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Musculoskeletal > Skeletal Muscle Physiology > Flashcards

Skeletal Muscle Physiology Flashcards

1
Q

Name some of the overall physiological functions of skeletal muscle

A

Maintaining posture
Purposeful movement
Respiratory movement
Heat production

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2
Q

What are the three types of muscles in the body?

A

Skeletal
Cardiac
Smooth

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3
Q

Which types of muscle are striated?

A

Skeletal

Cardiac

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4
Q

Skeletal muscle is innervated by the somatic/autonomic nervous system and is subject to voluntary/involuntary control.

A

Somatic

Voluntary

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5
Q

Skeletal muscle has neurogenic/myogenic initiation of contraction

A

Neurogenic

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6
Q

What is the neurogenic transmitter?

A

ACh

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7
Q

What are skeletal muscle fibres organised into?

A

Motor units

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8
Q

Define a motor unit

A

A single alpha motor neuron and all the skeletal muscle fibres it innervates

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9
Q

Muscles serving precise movements have many muscle fibres per motor unit. True/false?

A

False - have few muscle fibres per motor units

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10
Q

Give some examples of muscles with few fibres per motor unit

A

Intrinsic hand muscles

Extra-ocular muscles

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11
Q

What is the overall organisation of skeletal muscle?

A

Muscle -> muscle fibre -> myofibril -> sarcomere

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12
Q

What is the functional unit of muscle?

A

Sarcomere

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13
Q

Actin and myocin are arranged into sarcomeres. True/false?

A

True

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14
Q

What produces muscle tension?

A

Actin sliding on myosin

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15
Q

What is required for contraction and relaxation of muscle?

A

ATP

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16
Q

What switches on cross-bridge formation between actin and myosin?

A

Calcium

17
Q

Calcium binds to what in switching on cross bridge formation?

A

Troponin

18
Q

What occurs when there is no ATP to contract or relax skeletal muscle?

A

Rigor complex

19
Q

What are the two main factors in the gradation of skeletal muscle tension?

A

Number of muscle fibres contracting

Tension developed by each contracting fibre

20
Q

What effect does a shorter action potential than the duration of twitch have on muscle contraction?

A

It means repeated stimulation can bring about stronger and eventually tetanic contraction

21
Q

Tetanic contraction of cardiac muscle is normal. True/false?

A

False

22
Q

What is the optimum length of the muscle fibre for contraction?

A

Its normal resting length

23
Q

What is isotonic contraction of muscle?

A

When muscle tension remains constant but muscle fibre length changes

24
Q

When do isotonic contractions occur?

A

Body movements

Moving objects

25
Q

What is isometric contraction of muscle?

A

When muscle fibre length remains constant but muscle tension changes

26
Q

When do isometric contractions occur?

A

Supporting objects in fixed positions

Maintaining body posture

27
Q

What are the main differences between types of skeletal muscle fibres?

A

Pathway for ATP synthesis
Resistance to fatigue
Activity of myosin ATPase

28
Q

Each motor unit usually contains only one type of fibre. True/false?

A

True

29
Q

What are the metabolic pathways supplying ATP in muscle fibre?

A

Creatine phosphate
Oxidative phosphorylation
Glycolysis

30
Q

Name the three types of skeletal muscle fibres.

A 
Type I (slow-oxidative)
Type IIa (fast-oxidative)
Type IIx (fast glycolytic)
31
Q

Why are type I fibres slow?

A

Low myosin ATPase activity

32
Q

What is the main difference between type IIa and IIx muscle fibres?

A

IIa have high oxidative phosphorylation capacity

IIx have low

33
Q

What are type I fibres used for?

A

Prolonged low work aerobic activities (walking)

34
Q

What are type IIa fibres used for?

A

Prolonged moderate work activities (jogging)

35
Q

What are type IIx fibres used for?

A

Short-term high intensity activities (jumping)

36
Q

What occurs in the stretch reflex?

A

Stretching of muscle spindle increases afferent neuron firing which synapse in the spinal cord with the alpha motor neurons resulting in contraction of stretched muscle

37
Q

The knee jerk assesses which peripheral nerve?

A

Femoral

38
Q

Give some causes of myopathy

A

Congenital
Muscular dystrophy
Inflammation
Toxicity

39
Q

Give some symptoms of myopathy

A

Muscle weakness
Myalgia
Muscle stiffness

Musculoskeletal (22 decks)

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