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Y2 MSK > Physiology > Flashcards

Physiology Flashcards

1
Q

What is the largest tissue type in the body?

A

Muscle

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2
Q

All muscle in the body is striated. True/False?

A

False

Smooth muscle is not striated

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3
Q

Which division of the nervous system - autonomic or somatic - innervates skeletal muscle?

A

Somatic

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4
Q

Skeletal muscle fibres are organised into motor units. What are motor units?

A

A single alpha motor neuron + all the muscle fibres innervated by it

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5
Q

What determines the number of muscle fibres per motor unit?

A

The function of the muscle (whether it is concerned with powerful or precise movement)

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6
Q

Give examples of muscles that have few muscle fibres per motor unit

A

MUSCLES FOR FINE MOVEMENT
External eye muscles
Muscles of facial expression
Intrinsic hand muscles

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7
Q

What is contained within a muscle fibre?

A

Myofibrils: alternating (dark) thick myosin and (light) thin actin bands
Sarcomeres: functional units of muscle

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8
Q

Skeletal muscle contraction is brought about by myogenic initiation. True/False?

A

False

Neurogenic (nerve stimulated first)

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9
Q

Are there gap junctions between muscle fibres?

A

No

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10
Q

Which substance is released in response to action potential generation + presence in the T-tubule of the muscle fibre?

A

Calcium

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11
Q

What does calcium release by the sarcoplasmic reticulum cause?

A

Calcium binds to troponin, causing conformational change in tropomyosin complex to expose myosin-binding-site on actin to allow cross-bridge formation between actin and myosin

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12
Q

List the 4 zones of a sarcomere

A

A-band
H-zone
I-band
M-line

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13
Q

What does the A-band consist of?

A

Myosin + portion of actin that overlaps with myosin

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14
Q

Where is the H-zone?

A

Lighter area within A-band where actin doesn’t reach

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15
Q

Where is the M-line?

A

Extends vertically down the middle of the A-band within the centre of the H-zone

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16
Q

What does the I-band consist of?

A

Remaining portion of actin that is not part of the A-band

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17
Q

What 2 primary factors determine gradation of skeletal muscle tension?

A

Number of muscle fibres contracting within the muscle

Tension developed by each muscle fibre

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18
Q

What is meant by “motor unit recruitment”?

A

Stimulating numerous motor units to contract elicits stronger contraction

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19
Q

Tetanic contractions of skeletal muscle are not possible. True/False?

A

False

Cardiac muscle cannot be tetanised due to long refractory period

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20
Q

How is tetanic contraction of skeletal muscle brought about?

A

Generation of numerous action potentials one after the other amplify the contraction/skeletal muscle twitch

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21
Q

When can maximum tetanic contraction of skeletal muscle be achieved?

A

At rest (optimal length of muscle at this point)

22
Q

Name the 2 main types of skeletal muscle contraction

A

Isotonic

Isometric

23
Q

What is isotonic skeletal muscle contraction used for?

A

Body movements

Moving objects

24
Q

Muscle length changes in isotonic skeletal muscle contraction. True/False?

A

True

Muscle tension remains constant

25
Q

What is isometric skeletal muscle contraction used for?

A

Maintaining fixed positions

26
Q

Muscle length changes in isometric skeletal muscle contraction. True/False?

A

False

Muscle length is constant to allow tension to develop

27
Q

Velocity of muscle length shortening increases/decreases with increasing load

A

Decreases

28
Q

What is the stretch reflex?

A

Negative feedback mechanism that resists passive change to muscle length by contracting the muscle

29
Q

Once a muscle is stretched, how does the stretch reflex elicit contraction?

A

Afferent fibres fire and synapse with alpha motor neurons which, when stimulated, contract the stretched muscle

30
Q

What are the special sensory receptors for the stretch reflex, that, when stretched, elicit the reflex?

A

Muscle spindles AKA intrafusal fibres

31
Q

What are extrafusal fibres?

A

Ordinary muscle fibres

32
Q

Is the activity of the myosin ATP-ase fast or slow in type I muscle fibre? What effect does this have on resistance to fatigue?

A

Slow activity of myosin ATP-ase

High resistance to fatigue

33
Q

Is the speed of the myosin ATP-ase fast or slow in type II muscle fibre? What are the two divisions of type II fibres?

A

Fast activity of myosin ATP-ase
a = fast oxidative (aerobic)
b = fast glycotic (anaerobic)

34
Q

What is the difference between simple and compound synovial joints?

A 
Simple = one pair of articular surfaces
Compound = more than one pair of articular surfaces
35
Q

What is the fluid secreted by the synovial membrane in the joint capsule of synovial joints?

A

Synovial fluid

36
Q

What are the functions of synovial fluid?

A

Joint lubrication, reduce friction
Minimise wear-and-tear
Provides nutrition for chondrocytes

37
Q

What 3 main things provide joint lubrication?

A

Interstitial fluid
Synovium-derived hyaluronic acid
Synovium-derived lubricin

38
Q

How does rapid movement affect the properties of the synovial fluid?

A

Fluid becomes less viscous and elasticity increases to aid movement

39
Q

Normal synovial fluid is milky in colour. True/False?

A

False

Normally it is colourless

40
Q

Inflammatory synovial fluid is thin, orange, translucent and has a high white blood cell count. True/False?

A

False

All correct apart from colour - inflammatory SF is yellow

41
Q

Which type of cartilage is usually articular cartilage?

A

Hyaline

42
Q

What is the extracellular matrix of hyaline cartilage made up of?

A

Water 70%
Collagen 20%
Proteoglycans 10%

43
Q

The collagenous component of hyaline cartilage is mainly type 2 collagen. True/False?

A

True

44
Q

Which cells synthesise, organise and degrade the extracellular matrix of hyaline cartilage?

A

Chondrocytes

45
Q

What catabolic factors influence hyaline cartilage ECM breakdown?

A

TNF-alpha
IL-1
Stimulate proteolytic enzymes

46
Q

What anabolic factors influence hyaline cartilage ECM replacement?

A

TGF
IGF
Stimulate proteoglycan synthesis

47
Q

What markers indicate cartilage degradation?

A

Increased serum/synoval keratin sulphate

Increased type 2 collagen in synovial fluid

48
Q

What are the main symptoms of muscle disease?

A

Weakness
Pain (myalgia)
Stiffness
Delayed relaxation after voluntary contraction (myotonia)

49
Q

What are the main investigations used in muscle disease?

A 
EMG
Nerve conduction studies
Muscle enzyme - CK
Inflammatory markers - CRP, plasma viscosity 
Muscle biopsy
50
Q

What are the two other types of joints, that are not synovial? Give examples

A

Fibrous - no movement e.g. cranium

Cartilaginous - limited movement e.g. IV discs, pubic symphysis

51
Q

What makes up the lateral borders of sarcomeres?

A

Z discs

Y2 MSK (30 decks)

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