Topic 6B: Muscles Flashcards

1
Q

Other names for Skeletal Muscles

A
  • Striated muscle
  • Striped muscle
  • Voluntary muscle
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2
Q

What are tendons?

A

Skeletal Muscles that are attached to bones

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3
Q

What are Ligaments?

A
  • They attach bones to other bones

- hold them together

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4
Q

Skeletal Muscles are made up of…

A

Long Muscle Fibres

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5
Q

What are muscle fibres?

A

large bundles of long cells.

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6
Q

The cell membrane of the muscle fibre is called….

A

sacrolemma

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7
Q

When sacrolemma fold inwards and stick the sacroplasm, we call it….

A

Transverse T Tubules

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8
Q

What is the purpose of T Tubules?

A

Help into spread electrical impulses throughout the sacroplasm so they reach all parts of the muscle fibres

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9
Q

A network of internal membranes is called

A

sacroplasmic reticulum

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10
Q

What is the function of the sacroplasmic reticulum?

A

Stores and releases calcium ions that are need for contraction

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11
Q

What organelle is in muscle fibres?

A

lots of mitrochondria that release ATP for muscle contraction

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12
Q

Muscles are multinucleate. What does this mean?

A

Contain many nucleis

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13
Q

What are myofibrils?

A
  • long cylindrical organelles

- they are made up of proteins and are highly specialised

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14
Q

Myofibrils contain….

A
  • Thick myofilaments
  • Thin myofilaments
  • These move past each other to contract
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15
Q

If you put a myofibrils under a electron microscope what do you see?

A
  • Dark bands

- Light bands

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16
Q

What do dark bands contain?

A

-Thick myofilaments

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17
Q

What do light bands contain?

A

-Thin myofilaments

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18
Q

What are A bands?

A

Thick myofilaments overlapped with thin myofilaments

19
Q

What I bands?

A

Thin myofilaments only

20
Q

A myofibrils are made up of short unit called?

A

sacromeres

21
Q

The end of sacromeres are called?

22
Q

What is the middle of the sacromere called?

23
Q

What is the H-zone?

A

Contains only myosin filaments

24
Q

Do myofilaments contract?

A

No they slide over each other

25
Do sacromeres contract?
yes
26
What get shorter when the sarcomere contracts?
- I Bands | - H-Zone
27
What do myosin filaments have structurally?
- Globular heads that are hinged - binding site for actin - binding site for ATP
28
What do actin filaments have structurally?
- binding site for myosin heads | - actin-myosin binding sites
29
How are resting muscles maintained?
- actin-myosin binding site blocked by tropomyosin | - can't slide past each other because of myosin heads cant bind on actin filaments
30
What are muscle contraction triggered by?
An influx of calcium ions
31
What happens when action potential reaches the muscle cells?
- depolarises sacrolemma - depolarisation spreads down t-tubles to the sarcoplasmic reticulum - sacroplasmic reticulum releases stores ca2+ into sacroplasm
32
Outline the process of muslce contraction
- ca2 binds to protein on tropomyosin - changes shape and moves away exposing the actin myosin binding site - allows myosin head to bend - forms an actin myosin cross bridge - enerygy released from ATP causes myosin heads to bind and pull actin filament along in a rowing motion - Another ATP provides energy for myosin heads to dettach from the actin-myosin cross bridge - reattaches to a new actin myosin binding site - cycle repeats as long as calcium ions present
33
What is the role of Ca2+ in muscle contraction?
-Ca2+ binds to protein associated with tropomyosin which makes tropomyosin move away and expose the actin myosin binding site. -Ca2+ activates the enzyme ATP hydrolase which hydrolyses ATP to provide the energy needed for muscle contraction -
34
What is the role of ATP in muscle contraction?
- ATP releases energy which makes myosin bend which also pulls actin filaments along in a rowing motion - Another ATP breaks the actin myosin cross bridge
35
How does muscle contractions stop?
- muscles stop being stimulated - calcium ions leave the binding site - by active transport - back to sacroplasmic reticulum - causes tropomyosin to move back and block the actin myosin binding site - sacromeres lengthens again
36
Muscles will only contract if...
Myosin heads are attached to actin filaments
37
What provides the energy for muscle contraction?
ATP and Phosphocreatine (PCr)
38
How is ATP generated in aerobic respiration?
-via oxidative phosphorylation in cells mitrochondria | -
39
How is ATP generated in anaerobic respiration?
-rapidly by glycolysis
40
How is ATP generated in PCr?
- atp made by phosphorylating ADP - which adds a phosphate group taken from PCr - only used for short vigorous exercise - anaerobic processes(no oxygen needed) - its alactic (doesnt produce lactate)
41
Name the two types of muslce fibres?
slow twitch | fast twitch
42
What are the properties of slow twitch?
- contract slowly - used for posture - good for endurance activities eg long distance training - can work for a long time without being tired - energy released through aerobic respiration-use of o2 - lots of mitrochondria and blood vessels - reddich colour-alot of myoglobin
43
What are the properties of fast twitch?
- contract very quickly - used for fast movements - good for short bursts of speed and power - get tired very quickly - energy released through anaerobic respiration use of glycogen - Whitish colour because not much myoglobin