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PHYSL 212 > SMOOTH MUSCLE > Flashcards

SMOOTH MUSCLE Flashcards

(63 cards)

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1
Q

what are smooth muscle thin filaments made of

A

actin

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2
Q

what are smooth muscle thick filaments made of

A

myosin

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3
Q

why are there no striations in smooth muscle

A

lack of organization

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4
Q

how are actin filaments oriented

A
  1. parallel to long axis

2. oblique to long axis

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5
Q

what are dense bodies

A

electron dense regions where actin filaments come together

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6
Q

how are thick and think filaments organized

A

thick filaments interspersed bw thin filaments

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7
Q

what structure in skeletal muscle are dense bodies similar to

A

Z lines

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8
Q

what are thin filaments in smooth muscle lacking

A

troponin

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9
Q

what is the function of enzyme myosin light chain phosphates in smooth muscle

A

terminate contraction

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10
Q

what are 2 types of smooth muscle

A
  1. multi unit

2. unitary

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11
Q

where does unitary smooth muscle occur

A

large sheets

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12
Q

what connects individual smooth muscle cells in unitary

A

gap junctions

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13
Q

how does unitary smooth muscle function

A

as one.

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14
Q

how does multi unit smooth muscle differ from unitary

A

individual units not connected by gap junctions

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15
Q

what does lack of gap junctions in multi unit smooth muscle result in

A

little electrical coupling

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16
Q

MULTIUNIT what innervates multiunit smooth muscle

A

ANS

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17
Q

MULTIUNIT what do axons of post ganglionic fibre contain

A

branches

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18
Q

MULTIUNIT what do branches of post ganglionic fibre contain

A

vricosities

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19
Q

MULTIUNIT what do varicosities contain

A

transmitter

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20
Q

MULTIUNIT where does transmitter get released

A

surface of smooth muscle cells

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21
Q

UNITARY what innervates unitary smooth muscle

A

ANS

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22
Q

what causes spont electrical activity in smooth muscle cells

A

pacemaker potential

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23
Q

what does spont electrical activity result in

A

slow waves / regular oscillations in mem potential

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24
Q

what happens in step one of slow waves

A
  1. voltage gated Ca channels open

2. Ca moves into cell causing depol

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25
what happens in step two of slow waves
1. mem potential depolarizes to threshold 2. AP causes more Ca influx 3. AP causes contraction of smooth muscle
26
what happens in third step of slow waves
1. intracellular Ca concentration increases
27
what happens in forth step of slow waves
1. Ca dependent K channels open
28
what happens in fifth step of slow waves
1. K moves out of cell causing hyper polarization
29
what is sixth step of slow waves
1. Ca channels close during hyper polarization | 2. intracellular Ca concentration decreases
30
what happens in seventh step of slow waves
1. Ca dependent K channels close | 2. Cell becomes less hyper polarized (K ions not leaving)
31
what initiates cross bridge cycling in smooth muscle
Ca dependent phosphorylation of myosin
32
in smooth muscle when are myosin heads able to bind to actin filaments
when light chains phosphorylated
33
how is cross bridge cyclin initiated in smooth muscle
1. 4 Ca binds to calmodulin 2. Ca - calmodulin activates myosin light chain kinase 3 myosin light chain kinase phosphorylates regulatory light chain 4. myosin undergoes conformational change
34
what is the function of Ca in smooth muscle
induce chemical change in myosin
35
wha tis the function of Ca in skeletal muscle
induce physical change in actin
36
what is Ca binding protein in smooth muscle // what is Ca binding protein in skeletal muscle
calmodulin // troponin
37
which type of muscle (skeletal or smooth) is cross bridge cycling initiated sooner
skeletal
38
what is the function of calponin and caldesmon
tonically inhibit interaction bw actin and myosin
39
how can relaxation be induced in smooth muscle
1. de phosphorylating regulatory myosin light chains | 2. decreasing Ca levels in cyto
40
what is responsible for myosin light chain de phosphorylation
myosin light chain phosphotase
41
what are sources of Ca in smooth muscle
1. Ca can enter cyto through voltage dependent channels (in response to depol) 2. Ca can enter cyto through voltage -independent channels 3. Ca can enter cyto from SR
42
VOLTAGE DEPENDENT what is voltage dependent Ca channel in smooth muscle
1. L type Ca channel
43
VOLTAGE DEPENDENT how does L type Ca channel work
depol causes influx of Ca
44
VOLTAGE INDEPENDENT what are voltage independent channels in smooth muscle
1. ligand gated channel | 2. store-operated Ca channel
45
VOLTAGE INDEPENDENT where are ligand gated channels located
mem of smooth muscle cell
46
VOLTAGE INDEPENDENT how does ligand gated channel work
ligand binding cuases influx of Ca
47
VOLTAGE INDEPENDENT when are store-operated Ca channels opened
Ca levels in SR depleted
48
VOLTAGE INDEPENDENT where are store-operated Ca channels located
mem of smooth muscle cell
49
VOLTAGE INDEPENDENT what happens when store-operated Ca channels open
influx of Ca - increases intracellular Ca levels - replenishes SR Ca levels
50
CA RELEASE FROM SR what is Ca release channel of SR in smooth muscle
RyR3
51
what is lacking in smooth muscle
t tubule system
52
what in smooth muscle is similar to t tubules
calveoli
53
what channel is located in calveoli
volrage gated Ca channels
54
CA RELEASE FROM SR what are 2 methods of Ca release
1. calcium induced calcium release (ryanodine receptors) | 2. IP3 activation (ligand gated channels in mem of SR)
55
CA RELEASE FROM SR how does calcium induced calcium release work
1. Ca enters cell through voltage gated Ca channels | 2. Ca acts on ryanodine receptors to cause release of more Ca
56
CA RELEASE FROM SR how does OP3 activation work
1. ligand binds G protein coupled receptor 2. IP3 activates 3. IP3 acts on ligand gated channels in mem of SR
57
what are mechanisms of reducing Ca levels in cyto
1. NCX 2. PMCA 3. SERCA 4. calceriticulin
58
LATCH BRIDGE MECHANISM what is latch bridge mech
myosin heads remain attached to actin even after Ca conc falls (i.e. during relaxation)
59
LATCH BRIDGE MECHANISM what does decreased rate of detachment allow
1. lower rate of cross bridge cycling | 2. lower rate of ATP hydrolysis
60
LATCH BRIDGE MECHANISM what is result of cross bridge cycling
sustained contraction without expenditure of en
61
what is mech of excitation in skeletal muscle
neuromuscular transmutation
62
what is mech of excitation in cardiac muscle
1. pace maker | 2. gap junctions
63
what is mech of excitation in smooth muscle
1. synaptic transmission 2. hormone receptors 3. gap junctions

PHYSL 212 (22 decks)

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