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Biology 116 > Action Potentials > Flashcards

Action Potentials Flashcards

1
Q

NS functions

A

detect stimuli + any sort of change that occurs inside or outside body; respond to stimuli and carry out an action

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2
Q

key components of NS

A

CNS: brain + spinal cord; PNS: sensroy receptors + nerves for communication singals btwn CNS + rest of body

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3
Q

neuron

A

basic functional unity of NS; variety of shapes + size depending on fuction; characterized by cell body + cytoplasmic extensions that protrube out of neuron; dendrite, nerve, axon

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4
Q

neuron function

A

conduct messages via electrical singnal + integration of message

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5
Q

cell body

A

location of usual organelles (nucleus, mito, golgi, etc)

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6
Q

dendrite function

A

(tree branch) recieve info from env or other neurons and send signals to cell body

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7
Q

nerve

A

comprised of axons of many neurons held together by connective tissue; axons travel together to whatever part of body

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8
Q

axon

A

usually one long one; transmit neural impulse away from cell body to another nurons; end of axon = branches, tips of branches = synaptic terminals @ opp end of cell body

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9
Q

effector

A

part of org that produces response to stimuli; produces “effect”; ex: muscles, glands

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10
Q

axon hillock

A

cone shaped base of axon; region where axon begins extending away from cell body; location where signals will be generated

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11
Q

3 stages of NS info processing

A

(1) sensory input (2) integration (3) motor output

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12
Q

sensory input

A

stage 1 of NS info processing; detecting stimulus; sensory neuron = afferent neuron

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13
Q

afferent neuron

A

recieve sensory stimuli; conduct info toward processing center

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14
Q

integration

A

stage 2 of NS info processing; sensory input sorted out and interpreted in processing center (was it visual? auditory? now what?) human brain = 90% interneurons)

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15
Q

motor output

A

what is appropriate response to stimulus?; motor neuron = efferent neurons; transmit info from processing center and associate w appropriate responses to appropriate effector; part of org that produces response: muscles + glands

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16
Q

membrane potential

A

all animal cells w selectively permeable membrane; only excitable cells have ability to generate rapid changes in mem pot

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17
Q

selectively permeable membrane

A

some things geet in somethings don’t; polarity btwn inside + outside of cell so mems are “polarized”; charged diff btwn inside vs outside = neg mem pot; cytosol of cell = neg charge vs. extracellular fluid env on outside; mem pot = pot to do work actions

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18
Q

voltage

A

unit to measure mem pot

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19
Q

voltmeter

A

position electrode inside cell + outside cell; reference electrode, second electrode; measure charge diff btwn inside vs outside of cell

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20
Q

reference electrode

A

outside of cell

21
Q

second electrode

A

inside of cell

22
Q

resting potential

A

cell mem of axon at rest; not excited; RP = -70mV

23
Q

maintaining RP

A

sodium-potassium pump; ion channels

24
Q

sodium potassium pump

A

used to maintain RP; mem protein of cell along pm of cell body, dendrite, axon (entire neuron); one pump cycle: 3 Na+ ions move out and 2 K+ ions move in via active transport against concen gradient (needs ATP)

25
ion channels
pore in pm allow ions to diffuse across pm; any net movement of either pos of neg charges generates mem pot; K+ channels always open (leaky) = diffuse from inside to outside to maintain neg RP; many K+ channels more than Na+; 100x more permeable to K+; build up of pos charge on outside relative to inside and creates neg RP = -70mV bc neg inside vs pos outside
26
env factors that change RP
RP can be changed via sitmulus; chem, pressure, light
27
threshold
most are -55 mV; results in action potential
28
hyperpolarization
mem pot moves below RP; more neg than RP; decreases neuron's ability to generate a neural impulse; inhibitory; very important
29
graded potentials
shifts in mem pot; magnitube varies w strength of stimulus bc greater the stimulu greater change in mem pot; eventually decay/die out sometimes induce small electrical message that won't propagate (time +source)
30
deploarization
mem pot becomes more pos; above RP
31
action potentials
mem pot shifts significantly; massive change in voltage; deploarizaiton causes mem pot to reach -55mV threshold
32
voltage gated ions channels
part of AP; mem proteins control passage of specific ions (specific gates for specific ions) they open/close based on changes in voltage; reg by changes in voltage that control shape of protein that closes in one shape and open in another shape; facillitate diffusion allows ions to follow concern gradient (no ATP, via protein)
33
AP chain of events
neurons at RP no excitment all VG Na+ and VG K+ channels close + no ion movement; VG Na+ channel open; Na+ rushes into axon; mem depolarizes (less neg); gets closer to -55mV (threshold); magnitude of change in pot depends on stimulus strength: small stimulus won't reach -55mV bc few channels open but strong stimulus many channels open so it reaches -55mV
34
AP steps
rising potential, falling phase, undershoot
35
rising potential
AP; mem become very permeable to Na+ and most of VG Na+ channels open so Na+ rushes down gradient into cell; VG K+ channels closed so K+ stays inside to cause depolarization where inside cell = pos vs outside cell; causes +35mV spike in mem pot and reaches max deploraized state
36
falling phase
AP; most VG Na+ channels close so mem imperm to Na+; neuron = refracotry period so no other action pot possible bc Na+ channels close and won't open until they reset; VG K+ channels open slowly after threshold and fully open @ peak depolarization (+35mV); K+ rush outside cell (follow concen grad)
37
undershoot
AP; VG Na+ channels close and some VG K+ channels open; hyperpolarizaiton bc mem pot more neg than RP; eventually VG K+ channels close; mem returns to RP = -70mV
38
all or none event
whenever action pot steps happen it is always same process/outcome; intensity of sensation varies + depends on # neurons stimulated and freq of stimulation; we can differentiate diff levels of intensity
39
AP conduction
series of APs move as a signal along axon; prob: AP happens @ only one location on axon; need to move message down whole axon; so use conduction
40
AP via conduction
AP begins @ axon hillcok and wave of depolarization spread in one direction; as voltage shifts in one region it spreads to nearby VG Na+ channels further along axon; only one way stimulation "down" the axon away from cell body; wave-like stimulation down axon via VG Na+ channel openings leading to cont AP
41
myelin sheath
electrical insulation that surrounds axon; produced by 2 types of glial cells: oligodendrocytes (CNS) and schwann cells (PNS)
42
axon plasma mem
rich in myelin; white colored lipid produced by glial cells wrapped around axon; structure: internodes, nodes of ronvier, unmylinated axons
43
internodes
regions of axons covered by glial cells
44
nodes of ronvier
gaps in myelin sheath
45
unmylinated axons
grey matter, cont conduction, every spot along neuron depolarized/repolarized; hard work
46
AP conducation structure
myelinated axons = white matter; faster message tranmissions more E eff; @ nodes of ranvier: no myellin, high concen of VG Na+ and VG K+ channel; lots of depolarization = APs; APs jump node to node via saltatory conduction
47
saltatory conduction
APs jump node to node
48
multiple sclerosis
myelin sheath gradually deteriorates; replaced w scare tissue; slow neural transmission + loss of coordination

Biology 116 (27 decks)

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