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Phase 1 > MSK: Week 1 > Flashcards

MSK: Week 1 Flashcards

1
Q

What are 7 purposes of the skeleton

A
  • Raises us from the ground AGAINST GRAVITY
  • Determines basic body SHAPE
  • Transmits body WEIGHT
  • Forms jointed lever system for MOVEMENT
  • Protects vital structures from DAMAGE
  • Houses bone marrow
  • Mineral storage (ca2+ and phosphates)

Remember:
Gary Saw Will Moving Donkey Meek Mills

G - Gravity 
S - Shape
W - Weight
M - Movement
D - Damage
M - Marrow
M - Mineral storage
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2
Q

How many bones are there in the body

A

206

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3
Q

What are long bones

A

Tubular shapes with hollow shaft and expanded ends for articulation with other bones

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4
Q

What are short bones

A

Cuboidal shaped

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5
Q

What are flat bones

A

Plates of bones that are needed for protection

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6
Q

What are seasmoid bones

A

Round, oval nodules in a tendon

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7
Q

What is a cortical structure of a bone

A

Cortical = Compact

Cortical parts of a bone from the outer shell (cortex) of the bone

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8
Q

What are four roles of the cortical layer of a bone

A

Protect organs
Support whole body weight
Provide levels for movement
Storage of calcium

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9
Q

What is the trabecular part of the bone

A

Trabecular = SPONGY

Trabecular parts of the bone form the medulla of the bone at the ends, proximal to the joints

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10
Q

What are Two characteristics of the trabeculated part of bones

A

Trabeculated

Many Holes

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11
Q

Where are osteoclasts located

A

In spaces called Lacunae

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12
Q

What are the two microstructures of the bone

A

Woven and Lamellar bone

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13
Q

Woven Bone vs Lamellar Bones

A

Woven vs Lamella:

Made Quickly vs Made Slowly 
Disorganised vs Organised
No clear feature vs Layered
More flexible vs Less flexible
Weaker vs Stronger
More osteocytes vs Less Osteocytes
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14
Q

What is the role of the wide end of the bone

A

Spreads load over weak, low frictioned surface

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15
Q

What is the role of the hollow long bone

A

Keeps mass away from neutral axis - minimises deformation

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16
Q

Role of the trabecula part of the bone

A

Gives structural support while minimising mass

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17
Q

What is the role of the flat bone

A

Protective

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18
Q

Bone composition

A

50-70% minerals
20-40% organic matrix
5-10% water

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19
Q

What is the mineral part of the bone made of

A

Hydroxyapatite - crystalline form of calcium phosphate

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20
Q

What is the organic matrix made of

A

Type I collagen - 90% of all proteins present

Non-collagenous protein - 10% of all proteins

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21
Q

Describe the arrangement of collagen fibres in the extracellular matrix

A

The collagen molecules are arranged in ‘staggered’ form with mineral crystals situated in gaps between them

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22
Q

Why do we need minerals in our bones

A

Provides Stiffness

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23
Q

Why do we need collagen in our bones

A

Provides elasticity

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24
Q

Describe the origin of osteoblasts

A 
Mesenchymal stem cells -> Progenitors ->
Adipocytes
Osteoblasts
Chondrocytes
Myoblasts
Fibroblasts
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25
Q

What cells are inter-differentiating

A

Adipocytes -> Osteoblasts (vice versa)

Osteoblasts -> Chondrocytes (Vice Versa)

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26
Q

What are osteoids

A

Unmineralised parts of the bone matrix

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27
Q

What cell produces osteoids

A

Osteoblasts

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28
Q

Why are osteoids needed

A

to form bone tissue

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29
Q

What happens to osteoids when they are mineralised

A

It and adjacent bone cells will develop into new bone tissue

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30
Q

How do osteoblasts mineralise the matrix

A

Depositing crystals with collagen fibrils into the matrix

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31
Q

What collagen do osteoblasts produce

A

Type I

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32
Q

What factor affects the level of activity of the enzyme alkaline phosphatase

A

When bones are growing or bone cells are active

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33
Q

What two other substances do osteoblasts secrete

A
  • Non collagenous proteins

- Factors that regulate osteoclasts (RANKL)

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34
Q

Describe the origin of osteoclasts

A

Haematopoietic stem cells -> Determination -> Proliferation -> Differentiation -> Attachment

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35
Q

What enzyme causes proliferation

A

M-CSF

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36
Q

What is the role of OCG

A

Inhibits osteoclast production

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37
Q

What cell produces OCG

A

Osteoblasts

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38
Q

Define resorption

A

Absorption into the circulatory system of cells

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39
Q

What are four roles of osteoclasts

A

Resorb bone
Dissolve mineralised matrix
Breakdown collagen in bone
HIgh expression of TRAP + Cathepsin K

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40
Q

Role of TRAP

A

Degrades phosphoproteins in skeletal muscles

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41
Q

Role of Cathepsin K

A

A protein that breaks down bone and cartilage

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42
Q

Define modelling

A

Gross shape is altered, bone is added or take away

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43
Q

Define remodelling

A

All bone is altered, new bone replaces old bone

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44
Q

How does the bone enlarge during remodelling

A

Enlarges as cartilage grows

Cartilage is then replaced by bones

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45
Q

What are 7 reasons for bone-remodelling

A
  • Form bone shape
  • Replace woven bone with lamellar bone
  • Reorientate fibrils + Trabecullae to increase mechanical strength
  • Repair
  • Response to load
  • Obtain calcium
  • Disease
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46
Q

What is the most abundant type of collagen

A

Type I

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47
Q

Describe the structure of type I collagen

A

Look in book

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48
Q

How many alpha chains are present in collagen’s helix

A

Three

So it is called tropocollagen

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49
Q

What are collagen strands arranged into

A

fibrils

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50
Q

What are the collagen fibrils arranged into

A

Collagen Fibres

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51
Q

What is the tropocollagen made of (AA wise)

A

Gly-X-Y tripeptide continuously repeating

52
Q

What is the Y of Gly-X-Y

A

Usually proline or hydroxyproline

53
Q

What is the X of Gly-X-Y

A

Any AA

54
Q

What is the purpose of Y in Gly-X-Y

A

Allows for formation of alpha helix chain

55
Q

What holds the fibril molecules together

A

By covalent cross-links from lysine/hydroxylysine side-chains

56
Q

What cell guides the formation of fibrils

A

Fibroblasts

57
Q

Where do covalent cross-links take place in collagen

A

Between tropocollagen helices and within the triple helices themselves

58
Q

How do cross-links form within the triple helix

A

Due to 2 hydroxyglycine molecules

59
Q

What enzyme is needed to form cross-links

A

Lysyl Oxidase

60
Q

What element is required by lysyl oxidase

A

Copper

61
Q

How do cross-links form between tropocollagen molecules

A

Between three hydroxylysine molecules

Forms a structure called pyrodinoline

62
Q

What other force is acting in collagen

A

Hydrogen Bonding

63
Q

How do hydrogen bonds form in collagen

A

Between two hydroxyproline molecules within tropocollagen

64
Q

What compound is needed to produce hydroxyproline

A

Vitamin C

65
Q

What needs to happen to type I collagen before it is moved into the extracellular matrix to produce bone

A

Needs to be processed

66
Q

What happens during processing of tropocollagen

A

N-terminal peptide (P1NP) and C-terminal peptide (P1CP) need to be removed

67
Q

How can we measure bone formation rate

A

Checking P1NP + P1CP levels in the blood (usually P1NP) shows us collagen formation rate

68
Q

Why is P1NP the main way we check for bone formation rate

A

It is more stable than P1CP

69
Q

How do we break down tropocollagen

A

Cleave N and C telopeptides

70
Q

What two enzymes will go on to break down the rest of the tropocollagen molecule

A

Colaginase

Cathepsin K

71
Q

Where can NTx (N-terminal telopeptides) be measured

A

Urine

72
Q

Where can CTx be measured (C-terminal telopeptides)

A

In the blood

73
Q

Which is a better marker and why (NTx or CTx)

A

CTx because it is found in the blood

74
Q

When should CTx be measured

A

During fasting as it increases after a meal

75
Q

What two reasons are there for collagen breakdown

A

Pathological

Normal repair and replacement

76
Q

What are FACIT collagens

A

IX, XII, XIV

77
Q

What are Microfibrillar collagens

A

VI

78
Q

What are short-chain collagen

A

X + VIII

79
Q

What are basement membrane collagen

A

IV

80
Q

How can we measure bone formation

A

P1CP/P1NP

81
Q

How can we measure bone destruction

A

NTx/CTx

82
Q

What is the action of the iliopsoas muscle

A

Flexes lower limb at hip joint and assists in lateral rotation of the hip joint

83
Q

What is the iliopsoas innervated by

A

Psoas major: L1-L3 anterior rami

Iliacus: Femoral Nerve

84
Q

What muscles are the quadriceps femoris made of

A

Three vastus muscles

A rectus muscle

85
Q

What two structures pass through the adductor canal

A

Superficial femoral artery

Popliteal vein

86
Q

What does the popliteal vein form as it passes through the adductor canal

A

Superficial femoral vein

87
Q

What part of the body is the main reservoir for Ca2+

A

Skeleton = 1200g

88
Q

What are three roles of Ca2+

A
  • Normal Blood Clotting
  • Muscle Contractility
  • Nerve Function
  • Cell signalling
89
Q

What are active metabolites of calcium

A

Free-floating Ca2+

90
Q

What are inactive metabolites of calcium

A

Protein-bound calcium in the blood

91
Q

What protein do calcium ions bind to and circulate in the blood with

A

Albumin

92
Q

How does pH affect albumin binding to calcium

A

Increased pH = strong binding to calcium

Decreased pH = Weak binding to calcium

93
Q

How does high pH affect ionised calcium and inactive ion conc.

A

Decreased ionised calcium ions

Increased inactive ion conc.

94
Q

How is calcium re-absorbed at the intestines

A

Absorped by intestinal epithelial cells + bound to calbindin

Ca2+ is transferred to the opposite side of the cell without entering the cytosol

95
Q

How is calcium re-absorption controlled at the kidneys

A

PTH controls the amount of Ca2+ absorped in the intestines

Reduces amount of PO43- reabsorped

96
Q

Why do we need to decrease phosphate ions in the body to increase ionised calcium ion levels

A

Because phosphate will combine with calcium to form an insoluble salt

An increase phosphate ions conc. reduces amount of calcium ions in the ECF

97
Q

What is the major source of calcium in diet

A

Dairy Products

98
Q

What are three minor sources of calcium in the diet

A

Vegetables
Cereals
Oily Fish

99
Q

How much of calcium taken in by our diet is absorbed into the GI tract

A

30%

100
Q

Where does active absorption of calcium ion take place

A

Jejunum

Duodenum

101
Q

Where does passive absorption of calcium ion take place

A

Ileum + Colon

102
Q

What compound mediates absorption of calcium ions in the gut

A

Calcitriol

103
Q

How does decreased intake of calcium in our diet affect calcitriol levels

A

Increases them

104
Q

Why does calcitriol increase when calcium intake decreases

A

To increase the fraction of calcium re-absorped

105
Q

Where can we get ‘rapid release’ of calcium

A

From exchangeable calcium on bony surface + decreased excretion at kidneys

106
Q

Where can we get ‘slow release’ of calcium

A

From osteoclasts during bone resorption and increased reabsorption at intestines

107
Q

What two factors affect how much calcium is filtered at the glomerulus

A

GFR

The ultrafiltrable calcium (ionised or in protein complex)

108
Q

Describe calcium/phosphate ion re-absorption along the kidney nephron

A

Look in book

109
Q

Describe vit D synthesis pathway

A

7-dehydrocholsterol -> Vit D -> 25(-OH)D

  • > 1,25(OH)2D
  • > 24,25(OH)2D

1,25(OH)2D -> Intestines or bone

24,25(OH)2D -> Calcitroic Acid

110
Q

What is calcitriol

A

Active form of vit D

111
Q

Name three roles of phosphates

A

Intracellular signalling
Activation of protein kinase
Cell membrane component
Post-translational protein modification (Kinases and phosphatases)

112
Q

Role of kinases and phosphatases

A

Kinases - Add phosphate

Phosphatases - Remove phosphate

113
Q

What are normal levels of phosphates in the body

A

500 to 800 g

114
Q

What are normal serum levels of the phosphates in the body

A

0.8 to 1.5 mmol/L

115
Q

What would be the result of excess hydroxyapatite

A

Deposition in tissues other than bone

116
Q

What would be the result of a lack of hydroxyapatite

A

Poor bone mineralisation

117
Q

Four dietary sources of phosphates

A
  • Animal
  • Dairy
  • Soy
  • Seeds + Nuts
118
Q

Where does gut absorption of phosphates take place

A

Small intestines via passive diffusion

When conc. of phosphates decreases this becomes active via NA co-transporters

119
Q

Where is more unbound phosphates re-absorbed

A

80% at the PCT via Na-cotransporters

10% at the DCT

120
Q

What cell produces FGF-23

A

Osteocytes

121
Q

What does the osteocyte produce FGF-23 in response to

A

Increased phosphate levels
PTH
1,25(OH)2D
Dietary PO43- loading

122
Q

Describe FGF-23 action

A

Decreases expression of NA transporter in the renal tubules

Decreases 1-alpha hydroxylation of vitamin D (so less phosphate is reabsorbed at the gut)

123
Q

What is Klotha

A

Transmembrane protein

124
Q

What is Klotha needed for

A

Necessary for the function of FGF-23 as it acts as a receptor.

125
Q

What are the borders that make up the popliteal fossa

A

Superomedial Border (semimembranous)

Superolateral border (Biceps Femoris)

Inferomedial Border (Medial head of the gastrocnemius)

Inferolateral Border (Lateral head of the gastrocnemius and plantaris)

126
Q

What structures can I find in the popliteal fossa

A

Tibial nerve
Common fibular nerve
Popliteal nerve
Popliteal artery

Phase 1 (30 decks)

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