skeletal muscle Flashcards

1
Q

what are the motoneurones of the spinal cord called

A

alpha-motoneurones

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2
Q

where are the cells bodies of alpha motoneurones found?

A

ventral horn

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3
Q

what is a motor unit

A

single alpha motoneurone and all the muscle fibre it innervates

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4
Q

what is focal innervation

A

each muscle fibre is innervated by one alpha motoneurone

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5
Q

what NT is used at a neuromuscular junction

A

ACh

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6
Q

what type of receptor does ACh bind to at NMJ

A

nicotinic

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7
Q

what are end plate potentials

A

the depolarisation of the muscle membrane at the NMJ

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8
Q

how is smooth contraction achieved

A

each alpha motoneurone innervates muscle fibres that are spread throughout muscles and they fire asynchronously

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9
Q

how are muscle contractions made to be precise

A

the innervation ratio is inversely correlated w contractile precision

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10
Q

what is the innervation ratio

A

number of muscle fibres each alpha neurone activates, low is for more fine control

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11
Q

characteristics of type I muscle fibres

A
  1. slow twitch
  2. low contractile force
  3. high resistance to fatigue
  4. energy from oxidative phos
  5. red
  6. for posture
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12
Q

characteristics of type II

A
  1. fast twitch
  2. high contractile force
  3. low resistance to fatigue
  4. glycolytic source of energy
  5. white
  6. for rapid movement
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13
Q

how can we increase force of contaction

A
  1. recruit more alpha motoneurones
  2. increase AP firing rate of each alpha motoneurone -> leads to summation of contractions
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14
Q

what is tetanus

A

maximum summation, leads to paralysis

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15
Q

what are renshaw cells

A

inhibitory interneurones, use glycine as NT

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16
Q

where are renshaw cells found

A

spinal cord

17
Q

what do renshaw cells do and how

A

inhibit APs going to muscle by lateral inhibition

18
Q

what are gamma motoneurones

A

motoneurones that innervate muscle spindles

19
Q

what are the 2 parts that make up a muscle fibre

A

extrafusal fibre, intrafusal fibre

20
Q

what part of the muscle fibre causes contraction and interacts w alpha motoneurones

A

extrafusal fibre

21
Q

what does the gamma motoneurone innervate

A

intrafusal fibre

22
Q

what are the 3 types of intrafusal muscle

A
  1. Dynamic nuclear bag fiber
  2. static nuclear bag fiber
  3. nuclear chain fiber
23
Q

what types of intrafusal muscle are innervated by group Ia afferent fibres

A

all of them

24
Q

what info do group Ia fibres relay about intrafusal muscle

A

change in stretch and absolute stretch

25
Q

what information do the group II afferent fibres relay about intrafusal muscles

A

absolute stretch

26
Q

what does the gamma loop do

A

monitors muscle contraction and corrects it if required

27
Q

where are the golgi tendon organs found and what do they do

A

between the muscle and bone, they detect force of contraction in skeletal musc and protest the muscle from overloading (stops contraction)

28
Q

what innervates golgi tendon organs

A

Ib sensory neurones

29
Q

how does the golgi tendon reflex work

A

Ib sensory neurones activated, glycine released and alpha motoneurone inhibited so muscle cannot contract more