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ANS and Cardiac Physiology > Mechanisms of Muscle Contractions > Flashcards

Mechanisms of Muscle Contractions Flashcards

1
Q

Speed of contraction in smooth vs cardiac and skeletal muscle

A

Smooth- slow. Cardiac/skeletal- fast.

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2
Q

Ringer experiment: Increase and decrease Ca in heart cells

A

Increase calcium: larger contractions. Remove calcium: smaller contractions.

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3
Q

A Band

A

Delineates extent of thick filaments

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4
Q

I band

A

Area that does not contain thick filaments. Contains Z line.

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5
Q

Z line

A

Scaffolding proteins that anchor thin filaments.

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6
Q

Titin

A

Anchors thick filaments to Z lines.

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7
Q

Thin filaments composed of?

A

Actin, troponin, tropomyosin

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8
Q

Sliding filament theory

A

Myosin pulls along actin filaments towards Z lines.

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9
Q

Role of Calcium in Muscle Contraction in skeletal/cardiac muscle

A

Binds to troponin C, which moves tropomyosin to expose myosin binding sites.

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10
Q

What happens when ACh binds to AChR?

A

Na influx through skeletal muscle

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11
Q

Difference between calcium in skeletal muscle/cardiac muscle

A

In heart, both Ca influx and release from SR is needed for contraction. Skeletal muscle does not require calcium influx.

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12
Q

Difference between cardiac/skeletal muscle and their contractions

A

Heart has 1 contraction per action potential, skeletal muscle has many.

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13
Q

Structure of Smooth Muscle

A

No troponin, so myosin must be phosphorylated to interact with actin using MLCK.

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14
Q

How is calcium released from SR in smooth muscle?

A

Via IP3 receptors.

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15
Q

Can smooth muscle contraction occur without action potentials?

A

Yes, via IP3 receptors. Can contract with or without them.

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16
Q

How do smooth muscles contract?

A

Release of Ca from reticulum binds to calmodulin, activating MLCK, which phosphorylates myosin, causing contraction.

17
Q

MLCK

A

Myosin Light Chain Kinase, phosphorylates myosin light chains. Inhibited by cAMP.

18
Q

B adrenergic stimulation effect on smooth muscle

A

Relaxation, due to activation of AC, then cAMP. Inhibits MLCK

19
Q

A adrenergic stimulation effect of smooth muscle

A

Contraction, due to production of IP3, causes Ca release.

20
Q

NO affect on smooth muscle

A

Relaxation, activation of GC, cGMP inhibits MLCK.

ANS and Cardiac Physiology (10 decks)

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