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physiology. > study guide 2 > Flashcards

study guide 2 Flashcards

1
Q

what did Volta invent/do

A

invented the electric battery. proved electricity could be generated chemically

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2
Q

what is a cells resting membrane potential

A

-70mV

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3
Q

what do Na+/K+ pumps do

A

help maintain osmotic equilibrium and membrane potential in cells

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4
Q

what do K+ leak channels do

A

allow K+ to diffuse out of cells (passive transport)

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5
Q

what are fixed intracellular anions

A

organic anions that cannot leave the cell

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6
Q

what do fixed intracellular anions do

A

help with the transport of gases, nutrients, and other molecules

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7
Q

why does the thickness of the PM matter

A

plays a key role in protein function

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8
Q

how much of the cells total potassium ions are needed to establish the resting membrane potential

A

a very small amount

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9
Q

what is the INTRACELLULAR/CYTOSOLIC concentration for SODIUM ions (Na+)

A

5-15mM

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10
Q

what is the EXTRACELLULAR concentration for SODIUM ions (Na+)

A

145mM

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11
Q

what is the INTRACELLULAR/CYTOSOLIC concentration for POTASSIUM ions (K+)

A

140mM

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12
Q

what is the EXTRACELLULAR concentration for POTASSIUM ions (K+)

A

5mM

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13
Q

what are the main excitable cells in the body

A

neurons and muscle cells

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14
Q

what are some key features of AP (6)

A
  1. depend on VGNCs or VG calcium channels
  2. all or nothing events
  3. brief duration (~2ms)
  4. self propagating down the length of an axon.
  5. unidirectional w a constant amp. and wave shape
  6. high velocity of propagation (0-100 m/s)
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15
Q

what are the 3 states of VGNCs?

A

closed (and ready to open)
open (and conducting Na+ ions)
inactivated (similar to open, but non conducting)

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16
Q

how can ion channels be selective

A

surround a central pore, guarded by selectivity filter. ions have to shed their sphere of hydration to pass through

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17
Q

what is a selectivity filter

A

a region of an ion channel protein that ddetermines the specificity of a particular channel

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18
Q

what is loligo/ why is it studied

A

squid w big axon

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19
Q

what is the AP threshold

A

enough Na+ leaks in for any portion of the inner membrane to depolarize (all or nothing principal)

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20
Q

if the AP threshold is met, what is the probability of an AP being triggered

A

50%

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21
Q

do all VGNC’s have to open to trigger an AP

A

no, only needs to be ‘a sufficient amount’

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22
Q

what happens 1-2ms after VGNCs open

A

enter inactivated state stopping the flow of sodium ions

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23
Q

what is repolarization?

A

membrane returns to resting membrane potential

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24
Q

how do local anesthetcs work?

A

block the inner mouth of VGNCs and prevent Na+ conduction and thereby prevent APs in sensory neurons

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25
Q

what does tetrodotoxin (TTX) do

A

plugs the EXTRACELLULAR mouth of a VGNC pore

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26
Q

where does TTX come from

A

pufferfish, porcupine fish, ocean sunfish, triggerfish, blue ringed octopus, rough skinned new, moon snail

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27
Q

what is myelin

A

a fatty insulating sheath that surrounds nerves in the brain and spinal cord

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28
Q

what cells make myelin

A

schwann cells

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29
Q

what does myelination do for a neuron (2)

A
  1. increases the propagation velocity of APs
  2. decreases metabolic energy expenditure by the neuron (bc the Na/K pups dont need to transport as many ions post AP)
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30
Q

what are the gaps in the myelin sheath called

A

nodes of ranvier

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31
Q

know what an axon hillock is

A

ok

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32
Q

what ion channels are found in the nodes of ranvier

A

VGNCs

33
Q

what is saltatory conduction

A

AP jumps from one node of ranvier to the next, AP only occurs at nodes bc VGNCs are only present at the nodes

34
Q

what is a synapse

A

a point of very close physical contact between a neuron and another cell

35
Q

what are the different kinds of synapses

A

electrical, chemical (more??)

36
Q

where would you find a gap junction

A

electrical synapses

37
Q

explain connexins and connexons

A

6 connexins (individual proteins) make up 1 connexon
2 connexons form 1 gap junction

38
Q

what are skeletal muscles fibers encased in

A

connective tissue

39
Q

each skeletal muscle fiber in an adult human is innervated by how many presynaptic terminals of a somatic motor neuron

A

a SINGLE presynaptic terminal of a SOMATIC MOTOR NEURON

40
Q

what is a motor unit

A

basic functional units of a skeletal muscle

41
Q

why wouldnt all the muscle fibers be innervated by just one motor neuron

A

bc if there was just one innervating everything it would severely limit muscle’s ability to produce graded movements

42
Q

why study the NMJ

A

big and easy to find w microscope
also very hardy can survive in petri dish for a long time

43
Q

what are some unique features of the NMJ

A

junctional folds to incrase surface area

44
Q

what neurotransmitter is released at the NMJ

A

Acetylcholine (ACh)

45
Q

how much excess neurotransmitter is secreted at the NMJ and why

A

3X of ACh secreted as a safety factor to endsure muscle contraction

46
Q

once a neurotransmitter like ACh is released what happens to it

A

binds to something opening some kind of gated channel to allow sodium ions to flow into the postsynaptic cell (i couldnt find this one on the ppt and your study guide answer was too vague)

47
Q

what special enzyme is present in the snaptic cleft at the NMJ

A

acetylcholinesterase (AChE)

48
Q

explain this https://imgur.com/a/wGXjKDm

A

do it

49
Q

what are myofibrils

A

bundles of myofilaments

50
Q

what filaments are found in myofibrils

A

actin and myosin

51
Q

what are thick filaments made of

A

myosin II dimers

52
Q

what are thin filaments made of

A

actin

53
Q

what is a sarcomere

A

the contractile unit of a muscle fiber

54
Q

what are the 2 binding sites for on a myosin head

A

one for actin one for ATP`

55
Q

what are Z disks

A

protein that anchors the thin filaments and connects the myofibrils to each other

56
Q

what attaches to a Z disk

A

I band (isotropic band)

57
Q

what are I bands

A

Isotropic bands- actin bands (lighter)

58
Q

what are A bands

A

anisotropic bands- myosin bands (darker)

59
Q

whats an M line

A

a spot on the myosin filament where there are no myosin heads present- anchor for thick filaments

60
Q

what shortens during muscle contraction

A

sarcomeres shorten bc actin filaments slide relative to myosin filaments and the distance between adjacent Z disks becomes shorter

61
Q

do the filaments shorten during contraction

A

NO

62
Q

why is release of calcium so important for contraction

A

calcium binds to troponin and myosin binding site is exposed (on actin)

63
Q

what is troponin

A

a regulatory protein that moves tropomyosin aside and exposes myosin binding sites on actin when calcium is released during muscle contraction

64
Q

what is tropomyosin

A

long, fibrous protein that winds around actin fiber, blocks all myosin binding sites

65
Q

role of troponin I

A

prevents myosin from binding to actin in relaxed muscle
is the one stuck to the actin, like an anchor

66
Q

role of troponin C

A

calcium ion binds here

67
Q

role of troponin T

A

where the pulling happens

Troponin is a calcium-regulatory protein for the calcium regulation of contractile function in skeletal and cardiac muscles.

68
Q

why are T tubules important

A

permit rapid transmission of an AP into a cell. also plays important role in regulating cellular calcium concentration

69
Q

what is a triad

A

T-tubule plus 2 terminal cisternae

70
Q

what is RYR1

A

gatekeeper of calcium in the muscle cell. its mechanically gated by FOUR Cav1.1 channels

RYR1 channels are located in the membrane surrounding a structure in muscle cells called the sarcoplasmic reticulum. This structure stores calcium ions when muscles are at rest.

71
Q

what is Cav1.1

A

L type voltage gated Ca2+ channel. serves as a voltage center for E-C coupling in skeletal muscle fibers

voltage-gated calcium channel that plays a key role in skeletal muscle contraction

72
Q

where does most of the Calcium that plays a role in contraction come from

A

sarcoplasmic reticulum

73
Q

what happens to calcium once its released

A

after Ca2+ is released from SR, its IMMEDIATELY pumped back into SR by numerous Ca2+ ATPases (like SERCA)

74
Q

when is ATP used

A

during quick movements

75
Q

is atp only needed for contraction?

A

no needed for both contraction and relaxation- rigor mortis !!!

76
Q

what is SERCA and why is it important

A

Sarcoplasmic Endoplasmic Reticulum Calcium ATPase
constantly pumps calcium back into SR lumen

77
Q

what kind of paralysis does tetanus cause

A

spastic paralysis

78
Q

what kind of paralysis does botox cause

A

flaccid (lol) paralysis

physiology. (8 decks)

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