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80 Cards in this Set
- Front
- Back
Location where action potential is generated
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axon hillock, then carried down axon to synapse
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resting potential
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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
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resting potential
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-70mV
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membrane at rest
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-70mV and Na and K channels are closed
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Depolarization
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Na channel open, and Na starts to enter
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K channels begin to open as Na starts to close
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still part of depolarization
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repolarization
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Na channels closed, K channels begin to repolarize the membrane
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Hyperpolaization
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cell is too negative
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K channels close
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membrane equilibriates to resting potential
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action potential
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all or notheing,membrane completely depolarizes, or no action potential is generated; stimulus to membrane must be greater than the threshold stimulus
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absolute refractory period
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once action potential begins, no stimulus will create another action potnetial
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synapse
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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
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electrical synapse
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uncommon; composed of gap junctions between cells, cardiac muscle is an example; much faster and bidirectional compared to chemical synapse
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chemical synapse
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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
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neurotransmitter ataches to its receptor momentarily
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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
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neurotransmitters
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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)
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receptors in postynaptic membrane
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maybe ion channels (opening with respective neurotransmitter) or may act via 2nd messenger system
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second messenger system
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activates another molecule insidee the cell to make changes (usually more long term as involved in memory)
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G-protein
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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
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slowest step in transfer of nervouse signal
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chemcial synapse, unidirectional
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glial or neuroglial
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support cells
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more glialcells than neurons
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10:1
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neuroglia
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able to divide
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myelinated axons
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only vertebrates have
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astrocyte
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type of glial cell used in support
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oligodendrovytes
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glial cells that wrap many times around axons in CNS creating myelin sheath
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schwann cells
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where myelin produced in peripheral NS
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myelin
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increases rate at which axon can transmit signal
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white matter
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myelinated axon
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gray matter
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unmyelinated cell body
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node of ranvier
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space between myeline
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saltatory conduction
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action potential jumps from one node of ranvier to the other
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acetycholinesterase
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enzyme that degrades acetylcholine
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3 types of neurons
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sensory neuron, (afferent neuron), interneuron, motor (efferent) neuron
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sensory (afferent) neuron
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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)
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interneurons
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tansfer signals from neuron to neuron; 90% of neurons are interneuron
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motor (efferent) neuron
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carries signal to a muscle or gland called the effecotr
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nerves
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neuron processes ound together
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CNS
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functions to integrate nervous signals between sensory and motor neurons
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PNS
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divides into somatic nervous system and autonomic nervous system
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somatic
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voluntary, conscously ccontrolled, designed to respnse to external environemnt; neurons synapse directly on their effecots; use acetycholine as neurotransmitter
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autonomic
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primarily receives signals from viscera (organs) then to smooth muscle, cardiac, and glands; generally involuntary; divided into sympathetic and parasympathetic
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sympathetic ANS
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fight or flight (heart beat, constrict blood around organs to increase for muscle)
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parasympathetic ANS
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rest and digest; slows heart and increases digestive andexcretory activity
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ganglion
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cell bodies outside of CNS
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nucleus
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cell bodies inside CNS
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sympathetic signals
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originate in neurons founds in spinal cord
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parasympathetic signals
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originate in neurons founds in spinal cord and brain
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acetylcholine
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neurotransmitter used by all preganglionic neurons in ANS (autonomic nervous system) and by postsynaptic system parasympathetic nervous system (rest and digest)
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epinephrine or norepinephrine (also adrenaline or noradrenaline)
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used by post ganglionic neurons in the sympathetic (fight or flight) nervous system
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aceytcholine receptors
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cholinerigic receptors : nicotinic and muscarinic
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somatic nervous system
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innervates skeletal muscles (voluntary)
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autonomic nervous system
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innervates cardiace and smooth muscles, some glands tool involuntary
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neurotransmitter relatedx to somatic and parasympathetic
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acetylcholine
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neurotransmitter related to sympathetic nervous system (fight or flight)
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noreponephrine and epinephrine)
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lower brain
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medulla, hypothalamus, thalamus, cerebellum; integrates subconscious activity like breathing, blood pressure, salviation, emotion and reaction to pain and pleasure
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high brain
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cerenrum or cerebral cortex (incapable of functioning without lower brain); acts to store memories and process thoughts
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sensory receptors
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transduce phsyical stimuls to neural signals
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5 types of sensory receptors
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mechanoreceptors, thermorecptors, nocicpetors, electromagnetic receptrs (for light) and chemoreceptors (tests, smell, blood chemistry)
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lens of eye
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converging lens, so flattening the eye by relaxing ciliary muscles makes it less powerful and by moving the focal point away
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cornea
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where light first strikes the eye, made mostly of collagen, refractive index of 1.4 which means most light bending accurs here
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anterior cavity
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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)
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lens
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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
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retina
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covers the inside of the back (distal portion) of the eye; contains rods and cones;
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rods
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has pigments called rhodposin; rods sense all wavelengts in the visibal espectrum; rods cannot distinguish colors
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cones
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3 types, each with different pigment that is stimulated by a slightly different spectrum of wavelenghts
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rods
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no color
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cones
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color
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fovea
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part of retina containing mostly conres, most acute vision is in fovea
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iris
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colored portion of eye that creates the opeing called pupil
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iris made of
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circular and radial muscles,
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in dark enviornment
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the eye contracts the iris, and pupils dilate allowing more light (sympathetic)
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in bright environment
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in bright environment, pupils gets smaller via parasympathetic system
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basic parts fo the ear
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outer ear, middle ear, inner ear
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cochlea
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detect sound
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semicircular canals
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detect orientation and movement of the head
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sound wave hits pinna and travels to
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tympanic membrane, which begins the middle ear
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middle ear has 3 parts
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malleus, incus and stapes, which translate the wave of sound to the oval window
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hairs cells of organs of corti
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detects movement (ie., increassing and decreasing pressure from vestibular membrane)
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simple reflex arc
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does not require neurons in the brain
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