Muscle 5 Flashcards

1
Q

What is sliding filament theory based on?

A

Muscle proteins that slide past each other to generate movement

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2
Q

How is the length of muscle affected when muscle contracts?

A

When muscle contracts, it shortens

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3
Q

What remains constant in length during muscle contraction?

A

The A band

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4
Q

What does the A band contain?

A

Thick filaments of myosin

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5
Q

What is the I band rich in?

A

Thin filaments

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6
Q

What changes in length during muscle contaction?

A

The I band and the length of the sarcomere

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7
Q

How is the H zone affected by muscle contraction?

A

It gets smaller or disappears

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8
Q

What does the Sliding filament theory state?

A

That the sliding of actin past myosin generates muscle tension

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9
Q

How is the length of filaments affected during muscle contraction?

A

The filaments do not change in length but instead slide past each other

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10
Q

How are the A band, I band, Z lines, and H zones affected during muscle contraction?

A
  • A band: Remains constant
  • I band shortens
  • Z lines move closer together
  • H zone gets smaller or disappears
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11
Q

What is the Cross Bridge?

A

The head and hinge region of the myosin filament

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12
Q

What pulls the actin filaments towards the H zone?

A

The cross bridges or myosin heads

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13
Q

What is the mechanism of contraction?

A

The binding of actin to myosin forming cross-bridges that generate filament movement

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14
Q

What is the energy of ATP converted into during the cross bridge cycle?

A

Mechanical energy: Force and movement

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15
Q

What is the Attached State of the Cross-Bridge Cycle?

A

When the myosin head is attached to actin

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16
Q

What does the attached state represent?

A

The end of the previous cycle

17
Q

What did the actin and myosin previously release during the attached state?

18
Q

What happens in the first step of the cross-bridge cycle?

A

ATP binds to the myosin head causing the myosin to detach from the actin

19
Q

What happens after myosin detaches from the actin in cross bridge cycling?

A

The ATP is hydrolyzed causing the myosin heads to return to their resting conformation

20
Q

What do the products of hydrolysis of ATP in the cross bridge cycle do?

A

Remain attached to the relaxed myosin head

21
Q

What is the result of ATP hydrolysis during the cross bridge cycling?

A

The myosin moves and attaches to a new actin monomer

22
Q

What happens once The myosin binds to a new actin monomer in cross bridge cycling?

A

The organic phosphate is released from the myosin head, triggering a power stroke causing the myosin to pull the actin filament

23
Q

What happens once the power stroke occurs?

A

ADP is released from the myosin head and the myosin is in the attached state attached to the actin monomer

24
Q

What does the ATP binding to the myosin head do in cross bridge cycling?

A

Reduces the affinity of myosin for actin causing it to release from actin

25
What triggers a powerstroke?
The release of inorganic phosphate
26
What causes rigor Mortis?
The lack of ATP to release the myosin head from the attached state
27
How do Cardiac and Skeletal msucle control the cycle of contraction?
By preventing cross bridge formation involving tropomyosin and increased calcium levels