Physiology - Skeletal Muscle Flashcards

1
Q

what is the largest tissue type in the body?

A

muscle

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2
Q

what are the three types of muscle?

A

skeletal
cardiac
smooth

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3
Q

what muscle types are striated?

A

cardiac

skeletal

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4
Q

what muscle type is not striated?

A

smooth

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5
Q

what causes muscle striation?

A

alternating dark and light bands

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6
Q

what are the dark bands in muscle?

A

myosin thick filaments

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7
Q

what are the light bands in muscle?

A

actin thin filaments

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8
Q

what nervous system innervates skeletal muscle and what does this mean?

A

somatic

voluntary control

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9
Q

what nervous system innervates cardiac and smooth muscle and what does this mean?

A

autonomic

involuntary control

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10
Q

what mechanism initiates contraction of skeletal muscle?

A

neurogenic

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11
Q

what mechanism initiates contraction of cardiac muscle?

A

myogenic

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12
Q

in which type of muscle are neuromuscular junctions present?

A

skeletal

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13
Q

in which type of muscle are gap junctions present?

A

cardiac

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14
Q

what is the neurotransmitter at the neuromuscular junction?

A

acetylcholine

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15
Q

what are skeletal muscle fibres organised into?

A

motor units

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16
Q

what is a motor unit?

A

a single alpha motor neurone and all skeletal muscle fibres it innervates

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17
Q

what does the number of muscle fibres per motor unit depend on?

A

the functions served by the muscle

fine movement = less fibres

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18
Q

name two types of muscles with few fibres per motor unit

A

intrinsic hand muscle

extra ocular muscles

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19
Q

how are skeletal muscles organised?

A

parallel muscle fibres bundled by connective tissues

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20
Q

how long are skeletal muscle fibres?

A

the length of the muscle

21
Q

what attaches skeletal muscles to the skeleton?

22
Q

what is the predominant structure of skeletal muscle fibres?

A

myofibrils

23
Q

what is found within each myofibril?

A

sarcomeres

24
Q

what is the functional unit of muscle?

A

sarcomeres

25
what is the functional unit of an organ?
the smallest component capable of performing all of the organs functions
26
where are sarcomeres found?
between two Z lines
27
what are the four zones of a sarcomere?
A band H zone M line I band
28
what makes up the A band?
thick filaments | thin filaments that overlap
29
what is the H zone?
the lighter area in the middle of the A band where thin filaments don't reach
30
where is the M line found?
the middle of the A band and the centre of the H zone
31
what is the I band made of?
the remaining thin filaments that are not in the A band
32
what produces muscle tension?
sliding of actin filaments on myosin filaments
33
what does force generation depend on?
ATP dependent interactions between myosin and actin filaments
34
where are calcium ions stored in skeletal muscle fibres?
the lateral sacs of the sarcoplasmic reticulum
35
when are calcium ions released in skeletal muscle?
when the surface action potential spreads down the T tubules
36
what are T tubules?
extension of the surface membrane that dip into the muscle fibre
37
what two factors determine the gradation of skeletal muscle tension?
number of fibres contracting | the tension developed by each fibre
38
what is motor unit recruitment?
the stimulation of more motor units in a muscle
39
what is longer in skeletal muscle - the duration of the AP or the duration of the resulting twitch?
the twitch
40
how can a stronger contraction be achieved in skeletal muscle?
repetitive fast stimulation of the muscle
41
what is repetitive fast stimulation of muscle called?
tetanus
42
why can cardiac muscle not be tetanised?
long refractory period
43
how can maximal tetanic contraction be achieved?
when muscle is the optimal length before the onset of contraction
44
what are the two types of skeletal muscle contraction?
isotonic | isometric
45
what is isotonic contraction used for?
body movements | moving objects
46
what is isotonic contraction?
when muscle tension remains constant as the muscle length changes
47
what is isometric contraction used for?
supporting objects in fixed positions | maintaining body posture
48
what is isometric contraction?
when muscle tension develops at constant muscle lengths