the presense of a particular chemical. |
| metabotropic receptor | a type of transmitter receptor that does not contain an ion channel but may, when activated, use a G protein system to alter the functioning of the postsynaptic cell. |
| G proteins | a class of proteins that reside next to the intracelluar portion of a receptor and that are activated when the receptor binds an appropriate ligand on the extracelluar surface. |
| second messanger | a slow-acting substance in the postsynaptic cell that amplifies the effect of synaptic activity and signals synaptic activity within the postsynaptic cell. |
| degradation | the process by which neurotransmitter molecules are broken down into inactive metabolites. |
| reuptake | the process by which released synaptic transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping synaptic activity. |
| pinocytosis | the process by which synaptic neurotransmitter is repackaged into vesicles. |
| transporters | specialized receptors in the presynaptic membrane that recognize transmitter molecules and return them to the presynaptic neuron for reuse. |
| axo-dendritic | referring to a synapse in which presynaptic axon terminal synapses onto a dendrite of the postsynaptic neuron, either via a dendritic spine or directly onto the dendrite. |
| axo-axonic | referring to a synapse in which a presynaptic axon terminal synapses onto another axon's terminal. |
| dendro-dendritic | referring to a type of synapse connection forms between the dendrites of two neurons. |
| retrograde synapse | a synapse in which a signal (usually a gas neurotransmitter) flows from the postsynaptic neuron, thus counter to the usual direction of synaptic communication. |
| ectopic transmission | cell-cell communication based on release of neurotransmitter in regions outside traditional synapses. |
| varicosity | the axonal swelling from which neurotransmitter diffuses in a nondirected synapse. |
| nondirected synapse | a type of synapse in which the presynaptic and postsynaptic cells are not in close appostion; instead, neurotransmitter is released by axonal varicosities and diffuses away to affect wide regions of tissue. |
| neural chain | a simple kind of neural circuit in which neurons are attached linearly, end to end. |
| knee jerk reflex | a variant of the stretch reflex in which streching of the tendon beneath the knee leads to an upward kick of the leg. |
| convergance | the phenomenon of neural connections in which many cells send signals to a single cell. |
| divergence | the phenomenon of neural connections in whcih one cell sends signals to many other cells. |
| lateral interaction | especially in sensory systems, the phenomenon by which reciprocal connections among neurons at the same level in the hierarchy more sharply tune the repsonses of the system. |
| electoencephalogram (EEG) | a recording of gross electrical activity of the brain recorded from large electrodes placed on the scalp |
| event-related potential (ERP) | a large change in electrical potential in the brain that is elicited by a discrete sensory or motor event. |
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Doublefault84