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Year 1: All Units > MSK: Skeletal Muscle > Flashcards

MSK: Skeletal Muscle Flashcards

1
Q

Name the 3 arrangements of skeletal muscle.

A
  1. Parallel
  2. Pennate
  3. Circular
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2
Q

What are the 3 sub catalogues of parallel arranged skeletal muscle?

A
  1. Strap (fibres run longitudinally)
  2. Fusiform (cylindrical and wider in the centre with tapered off ends)
  3. Fan shaped (fibres converge at one end)
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3
Q

Describe the structure of pennate muscles.

A

They have one or more aponeuroses running through the muscle body from the tendon and the fascicles of the muscle fibres attach these to the aponeuroses at an angle.

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4
Q

What are the 3 subcategories of pennate muscles?

A
  1. Unipennate (fascicles are on the same side as the tendon)
  2. Bipennate (fascicles on both sides of the central tendon)
  3. Multipennate (central tendon branches)
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5
Q

Describe circular muscles.

A

The fibres form concentric rings around a sphincter or opening.

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6
Q

What are synergists?

A

Muscles that act to assist the primary mover. (Acting alone they cannot perform the movement of the agonist)

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7
Q

What are neutralisers?

A

They prevent unwanted actions that the agonist (muscle) can perform.

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8
Q

What are fixators? (Stabilisers)

A

They act to hold a body part (joint) immobile whilst another body part is moving.

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9
Q

What does the term contraction refer to?

A

The active cycling of cross bridges between the actin thin filaments and the Myosin thick filaments.

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10
Q

What is isotonic contraction?

A

Where the tension within the muscle remains constant and the length changes.

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11
Q

What are the 2 subtypes of isotonic contraction?

A
  1. Concentric (muscle shortens)

2. Eccentric (muscle lengthens)

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12
Q

What are the 3 types of muscle contraction?

A
  1. Isometric contraction (equal tension)
  2. Isotonic contraction (equal length)
  3. Passive stretch
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13
Q

What is isometric contraction?

A

It’s the contraction that occurs when the load against the muscle equals the contractile force being generated.

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14
Q

What is passive stretch?

A

When the muscle is being lengthened whilst in a passive state, I.e. Not being stimulated to contract.

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15
Q

What protein is important in muscle contraction?

A

Titin

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16
Q

What is the function of titin?

A

Connects the Z line to the M line in the sarcomere.

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17
Q

What type of motor neurones innervate skeletal muscle?

A

Alpha motor neurones

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18
Q

Where are the cell bodies of the neurones which innervate skeletal muscle found?

A

Ventral horn of the spiral chord (for the muscle of the limbs and trunk) or the motor nuclei of the brain stem (for the head and face)

19
Q

What is the structure which connects individual muscle fibres and the alpha motor neurone?

A

Neuromuscular junction

20
Q

Define a motor unit.

A

An alpha motor neurone and the group of individual muscle fibres that it innervates.

21
Q

Which will have more muscle fibres in each motor unit?

A

Powerful muscles where fine control is less important e.g. Gastrocnemius

22
Q

What are type 1 fibres also known as?

A

Slow muscle fibres

23
Q

What are type 2 muscle fibres also known as?

A

Fast muscle fibres

24
Q

What are the 2 types of fast muscle fibres present in humans?

A
  1. IIA

2. IIX

25
Q

Which type of fast fibres are also known as intermediate fibres between fast and slow?

A

IIA

26
Q

Why are type 1 fibres resistant to fatigue?

A

High mitochondria content and use of oxidative metabolism to produce ATP

27
Q

Are IIA fibres classified as glycolytic or oxidative?

A

Both!

28
Q

Are IIX fibres classified as glycolytic or oxidative?

A

Glycolytic

29
Q

TRUE OR FLASE: most muscle are composed of a mixture of different types, it is the proportion of fast to slow fibres which determines the function

A

True

30
Q

What 2 factors does the contractile force produced by a muscle depend on?

A
  1. Size principle

2. Rate code

31
Q

What is he size principle?

A

Small motor neurones are recruited before large ones.

32
Q

In general, what order does the size principle determine the motor unit will follow?

A

Type I first, then type IIA, then type IIX.

33
Q

What is the rate code?

A

The frequency at which muscle fibres are stimulated by their alpha neurone.

34
Q

What is the name of the term given to the phenomenon where no further force can be produced by a muscle?

A

Tetany

35
Q

What is tone?

A

Degree of tension

36
Q

What is the term given to a lack of muscle tone?

A

Hypotonia

37
Q

Where is skeletal muscle tone controlled?

A

Locus coeruleus in the motor control centre of the brainstem

38
Q

What are dihydropyrdine receptors also known as?

A

Voltage-gated L-type Calcium channels

39
Q

What is malignant hyperthermia?

A

A condition triggered by some volatile anaesthetic agents which lead to uncontrolled increase in oxidative metabolism, and hence increase in body temperature.

40
Q

What is the most common cause of malignant hyperthermia?

A

Polymorphism in ryanodine receptor

41
Q

How much ATP is stored in muscle fibre?

A

Very little (sufficient for only a few seconds of contraction)

42
Q

Name an additional short term store of ATP within muscle fibres.

A

Creatine phosphate

43
Q

Name a disadvantage of using glycolysis under anaerobic conditions.

A

Lactate is produce from pyruvate by the action of lactate dehydrogenase.

44
Q

For prolonged activity, what does the muscle do in order to be sufficiently supplied with ATP?

A

Switches to beta oxidation of fatty acids released from triglycerides stored in a diode tissue.

Year 1: All Units (66 decks)

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