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| the life processes within neurons, specialized to use both electrical and chemical signals |
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| the propagated electrical mesage of a neuron that travels along the axon to the presynaptic axon terminals |
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the chemical released when the action potential reaches the axon terminals to stimulate spinal motoneurons
in response, motoneurons send action potentials down their own axons to release another neurotransmitter to the muscles. |
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| atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons |
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negatively charged ion
majority in the brain |
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| all ions are dissolved in this (cytoplasm) |
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| fluid in the spaces between cells and in the vascular system |
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| small electrode used to record electrical potentials from living cells |
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| resting membrane potential |
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Definition
a neuron at rest exhibits this. A difference in electrical potential across the membrane of a nerve cell during an inactive period
around -50 to -80 (schein says -70) |
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| negative electrical potential difference relative to a reference electrode. |
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| the lipid bilayer that ensheaths a cell |
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| structure of the neuronal cell membrane, consists of two layers of lipid molecules, within which float proteins such as receptors |
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| a pore in the cell membrane that permits the passage of certain ions through the memberane when the channels are open. |
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| they can open and close rapidly in response to various influences |
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| selectively allows ions to enter |
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| spontaneous spread of molecules of one substance among molecules of another substance until a uniform concentration is achieved. |
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| variation of concentration of a substance within a region |
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| driving force. propensity of charged molecules or ions to move, via diffusion, toward areas with the opposite charge. |
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| positively charged cations are attracted to |
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| the negative charged interior of the cell |
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| the cell interior and so tend to exit to the extracellular fluid |
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| mechanism neurons use. energetically expensive that pushes sodium ions out of a cell and potassium ions in |
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the point at which the movement of ions across the cell membrane is balanced, as the electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in the opposite direction.
this leads to resting potential |
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| mathematical function predicting the voltage needed to just counterbalance the diffusion force pushing an ion across a semipermeable membrane. |
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| an increase in membrane potential (neuron becomes more negative on the inside, relative to the outside. hyperpolarized neuron is -70mV when resting is -60mV |
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| decrease in membrane potential. neuron becomes less negative and closer to 0 |
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| electrical potential is initiated by stimulation at a specific site, which is a graded response that spreads passively across the cell membrane, decreasing in strength with tim eand distance |
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| stimulus intensity that is just adequete to trigger an action potential at the axon hillock |
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| amplitude of the action potential is independent of the magnitude of the stimulus. fires at full amplitude or doesnt fire |
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| positive or negative change in the membrane potential that may follow an action potential |
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| beyond a certain poitn the channels become transiently inactivated or exhausted |
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| Absolute refractory phase |
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| brief period of complete insensitivity to stimuli |
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| relative refractory phase |
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| period of reduced sensitivity during which only strong stimulation produces an action potential |
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| How does the action potential travel |
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Definition
regenrated along the length of the axon.
ex)matchbook example |
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| speed at which action potential is propagated along the length of an axon |
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action potential jumps from node to node
makes conduction much quicker
myelin sheath ensures the potential is not lost between jumps (fast conduction rate) |
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Definition
| when neurotransmitters briefly alter the resting potential of the postsynaptic cell |
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| excitatory postsynaptic potential (EPSP) |
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Definition
| depolarizing potential in the post synaptic neuron that is cause by excitatory presynaptic potentials. Increase the probability that the postsynaptic neuron will fire an action potential |
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| brief delay between the arrival of an action potential at the axon terminal and the creation of postsynaptic potential. reflects time needed for the transmitter to be released and diffuse across cleft. |
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| Inhibitory postsynaptic potential (IPSP) |
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| hyperpolarizing potential in the postsynaptic neuron that is caused by inhibitory connections. IPSPs decrease the probability that the post synaptic neuron will fire an action potential |
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Depolarizing = ________
Hyperpolarizing = ________ |
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| the summation at the axon hillock of postsynaptic potentials from across the cell body. If this sumation reaches threshold, an action potential is triggered. |
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summation of postsynaptic potentials that reach the axon hillock at different times.
closer in time they occur, the more complete the summation. |
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augment the receptive surface of the neuron and increase amount of input information a neuron can handle.
father out on a dendrite a potential is produces, less effect potential should have, potential decreases in amplitude as it spreads |
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| process by which synaptic neuron transmitter is repackaged into synaptic vesicles. |
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| substance that binds to receptor molecules, such as those at the surface of the cell |
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| any substance, produced within the body, that bings to the type of receptor under study |
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| any substance, produced within the body, that bings to the type of receptor under study |
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| substance originating from outside the body that binds to the type of receptor under study |
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| neurotransmitter produced and released by parasympathetic postganglionic neurons, by motoneurons, adn by neurons throughout the brain |
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| protein that captures and reacts to molecules of a neurotransmitter or hormone |
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| alkaloid neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle |
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| neurotoxin, isolated from the venom of the banded krait, selectively locks acetylecholine receptors |
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| molecule that binds a receptor molecule and initiates a response like that of another molecule, usually a neurotransmitter |
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| molecule that interferes with or prevents the action of a transmitter |
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| cells that use acetylcholine as their synaptic transmitter |
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| increase in receptor numbers |
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| decrease receptor density |
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| a receptor protein that includes an ion channel that is opened when the receptor is bound by an appropriate ligand |
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| ion channel that opens or closes in response to the presence of a particular chemical |
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| 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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| 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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| 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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| chemical breakdown of a neurotransmitter into inactive metabolites |
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| process by which released synaptic transmitter molecules are taken up and reused by the presynaptic neuron, stopping activity |
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| bring the transmitter back inside |
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| referring to a synapse in which a presynaptic axon terminal synapses onto a dendrite of the postsynaptic neuron, via dendritic spine or directly onto the dendrite |
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| referring to a synapse in which a presynaptic axon terminal synapses onto the cell body (soma) of the postsynaptic neuron |
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| referring to a synapse in which a presynaptic axon terimal synapses onto another axons terminal |
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| referring to a type of synapse in which a synaptic ocnnection froms between the dendrites of two neurons |
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| synapse in which a signal flows from the postsynaptic neuron to the presynaptic neuron, thus counter to the usual direction of synaptic communication |
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| cell-cell communication based on release of neurotransmitter in regions outside traditional synapses |
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| axonal swelling from wich neurotransmitter diffuses in a non directed synapse |
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| 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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| simple kind of neural circuit in which neurons are attached linearly, end to end |
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| variant of the stretch reflex in which stretching of the tendon beneath the knee leads to an upward kick of the leg |
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| phenomenon of neural connection in which many cells send signals to a single cell |
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| phenomenon of neural connections in which one cell sends singles to many other cells |
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| electroencephalogram (EEG) |
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Definition
| recording of spontaneous brain potentials |
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| Event-related potential (ERP) |
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Definition
| evoked potential. Averaged EEG recordings measuring brain responses to repeated presentations of a stimulus. components of the erp tend to be reliable because the background noise of the cortex has been averaged out. |
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