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165 Cards in this Set
- Front
- Back
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The three major roles of the nervous system
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sensory input
sensory integration motor response |
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Endocrine glands secrete hormones which take how long to take effect?
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usually hours
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Difference between sensory pathways and motor pathways
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Sensory - carry info to the spinal cord and brain
motor - transmit nerve impulses from CNS to muscle or glands |
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Nervous System's two main divisions
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Central and Peripheral
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Cell body of a neuron contains what?
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the nucleus, mitochondria that supply ATP, and ribosomes that manufacture proteins
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Dendrites
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short, branched extensions that transmit info toward the cell body
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Axon is also called the what?
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nerve fiber
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Axon is typically a what of the cell body?
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single long extension
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Each terminal extension of an axon connects to what?
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another cell at a synapse
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Synapse
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junction where a neurons connect
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Usually, the axon conducts nerve impulses from the cell body to what?
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a muscle, gland, or another neuron
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what in the peripheral nervous system, what is the major type of cell that forms the myelin sheath?
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schwann cells
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what are the short intervals between individual schwann cells?
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nodes of ranvier
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The three classes of neurons are
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sensory neurons
motor neurons interneurons |
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sensory neurons do what?
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bring info toward the CNS.
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what do sensory neurons respond to?
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light
sound heat touch odors taste |
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a motor neuron conducts its message from what to what?
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the central nervous system to ward an effector
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what is an effector?
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a muscle or gland cell
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what do interneurons do?
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connect one neuron to another within the CNS
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large, complex networks of what recieve info from sensory neurons, process this info, and generate the messages that the motor neurons carry to effector organs?
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interneurons
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about what percent of neurons are interneurons?
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90%
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which type of neuron reside only in the CNS?
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interneurons
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where do sensory neuron parts lie in relation to both nervous systems?
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CNS: axons endings
PNS: dendrites, cell body, and most of the axon |
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where do motor neuron parts lie in relation to both nervous systems?
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CNS: cell body and dendrites
PNS: axon |
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resting potential
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the state a neuron is in when it's not conducting a message
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At rest, a neuron's membrane is polarized, or carries a slightly ____ electrical charge relative to the outside
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negative
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this resting potential measures around ____ milivolts
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-70
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soma
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cell body of a neuron
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Multiple Sclerosis cause
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the deterioration of the myelin sheath around many axons
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terminal buttons
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clusters of small knobs that secrete chemicals called neurotransmitters at the end of each axon
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neurotransmitters
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serve as messengers that may activate neighboring neurons
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neurons typically synapse on the dendrites of other cells, but they may also synapse on ____ or ___
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a soma or axon
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neouroglia or glia
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cells found throughout the nervous system that provide various types of support for neurons
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glia tend to be ____ that neurons and outnumber them by __ to one and also account for __% of the brain's volume
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smaller
ten 50 |
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help remove neurons' waste produces and supply nourishment
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neuroglia
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____ play a complicated role in orchestrating the development of the nervous system in the ____ ____
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human embryo
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Squid have a giant pair of ____ that are about ___ times larger than tose in humans
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squid
1 hundred |
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hodgkin and huxley
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researched neural impulses through squid axons
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both inside and outside the neuron are fluids containing ____
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ions
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what molecules flow back and forth across the cell membrane of a neuron?
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K+
Na+ Cl- |
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do the electric atoms cross the membrane at the same rate?
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no
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the difference in atoms flow rate across the neural membrane leads to a slightly ___ concentration of ____ charged ions inside the cell
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higher
negatively |
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when a neuron is stimulated, ___ in its cell membrane ____, allowing ___ to flow in
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channels
open NA+ |
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action potential
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a very brief shift in a neuron's electrical charge that travels along an axon. happens when NA+ flows in.
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absolute refractory period
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the minimum length of time after an action potential during which another action potential cannot begin
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synaptic cleft
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microscopic gap between the terminal button of one neuron and the cell membrane of another neuron
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PSP
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postsynaptic potential
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excitatory PSP
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a positive voltage shift that increases the likelihood that the postsynaptic neuron will fire action potentials
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inhibitory PSP
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opposite of excitatory PSP
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reuptake
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a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane
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(Psych) Quote: "The firing of a single neuron is not enough to create the twitch of an eyelid in sleep, let alone a conscious impression... Millions of neurons must fire in unison to produce the most trifling thought"
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Rita Carter
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what happens to the neurotransmitters when they are released into the synaptic cleft?
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they either bind to receptor sites and are eventually deactivated by enzymes, drift away, or are sponged up by the presynaptic neuron
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the creation of new synapses is less important that what when it comes to the sculpting of neural networks
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elimination of old synapses
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how many classic, well-established neurotransmitters are there? how many additional chemicals that function as neurotransmitters?
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9
40 |
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The only transmitter between motor neurons and voluntary muscle movement
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Acetylcholine
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3 things acetylcholine contributes to other than voluntary movement
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attention
arousal memory |
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agonist
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a chemical that mimics the action of a neurotransmitter
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antagonist
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a chemical that opposes the action of a neurotransmitter (blocks receptor site)
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what are the three monoamines?
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dopamine
norepinephrine serotonin |
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degeneration of what type of neuron causes parkinson's disease?
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dopamine
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what neurotransmitter plays a prominent role in the regulation of sleep and wakefulness?
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serotonin
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(psych) people who suffer from depression appear to have lowered levels of activation at ____ and ____ synapses
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norepinephrine
serotonin |
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neurotransmitter implicated in the development of schizophrenia
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dopamine
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(psych) acetylecholine functions
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activates motor neurons control skeletal muscles, contributes to the regulation of attention, arousal, and memory
some receptors are stimulated by nicotine |
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(psych) dopamine functions and characteristics
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contributes to the control of voluntary movement, pleasurable emotions
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(psych) norepinephrine functions and characteristics
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contributes to modulation of mood and arousal
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(psych) cocaine and amphetamines elevate activity at these synapses
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dopamine and norepinephrine
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(psych) serotonin
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involved in sleeping, eating, and aggression
abnormal levels may lead to OCD or depression |
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(psych) endorphins
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resemble opiate drugs in structure and effects
contribute to pain relief and perhaps to some pleasurable moments |
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(psych) morphine derived from what?
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opium plant
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experts believe there are how many neurons in the brain?
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100 billion
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subdivisions of the peripheral nervous system
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somatic and autonomic
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somatic nervous system
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made up of nerves that connect to voluntary skeletal muscles and to sensory receptors
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two types of nerve fibers
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afferent and efferent
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afferent nerve fibers
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axons that carry info inward to the CNS form the periphery of the body
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are somatic nerves "one way streets" or "two-way streets"?
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two
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how many axons does each body nerve contain?
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many
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autonomic nervous system
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made up of nerves that connect to the heart, blood vessels, smooth muscles, and glands
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Scientist that called the autonomic system "fight-or-flight"
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Walter Cannon
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two branches of the autonomic nervous system
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sympathetic division and parasympathetic division
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sympathetic division
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the branch of the autonomic nervous system that mobilizes the body's resources for emergencies
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what are two things that happens when the sympathetic division is activated?
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slows digestion and drains blood from the periphery
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key sympathetic nerves send signals to ____, triggering the release of ____ that ready the body for ____
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adrenal glands
hormones exertion |
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parasympathetic division
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branch of the autonomic nervous system that generally conserves bodily resources
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parasympathetic division
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branch of the autonomic nervous system that generally conserves bodily resources
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To enter the CSF, substances in the blood have to cross the ___, which is a ____ that ____
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blood-brain barrier
semipermeable membrane stops some chemicals from passing between the bloodstream and the brain |
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The average human brain weighs about
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3 lbs
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At rest, a neuron's membrane is ____
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polarized
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A neuron has a resting potential because it maintains ____ across its membrane
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an unequal distribution of ions
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Membrane protein that helps maintain gradient in resting neurons
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sodium-potassium pump
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sodium-potassium pump works how?
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pumps 3 Na out of the cell for every 2 K that enter, at a cost of 1 ATP molecule per cycle
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In a neuron at rest, the concentration of K is much ____ inside the cell than outside, while the reverse is true for Na
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higher
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the nervous system devotes about ____ of its total energy budget to maintaining the resting potential of its neurons
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3/4
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during a ____, Na and K quickly redistribute across a small patch of the axon's membrane
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action potential
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graded potential
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some Na begins to leak into the cell, causing the interior to become less negative
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If the stimulus is strong enough, it may spread to a ____ near the soma
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trigger zone
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the trigger zone has a higher concentration of __ than the dendrites of cell body
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Na
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threshold potential
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about -50 mV
additional Na gates open which triggers the action potential |
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once Na channels close, ___ channels open
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Ka
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a neural impulse usually begins ____ and moves down ___ toward ____
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at the trigger zone
the axon axon terminal |
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refractory period
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membrane reestablishes its resting potential
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____ and ____ have a low concentration of Na channels in comparison to ____ and ___
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dendrites and the cell body
the trigger zone and axons |
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Only areas with a ____ can propagate action potentials
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high concentration of Na channels
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since the myelin sheath prevents ion flow across the membrane, Na channels are concentrated where?
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at the exposed nodes of Ranvier
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How much faster do the nodes of Ranvier conduct a neural impulse compared to neurons with a bare axon?
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up to 100 times faster
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Illness can result if an axon has too much or too little ____
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myelin
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Tay-Sachs disease
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cell membranes accumulate excess lipid and wrap around nerve cells, burying them in fat so that they cannot transmit messages to each other and to muscle cells.
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opposite of MS
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Tay-Sachs disease
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some scorpion neurotoxins cause what?
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an axon's sodium channels to become stuck in the open position and other neurotoxins block the K channels
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How do scorpion neurotoxins cause continuous pain?
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because of the membrane depolarization which triggers a continuous barrage of action potentials
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the end of a presynaptic cell's axon has
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synaptic terminals
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synaptic terminals
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tiny knowbs that enlarge at the tips. contain many small sacs that hold neurotransmitter molecules
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synaptic terminals dump their neurotransmitters into the synaptic cleft by
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exocytosis
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endocytosis
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form of transport in which the cell membrane engulfs extracellular material
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when the neurotransmitter contacts the receptor, ____ changes
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the shape of the receptor
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what happens when a receptor receives a neurotransmitter?
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ion channels open in the membrane, either increasing or decreasing the probability that an action potential will occur
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how does a neuron decide whether to pass a neural impulse to the next cell in the pathway?
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synaptic integration
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how does a neuron decide whether to pass a neural impulse to the next cell in the pathway?
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synaptic integration
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synaptic integration
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evaluates income neurotransmitters. It the cell receives more excitatory votes than inhibitory votes, then they cell is stimulated
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myasthenia gravis symptoms
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progressive muscular weakness
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GABA stands for
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gamma amino butyric acid
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excess GABA leads to excess ____ and ____
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norepinephrine and dopamine
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deficient GABA leads to
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excess dopamine
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norepinephrine heightens ____ and ____
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alertness and mood
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poisonous nerve gases and some insecticides prevent ____ from breaking down in the synaptic cleft
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acetylcholine
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excess acetylcholine overstimulates what?
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skeletal muscles
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SSRI
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selective serotonin reuptake inhibitors
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Guillain-Barre syndrome
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the immune system attacks and destroys the nerves of the PNS
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2 types of nervous tissue in the CNS
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gray matter and white matter
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gray matter consists of
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somas and synapses
the outer surface of the brain, a few inner structures, and the central core of the spinal cord |
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gray matter functions
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info processing happens here;
sensory, motor, and association areas |
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white matter consists of
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myelinated axons transmitting info throughout the CNS
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white matter located at
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the periphery of the spinal cord; also most of the inner structures of the brain
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white matter functions
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transmits info within the brain
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what handles reflexes?
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the spinal cord (without the brain)
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reflex arc
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neural pathway that links a sensory receptor and an effector such as a muscle
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reflex arc's journey
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action potential is generated along the sensory neuron's axon. then the axon syapses with a motor neuron in the spinal cord. the motor neuron's axon exits the spinal cord, and its activation stimulates a stimulates a skeletal muscle cell to contract
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at any time, brain activity consumes __% of the body's oxygen and __% of its blood glucose
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20
15 |
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permanent brain damage occurs after how long without oxygen?
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five minutes
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The three subdivisions of the brain
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midbrain, hindbrain, forebrain
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the brain stem is made out of
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the midbrain and hindbrain
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the section of hindbrain closest to the spinal cord
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the medulla oblongata
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medulla oblongata regulates and controls what?
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breathing, bp, bpm, and reflex centers for coughing, vomiting, sneezing, hiccoughing, defecating, and swallowing
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area above the medulla and what it means
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pons; bridge
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pons' function
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connects brain with the spinal cord and connects the forebrain with the cerebellum
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cerebellum does what?
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refine motor messages and coordinate muscle movements subconsciously
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the largest part of the hindbrain. and it's AKA
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cerebellum; little brain
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narrow brainstem region
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midbrain
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midbrain receives
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sensory info as it passes it to the forebrain
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part of the brain that contains structures important in complex functions such as learning, memory, language, motivation, and emotion
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forebrain
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thalamus acts as
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a relay center for sensory input. sends it to the appropriate part of the cerebellum
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links the nervous and endocrine systems
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hypothalamus
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cerebrum does what?
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control the qualities of of what we consider the "mind"; learning, perception, intelligence, and emotion
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cerebrum - white or gray
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white
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cerebrum occupies __% of the brain
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83
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divided into two hemispheres
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cerebrum
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cerebral cortex. what and color
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outer layer of the cerebrum; gray
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cerebral cortex's function
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where neural integration occurs; sensory areas receive and interpret messages from sense organs
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cerebral palsy
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a disorder of posture of muscle movement from damage to the motor regions of the brain
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limbic system
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a collection of forebrain structures that surrounds the corpus callosum and thalamus
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limbic system is made up of
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amygdala, hippocampus, hypothalamus
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blood-brain barrier
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helps protect the brain from extreme chemical fluctuations
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parkinsons symptoms
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tremors, weakness, slow movement, and loss of coordination
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ALS
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amyotrophic lateral sclerosis; initial symptoms: muscle twitches, dropping objects
Later symptoms: leaves patient ENTIRELY paralyzed yet senses and mental function remain |
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synonymous mutations
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the two genes encode identical proteins, so the original gene is essentially a "synonym" of the mutated one
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