Lecture 2 - Mechanisms of muscle contraction Flashcards

1
Q

What are the three different types of muscle? [3]

A
  • Smooth muscle
  • Cardiac muscle
  • Skeletal muscle
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2
Q

List the key features of Smooth muscle.

A
  • Mono-nucleated
  • Non-striated
  • Involuntary control
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3
Q

List the key features of Cardiac muscle.

A
  • Mono-nucleated
  • Striated and branched
  • Involuntary control
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4
Q

List the key features of Skeletal muscle.

A
  • Multi-nucleated
  • Striated and elongated
  • Voluntary control
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5
Q

What is a prime mover?

A

Main muscle producing most of the force during movement

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6
Q

What is an antagonist?

A

Muscles that oppose the prime mover

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7
Q

What is an synergist?

A

Muscles that work with the prime mover

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8
Q

What is a fixator?

A

Muscles that prevent a bone from moving

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9
Q

What is a flexor?

A

Muscles that work to close a joint

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10
Q

What is an extensor?

A

Muscles that work to open a joint

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11
Q

What is abduction?

A

Motion that pulls a structure away from the midline

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12
Q

What is adduction?

A

Motion that pulls a structure towrds the midline

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13
Q

What does a muscle contain?

A

A number of fascicles

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14
Q

What do fascicles contain?

A

A number of muscle fibres

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15
Q

What are the two bands within myofibrils?

A
  • Dark band: remains constant length

- Light band: change length when muscle lengthens or shortens

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16
Q

What is a sacromere?

A

Smallest contractile unit in a muscle fibre

17
Q

How many sacromeres are in a muscle fibre?

A

~20,000

18
Q

What are sarcomeres made from? [3]

A
  • Actin filaments
  • Myosin filaments
  • Stabilisation and regulation proteins
19
Q

What is the thin filament made form?

A
  • Actin
  • Tropomyosin
  • Troponin
20
Q

What is the thick filament made from?

A

Myosin

21
Q

True or False? A sarcomere contract they get larger.

A
  • False

- They get shorter

22
Q

What does the contraction of the sacromeres cause to happen?

A

The powerstroke

23
Q

What is the state of the sacromere during rest (step1)?

A
  • Ca2+ conc is low
  • Myosin heads are ADP-bound
  • Actin binding sites are blocked by troponin
24
Q

What is the state of the sacromere during activation (step2)?

A
  • Ca2+ release from cisternae
  • Ca2+ binds to troponin
  • Exposes actin binding sites
  • Cross-bridge is formed
25
Q

What is the state of the sacromere during sliding of filaments (step3)?

A
  • Energy stored in myosin heads is released

- Power stroke

26
Q

What is the state of the sacromere during nyosin detachment (step4)?

A
  • ATP binds to myosin heads making them detach from binding site
  • Actin binding sites are empty and can form another cross bridge
27
Q

What is the state of the sacromere during reactivation of myosin (step5)?

A
  • Energy release from ATP > ADP reaction is stored in myosin heads
  • High Ca2+ = muscle continues to contract
  • Low Ca2+ = myosin heads are unable to form cross-bridge
28
Q

What happens during a low frequency of unintended APs?

A

Twitching

29
Q

What happens during a high frequency of unintended APs?

A

Tetani

30
Q

What is concentric contraction?

A
  • Force > Load

- Muscle shortens

31
Q

What is eccentric contraction?

A
  • Force < Load

- Muscle lengthens