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Body logistics > L9/10- Skeletal muscle > Flashcards

L9/10- Skeletal muscle Flashcards

1
Q

function of skeletal muscle

A
  • To contract and cause movement
  • To keep joints stable
  • Homeostasis- generate heat
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2
Q

structure of skeletal muscle

A
  • Each skeletal muscle fibre is made up of many single cylindrical muscle cells
  • Muscle fibres are bundled together to form muscle fascicles
  • An individual skeletal muscle may be made up of thousands of muscle fibres bundled together in fasicals
    o Wrapped in a connect tissue covering (fascia)
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3
Q

what covers muscle fasicles

A

fascia- loose connective tissue

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4
Q

connective tissue which covers skeletal muscle

A

1) epimysium
2) perimysium
3) endomysium

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5
Q
  1. Epimysium:
A

wraps each muscle, providing structural support, maintaining structural integrity (connective tissue). Also separates muscle from other tissues

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6
Q
  1. Perimysium:
A

separates muscle fascicles-organising individual muscle fibres which form muscles

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7
Q
  1. Endomysium:
A

inside each fascicle, each muscle fibre is encased in a thin connective tissue layer of collagen and reticular fibres. Contains nutrients to support the muscle fibre- supplied by blood vessels

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8
Q

muscles are attached to bone via

A

tendons

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9
Q

movement is dependent on the

A

direction of muscle fibre contraction

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10
Q

point of origin

A
  • is the attachment site that doesn’t move during contraction
  • Usually proximal (closer to the body)
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11
Q

point of insertion

A
  • the attachment site that does move when the muscle contracts
  • Usually distal (further away from the body)
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12
Q

skeletal muscles are well supplies with blood vessels for

A

for nourishment (glucose) , oxygen delivery (for respiration- ATP) and waste removal (lactic acid).

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13
Q

somatic motor neurones signal

A

fibres to contract

- nervous impulse from somatic NS

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14
Q

thin muscle fibres require

A

less blood supply

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15
Q

thick muscle fibres require

A

more blood supply

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16
Q

three types of striated muscle

A
  • slow twitch
  • intermediate
  • fast twitch
17
Q

what type of muscle is slow twitch

A

type 1

18
Q

what type of muscle is intermediate

A

type 2A

19
Q

type of muscle is fast twitch

A

type 2B

20
Q

what type of respiration does slow twitch (T1) muscle do

A

aerobic

21
Q

what type of respiration does fast twitch (T2A) muscle do?

A

anaerobic

22
Q

what type of respiration does intermediate muscle do?

A

aerobic

23
Q

slow twitch features

A

o Rich capillary supply
o Fatty acids- lots of ATP/CO2
o Aerobic- lots of myoglobin to provide oxygen – red
o Many mitochondria
o Many cytochromes
o Fatigue resistant
o Endurance type activities, standing and walking

24
Q

intermediate features

A 
o	Rich capillary supply
o	Fatty acids and glycogen- lactase
o	Aerobic
o	High myoglobin- red to pink
o	Many intermediate mitochondrial numbers
o	Many cytochromes
o	Moderate fatigue resistant
o	Standing/walking- assist type 1 and 2B activities
25
Q

fast twitch features

A 
o	Poor capillary supply
o	Glycogen- lactate/little ATP
o	Anaerobic
o	Low myoglobin levels (white)
o	Few mitochondria and cytochromes
o	Rapidly fatigues
o	Strength and anaerobic type activities
o	Sprinting etc
26
Q

what is produced in fast witch fibres

A

lactate - no oxidative phosphorylation and only small production of ATP

  • insufficient oxygen supply
27
Q

colour of slow twitch

A

red (myoglobin)

28
Q

why does slow twitch need myoglobin

A

in constant need of oxygen- sustained exercise e.g. endurance

29
Q

colour of intermediate

A

pink (some myoglobin)

30
Q

colour of fast twitch

A

white

31
Q

extrinsic muscle

A

have insertions in bone or cartilage e.g. protruding the tongue, retracting is and moving it from side to side

32
Q

intrinsic muscle

A

Not attached to bone- attached to other muscle.

e.g. allows the tongue to change shape but not position- aids swallowing

33
Q

skeletal muscle is

A

striated

34
Q

Innervation of skeletal muscle- Neuromuscular junctions (NMJs)

A
  • Small terminal swellings of the axon which contain Ach
    o Nerve impulses release acetylcholine
    o Ach binds to receptors on the sarcolemma and initiated AP to be propagated along the muscle (T-tubule- deep into the muscle)
35
Q

myasthenia graves is what type of disease

A

autoimmune

36
Q

in myasthenia gravis antibodies are directed against

A

ACh receptor

- blocking it

37
Q

30% reduction in receptor number

A

sufficient for symptoms

  • endplate invaginations reduced
  • reduced synaptic transmission
38
Q

what does myasthenia gravis cause

A

intermittent muscle weakness

Body logistics (39 decks)

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