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Physiology I Block 2 > Smooth Muscle > Flashcards

Smooth Muscle Flashcards

1
Q

what kind of organ are smooth muscles a major component of

A

hollow organs

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2
Q

sustained contraction is synonymous with

A

tonic contraction

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3
Q

functionally what are the two ways smooth muscles can be classified

A

phasic or tonic

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4
Q

what are examples of places smooth muscle would contract phasically

A

esophagus, urinary bladder

the smooth muscles contracts, for example w/ bladder, depending on volume

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5
Q

what are examples of smooth muscles tonically contracted

A

sphincters

don’t want to poop yourself!

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6
Q

compare energy required for smooth muscle vs. skeletal muscle

A

MUCh less energy required for smooth muscle.

1/10 - 1/300

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7
Q

what do smooth muscle cells NOT possess that skeletal does

A

troponin c

t tubules

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8
Q

describe the physical properties of smooth muscle cells

A

individual, long, mononucleate, they have actin, myosin, tropomyosin

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9
Q

what links smooth muscle instead of z line

A

dense bodies

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10
Q

are their sarcomeres in smooth msucle

A

no, not distinct

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11
Q

what are contractile units made up of in smooth muscle

A

interdititating thick and thin filaments connected by dense bodies

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12
Q

contraction in smooth muscle is based on

A

thick and thin filaments sliding over each other

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13
Q

dense bodies serve same role as what in smooth msucle

A

z disks

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14
Q

what are intermediate junctions

A

where multiple cells meet and are connected via dense bodies

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15
Q

are smooth muscle cells connected via gap junctions

A

yes

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16
Q

describe concentration of ATPase in smooth msucle compared to skeletal

A

smooth muscle has less, but it can contract more strongly than skeletal

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17
Q

are there t tubules in smooth muscle

A

no

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18
Q

describe the SR in smooth muscle

A

less developed than in skeletal

still stores and releases calcium

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19
Q

what plays the majority role in calcium release to smooth msucle

A

extracellular calcium, SR has a more minor role

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20
Q

what are the two different physiological classifications of smooth muscle

A

multi-unit

single unit

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21
Q

describe qualities of multi-unit smooth muscle

A

no gap junctions
no spontaneous contraction
activated by extrinsic innervation or hormonal diffusion
each smooth muscle cell receives its own synaptic input
rarely have AP
local depol is what causes contraction

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22
Q

what are examples of plces in body with multi-unit smooth muscle

A

iris muscle of eye
ciliary muscle of eye
vas deferens
piloerector muscles

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23
Q

what are the other ways to say single-unit smooth muscle

A

unitary
visceral
syncytial

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24
Q

what are characteristic of single-unit smooth muscle

A 
all cells coordinate when they contract
Gap junctions!
spontaneously active
dont need extrinsic innervation to contract
they can self excite
AP normally occur
muscle must depol before AP
RMP is more pos. than skeletal muscle
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25
Q

what are examples of places in body with single-unit smooth muscle

A 
GI tract
bile ducts
bladder,
ureter
uterus
blood vessels
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26
Q

what are the three ways AP can occur in visceral smooth muscle

A

spike potential
action potentials with plateaus
slow wave potentials

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27
Q

visceral smooth muscle means

A

single unit smooth muscle

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28
Q

describe a spike potential

A

it is what is seen in skeletal muscle
duration of AP 10-50 msec
can be elicited via electrical, hormones, transmitters, stretch, spontaneous generation in muscle fiber itself

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29
Q

what can elicit a AP in spike potential

A

electrical, hormones, transmitters, stretch, spontaneous generation in muscle fiber itself

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30
Q

draw a spike AP

A

pg 10

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31
Q

describe AP with plateaus

A

onset timilar to spike AP
delayed repolarization
so ultimately longer AP

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32
Q

draw out AP with plateaus

A

pg 11

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33
Q

describe AP with slow wave potentials

A

this is what produces tonic muscle contraction
it is not AP but the membrane gets depol and repol slowly, but not enough to make AP.
there can be AP on top of peak
the waves will still produce weak contraction (tonic)
gap junctions

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34
Q

what is another way to say slow wave potential

A

basic electrical rhythm

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35
Q

What does BER stand for

A

basic electrical rhythm

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36
Q

frequency of slow waves vary with

A

location of the smooth muscle

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37
Q

what generates the slow waves

A

interstitial cells of cajal

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38
Q

draw out slow wave potential

A

pg 12

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39
Q

once interstitial cells of cajal make slow wave, how is it spread across the smooth msucle

A

gap junctions

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40
Q

interstitial cells of cajal are considered what

A

pacemaker cell in smooth muscle

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41
Q

smooth muscle is innervated extrinsically by

A

ANS

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42
Q

smooth musle is innervated intrinsicly by

A

enteric neural plexi

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43
Q

are there structurally specialized end plates in smooth muscle

A

no

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44
Q

action or spike potentials are generated in response to:

A

 Neural stimulation (shown below)
 Hormonal stimulation
 Stretching the muscle

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45
Q

in longitudinal smooth muscle what regulates the syncytial activity

A

interstitial cells & myenteric plexus

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46
Q

what is the major exception b/w contraction of smooth msucle vs. skeletal

A

smooth muscle: much slower contractile velocity

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47
Q

why does smooth muscle have a slow contractile velocity

A

slow ATPase activity - so rate of activatoin

number of crossbridge interactions

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48
Q

in smooth muscle, what does calcium bind to

A

calmodulin (CM)

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49
Q

what does CM stand for

A

calmodulin

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50
Q

what two enzymes are specific for contraction in smooth muscle

A

myosin light chain kinase

myosin light chain phosphatase

51
Q

look up video on smooth muscle contraction and draw diagram

A

:D

52
Q

whatt is function of myosin light chain kinase

A

phosphorylates regulatory site on light chain of myosin

53
Q

what is function of myosin light chain phosphatase

A

dephosphorylates regulatory site on light chain of myosin

54
Q

describe the order of what happens in smooth muscle one calcium enters

A

it binds to calmodulin
myosin light chain kinase phosphorylates → phosphorylates myosin → crossbridge → catalyze ATP dependent actin and myosin sliding

to turn off: dephosphorylate via mysoin light chain phosphatase

55
Q

what does MLCK stand for

A

myosin light chain kinase

56
Q

when MLCk is actie what specifically does it do

A

phosphorylate myosin head of thick filaments so they can interact with actin thin filaments

57
Q

describe phasic contraction

A

twitch-like shortening followed by relaxation

58
Q

describe tonic contraction

A

force sustained for long period

59
Q

describe how tonic contractions work

A

calcium enters and initiates phosphorylation and contraction, then calcium levels fall and it just keeps sustaining that contraction

60
Q

in smooth muscle, release of Ca from SR is function of

A

second messenger, IP3

61
Q

how is calcium taken out of the cell

A

ATP calcium pump

Na-Ca exchanger

62
Q

Draw the DAG/PIP pathway and how it relates to calcium

A

pg 23

63
Q

how does smooth muscle couple excitation to contraction

A

sarcolemma depol → voltage gated calcium channels
chemical agents → neutotransmitters and hormones bind to release calcium
stretch → stretch sensitive calcium channels opened on sarcollema

64
Q

an increase in tension in smooth muscle will result in

A

depolarization

65
Q

describe Vmax and Fmax in smooth muscle compared to skeletal

A

force velocity relationship
Vmax low
Fmax the same

66
Q

list the similarities b/w smooth and skeletal muscle

A

Actin and myosin required for cross-bridge cycling
Myosin head contains binding site for actin
Blocked when Ca2+ levels are low
Open when Ca2+ binds to troponin or calmodulin
Binding of actin and myosin causes
ATP energy release from myosin ATPase
Cycling of the cross-bridges

67
Q

does phasic contraction last long

A

no

68
Q

tonic contractions will be contracted until

A

there is signal telling it to relax

69
Q

draw graph for patterns of contraction in differnt smooth muscles

A

pg 4

70
Q

in blood vessels there is always some

A

tone/tonic contraction

71
Q

why do blood vessels always have some tone

A

to work against the pressure of blood flowing through it

72
Q

smooth muscle cells don’t use as much

A

ATP

73
Q

which is more efficient smooth or skeletal muscle

A

smooth

74
Q

what are all the pits in the pic of smooth muscle

A

caveoli - more extensive in smooth muscle

75
Q

what are all the lines in the pic of smooth muscle

A

actin and myosin

76
Q

skeletal muscle has very extensive

A

intracellular membrane network of SR

77
Q

Is SR well developed in smooth muscle

A

no

78
Q

dense bodies

A

contain α-actinin as found in Z lines in skeletal muscle, and anchor actin filaments to form diagonal lattice of contractile units

79
Q

membrane-associated dense bodies

A

appear to serve as anchors for thin filaments and transmit the force of contraction to adjacent cells.

80
Q

intermediate filaments in smooth muscle

A

contain desmin and hold dense bodies in place

81
Q

visceral smooth msucle have high degree of

A

gap junctions

want to act in same time frame as functional unit

82
Q

thick filaments in smooth muscle

A

contain myosin

83
Q

thin filaments in smooth muscle

A

contain actin and tropomyosin (no troponin complex*)

84
Q

in multiunit there is direct

A

innervation of each cell

85
Q

single unit smooth muscle has modulation of activity but it’s not

A

innervating every one

it has gap junctions

86
Q

What modultes and regulates single unit smooth msucle

A

ANS

87
Q

depending on size of amplitude of slow wave potential determines

A

how much tensino you get

88
Q

variscosity

A

where transmitter is stored

in synaptic vessicles and released b/c of AP

89
Q

plateau in unitary smooth muscle due to

A

voltage gated potassium channels

90
Q

what is BER

A

depolarization, repolarization, about 35 mv

91
Q

what is the mv of the BER

A

about 35 mv

92
Q

sometimes during BER it will reach thershold (hormones, stretch, etc.) and what will happen

A

amplitude will change and get AP on top of it

93
Q

when smooth muscle contraction is must more forceful what is happening

A

AP created in BER

94
Q

frequency of BER based on activity of

A

ICC (interstitial cells of cajal)

95
Q

stomach BER

A

3/min

96
Q

SI BER

A

11-12/min

97
Q

colon BER

A

2-13/min

98
Q

why is there high freq in SI

A

reuptake, moving everything along

99
Q

ICC stands for

A

interstitial cells of cajal

100
Q

in between long muscular and circular muscular layer are

A

ICC

101
Q

ICC are in communication with

A

muscles that modulate and determine activity of the smooth muscles

102
Q

in most regions frequency of ICC

A

same frequency

103
Q

how is slow wave amplitude modified

A

ex: responding to Ach

104
Q

the more Ach that comes in the more

A

AP

105
Q

the more spike potentials on top of cell wave the

A

stronger the contraction will be

106
Q

ex of parasympathetic stimulation

A

Ach

107
Q

EC coupling in smooth muscle, what are entyr pathways

A

calcium

108
Q

calcium doesn’t bind to what in smooth

A

troponin c

109
Q

what does calcium bind to in smooth muscle

A

calmodulin

110
Q

what has to occur in order to stimulate myosin light chain kinase

A

calcium bind to calmodulin

111
Q

in smooth musle what direction is it contraction

A

myosin heads are all different direction so you get contraction all over

112
Q

to relax smooth muscle have

A

dephosphorylate

113
Q

how many molecules of ATP for every cycle in smooth muscle contraction

A

2

114
Q

what dephosphorylates myosin

A

myosin light chain phosphatase

115
Q

calcium is pumped out of cell and exchanged for ____ when repolarizing

A

sodium

116
Q

draw pic for the way myosin heads contract in smooth muscle

A

pg 20

117
Q

you can get calcium release from SR to assist with EC coupling, but it’s not

A

the major pathway

118
Q

latch-bridge formation

A

producing force development and maintain the force for long period of time b/c have decreased number of activated crossbridges that are not using as much energy

119
Q

if intracellular calcium down b/c of long stimulation will get

A

latch-bridge formation

120
Q

if dephosphorylate all myosin get

A

complete repolarization

121
Q

what are all the ways calcium can enter cell in smooth muscle

A

voltage gated calcium channel
leak channels
ligand gated channels
agonist or ligrand gated channels taht go through g proteins (DAG/IP3)

122
Q

how does calcium leave cell in smooth muscle

A

calcium ATPase
sodium calcium exchanger
calcium ATPase in SR

123
Q

smooth muscle has more ability to have different proload and operates in wider range meaning it can

A

accommodate different volumes

Physiology I Block 2 (7 decks)

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