Chapter 2 Flashcards
excitatory postsynaptic potential
graded depolarization
inhibitory postsynaptic potential
temporary hyperpolarization of a membrane
postsynaptic neuron
neuron that receives transmission from another neuron
presynaptic neuron
neuron that delivers transmission to another neuron
reflex arc
circuit from sensory neuron to muscle response
spatial summation
combination of effects from two or more synapses onto a single neuron
spontaneous firing rate
periodic production of action potentials without synaptic input
synapse
gap as a point of communication between two neurons chemically
temporal summation
effect of repeated stimuli within a brief time
acetylcholine
modified amino acid
amino acids
glutamate, GABA, glycine, aspartate
amphetamine
drug that blocks reuptake of dopamine
autoreceptors
receptor on presynaptic neuron that provide negative feedback by responding to the released transmitter by inhibiting further release
cannabinoids
excites negative-feedback receptors on presynaptic cells
catecholamines
dopamine, norepinephrine, epinephrine
exocytosis
release of neurotransmitter from presynaptic neuron into synaptic cleft
g protein
gap junction
direct contact of one neuron with another, enabling electrical transmissions
ionotropic effects
synaptic effect that depend on rapid opening of a gate in the membrane
ligand-gated channels
channel that opens when a neurotransmitter attaches to it
metabotropic effects
sequence of metabolic reactions that produce slow, long-lasting effects
methylphenidate
stimulant drug prescribed for ADHD that increases the stimulation of dopamine synapses by blocking the reuptake of dopamine by the presynaptic neuron
monoamines
chemicals formed by a change in certain amino acids, catecholamines or indoleamines
neuropeptides
chain of amino acids: endorphins, substance P, neuropeptide Y
nitric oxide
a gas released by many small local neurons
pituitary gland
an endocrine gland attached to the base of the hypothalamus
purines
ATP, adenosine
releasing hormones
hormone released by the hypothalamus that flows through the blood to the anterior pituitary
reuptake
reabsorption of a neurotransmitter by the presynaptic terminal
second messenger
a chemical that, when activated by a neurotransmitter, initiates communication to many areas within the neuron
synaptic cleft
the space between the presynaptic and postsynaptic neurons
transmitter-gated channels
ion channel that opens temporarily when a neurotransmitter binds to it
vasopressin
antidiuretic hormone released by posterior pituitary, raises blood pressure and enables kidneys to conserve water
vesicles
tiny nearly spherical packets filled with neurotransmitter molecules
what evidence led sherrington to conclude that transmission at a synapse is not the same as transmission along an axon?
the velocity of conduction through a reflex arc is slower than the velocity of an action potential along an axon, a delay must occur at the junction between two neurons
what ion gates in the membrane open during an EPSP?
sodium gates open
what gates open during an IPSP?
chloride gates open
what was sherrington’s evidence for inhibition in the nervous system?
a reflex that stimulates a flexor muscle prevents contraction of the extensor muscles of the same limb, sherrington inferred that an interneuron that excites one set of motor neurons inhibits the input to another set
can an inhibitory message flow along an axon?
no, only action potentials propagate along an axon, inhibitory messages decay over time and distance
sherrington based his conclusions on what type of evidence?
observations of reflexive responses
what was loewi’s evidence that neurotransmission depends on the release of chemicals?
when loewi stimulated a nerve that increased or decreased a frog’s heart rate, he could withdraw fluid from the area around the heart, transfer it to another frog’s heart, and thereby increase or decrease its rate also
indoleamines
serotonin
across species, how much do neurotransmitters vary?
most animals have all or nearly all the same neurotransmitters
when the action potential reaches the presynaptic terminal, which ion must enter the presynaptic terminal to evoke release of the neurotransmitter?
calcium
ionotropic synapses are most important for what types of behavior?
most important when precise timing is important, visual or auditory perception
how do LSD and opiate drugs influence behavior?
LSD binds to one type of serotonin receptor, opiates bind to endorphin receptors
what happens to acetylcholine molecules after they stimulate a postsynaptic receptor?
enzyme acetylcholinesterase breaks acetylcholine molecules into two smaller molecules, acetate and choline. The presynaptic neuron then reabsorbs the choline
what happens to serotonin and catecholamine molecules after they stimulate a postsynaptic receptor?
most serotonin and catecholamine molecules are reabsorbed by the presynaptic terminal, some of their molecules are broken down into inactive chemicals, which then diffuse away
how do amphetamine and cocaine influence synapses?
they block reuptake of released dopamine, serotonin, and norepinephrine
why is methylphenidate generally less disruptive to behavior than cocaine, despite the drugs’ similar mechanisms?
the effects of a methylphenidate pill rise and fall more slowly than those of cocaine
how do cannabinoids affect neurons?
cannabinoids released by the postsynaptic neuron attach to receptors on presynaptic neurons, where they inhibit further release of both glutamate and GABA
nicotine
mimics effect of acetylcholine, which increases dopamine release
MDMA (ecstasy)
releases dopamine, serotonin, and norepinephrine
which part of the pituitary is neural tissue, similar to the hypothalamus? which part is glandular tissue and produces hormones that control the secretions by other endocrine organs?
the posterior pituitary is neural tissue like the hypothalamus, the anterior pituitary is glandular tissue and produces hormones that control several other endocrine organs
what do releasing hormones do?
hypothalamus secretes releasing hormones, which control release of hormones by the pituitary gland
brain excitatory neurotransmitter
glutamate
brain inhibitory neurotransmitter
GABA
what happens when a neurotransmitter binds to a metabotropic receptor?
bends the receptor protein
