Chapter 3 Flashcards
Neurophysiology
Studying the specialized life processes that allow neurons to use chemical and electrical processes to sum up vast amounts of information and pass it on to other neurons.
Ions/Anions/Cations
Ions-electrically charged molecules
anions-negatively charged
cations-positively charged
Microelectrode
Inserted into the interior of a neuron to place an electrode into a neuron
Resting Potential
Between -50 to -80 millivolts (mV)
Ion Chanel
tubelike pore that allows ions of a specific type to pass through it.
Potassium ions (K+) and Sodium Ions (Na+)
Two ions that are important with the action potential/firing of a cell
Selective permeability
allowing some things to pass but not others. Cell membrane of a neuron is this way.
Electrostatic Pressure/Diffusion
Both part of creating an action potential/rebalancing cells charge
Electrostatic Pressure - charged particles exerting electrical forces on one another. Like charges repel and opposites attract
Diffusion - force that causes molecules of a substance to spread from regions of high concentration to regions of low concentration
Sodium-Potassium pumps
Pump three Na+ ions out for every two K+ ions pumped in.
Equilibrium Potential
The electrical charge that exactly balances the concentration of the gradient (around -60 mV) Also the resting potential of cells ^
Hyperpolarization/Depolarization
Hyper - increase in membrane potential, neuron is even more negative.
Depol - decrease in membrane potential, neuron is closer to zero.
Local Potentials
Ripples that spread across the membrane after the action potential and get smaller as they spread from the point of stimulation.
Threshold/Action Potential
Threshold= -40 mV
Action potential - sudden and brief response to reaching threshold lasting .5-2.0 milliseconds. A rapid reversal of the membrane potential that momentarily makes the inside of the membrane positive with respect to the outside. Follows the all-or-none property.
After potentials are small potential changes immediately after the spike
Voltage-gated Na+ channel
Tubular, membrane-spanning protein, the central Na+ selected pore is gated. Electrically stimulated to open and allow Na+ ions through for a short period.
Refractory
(Temporarily unresponsive or inactivated) After one action potential, the axonal membrane is unable to respond to a second stimulus and be _____.
Absoute Refractory/Relative Refractory
Absolute - Brief period immediately following the production of an action potential in which no amount of stimulation can induce another action potential
Relative - Only a strong stimulation well beyond threshold can produce another action potential.
Conduction Velocity
varies with diameter of axon, it is the speed of action potentials along axons.
Saltatory Conduction
When the action potential “jumps” across Nodes of Ranvier between myelinated axon chunks.
Multiple Sclerosis is a disease which myelin is compromised.
Excitatory Postsynaptic Potential (EPSP) and Inhibitory Postsynaptic Potential (IPSP)
EPSP-Na+ channels open to let in more positive ions, thus pushing the charge closer to the threshold.
IPSP-becomes more polarized/further away from threshold. Usually caused by channels permitting Chloride ions (Cl-).
Spatial and Temporal Summation
Spatial - action potentials have different physical origins along cell body
Summation - action potentials come from a single location after one another.
Calcium Ions (Ca2+)
Ions which come into the axon terminal from the extracellular through Ca2+ channels which open at the arrival of the action potential. This causes synaptic vesicles to bind to the cell membrane and release the neurotransmitter.
Synaptic Delay
Time needed for Ca2+ to enter the terminal and for transmitter to diffuse across the cleft and interact with the receptors on the postsynaptic cell.
Ligand
substance that binds to receptor molecules, such as neurotransmitter or drugs that bind with postsynaptic receptors.
Acetylcholine (ACh)
Neurotransmitter that is produced and released by parasympathetic postganglionic neurons, by motoneurons and neurons throughout the brain. Fits into ligand binding sites. Neuromuscular PNS junctions/basic movement and learning and CNS memory/arousal/award process.
Neurotransmitter receptor
“receptor” a specialized protein, often embedded in the cell membrane that selectively senses and reacts to molecules of a corresponding neurotransmitter or hormone.
Curare/Bungarotoxin
Neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle. Bungarotoxin is isolated from the venom or the “many-branded krait” that selectively blocks acetylcholine receptors.
Agonists and Antagonists
Agonists-substance that mimics or potentiates that actions of a transmitter or other signaling molecule
Antagonists-substance that blocks or attenuates the actions of a transmitter or other signaling molecule.
Cholinergic
Cells that use acetylcholine as their synaptic transmitter
Degradation and Acetylcholinesterase (AChE)
Chemical breakdown of a neurotransmitter into inactive metabolites. Ace….is the enzyme that inactivates the transmitter acetylcholine.
Reuptake
process which released synaptic transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping synaptic activity. Transporters used.
Transporter
Specialized membrane component that returns transmitter molecules to the presynaptic neuron for reuse. Process of reuptake.
Axo-dentritic
Synapse which a presynaptic axon terminal, synapses to a dendrite of the postsynaptic neuron either via a dendritic spine or directly onto the dendrite itself.
Axo-somatic
Synapse where a presynaptic axon terminal synapses onto the cell body (soma) of the postsynaptic neuron.
Axo-axonic
Synapse where a presynaptic axon terminal synapses onto the axon terminal of another neuron.
Dendro-dendritic
Synapse where a synaptic connection forms between the dendrites of two neurons.
Electroencephalograms (EEGs)
Record the gross electrical activity of the brain via large electrodes placed on the scalp.
Event-related potentials (ERPs)
“evoked potential” averaged EEG recordings which measure brain responses to specific stimuli.
Epilepsy/Seizure
Brain disorder marked by sudden changes in the electrophysiological state of the brain which are called seizures. Grand mal are the biggest followed by petit mal. Complex partial seizures don’t involve the entire brain and produce a wide variety of symptoms preceded by an unusual sensation, or aura.
