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Systems Physiology > Smooth Muscle Excitation Contraction Coupling > Flashcards

Smooth Muscle Excitation Contraction Coupling Flashcards

1
Q

What is smooth muscle conduction controlled by?

A

Myosin

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2
Q

What is different about actin in smooth muscle?

A

No troponin or tropomyosin

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3
Q

What replaces t tubules in smooth muscle?

A

Caveoli

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4
Q

What are caveoli?

A

Small invaginations in the membrane

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5
Q

What type of smooth muscle is in hollow organs?

A

Unitary/syncytial

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6
Q

What ion determines smooth muscle membrane potential and muscle contraction?

A

Calcium

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7
Q

What are two possible sources of calcium?

A

Extracellular
Sarcoplasmic reticulum

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8
Q

3 ways calcium channels can be opened in smooth muscle?

A

Leaky sodium channels
Stretch
Neuromuscular junction varicosities

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9
Q

How can calcium release be initiated?

A

G reactive protein stimulation by vasoconstrictors

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10
Q

What is activated after G reactive proteins are stimulated?

A

Phospholipase C

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11
Q

What does IP3 do?

A

Triggers calcium release from sarcoplasmic reticulum

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12
Q

What must happen to calcium first to initiate contraction?

A

Bind to calmodulin

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13
Q

What enzyme does calmodulin activate?

A

Myosin light chain kinase

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14
Q

What does myosin light chain kinase do?

A

Phosphoralytes myosin head causing conformational change

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15
Q

What enzyme prevents smooth muscle contraction?

A

Myosin light chain phosphatase

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16
Q

What is myosin light chain phosphatase activated by?

A

Vasodilators

17
Q

Why does smooth muscle contraction last longer than skeletal?

A

The primary calcium pump is slower

18
Q

How can smooth muscle contraction be terminated in the absence of calcium?

A

Dephosphorylation of myosin light chains by myosin light chain phosophatase

19
Q

What is an action potential in smooth muscle called?

A

A spike potential

20
Q

Typical resting membrane potential for smooth muscle?

A

Between -60 and -50 mv

21
Q

What is responsible for slow waves and what happens as a result?

A

Leaky sodium channels in, drifting membrane potential

22
Q

What kind of tissues have leaky sodium channels and where are they found?

A

Self-excitatory tissue in SA/AV node in right atria as well as in interstitial cells of Cajal in intestines

23
Q

Where in the body does the smooth muscle action potential plateau?

A

Uterus
Larger blood vessels
Ureter

Systems Physiology (11 decks)

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