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02- MSK > Physiology > Flashcards

Physiology Flashcards

1
Q

name the physiological functions of skeletal muscle

A

posture

movement/ respiratory movements

heat production

contributor to whole body metabolism

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2
Q

skeletal muscle is striated/non striated and voluntary/ non voluntary

A

striated and voluntary

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3
Q

which nerves innervate skeletal muscle?

A

somatic nervous system

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4
Q

skeletal muscle has _______ initaion of contraction

A

neurogenic

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5
Q

what is the transmitter at the neuromuscular junction of skeletal muscle

A

Ach

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6
Q

skeletal muscle fibres are organised into what?

A

motor units- single alpha motor neuron

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7
Q

muscles that allow for precise movements will have fewer/greater motor fibres per unit than for power?

A

fewer

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8
Q

sort into levels of organisation 1. muscle fibre 2. sarcomere 3. myofibril 4. actin/filamin 5. whole muscle

A
  1. actin/filamin 2. sarcomeres 3. myofibrils 1. muscle fibre 5. whole muscle
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9
Q

define functional unit

A

smallest component capable of performing all the functions of that organ

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10
Q

sarcomere is found between what two lines?

A

Z lines

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11
Q

what are the four zones of the sarcomere

A

A- band

H- zone

M- line

I- band

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12
Q

describe the A- band

A

thick filaments with portions of thin filamwetns that overlap in both ends of thick filaments

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13
Q

describe the H- zone

A

lighter area of the A-band where thin filaments dotn reach

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14
Q

describe the M-line

A

extends vertically down A-band within the centre of H-zone

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15
Q

describe I-band

A

remaining portion of thin filaments that don’t project in A-band

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16
Q

muscle contraction is caused by what?

A

actin filaments sliding on myosin filaments

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17
Q

force generation of muscle depends on what?

A

ATP- dependant interaction

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18
Q

in skeletal muscle fibres Ca2+ is released from where?

A

lateral sacs of the sarcoplasmic reticulum

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19
Q

the surface action potential of skeletal muscle spreads down what?

A

the transverse (T)- tubules (extensions of the surface membrane)

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20
Q

what allows simultaneous contraction of muscle fibres?

A

motor units

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21
Q

stimulating more motor units to achieve a stronger contraction is known as what?

A

motor unit recruitment

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22
Q

asynchronous motor unit recruitment during submaximal contractions helps prevent what?

A

muscle fatigue

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23
Q

tension developed by each contracting muscle fibre depends on what two things?

A

frequency of stimulation and summation of contractions

length of muscle fibre

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24
Q

the action potential in skeletal muscle is longer than the duration of the resulting twitch true/false

A

false- the AP is shorter

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25
Q

describe single twitch in skeletal muscle

A

the muscle fibre has completely relaxed before being restimulated

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26
Q

with single twitch the second twitch is the same/greater magnitude than the first twitch

A

same magnitude

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27
Q

what happens if a muscle fibre is restimulated before it has completely relaxed?

A

the second twitch is added to the first resulting in twitch summation

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28
Q

what is tetanus?

A

when a muscle fibre is stimulated so rapidly it doesn’t have time to relax between stimuli- maximal sustained contraction

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29
Q

what type of muscle cannot be tetanised and why?

A

cardiac muscle- long refractory period

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30
Q

when is maximal tetanic contraction achieved?

A

when the muscle is at its optimal length before the onset of contraction

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31
Q

the tension developed by skeletal muscle increases with what?

A

frequency of stimulation

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32
Q

what is the optimal length of skeletal muscle in the body?

A

the resting length

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33
Q

what are the two types of skeletal muscle contraction?

A

isotonic isometric

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34
Q

what movements is isotonic contraction useful for?

A

body movements moving objects

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35
Q

describe isotonic contraction

A

muscle tension remains constant as the muscle length changes

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36
Q

what movements is isometric contraction useful for?

A

supporting objects in fixed posn

maintaining body posture

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37
Q

describe isometric contraction

A

muscle tension develops at constant muscle length

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38
Q

how is muscle tension developed in both isotonic and isometric contractions?

A

transmitted to bone via elastic components of muscle

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39
Q

what are the contractile and elastic components of muscle?

A

contractile- sarcomeres

elastic- connective tissue/tendon

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40
Q

the velocity of muscle shortening increases/decreases as the load increases?

A

decreases

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41
Q

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

A

ATP synthesis pathway

resistance to fatigue

activity of myosin ATPase

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42
Q

what are some of the metabolic pathways that supply ATP in muscle fibres?

A

transfer of high energy phosphate from creatine phosphate to ADP (immediate source)

oxidative phosphorylation (O2 present)

glycolysis (O2 isn’t present)

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43
Q

what are the three types of skeletal muscle fibres?

A

Type I- slow oxidative

Type IIa- fast oxidative

Type IIx- fast glycolytic

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44
Q

give some feature of type I- slow oxidative muscle fibres

A

slow twitch

many mitochondria

low myosin ATPase activity

low glycogen content

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45
Q

what activities are type I- slow oxidative fibres useful for?

A

prolonged low work aerobic activitities e.g posture, walking

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46
Q

give some features of type IIa fast oxidative muscle fibres

A

intermediate twitch fibres

many mitochondria

high myosin ATPase activity

intermediate glycogen content

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47
Q

what activities are type IIa fast oxidative fibres useful for?

A

aerobic and anaerobic metabolism, prolonged moderate work e.g jogging

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48
Q

give some features of type IIx fast glycolytic muscle fibres

A

fast twitch

few mitochondria

high myosin ATPase activity

high glycogen activity

49
Q

what activities are type IIx fast glycolytic muscle useful for?

A

anaerobic metabolism used for short term high intensity activiites e.g jumping

50
Q

what is the simplest form of coordinated movement

A

reflex action

51
Q

define reflex

A

reflex action is a stereotyped response to a specific stimulus

52
Q

the stretch reflex is the simplest form of what kind of reflex?

A

monosynaptic spinal reflex

53
Q

what is the stretch reflex?

A

negative feedback that resists passive change in muscle length to maintain optimal resting length of muscle

54
Q

what does the stretch reflex help with?

A

posture e.g while walking

55
Q

what sensory receptor in muscle is activated by muscle stretch?

A

muscle spindle

56
Q

stretching the muscle spindle increases firing in what? where do they synapse?

A

afferent neurons synapse in the spinal cord with the alpha motor neurons

57
Q

what are muscle spindles a collection of and what are they known as?

A

collection of specialised muscle fibres known as intrafusal fibres

58
Q

what are ordinary muscle fibres referred to as?

A

extrafusal fibres

59
Q

where are muscle spindles found?

A

within the belly of muscles and run parallel to ordinary muscle fibres (extrafusal)

60
Q

what are annulospiral fibres?

A

the sensory nerve endings of muscle spindles

61
Q

do muscle spindles have their own efferent (motor) nerve supply?

A

yes- gamma motor neurons

62
Q

What do the gamma motor neurons do to muscle spindles?

A

Adjust the level of tension in muscle spondles to maintain their sensitivity during muscle contraction

63
Q

contraction of intrafusal fibres contributes to the overall strenght of muscle contraction true/false?

A

false- they do not contribute to the overall strength of contraction

64
Q

give examples of some geneticalluy determined myopathies

A

congenital

chronic degeneration e.g Muscular dystrophy

abnormalities in membrane ion channels e.g myotonia

65
Q

give an example of aqcuired inflammatory myopathies

A

polymyositis

66
Q

give an example of a non-inflammaotory acquired myopathy

A

fibromyalgia

67
Q

give an example of an endocrine acquired myopathy

A

cushing syndrome

thyroid disease

68
Q

give an example of a toxic acquired myopathy

A

alcohol

statins

69
Q

what are the symptoms of muscle disease

A

muscle weakness/tiredness

delayed relaxation after voluntary contraction (myotonia)

muscel pain (myalgia)

muscle stiffness

70
Q

what are some useful investiagtions in neuromuscular disease?

A

Electromyography (EMG)- electrodes detect presence of muscular activity

nerve conduction studies

muscle enzymes (CK)

Inflammatory markers C reactive Protien (CRP), plasma viscosity (PC)

muscle biopsy

71
Q

What are the three type of joint in the body?

A

Synovial

fibrous

cartilaginous

72
Q

describe fibrous joints and give an example

A

bones united by fibrous tissue

dont allow any movement

bones of the skull in adults

73
Q

descirbe cartilaginous joints and give examples

A

bones united by cartliage

limited movement

intervertebral discs, pubic symphsis, costochondral joints

74
Q

desrcibe synovial joints

A

seperated by a cavity and united by fibrous capsule

75
Q

which joint is described as being amphiarthosis?

A

cartilaginous joint

76
Q

which joint is described as being synarthrosis?

A

fibrous joint

77
Q

which joint is described as being diarthrosis?

A

synovial joint

78
Q

where is synovial fluid found?

A

the synovial cavity

79
Q

in addition to the fibrous capsule what other structures unite and support synovial joints?

A

ligaments

tendons

bursae

80
Q

the synovial membrane lines what aspect of the fibrous capsule?

A

the inner aspect

81
Q

is the synovial membrane vascularised?

A

yes- it is a vascular connective tissue with capilary networks and lymphatics

82
Q

synovial cells (fibroblasts) within the synovial membrane produce what?

A

synovial fluid

83
Q

what are the two classes of synovial joint?

A

simple- one pair of articular surfaces

compound- more than one pair of artivualr surfaces

84
Q

give an example of a simple synovial joint

A

metacarpophalangeal joint

85
Q

give an example of a compound synovial joint

A

elbow joint

86
Q

with regards to stress distribution the greatest share of loading energy is taken up where?

A

the muscles and tendons crossing each joint

87
Q

give some functions of synovial fluid

A

lubrication

reduces friction

aids in nutrition of articular cartliage

supplies chondrocytes with O2 and removes CO2

88
Q

the synovial fluid is continously replenished adn absorbed by what?

A

synovial membrane

89
Q

what is responsible for the high viscosity of synovial fluid?

A

hyaluronic acid (mucin)- prod by synovial cells

90
Q

uric acid in the synovial fluid are dervied by what?

A

dialysis of blood plasma

91
Q

the synovial fluid contains few cells normally, what are these mainly?

A

mononuclear leucocytes

92
Q

rapid movement is associated with inc/dec viscosity and inc/dec elasticity?

A

decreased vscosity

increased elasticity

93
Q

in what disease do the viscous/elastic properties of synovial fluid become defective?

A

osteoarthritis

94
Q

what colour is normal synovial fluid?

A

clear and colourless

95
Q

what is the WBC count in normal synvoial fluid?

A

<200 WBC/mm3 of which polymorphs are usually <25/mm3

96
Q

when would synovial fluid turn red?

A

traumatic synovial tap

haemorrhagic arthirits

97
Q

what kind of synvoial fluid would have a straw/yellow colour and give a total white cell count of 2,000-75,00

A

inflammatory synovial fluid

98
Q

what kidn of synovial fluid would give a total white cell count of >100,000

A

septic synovial fluid

99
Q

the thin and opaque appearance of synovial fluid from a severely infected joint is due to what?

A

the very high polymorph count

100
Q

what ares some of the main functions of articular cartliage?

A

low friction- help prevent wear-and-tear

distributes pressure

101
Q

what are the four zones of articualr cartilage?

A

superfical

middle

deep

calcified

102
Q

articualr cartilage is usually which type?

A

hylaiine

103
Q

the ECM of articualr cartilage is synthesized, degraded and maintained by what cells?

A

chondrocytes

104
Q

articular cartliage is vascular/avasuclar?

A

avascular

105
Q

from what does articular cartilage recieve nutrients and O2

A

via synovial fluid

106
Q

describe the rate of ECM degradation with the rate it is replaced in an normal joint

A

degredation doesnt exceed the rat eof replacement- there is a balance

107
Q

changes in the relative amounts of the components of the ECM (water, collagen, proteoglycans) would also change what?

A

the mechanical properties of the cartilage

108
Q

what would occur if the rate of ECM degredation exceeds the rate of synthesis?

A

joint disease

109
Q

what are the catabolic factors in the ECM?

A

TNF alpha

IL- 1

110
Q

what do catabolic factors do in the ECM?

A

stimulate proteolytic enzymes and inhibit proteoglycan synthesis

111
Q

what are the anabolic factors in the ECM?

A

tumour grwoth factor TGF

insulin like growth factor (IGF)-1

112
Q

what do anabolic factors do in the ECM?

A

stimulate proteoglycan synthesis and counteract effects of IL-1

113
Q

what are some markers of cartilage degredation?

A

Serum and synovial keratin sulphate

Type II collagen in synovial fluid

114
Q

deterioration of cartilage with age gives rise to what condition?

A

osteoarthritis

115
Q

synovial cell proliferation and inflammation casue what condition?

A

rheuamatiod arthritis

116
Q

depsoition of salt crystals e.g uric acid can cause what conditio?

A

gouty arthritis

117
Q

injury and inflammation to periarticular structures causes what condition?

A

soft tissue rheumatism e.g injury to tendon causes tendonitis

118
Q

subchondral sclerosis and subchondral cyst formation will be present in what condtion?

A

osteoarthritis

119
Q
A

02- MSK (7 decks)

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