Exam 2 Flashcards
A- lions and K+ lions have _____ concentration inside the axon
Higher
CI- ions and Na+ ions are more concentrated ______ the axon
Outside
Inside the cell
Intracellular
Extracellular
Outside the cell
_______ can be produced by an influx of sodium ions and is produced by the opening of normally closed gates sodium channels
Depolarization
Large, brief reversal in polarity of an axon and lasts one millisecond
Action Potential
Voltage on a neural membrane at which an action potential is triggered via opening of the Na+ and K+ voltage sensitive channels
Threshold potential
The state of an axon in the polarizing period when an action potential cannot typically occur
Absolute Refractory Period
Increased electrical current is required to produce another action potential, potassium channels still open
Relative Refractory Period
Propagation of an action potential on the membrane of an axon. Size and shape of the action potential remain constant along the axon
Nerve impulse
Part of the axon that is not covered by myelin
Node of Ranvier
Propagation of an action potential at successive nodes of ranvier
Saltatory Conduction
how neurons integrate information
through dendritic spines, a neuron can establish more than 50,000 connections to other neurons.
Nerve impulses traveling from other neurons bombard the receiving neuron with all manner of inputs (excitatory and inhibitory)
The cell body, located between the dendritic tree and its axon, can receive inputs from many other neurons
Brief depolarization of a neuron membrane in response to stimulation. Neuron is more likely to produce an action potential
Excitatory Postsynaptic Potential (EPSP)
Brief hyperpolarization of a neuron membrane in response to stimulation–Neuron is less likely to produce an action potential
Inhibitory Postsynaptic Potential (IPSP)
______ are associated with the opening of sodium channels: allows influx of Na+
Excitatory Postsynaptic Potential (EPSP)
______ are associated with the opening of potassium channels (allows an influx of K+) or with the opening of chloride channels (allows an influx of Cl−)
Inhibitory Postsynaptic Potential (IPSP)
Pulses that occur at approximately the same time on a membrane are summed
Temporal Summation
Pulses that occur at approximately the same location on a membrane are summed
Spatial Summation
Junction of cell body and axon. Rich in voltage-sensitive channels. Where EPSPs and IPSPs are integrated. Where action potentials are initiated
The Axon Hillock
Reverse movement of an action potential from the axon hillock into the dendritic field
Back Propagation
How Sensory Stimuli Produce Action Potentials
We receive information about the world through–bodily sensations (touch and balance)–auditory sensations (hearing)–visual sensations (sight)–chemical sensations (taste and olfaction)•Neurons related to these diverse receptors all have ion channels on their cell membranes.•These ion channels initiate the chain of events that produces a nerve impulse
part of the muscle membrane that is contacted by the axon terminal
End Plate
Chemical transmitter that the axon terminal releases at the muscle end plate
Acetylcholine
NT that acts as a hormone to allow fight or flight during times of stress and as a neurotransmitter in the central nervous system
Epinephrine (EP, or adrenaline)
Chemical released by a neuron onto a target with an excitatory or inhibitory effect
Neurotransmitter
The junction where messenger molecules (neurotransmitters) are released from one neuron to excite or inhibit the next neuron
Chemical Synapse
Where the action potential terminates to release the chemical message
Presynaptic Membrane (axon terminal)
The receiving side of the chemical message; EPSPs or IPSPs are generated
Postsynaptic Membrane (dendritic spine)
Small gap where the chemical travels from presynaptic to postsynaptic membrane
Synaptic Cleft (space between)
Small membrane-bound spheres that contain the neurotransmitter(s)
Synaptic Vesicle (presynaptic)
Membranous compartment that holds several vesicles containing the neurotransmitter(s)
Storage granule (presynaptic)
Site to which a neurotransmitter molecule binds
Postsynaptic receptor (postsynaptic)
Study of the ways drugs affect the nervous system and behavior
Psychopharmacology
Chemical compounds administered to produce a desired change
Drugs
Substance that acts to alter mood, thought, or behavior, used to manage neuropsychological illness
Psychoactive Drug
How the Body Eliminates Drugs
Drugs are broken down (catabolized) in the kidneys, liver, and intestines.
Drugs are excreted in urine, feces, sweat, breast milk, and exhaled air.
Some substances that cannot be removed may build up in the body and become toxic
Drug Action at Synapses
Most psychoactive drugs exert their effects by influencing synaptic chemical signaling
Substance that enhances the function of a synapse
Agonist
Substance that blocks or decreases the function of a synapse
Antagonist
Drugs affect the synaptic function via:
Synthesis, Packaging and storage, release, receptor interaction, inactivation by reuptake, degradation
When a response to a drug weakens with repeated use.
Tolerance
Increase in number of enzymes in the liver, blood, or brain used to break down a substance
Metabolic tolerance
Activities of brain cells adjust to minimize effects of the substance
Cellular tolerance
People learn to cope with being intoxicated. Context can be powerful: tolerance levels higher for places where drug is typically taken.
Learned tolerance
Increased effects from the drug from successive doses.
Sensitization
Most drugs that have psychoactive effects influence chemical reactions at neuronal ____.
synapses
People have been using drugs for therapeutic and recreational reasons throughout history
Psychoactive Drugs