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80 Cards in this Set

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Location where action potential is generated
axon hillock, then carried down axon to synapse
resting potential
established by equilibrium between passive diffusion of ions across the membrane of the Na/K pump; 3 Na pumped out for every 2 K pumped in. eventually inside is more negative
resting potential
-70mV
membrane at rest
-70mV and Na and K channels are closed
Depolarization
Na channel open, and Na starts to enter
K channels begin to open as Na starts to close
still part of depolarization
repolarization
Na channels closed, K channels begin to repolarize the membrane
Hyperpolaization
cell is too negative
K channels close
membrane equilibriates to resting potential
action potential
all or notheing,membrane completely depolarizes, or no action potential is generated; stimulus to membrane must be greater than the threshold stimulus
absolute refractory period
once action potential begins, no stimulus will create another action potnetial
synapse
neural impulses are transmitted from one cell to another chemically or eleectrically; transmission from one cell to another is the slowest part of the process of cellular commuication in nervouse system
electrical synapse
uncommon; composed of gap junctions between cells, cardiac muscle is an example; much faster and bidirectional compared to chemical synapse
chemical synapse
more common; unidirectional; when action potentical comes, Ca released from vesicales and causes neurotransmitter vesicles to be released via exocytosis into synaptic ; neurotransmitter diffuses via brownian motion in synaptic cleft; Postsynaptic membrane has receptors for the nuerotranmitters which then allow ions to move across posttynaptic membarane via protein ionophosres; completes neural impulse and not attenuated
neurotransmitter ataches to its receptor momentarily
if it remains in the synaptic cleft, it may cause nerve to repeat firing, so its recycled, destroyed via enzyme or reabsorbed by presynaptic cell via active transport
neurotransmitters
may be inhibitory or excitatory, but not both. However, some neurotramsitters like acetylcoline may behave depedning on the receptor (inhibit in heart, excite n intestine)
receptors in postynaptic membrane
maybe ion channels (opening with respective neurotransmitter) or may act via 2nd messenger system
second messenger system
activates another molecule insidee the cell to make changes (usually more long term as involved in memory)
G-protein
commonly initiate 2nd messenger; attached to receptor protein along the inside of the postynaptic membrane; when recepor stimulate by neurotransmitter, part of G-protein (called alpha subunit) breaks free; alpha subunit may: activate seperate specific ion channels, activatve second messengaer (cAMP) activalte intracellular enzymes, activate gene transcription
slowest step in transfer of nervouse signal
chemcial synapse, unidirectional
glial or neuroglial
support cells
more glialcells than neurons
10:1
neuroglia
able to divide
myelinated axons
only vertebrates have
astrocyte
type of glial cell used in support
oligodendrovytes
glial cells that wrap many times around axons in CNS creating myelin sheath
schwann cells
where myelin produced in peripheral NS
myelin
increases rate at which axon can transmit signal
white matter
myelinated axon
gray matter
unmyelinated cell body
node of ranvier
space between myeline
saltatory conduction
action potential jumps from one node of ranvier to the other
acetycholinesterase
enzyme that degrades acetylcholine
3 types of neurons
sensory neuron, (afferent neuron), interneuron, motor (efferent) neuron
sensory (afferent) neuron
receive signals from a receptor that interacts with ints enviornment, sensory bneuron transfer signal to other neurons (99 % os sensory input is discarded by brain)
interneurons
tansfer signals from neuron to neuron; 90% of neurons are interneuron
motor (efferent) neuron
carries signal to a muscle or gland called the effecotr
nerves
neuron processes ound together
CNS
functions to integrate nervous signals between sensory and motor neurons
PNS
divides into somatic nervous system and autonomic nervous system
somatic
voluntary, conscously ccontrolled, designed to respnse to external environemnt; neurons synapse directly on their effecots; use acetycholine as neurotransmitter
autonomic
primarily receives signals from viscera (organs) then to smooth muscle, cardiac, and glands; generally involuntary; divided into sympathetic and parasympathetic
sympathetic ANS
fight or flight (heart beat, constrict blood around organs to increase for muscle)
parasympathetic ANS
rest and digest; slows heart and increases digestive andexcretory activity
ganglion
cell bodies outside of CNS
nucleus
cell bodies inside CNS
sympathetic signals
originate in neurons founds in spinal cord
parasympathetic signals
originate in neurons founds in spinal cord and brain
acetylcholine
neurotransmitter used by all preganglionic neurons in ANS (autonomic nervous system) and by postsynaptic system parasympathetic nervous system (rest and digest)
epinephrine or norepinephrine (also adrenaline or noradrenaline)
used by post ganglionic neurons in the sympathetic (fight or flight) nervous system
aceytcholine receptors
cholinerigic receptors : nicotinic and muscarinic
somatic nervous system
innervates skeletal muscles (voluntary)
autonomic nervous system
innervates cardiace and smooth muscles, some glands tool involuntary
neurotransmitter relatedx to somatic and parasympathetic
acetylcholine
neurotransmitter related to sympathetic nervous system (fight or flight)
noreponephrine and epinephrine)
lower brain
medulla, hypothalamus, thalamus, cerebellum; integrates subconscious activity like breathing, blood pressure, salviation, emotion and reaction to pain and pleasure
high brain
cerenrum or cerebral cortex (incapable of functioning without lower brain); acts to store memories and process thoughts
sensory receptors
transduce phsyical stimuls to neural signals
5 types of sensory receptors
mechanoreceptors, thermorecptors, nocicpetors, electromagnetic receptrs (for light) and chemoreceptors (tests, smell, blood chemistry)
lens of eye
converging lens, so flattening the eye by relaxing ciliary muscles makes it less powerful and by moving the focal point away
cornea
where light first strikes the eye, made mostly of collagen, refractive index of 1.4 which means most light bending accurs here
anterior cavity
where light enters after cornea, filled with aqueaous of himor produced by ciliariy process an dleaks out of canal of sclemm (blockage of canal -> glaucoma)
lens
light enters after anterior cavity; ciliarly muslces are connected which when tightend circle opening is more like a spehere and prings focal point closer; when it relaxes, more flattened and focal poitn father
retina
covers the inside of the back (distal portion) of the eye; contains rods and cones;
rods
has pigments called rhodposin; rods sense all wavelengts in the visibal espectrum; rods cannot distinguish colors
cones
3 types, each with different pigment that is stimulated by a slightly different spectrum of wavelenghts
rods
no color
cones
color
fovea
part of retina containing mostly conres, most acute vision is in fovea
iris
colored portion of eye that creates the opeing called pupil
iris made of
circular and radial muscles,
in dark enviornment
the eye contracts the iris, and pupils dilate allowing more light (sympathetic)
in bright environment
in bright environment, pupils gets smaller via parasympathetic system
basic parts fo the ear
outer ear, middle ear, inner ear
cochlea
detect sound
semicircular canals
detect orientation and movement of the head
sound wave hits pinna and travels to
tympanic membrane, which begins the middle ear
middle ear has 3 parts
malleus, incus and stapes, which translate the wave of sound to the oval window
hairs cells of organs of corti
detects movement (ie., increassing and decreasing pressure from vestibular membrane)
simple reflex arc
does not require neurons in the brain