chapter 1-3 Flashcards
neurophysiology
study of the specialized life processes that allow neurons to use chemical and electrical signals to process and transmit information
action potential
rapid depolarization of electrical signal change along the axon
ions
electrically charged molecules
anions
negatively charged molecules
cations
positively charged
microelectrode
small electrode to record electrical potentials inside living cells
resting potential
electrical difference across membrane
selective permeability
allowing somethings to pass through ion channel, but not others
diffusion
spread of molecules from high concentration to low through a solvent
-drop of dye spreads in water
electrostatic pressure
charged molecules or ions move toward areas with opposite charge
equilibrium potential
electrical charge that exactly balances concentration gradient
hyperpolarization
increase in membrane potential (more - on the inside)
depolarization
decrease in membrane potential
local potentials
electrical potential that is initiated by stimulation
threshold
the stimulus intensity that is just adequate to trigger an action potential in an axon
all-or-none property
an action potential either fires at its full amplitude, or not at all
after potentials
the positive or negative change in membrane potential that may follow an action potential
volted-gated Na+ channel
Na+ selective channel that opens/closes in response to changes in the voltage of the local membrane potential
refractory
temporarily unresponsive
absolute refractory phase
no amount of stimulation can induce another action potential because Na+ channel is closed
relative refractory phase
only strong stimulation can depolarize the axon to threshold to produce another action potential
saltatory conduction
the action potential jumps from one node of ranvier to the next
postsynaptic potentials
brief changes in the membrane potential of the postsynaptic cell
inhibitory postsynaptic potential
hyperpolarization potential in a neuron (decreases probability of action potential)
excitatory postsynaptic potential
depolarization potential in a neuron that is normally caused by synaptic excitation (increases probability of action potential)
spatial summation
summation of postsynaptic potentials that reach the axon hillock from different locations across the cell body
temporal summation
spread of time postsynaptic potentials reach the axon hillock
synaptic delay
brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential
sodium-potassium pump
exchanging three sodium ions for every two potassium ions from the intracellular environment.
ligand
substance that binds to receptor molecules.
agonists
molecules that act like transmitters at a receptor of that transmitter: activates the receptor
antagonists
interfere with or prevent the action of a transmitter, don’t activate receptors
degradation
chemical breakdown of a neurotransmitter into inactive metabolites
reuptake
transmitter molecules are cleared by bein absorbed back into the axon terminal that released them
transporters
return transmitter molecules to the presynaptic neuron for reuse
electroencephalograms (eegs)
the recording of ross electrical activity of the brain via large electrodes placed on the scalp
event-related potentials
EEG responses to a single stimulus such as a flash of light
epilepsy
major sudden changes in the electrophysical state of the brain
tonic-clonic seizures
neurons fire in high-frequency bursts, accompanied by rhythmic contractions of the body
simple partial seizures
spike-and-wave EEG activity is evident for 5-15 seconds
complex partial seizures
do not involve the entire brain and thus can produce a wide variety of symptoms, often preceded by an unusual sensation of aura
conduction velocity
the speed of propagation of action potentials, varies with axon diameter
neurons
basic unit of the nervous system composed of dendrites, an axon, and a transmitting axon terminal
glial cells
provides a variety of support functions but also participates in information processing
4 functional zones of information processing
- input zone: dendrites receive information via synapses
- integration zone: neurons cell body combines info, then decides to send the signal out or not
- conduction zone: axons carry the neuron’s own electrical signals away from the cell body
- output zone: axon terminals transmit the neurons signals across synapses to other cells
axon terminals
specialized swellings at the ends of the axon
multipolar neurons
many dendrites and a single axon (most common)
ion channels
proteins that span the membrane and can allow ions to pass through
exogenous
substances from outside the body
endogenous
substances from inside the body
neurotransmitter receptors
protein molecules embedded in the postsynaptic membrane that recognize a specific transmitter
ionotropic receptor
a receptor protein containing an ion channel that opens when the receptor is bound by an agonist
metabotropic receptors
doesn’t contain ion channels but use a secondary-messenger system to open nearby ion channels or to produce other cellular effects
G-protein-coupled receptors (GPCRS
receptor, when activated extracellularly, initiates a G protein signaling mechanisms inside the cell
amino acid neurotransmitters
a neurotransmitter that is an amino acid
amine neurotransmitter
a neurotransmitter based on modifications of a single amino acid nucleus
peptide neurotransmitter
a neurotransmitter consisting of a short chain of amino acids
gas neurotransmitters
a neurotransmitter that is a soluble gas
co-localization
the synthesis and release of more than one type of neurotransmitter by a given presynaptic neuron
acetylcholine
plays a major role in transmission in the forebrain
- memory
cholinergic
cells that use acetylcholine as their synaptic transmitter
basal forebrain
major source of cholinergic projections in the brain and has been implicated in sleep
dopamine
mesostriatal pathway-substanitia nigra of the midbrain: motor control
mesolimbocortical pathway: ventral tegmental area: learn by positive reinforcement
-aspects of behavior
dopaminergic
cells that use dopamine as their synaptic transmitter
substantia nigra
brainstem structure that innervates the basal ganglia and is a major source of dopaminergic projections
ventral tegmental area
portion of midbrain that projects dopaminergic fibers to the nucleus accumben
serotogenic
referring to cells that use serotonin as their synaptic transmitter
raphe nuclei
a string of nuclei in the midline of the midbrain and brainstem that contain most of the serotogenic neurons of the brain
serotonin
control of behavior: mood, vision, sexual behavior, anxiety, sleep
norepinephrine
active in the brain and symphatic nervous system: alertness to mood and sexual behavior
retrograde neurotransmitters
diffusing from the postsynaptic neuron back to the presynaptic neuron
agonists
drugs that mimic or potentiate the actions of a transmitter
antagonists
drugs that reduce the normal actions of a neurotransmitter
bioavailable
able to interact with physiological mechanisms
biotransfermation
process in which enzymes convert a drug into a metabolite that is itself active
pharmacokinetics
the factors that affect the movement of a drug into, through, and out of the body
binding affinity
degree of chemical attraction between a ligand and a receptor
efficacy
the ability of a bound ligand to activate the receptor
metabolic tolerance
metabolic organs become more effective at eliminating the drug from the bloodstream before it can have an affect
functional tolerance
target tissue may change its sensitivity to the drug
down-regulate
in response to an agonist - fewer receptors
up-regulate
in response to an antagonist - more receptors
cross-tolerance
tolerance to one drug causes an individual to develop tolerance for another
autoreceptors
tells the axon terminal how much transmitter has been released
first-generation antipsychotics
acts as selective antagonists of dopamine D2 receptors in the brain
(treats hallucinations and delusions)
second-generation antipsychotics
dopaminergic and nondopaminergic (blockade of certain serotonin receptors), relieve some behavior symptoms
affective disorders
disturbances of mood
antidepressant
increase synaptic transmission
-monoamine oxidase inhibitors(prevent breakdown of monoamines at the synapses)
accumulation of transmitters, prolonging their activity
tricyclic antidepressants
block reuptake of serotonin and norepinephrine
selective serotonin reuptake inhibitors
block reuptake at serotonergic synapses
serotonin-norepinephrine reuptake inhibitors
block reuptake of both
barbiturate
depressant activity in the nervous system (addictive), reduce anxiety, promote sleep, avoid epileptic seizures
benzodiazepines
act as agonists on GABAa receptors and enhance the inhibitory effects of GABA
periaqueductal gray
high density of opioid receptors and is where opiates exert much of their painkilling effects
endogenous opioids
bodys own opioid (enkephalins, endorphins, dynorphins)
anandamide
produces some of the physiological and psychological effects of cannabinoid
hallucinogens
stimulation of serotonin receptors, alter sensory perception and produce unusual experiences through diverse neural actions
nucleus accumbens
recieves dopaminergic innervation from the ventral tegmental area associated with pleasurable sensations with drugs
insula
role in addiction, craving, and pleasure
bipolar neurons
single dendrite on one end, on axon on the other
unipolar neurons
single extension(axon) branches in two directions, one end is input, other is output (terminals), transmit touch to the spinal cord
presynaptic membrane
transmits info by releasing neurotransmitter
postsynaptic membrane
receives information
synaptic cleft
gap that separates presynaptic membrane from postsynaptic membrane
synaptic vesicles
spherical, contains neurotransmitters
axon hillock
gather and integrate info arriving
oligodendrocytes/schwann cells
wrap around successive segments of axons to insulate them with fatty substances called myelin
nodes of ranvier
gaps between sections of myelin where the axon is exposed
astrocytes
control local blood flow to increase amount reaching more active brain regions by stretching between neurons and fine blood vessels
microglial cells
tiny and mobile, clean up sites of injury
axon collaterals
a branch of an axon
axonal transport
transportation of materials between neuronal cell body to an axon
peripheral nervous system
nerves: sensory and motor
somatic nervous system
nerves that interconnect the brain and the major muscles and sensory systems of the body
autonomic nervous system
consists of nerves that connect primarily to the internal organs
sympathic nervous system
fight or flight; axons innervate the sympathic ganglia
parasympathetic nervous system
helps relax the body, originate in the brain stem
gray matter
outer layers of the cortex containing neuronal cell bodies and dendrites
white matter
transmits info, myelin
cerebral cortex
outer covering of the cerebral hemispheres, contains neuron bodies
corpus callosum
bundle of axons that connect the two cerebral hemispheres
basal ganglia
are important in motor control and consists mainly of the caudate nucleaus, putamen, and globus pallidus
limbic system
involved in emotion and learning
-amygdala, hippocampus/fornix, cingulate gyrus, olfactory bulb, thalamus, hypothalamus
amygdala
emotional regulation and perception of odor
hippocampus/fornix
learning and memory
cingulate gyrus
direction of attention
olfactory bulb
sense of smell
thalamus
directs almost all incoming sensory info to appropriate regions
hypothalumus
hunger, thirst, temperature, regulation, sex
midbrain
substantia nigra, periaqueductal gray, reticular formation
substantia nigra
part of the basal ganglia
pariaqueductal gray
perception of pain
reticular formation
sleep and arousal
brainstem
cerebellum, pons, medulla
cerebellum
3 layers, motor coordination and control, learning
pons
point of origin for several cranial nerves
medulla
transition between brain and spinal cord
meninges
dura mater(outer), pia mater(inner), and arachnoid membrane(cerebrospinal fluid in-between)
nissl stains
visualize all of the cell body; measure size and number
golgi stains
only a few cells completely fills a small proportion of neurons; types and shapes of neurons
autoradiography
can reveal cells that exhibit a specific property
tract tracers
help visualize neural pathways
computerized axial tomography
a measure of x-ray absorption at several positions around the head - anatomical map based on tissue density
magnetic resonance imaging
high resolution images, fewer damaging effects than ct; when protons relax, they emit radio waves that differ by tissue density
functional MRI
image localized changes in the brains activity(uses oscillating magnetic fields testing oxygen use and blood flow)
positron emission tomography
gives images of brain activity
-short lived radioactive chemicals into the bloodstream indicate location
-identifies which brain regions contribute to specific functions
transcranial magnetic stimulation
briefly stimulates discrete cortical regions, then record observed changes in behavior
magnetoencephalography
measure the tiny magnetic fields given off by active neurons during cognitive processing, doesn’t tell you where
Drugs that stimulate the _______ pathway provide powerful positive rewards that may eclipse the pleasures derived from other activities.
dopaminergic
Higher doses of a drug tend to increase the proportion of receptors that are bound and affected by the drug, thereby increasing the response. This relationship is called the
dose-response curve
glutamate
the most common excitatory transmitter
-memory
opioid peptides
mimic opiate drugs such as morphine and reduce the perception of pain
blood-brain barrier
tight junctions between the cells of blood vessels in the CNS prevent the movement of large molecules; can limit drug availability
endocannabinoid
analogs of marijuana produced in the brain, such as anandamide
stimulant
increase nervous system activity by increasing excitatory input or decreasing inhibitory activity
-caffeine, nicotine, cocaine, amphetamines,
