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Cardio Exam 1 > Skeletal and Smooth Muscle > Flashcards

Skeletal and Smooth Muscle Flashcards

1
Q

types of muscle cells

A
  • skeletal
  • smooth
  • cardiac
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2
Q

which types of muscle cells are striated

A
  • skeletal

- cardiac

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3
Q

what is a skeletal muscle cell called?

A
  • muscle fiber

- myofiber

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4
Q

myofibers are composed of

A
  • myofibrils
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5
Q

myofibrils contain

A
  • myofilaments

- thick and thin

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6
Q

what is the functional unit of the myofibril called?

A
  • sarcomere
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7
Q

plasma membrane of the myofiber called

A
  • sarcolemmea
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8
Q

what are T tubules

A
  • infoldings that bring plasma membrane deep into myofibril
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9
Q

thick filament is made of

A
  • myosin
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10
Q

thin filament is made of

A
  • actin
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11
Q

what is on top of actin

A
  • tropomyosin and troponin
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12
Q

z lines define

A
  • a single sarcomere
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13
Q

Triad is composed of

A
  • T-tubular system and sarcoplasmic reticulum
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14
Q

neuromuscular junction is the synapse between

A
  • somatic motor neuron

- skeletal muscle fiber

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15
Q

post synaptic region of the skeletal muscle at the NMJ

A
  • motor end plate
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16
Q

all the motor fibers innervated by one somatic motor neuron

A
  • motor unit
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17
Q

a somatic motor neuron innervates

A
  • more than one muscle fiber
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18
Q

a muscle fiber is innervated by

A
  • ONLY ONE SOMATIC MOTOR NEURON
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19
Q

start of somatic motor neuron events

A
  • post synaptic potentials summate to exceed threshold

- action potential initiated

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20
Q

what happens after the action potential is initiated

A
  • AP conducted along axon to terminal

- terminals depolarize

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21
Q

what happens when the terminals depolarize?

A
  • voltage gated calcium channels open
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22
Q

what happens after voltage gated calcium channels open?

A
  • calcium enters the presynaptic terminal
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23
Q

what happens after calcium enters the presynaptic terminal

A
  • vesicles containing acetylcholine undergo exocytosis

- acetylcholine diffuses across synaptic cleft

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24
Q

what does acetylcholine bind to

A
  • nicotinic acetylcholine receptor channels
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25
Q

what happens after acetylcholine binds to nicotinic acetylcholine receptor channels

A
  • receptor channels open which increase the permeability of synaptic membrane to Na and K
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26
Q

what happens after receptor channels open

A
  • Na influx exceeds K+ efflux

- produces a depolarizing graded potential called EPP

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27
Q

what happens after the EPP is generated

A
  • EPP exceeds threshold and initiates muscle action potential
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28
Q

what happens after the EPP initiates the muscle action potential

A
  • voltage-gated Na+ channels open as the sarcolemma depolarizes
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29
Q

muscle action potential is conducted along

A
  • the sarcolemma and into T tubules
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30
Q

what happens after the muscle action potential is conducted along the sarcolemma and T tubules

A
  • voltage gated L-type calcium channels in T tubules open
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31
Q

voltage gated L-type calcium channels in T tubules have what kind of receptor

A
  • DHP receptor
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32
Q

what happens after voltage gated L-type calcium channels in T tubules open

A
  • causes calcium release channels in SR to open
33
Q

what kind of receptors do calcium release receptors in SR have?

A
  • Ryanodine receptors
34
Q

what happens after calcium release channels in SR open?

A
  • calcium diffuses out of SR

- Calcium concentration near sarcomeres increases

35
Q

what happens after calcium concentration near sarcomeres increases

A
  • cross-bridges form
  • contraction begins
  • sarcomeres shorten
36
Q

what is an abundant source of calcium

A
  • sarcoplasmic reticulum
37
Q

depolarization of sarcolemma is propagated down

which causes

A
  • T tubules

- opening of the DHP receptors

38
Q

what do the DHP receptors do

A
  • couple to ryanodine receptors

- causes Calcium move out of SR into cytosol

39
Q

what does calcium bind to

A
  • calcium binds to troponin and removes troponin/tropomyosin complex blocking actin
40
Q

what does calcium binding to troponin and blocking of tropomyosin allow to happen

A
  • cross bridge formation

- power stroke

41
Q

calcium binding from the SR in response to a single action potential

A
  • sufficient to bind all sites on troponin to expose actin binding sites for maximum cross bridge binding
42
Q

what happens with decreased calcium in the muscle

A
  • troponin complex blocks myosin binding sites on actin

- results in relaxation

43
Q

calcium is taken up into the SR by

A
  • Calcium ATPase (SERCA)
44
Q

how does muscle contraction compare to the action potential

A
  • muscle contraction extends far beyond the action potential
45
Q

smooth muscles are what kind of shape?

A
  • spindle shaped
46
Q

do smooth muscles have actin and myosin?

47
Q

do smooth muscles have sarcomeres?

A
  • no

- they have dense bodies

48
Q

filaments in smooth muscles are organized how

A
  • diagonally
49
Q

sliding filaments during contraction causes

A
  • cell to ballon out
50
Q

do smooth muscles fire action potentials

A
  • may or may not
51
Q

what regulates degree of contraction of smooth muscle

A
  • cytosolic calcium
52
Q

smooth muscles surround

A
  • hollow structures and organs that undergo changes in volume
53
Q

result of cell contraction in smooth muscle (in regard to lumen)

A
  • shrinks lumen diameter
54
Q

vascular smooth muscle is under what kind of control?

A
  • involuntary control
55
Q

what can control vascular smooth muscle

A
  • hormones
  • neurotransmitters from ANS
  • local stimuli
56
Q

multiunit smooth muscle electrical coupling between cells

A
  • little electrical coupling between cells
57
Q

multiunit smooth muscle contractions

A
  • may contract independently of its neighbor

- finer control

58
Q

multiunit smooth muscle contraction example

A
  • iris and ciliary body of eye
59
Q

single unit smooth muscle electrical coupling between cells

A
  • extensive electrical coupling between cells
60
Q

single unit smooth muscle contraction

A
  • coordinated contraction of many cells
61
Q

single unit smooth muscle contraction example

62
Q

two sources of calcium in smooth muscle

A
  • extracellular

- sarcoplasmic reticulum

63
Q

calcium binds what in smooth muscle

A
  • calmodulin
64
Q

calcium binding calmodulin does what

A
  • activates myosin light chain kinase
65
Q

role of MLCK

A
  • phosphorylates myosin
  • cross bridge formation
  • contraction
66
Q

roles of MLCP (myosin light chain phosphatase)

A
  • dephosphorylates myosin
  • cross bridges uncouple
  • relaxation
67
Q

activity of MLCP

A
  • constitutive
68
Q

cross bridge activation in smooth muscle compared to skeletal muscle

A
  • slow and energy efficient
69
Q

smooth muscle form of myosin ATPase activity versus skeletal muscle

A
  • low rate of ATPase activity
70
Q

shortening in smooth muscle versus skeletal muscle

71
Q

fatigue of smooth muscle

why

A
  • do not fatigue during prolonged activity

- due to low rate of energy utilization

72
Q

role of nitric oxide in smooth muscle

A
  • smooth muscle relaxation

- most potent vasodilator

73
Q

nitric oxide produced by

A
  • endothelial cells
74
Q

nitric oxide stimulates

enzyme involved

A
  • GTP -> cGMP

- through guanylate cyclase

75
Q

cGMP activates

A
  • protein kinase G
76
Q

protein kinase G stimulates

A
  • reuptake of cytosolic calcium

- opening of calcium activated potassium channels

77
Q

result of protein kinase G

A
  • cysotolic calcium levels fall
  • MLCK activity decreases
  • decreased cross bridge formation
  • relaxation
78
Q

smooth muscle contraction graded based on

A
  • amount of cytosolic calcium available

Cardio Exam 1 (25 decks)

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