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Revision Cards > Week 112 - Injury/trauma to wrist > Flashcards

Week 112 - Injury/trauma to wrist Flashcards

1
Q

What are Langers lines?

A

The natural grain of the skin, cut in same direction to reduce scarring.

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2
Q

What do Fibroblasts do?

A

Fibroblasts make collagen, glycosaminoglycans, glycoproteins, reticular and elastic proteins.

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3
Q

What do Chondrocytes do?

A

They produce and maintain cartilage through collagen and glycoproteins.

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4
Q

What do Osteoblasts do?

A

Produce bone.

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5
Q

What do Myoblasts do?

A

Produce muscle.

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6
Q

What do Tenocytes do?

A

They are tendon cells, elongated fibroblasts that synthesise tendon fibres.

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7
Q

What does a tendon do?

A

Links muscle to bone, transmits the force.

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8
Q

What does a ligament do?

A

Links bone to bone, holds joint in place.

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9
Q

What does the meniscus do?

A

Acts as a shock absorber.

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10
Q

What is the role of the articular cartilage?

A

Pressure tolerance, protects bone.

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11
Q

What does the synovium do?

A

Lubricates the joint.

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12
Q

What are the two types of cell that form tissue?

A
  • Parenchymal cells - produce main function of tissues.

* Support cells - produce structural scaffolding.

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13
Q

Connective tissue is the collective term for what two things?

A

1) Support cells

2) Extra Cellular Matrix (ECF)

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14
Q

What are the four classes of macromolecules in extra cellular matrix?

A

Collagen, Elastin, Glycoproteins, Proteoglycans.

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15
Q

What is the most abundant class of proteins in the body and what percentage does it account for?

A

Collagens, ≈20%

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16
Q

What are the four major families of collagen?

A

1) Fibrillar Collagens
2) Fibril-Associated Collagens
3) Sheet-forming and anchoring Collagens
4) Transmembrane collagens

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17
Q

What is the function of fibrillar collagen?

A

Rod-like molecules, provide mechanical strength.

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18
Q

What is the function of fibril-associated collagens (FACIT)?

A

Link fibrillar collagens to one another or ECM.

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19
Q

What is the purpose of sheet-forming and anchoring collagen?

A

Connect basal laminae in skin to underlying connective tissue.

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20
Q

What is the function of transmembrane collagen?

A

Functions as adhesion receptors.

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21
Q

What is the basic structure of collagen?

A

A triple-helix of 3 polypeptide chains.

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22
Q

Which soft body tissue has the highest tensile strength?

A

Tendons.

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23
Q

How are tendons organised?

A
  • Collagen fibrils > Collagen Fibres > 1º2º3º Collagen bundles > Tendon.
  • The bundles are surrounded by a membrane called endotenon.
  • The tendon is surrounded by epitenon.
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24
Q

What weight percentage does water make up in tendons?

A

55%

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25
Q

What is the biochemical composition of tendons?

A
  • 70-80% of dry weight is collagen.

* <1% proteoglycans

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26
Q

What is the main type of collagen in tendons and what are the minor collagens?

A
  • 95% Type I collagen

* 5% type III and IV

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27
Q

What is the function of proteoglycans in tendons?

A

Regulate collagen fibril size and bind water to resist compression.

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28
Q

What are the functions of tendons?

A
  • Allows muscle belly to be some distance from the site of action.
  • Eliminates the need for muscle for the entire length between origin and insertion.
  • Can act as a pulley.
  • Enables muscle action to be focused.
  • Act as springs - store energy during locomotion.
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29
Q

What is the name of the specialised structure present in the tendon when it inserts into a bone?

A

Enthesis - made of fibrocartilage.

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30
Q

What is the function of Enthesis fibrocartilage?

A

Present where tendons insert into bones, helps to dissipate compressive forces, thus reducing wear and tear.

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31
Q

Which part of the composition of tendon increases to form fibrocartilage?

A

Increased concentration of proteoglycans.

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32
Q

What is the basic structure of proteoglycans?

A

‘Bottle brush’
Proteo - A protein core.
Glycan - Contains glycosaminglyan chains, that branch off the main core.

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33
Q

What is the major proteoglycan in cartilage?

A

Aggrecan

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34
Q

What is a ‘wrap-around’ region?

A

A part of a tendon that wraps around bony pulleys, fibrocartalaginous.

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35
Q

What occurs at the myotendinous junctions that increases mechanical strength?

A

Muscle fibres split which increases the amount of anchorage available.

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36
Q

Which type of connective tissue provides the majority of proprioception?

A

Ligaments, as they are more vascular than tendons.

37
Q

What is the biochemical composition of ligaments?

A
  • Water 60-70% weight.
  • Collagen 70-80% dry weight.
  • Elastin <5% dry weight.
38
Q

What is the collagen composition of ligaments?

A
  • 70-80% of dry weight.
  • 90% type I
  • 10% type III
39
Q

What are the functions of ligaments aside from stability?

A
  • Provide information to the brain (proprioception, joint stability, pain)
  • Attachment point for muscles.
  • Tie down soft tissue onto bone.
40
Q

What does immobilisation do to tendons?

A

Decreased mechanical strength, decreased proteoglycan content.

41
Q

What does exercise do for tendons?

A

Increased collagen fibril size, increased size and stiffness.

42
Q

What is a motor unit?

A

A single motor neurone and the muscle fibres it innervates.

43
Q

What is a motor neuron pool?

A

All the motor neurones that supply one complete muscle.

44
Q

What is the name of the region of a muscle fibre directly under the terminal portion of the axon?

A

Motor end plate.

45
Q

What receptors are present on the motor end plate?

A

Nicotinic receptors.

46
Q

What is the name for a single muscle cell and how is it composed?

A

Muscle fibre. Formed of myofibrils(formed of myofilaments), in a specialised cytoplasm known as the sarcoplasm, it has many mitochondria and multiple peripheral nuclei. The cell membrane is known as the sarcolemma.

47
Q

What is the name of a single, repeating, functional unit of a myofibril?

A

Sarcomere

48
Q

What is a sarcomere composed of?

A

Thick and thin filaments

49
Q

What is the thick filament of a myofibril?

A

Myosin.

50
Q

What is the thin filament of a myofibril?

A

Actin, also contains troponin and tropomyosin which regulate contraction.

51
Q

How are the filaments arranged in a sacromere?

A
  • A band - composed of the thick filaments
  • Z line - the end of the thin filaments
  • H zone - The thick filament where the thin filament does not overlap.
  • M line - Proteins that link the thick filaments in the centre.
  • I band - The thin filament where it is not overlapped by the thick filaments.
52
Q

What is the A band?

A

The thick filaments.

53
Q

What is the Z line?

A

The end of the thin filaments (lateral edge of the sacromere)

54
Q

What is the H zone?

A

The thick filament where the thin filaments don’t overlap.

55
Q

What is the M line?

A

The centre of the sacromere, a line of protein that bind the thick filament together.

56
Q

What is the I band?

A

The portion of the thin filament where it is not overlapped by the thick filaments.

57
Q

What is the structure of myosin?

A

Myosin is the thick filament and has glomerular heads that project out, these heads have binding sites for Actin and ATP.

58
Q

What is the structure of the thin filament?

A
  • Actin backbone.
  • Tropomyosin is a rod-shaped molecule of 2 intertwined peptides.
  • Troponin is a small globular protein bound to the actin and tropomyosin.
59
Q

What is the sliding filament mechanism?

A

This is how muscle contraction works.
• Ca2+ binds to the troponin which alters the shape of the tropomyosin revealing myosin binding points on the actin.
• The myosin heads bind to the actin.
• The power stroke then occurs with the use of stored energy to slide the actin over the myosin.
• ATP then binds to the myosin head and breaks the cross bridge, allowing the myosin head to bind to the actin at the next ‘notch’.

60
Q

Which regions of the sacromere decrease in length when contraction occurs?

A

the I-Band and the H-Zone.

61
Q

Where is the Ca2+ stored in the muscle fibre?

A

In the sarcoplasmic reitculum.

62
Q

What causes the release of Ca2+ leading to muscle contraction?

A

An AP travels down T-tubules to the sarcoplasmic reticulum and Ca2+ is released.

63
Q

What are the four sources of ATP in skeletal muscle?

A

1) Dephosphorylation of phosphocreatine.
2) Aerobic respiration
3) Anaerobic respiration
4) Oxidation of free fatty acids.

64
Q

Briefly describe dephosphorylation of phophocreatine.

A

ADP + PC ≈ ATP + C

Very limited stores of PhosphoCreatine.

65
Q

Briefly describe Aerobic Repiration.

A

Glucose + 2ATP + O2 > 6CO2 + 6H20 + 36ATP

66
Q

Briefly describe Anaerobic respiration.

A

Glycogen + 2ATP > 2 lactic acid + 4ATP

67
Q

Briefly describe oxidation of free fatty acids.

A

FFA + O2 > CO2 H20 +nATP

68
Q

What are the three main mechanisms of muscle contraction?

A
  • Isometric
  • Isotonic
  • Eccentric
69
Q

What is Isometric muscle contraction?

A

This is when a muscle develops tension but does not contract.

70
Q

When does isometric muscle contraction occur?

A

When a muscle supports something in a constant position, e.g. lifting a heavy load without actually lifting it.

71
Q

What is Isotonic muscle contaction?

A

When the muscle shortens while the load on the muscle remains constant.

72
Q

What is eccentric muscle contraction?

A

This is where the muscle extends whilst resisting an opposing force.

73
Q

Which type of twitch fibre has a high ATPase activity?

A

Fast twitch (Type II)

74
Q

What are type I twitch fibres?

A

Slow twitch, lower ATPase activity.

75
Q

Which type of twitch fibre has a lower ATPase activity?

A

Slow twitch (Type I)

76
Q

What are Type II twitch fibres?

A

Fast twitch, high ATPase activity.

77
Q

What are the two main pathways with which muscle fibres produce ATP?

A

Oxidative and Glycolytic

78
Q

What are Oxidative muscle fibres also known as?

A

Red muscle fibres (due to high concentrations of myoglobin).

79
Q

Describe oxidative muscle fibres.

A

Also known as red muscle fibres, these have numerous mitochondria and have a high capacity for oxidative phosphorylation.

80
Q

Which two factors allow oxidative muscle fibres to have a high capacity for oxidative phosphorylation?

A
  • High levels of myoglobin, increases rate of oxygen diffusion and allows for a small store of oxygen.
  • Surrounded by small muscle fibres.
81
Q

What are glycolytic muscle fibres also known as?

A

White muscle fibres (due to lack of myoglobin).

82
Q

Describe glycolytic muscle fibres.

A

White muscle fibres, contain few mitochondria but large stores of glycogen and high levels of glycolytic enzymes.

83
Q

Three types of muscle fibre can be distinguished by speed of contraction and metabolic activity. What are they?

A
  • Slow twitch fibres (Type I)
  • Fast twitch (Type IIa)
  • Fast twitch (Type IIb)
84
Q

Describe slow twitch muscle fibres Type I.

A
  • Low Myosin-ATPase activity
  • Very resistant to fatigue.
  • Rich in mitochondria and enzymes for OP.
85
Q

Describe fast twitch (Type IIa) muscle fibres.

A
  • High Myosin-ATPase activity.
  • Red muscle fibres.
  • Contains many mitochondria and enzymes for oxidative metabolism.
  • Also contain glycogen stores and enzymes from glycolytic metabolism.
  • Resistant to fatigue.
86
Q

Describe fast twitch (Type IIb) muscle fibres.

A
  • High myosin-ATPase activity.
  • White fibres - poor blood supply, little myoglobin
  • Rich in glycogen stores and enzymes for anaerobic glycolysis.
  • Fatigue rapidly.
87
Q

What is the order of recruitment of muscle fibres based on the number of motor units recruited?

A

1) Type I
2) Type IIa
3) Type IIb

88
Q

What is the investigation used for neuromuscular disorders?

A

Electromyography.

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