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biology > Muscles And Movement > Flashcards

Muscles And Movement Flashcards

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AP® Biology flashcards
1
Q

How do skeletal muscles attach to bones?

A

By tendons

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2
Q

How are bones held together?

A

Ligaments

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3
Q

What is an extensor?

A

A muscle that straightens a joint when it contracts

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4
Q

Muscles that work together are called?

A

Antagonist pairs

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5
Q

What is skeletal muscle made up of?

A

Long muscle fibers

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6
Q

Describe the structure of muscle fibers

A

Long cells

Cell membrane is called the sarcolemma

Bits of sarcolemma fold inwards across the muscle fibre and stick into the sarcoplasm

These folds are called transverse (T) tubules and they help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre

A network of internal membranes called the sarcoplasmic reticulum runs through the sarcoplasm

The sarcoplasmic reticulum stores and releases Ca2+ ions that are needed for muscle contraction

Muscle fibres contain lots of mitochondria to provide ATP for muscle contraction

Multinucleate (contain many nuclei)

Muscle fibres made up of long, cylindrical organelles called myofibrils which are made from proteins

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7
Q

What do myofibrils contain?

A

Thick Myosin filaments

Thin Actin filaments

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8
Q

What are thick myofilaments made up of?

A

Myosin (a protein)

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9
Q

What are thin myofilaments made up of?

A

Actin (a protein)

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10
Q

What would you see if you looked at a myofibril under an electron microscope?

A

A pattern of alternating dark and light bands

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11
Q

What do A-bands contain?

A

Thick myosin filaments and some overlapping thin Actin filaments

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12
Q

What do I-bands contain?

A

Thin Actin filaments only

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13
Q

What are the short units in a myofibril called?

A

Sarcomeres

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14
Q

What does a Z-line indicate?

A

The end of each sarcomere

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15
Q

What line is shown in the middle of each sarcomere and the middle of the Myosin filaments?

A

M-line

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16
Q

What does the H-zone contain?

A

Myosin filaments only

17
Q

Explain the sliding filament theory

A
  • Myosin and actin filaments side over one another to make the sarcomeres contract
  • The simultaneous contraction of lots of sarcomeres means the myofibrils and muscle fibres contract
  • Sarcomeres return to their original length as the muscle relaxes
18
Q

Describe how myofilaments, muscle fibres, myofibrils and muscles are related to each other

A
  • muscles are made up of bundles of muscle fibres
  • muscle fibres contain long organelles called myofibrils
  • myofibrils contain bundles of myofilaments
19
Q

Describe the structure of Myosin filaments

A
  • globular heads that are hinged to allow movement back and forth
  • each head has a binding site for actin and a binding site for ATP
20
Q

Describe the structure of actin filaments

A
  • contain binding sites for myosin heads called actin-myosin binding sites
  • tropomyosin and troponin are found between actin filaments
  • these proteins are attached to each other and help myofilaments move past each other
21
Q

Explain the role of tropomyosin in a resting muscle

A
  • blocks the actin-myosin binding site
  • this means myofilaments can’t slide past each other because the Myosin heads can’t bind to the actin-myosin binding site on the actin filaments
22
Q

What triggers a muscle contraction?

A

An action potential

23
Q

What are the two different muscle fibres present in skeletal muscles?

A
  • Slow twitch

- Fast twitch

24
Q

Properties of slow twitch muscle fibres

A
  • Contract slowly
  • Used for posture
  • Good for endurance activities
  • Can work for a long time without getting tired
  • Energy’s released slowly through aerobic respiration. This means there is lots of mitochondria and blood vessels to supply the muscles with oxygen
  • Reddish in colour as they are rich in myoglobin, a red-coloured protein
25
Q

Properties of fast twitch muscle fibres

A
  • contract very quickly
  • used for fast movement
  • good for short bursts of speed and power
  • tire very quickly
  • energy’s released quickly through anaerobic respiration using glycogen. There are few mitochondria or blood vessels
  • whitish in colour because of lack of myoglobin
  • this means they can’t store much oxygen

biology (20 decks)

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