Muscle structure Flashcards

Based on Yeo lectures. Basics of muscular structure

1
Q

What are the three types of muscle?

A

Smooth, cardiac, skeletal

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2
Q

What is the definition of contraction?

A

The active state of muscle generating tension

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3
Q

What are the three types of contraction?

A

Isometric (no length change), concentric (shortening), and eccentric (lengthening)

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4
Q

What is the definition of tension?

A

A pulling force exerted by each end of muscle

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5
Q

What is the hierarchy of muscle?

A
Actin + myosin filaments
Sarcomeres
Myofibril
Fibers
Fascicles
Muscle
Compartments
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6
Q

Outline the sliding filament theory

A
	A.p. along sarcolemma
	Down t-tubules
	To SR
	Ca2+ released
	Bind to troponin
	Tropomyosin moved aside
	Myosin head binds to actin (cross-bridges)
	Myosin head moves backwards
•	- ADP + Pi released
	Actin filament pulled past myosin
	ATP to myosin head
	Cross-bridges hydrolysed
•	- ATP --> ADP + Pi
	Myosin head moves to original position
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7
Q

What are fibers covered in?

A

Endomysium, which carries capillaries and the nerves that innervate each fiber

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8
Q

What are fasicles covered in?

A

Peromysium, which protects muscle fibres and provides pathways for nerves and blood vessels

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9
Q

What are muscles covered in?

A

Epimysium, which transfers tensions to the tendon

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10
Q

What are compartments separated by?

A

Fascia, which is a sheet of fibrous tissue

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11
Q

How is force transferred?

A

The contractile fibres generate tension, applying force to both ends. This force is gathered in tension and the resultant force pulls bone, transferring force from fibre to bone

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12
Q

What is the name of the point at which tendon connects to muscle?

A

Musculo-tendinous junction

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13
Q

What is the name of the point at which tendon connects to bone?

A

Teno-osseous junction

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14
Q

What is the composition of tendons?

A

Consist of collagen fibres arranged parallel to force application of muscle

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15
Q

What is an aponeurosis?

A

A sheet of fibrous tissue taking the place of a tendon in sheet-like muscles with a wide area of attachment

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16
Q

What are the two different types of fibres?

A

Parallel and penniform

17
Q

What is the indicative feature of penniform fibres?

A

The fibres run diagonally to tendon

18
Q

What is a physiological cross-sectional area?

A

The cross-section of muscle perpendicular to fibres; the sum total of all of the cross sections of fibers in the muscle in the plane perpendicular to the direction of the fibers

19
Q

Which fibre has a smaller PCSA?

A

Parallel fibres, meaning it is weaker

20
Q

Which fibre is slower to contract?

A

Penniform, as fibres must shorten more for the same length of contraction

21
Q

What type of connective tissue is normally present for penniform fibres?

A

Aponeurosis

22
Q

What are the the three types of penniform fibres?

A

Uni, bi, multi-pennate

23
Q

What is the pennation angle?

A

The angle made by fascicles and the line of action of the muscle

24
Q

What is the significance of having a greater pennation angle?

A

Smaller force is transmitted. The angle also increases with contraction

25
Q

What are the different types of parallel fibres?

A

Flat, fusiform, strap, convergent, circular

26
Q

How do you calculate muscle volume?

A

MV = m/(density)

27
Q

How do you calculate CSA?

A

CSA = MV/L

28
Q

How do you calculate PCSA?

A

mcos(theta)/(density)L

29
Q

What is the Contractile Component of the Hill-type muscle?

A

Active force generated by x-bridges; fibres

30
Q

What is the Parallel Elastic Component?

A

Inside of sarcomere, the passive force in parallel with the CC; connectin

31
Q

What is the Series Elastic Component?

A

Outside of sarcomere, can change length independent of x-bridges; shock absorption; tendons

32
Q

What are Type 1 fibres?

A

Slow-twitch; oxidative

33
Q

What are Type 2a fibres?

A

Inter-mediate; oxidative-glycolytic

34
Q

What are Type 2b fibres?

A

Fast-twitch; glycolytic

35
Q

What are features of skeletal muscles?

A

Striated, multinucleate, and unbranched

36
Q

What is smooth muscle used for?

A

To push something; blood flow, peristalsis, and child birth

37
Q

What are features of cardiac muscle?

A

Have intercalated discs (interdigitations), and is branched