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Cell Biology > L11 Muscle Contraction > Flashcards

L11 Muscle Contraction Flashcards

1
Q

Muscle cells are known as…

A

Muscle fibres 💪

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2
Q

Muscle fibres are 100 µm in diameter, which is much ( larger / smaller / the same ) as a typical somatic cell.

A

Larger

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3
Q

Muscle fibres are made up of bundles of…

A

Myofibrils

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4
Q

Myofibrils contain repeating units, known as…

A

Sarcomeres

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5
Q

In contraction there is no change in filament length, however, the overlap between thin and thick filaments increases. This is called the…

A

“Sliding Filament Hypothesis of Muscle Contraction”

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6
Q

The A band is defined as the distance across the…

A

Thick filament

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7
Q

The M line is down the centre of the…

A

Thick filament

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8
Q

The I band is the area of only…

A

Thin filament

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9
Q

The H zone is the area of only…

A

Thick filament

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10
Q

The Z line / disk is down the centre of the…

A

Thin filament

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11
Q

During contraction, the A band…

A

Does not change

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12
Q

During contraction, the I band…

A

Decreases in length (because there is more area of overlap)

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13
Q

During contraction the H zone…

A

Decreases in length (because there is more area of overlap)

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14
Q

The thick filaments are made from…

A

Myosin

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15
Q

Myosin has a globular head and a…

A

Long tail

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16
Q

Thin filaments are made from (3)…

A
  • Actin
  • Tropomyosin
  • Troponin
17
Q

G-Actin molecules join up to form long chains known as..

A

F-Actin

18
Q

The thin filament is structured as an F-actin double helix interwoven with…

A

Tropomyosin

19
Q

Troponin is comprised of 3 subunits, known as…

A

I, T, C

20
Q

Troponin I and T subunits bind to ? and ? which blocks the myosin binding site.

A
  • Actin

* Tropomyosin

21
Q

Troponin C binds with Ca2+, which…

A

Exposes the myosin binding site

22
Q

The action potential moves from the junctional folds down the T-Tubule and activates an…

A

A-Triad

23
Q

The A-Triad is made up of the T-Tubule and the…

A

Terminal cysternae on either side

24
Q

Cross bridge formation is when…

A

Myosin initially binds to actin

25
Q

Step 1 of muscle contraction - Myosin is in…

A

A high energy state, with ADP + Pi still attached

26
Q

Step 2 of muscle contraction - Myosin head rotates, shifting the thin filament closer to the centre of the sarcomere. This is called the…

A

Power stroke

27
Q

If Ca2+ and ATP are still present the process can repeat.

ATP binds to the myosin head, which causes (2)…

A

The release of ADP + Pi and the decoupling of actin from myosin

28
Q

Energy in the form of ATP is needed to ( make / break ) the bond between myosin and actin.

A

Break

29
Q

Muscle relaxation occurs when Ca2+ is…

A

Removed by the Sarcoplasmic Reticulum via Calcium ATPase pump

Cell Biology (21 decks)

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