Structure of skeletal muscles Flashcards

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1
Q

What is the plasma membrane called that encloses the muscle fibres?

A

Sarcolemma

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2
Q

What is the shared cytoplasm called between muscle fibres?

A

Sarcoplasm

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3
Q

What are myofibrils?

A

Long cylindrical organelles made of protein that are specialised for contraction

They make up the muscle fibres

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4
Q

What are the two types of protein filaments that myofibrils make up?

A

Actin - the thinner filament
-Two strands twisted around each other

Myosin - the thicker filament
-Consists of long rod-shaped fibres with bulbous heads that project to one side

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5
Q

What are light bands?

A

Areas where the actin and myosin filaments do not overlap

Also known as I bands

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6
Q

What are dark bands?

A

Presence of thick myosin filaments

Edges are dark because the myosin is overlapped with the actin

Also known as A bands

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7
Q

What is the z-line?

A

Line found in the centre of each light band

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8
Q

What is a sarcomere?

A

Distance between two z lines

When the muscle contracts, the sarcomere shortens

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9
Q

What is the h-zone?

A

Lighter coloured region found in the centre of each dark band

Only myosin filaments are present

When the muscle contracts, the h-zone decreases

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