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103 Cards in this Set
- Front
- Back
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dendrites are extensions of _____ neurons that provide receptive surface for ______ neurons
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postsynaptic, receptive for presynaptic |
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what are dendrites |
extensions of postsynaptic neurons that provide receptive surface for presynaptic neurons |
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what provides pathway for action potential from cell body to synapse? |
axon |
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axon connects what to what |
cell body to synapse |
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what wraps around axon to increase conduction speed? |
myelin |
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what is myelin, what does it do |
wraps around axon, increase conduction speed |
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can glial cells generate nerve impulses? |
no |
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can glial cells insulate axons? |
yes |
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can glial cells supply neurons with nutrients? |
yes
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can glial cells fight infections? |
yes |
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glial cells CANNOT __________ |
generate nerve impulses/control synapses |
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concentration of ____ ions higher on outside, ____ ions higher on inside |
sodium Na OUTSIDE, potassium K INSIDE |
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rapid depolarization of neuron during first half of action potential due to ...... |
entry of Na+ ions into cells through gated sodium channels |
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what is threshold of neuron? |
membrane voltage at which membrane potential becomes an action potential |
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differences btw neuronal signaling and endocrinal signaling |
neuronal is FAST and specific, endocrinal is slow and broad |
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nerve signal transmission alternates between _____ signaling within cells and _____ signaling between cells |
electrical within, chemical between |
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three jobs of glial cells |
support metabolism and immunity, nourish, insulate neurons |
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ratio glial cells to neurons |
10:1 |
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almost all animal cells have _____ resting potential at rest, why? |
negative, because of potassium leaving through "leak" K channels |
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how to measure membrane voltages (potentials)? |
insert tiny electrodes into cells |
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describe action potential spike event |
all-or-none |
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what causes any action potential spike |
opening and closing of VOLTAGE-gated ion channels |
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what happens at threshold? |
voltage-gated Na+ channels are opened |
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after threshold, what causes more gates to open? |
positive feedback |
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why does axon quickly return to negative potential (falls)? 2 reasons |
1. voltage-gated K+ channels open slowly, K+ moves out 2. voltage-gated Na+ channels close |
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what cannot happen during refractory period? |
voltage-gated Na+ channels CANNOT REOPEN |
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what 2 factors can increase speed of action potential propagation? |
large axon diameter, vertebrates have myelin sheath |
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as diameter of axon increases, resistance to current flow ______ |
decreases |
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multiple sclerosis caused by |
immune system attacking myelin |
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true or false. multiple sclerosis affects axon |
FALSE, affects myelin |
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true or false. multiple sclerosis affects myelin |
true |
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where do neurons communicate with each other |
at synapses |
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neurotransmitter synthesized where? stored where? |
synthesized in cell bodies, stored in axon terminals |
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what stimulates release of neurotransmitters? |
elevated calcium concentration! and action potentials |
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where do neurotransmitters bind? what is result? |
ligand-gated channels in postsynaptic membrane... changes ion flow (Na+ comes in), depolarization! |
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describe postsynaptic potentials |
graded (not all-or-none), small, decay with distance |
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what is summation |
multiple synapses add together in time or over space to influence threshold |
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describe summation referring to time |
same location, fired at different times |
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describe summation referring to over space |
different locations |
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inhibitory and excitatory _____ but are still examples of what type of summation |
cancel, over space! |
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true or false. many neurons to one synapse. |
FALSE, vice versa |
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true or false. many synapses to one neuron |
true |
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how many neurotransmitters can one synapse use? |
just one |
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acetylcholine does what, major nt of which system? |
controls mm, heart rate, and brain function (memory) PARAsympathetic nervous system |
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acetylcholine is ______ on skeletal mm, but _________ on the heart |
excitatory skeletal, inhibitory heart |
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norepinephrine aka |
noradrenaline |
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norepinephrine does what |
part of fight-or-flight (sympathetic system) in brain, regulates normal processes |
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norepinephrine usually _______ |
excitatory, but can be inhibitory in some brain areas |
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dopamine |
pleasure |
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serotonin |
mood |
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low serotonin = |
depression |
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CNS |
brain and spinal cord |
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brain |
anterior enlargement of CNS |
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PNS, divides into... which divides into....which divides into... |
anything outside CNS divides into sensory (afferent) division and motor (efferent) division motor (efferent) division divides into somatic/autonomic autonomic divides into symp and parasymp |
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nerve |
bundle of axons in PNS, carries info to and from CNS |
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ganglia |
swellings containing aggregates of cell bodies and processes (neurons) |
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most bilaterally symmetrical animals have _____ nervous systems |
cephalized |
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vertebrate nerve cords are ______, invertebrate nerve cords are _____ |
vertebrate = dorsal, invertebrate = ventral |
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afferent neurons do what |
carry sensory info from sensory cells INTO CNS |
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what do sensory cells do |
convert stimuli into action potentials |
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efferent neurons do what |
carry commands to effectors, LEAVE CNS |
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examples of effectors |
muscles and glands |
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interneurons do wha |
store info and communicate between neurons |
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effectors are what |
target organs whose activities change in response to neural commands |
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which neurons control skeletal mm |
somatic efferent |
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parasympathetic division ______ airways, sympathetic _______ airways |
para = constricts, sym = relaxes |
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parasympathetic division ______ heartbeat, sympathetic _____ heartbeat |
para = slows, symp = accelerates |
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parasympathetic _______ digestion, sympathetic ______ digestion |
para= stimulates, symp = inhibits |
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parasympathetic and sympathetic effect on sex organs |
para = penile/clitoral arousal sympathetic = orgasm, vaginal contraction |
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somatic nervous system releases ________ to do what |
acetylcholine, stimulate skeletal m |
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autonomic nervous system, sympathetic division releases _______ |
norepinephrine |
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autonomic nervous system, parasympathetic division releases ______ |
acetylcholine |
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what types of molecules in cells serve as ion transporters and ion channels? |
proteins |
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voltage differences found only where? |
across cell membranes |
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when inside of neuron becomes less negative due to influx of Na+, membrane has become _______ |
depolarized |
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action potentials: describe speed, propagation, stimulation |
brief, no loss of magnitude, stimulate each succeeding region in axon |
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do action potentials occur along axon simultaneously? |
NOPE |
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neuron with a large array of dendrites would be able to |
collect info from wider range of sources |
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describe what happens when you step on a tack |
sensory receptors in foot send action potentials to spinal cord via sensory neurons sensory neurons synapse with interneurons, result in withdrawal reflex involving spinal nn |
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neuron is "addressed" why? |
can convey impulses to specific location in CNS |
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action potential aka |
nerve impulse |
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where is electrical signal generated in axon? |
axon hillock |
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what are nodes of Ranvier |
gaps between myelin |
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speed of action potential |
55 mph |
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CNS vs PNS glial cells, which perform the same job? |
CNS- oligodendrocytes, microglia, astrocytes PNS- Schwann cells, satellite cells schwann cells and oligodendrocytes! |
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neuromuscular junction |
motor neuron connected to muscle |
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difference between nerve and neuron |
nerve- consists of axons of many nerves bound together neuron- specialized cell type that transmits electrical signals |
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what does it mean to have a negative voltage |
cell interior less positive than exterior |
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what is resting potential? |
inside more negative than outside, usually about -65 mV |
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stronger membrane potential = more _______ neuron |
polarized |
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hyperpolarized vs depolarized |
hyper = more negative (-90 mV) de = less negative (-50 mV) |
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what reduces voltage? |
(hyperpolarization) positive flows out OR negative flows in |
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what increases voltage |
(depolarization) positive flows in OR negative flows out |
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which channels are always open? what is result? |
ungated potassium channels ALWAYS open = net OUTFLOW of potassium |
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why do action potentials move in one direction? what happens if started in middle of axon? |
sodium (Na) gated ion channels behind zone of depolarization stay closed in middle, would go both ways |
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which formed by cells held together by gap junctions: electrical or chemical synapses? |
electrical |
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which releases neurotransmitters: electrical or chemical synapses? |
chemical |
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describe steps of chemical synapse |
voltage-gated ion channel for Ca2+ opens, flow in... high Ca2+ conc causes synaptic vesicles to fuse with membrane, release nt into synaptic cleft... nt binds to receptor protein on ligand-gated ion channel, opens channels, allows Na+ diffusion... depolarizes membrane, ACTION POTENTIAL |
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3 sources of CNS input |
conscious sensory info, unconscious sensory info, hormones |
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3 ways of CNS output |
voluntary commands, autonomic commands, neurohormones |
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afferent neurons transmit signals from _______ to ________, through the _____ root |
body to spinal cord, enter through DORSAL |
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efferent neurons transmit signals from _______ to _______, through the _______ root |
spinal cord to rest of body, exit through VENTRAL |
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reflex |
afferent axons communicate with efferent axons WITHOUT processing by the brain |
