MSK: Week 2 Flashcards
1
Q
Role of osteoblasts during bone turnover
A
They add new bone tissue - Ossification
2
Q
Role of osteoclasts during bone turnover
A
They resorb mature bone tissue from the skeleton
3
Q
What two things to osteoclasts secrete into the extracellular matrix
A
Proteolytic enzymes Several acids (citric acid + lactic acid)
4
Q
Where is lactic acid and citric acid produced in the osteoclasts
A
Mitochondria
5
Q
Why do osteoclasts secrete proteolytic enzymes and acids
A
To break down the organic matrix
6
Q
How do osteoclasts take in broken down bone matrix and crystals
A
Phagocytosis so they are moved into the blood
7
Q
What two ways do osteoclasts and osteoblasts communicate with each other to regulate bone turnover rates
A
Coupling: Bone formation occurs at the site of previous bone resorption
Balance: Amount of bone removed by osteoclasts should be replaced by osteoblast activity
8
Q
Where are osteoclasts derived from
A
Myeloid progenitor cells
9
Q
What are cytokines involved in
A
Inflammatory and infectious diseases
10
Q
What are two properties of cytokines
A
Redundancy
Pleiotroptism
11
Q
Define redundancy
A
Most of the functions of cytokines can be performed by many different cytokines
12
Q
Define pleiotropism
A
A single cytokine has many different functional effects on many different cell types
13
Q
Define a hormone
A
Released from organs into the blood
14
Q
Define a neurotransmitter
A
Released by nerves
15
Q
Define autocrine
A
If a cytokine acts on the cell that secretes it
16
Q
Define paracrine
A
If the action is restricted to the immediate vicinity of a cytokine’s secretion
17
Q
Define endocrine
A
If a cytokine diffuses directly into the blood and is transported to different regions of the body
18
Q
What four hormones mediate the action of osteoclasts
A
1,25(OH)2D
PTH
Oestrogen
Leptin
19
Q
What is the role of OPG
A
Prevent resorption by osteoclasts by binding to RANK-Ligand receptors
20
Q
What are four functions of Ligaments
A
Attach bone to bone
Increase mechanical strength of joints
Guide joint motion
Prevent excessive motion
21
Q
What are five functions of tendons
A
Connect muscle to bone (insertions) Aid joint stability Stabilise joints Enable joint motion Interact with ligaments to regulate load exerted on them
22
Q
Why are fibres in tendons and ligaments arranged in parallel fibres
A
Enables tissue to sustain high tensile strengths
23
Q
What cells are found in tendons and ligaments that modify the extracellular matrix
A
Fibroblasts (tenocytes)
24
Q
What is the consequence of a decrease in fibroblast numbers
A
Causes low turnover rate and poor capacity for healing
25
How much of tissue volume do fibroblasts make up (percentage)
20%
26
What percentage of tissue volume is made up by Extracellular matrix
80%
27
How much of the ECM is made up of water
70%
28
How much of the ECM is mad up of solids
30%
These are collagen and ground substances
29
Describe the vascularisation of tendons and ligaments
They are sparsely vascularised
30
What is the consequence of ligaments and tendons being sparsely vascularised
Poor, slow capacity for healing
31
Describe the structure of tendons and ligaments
Look in book
Outer layer is called epitenon
Layer surrounding fascicles is known as endotenon
32
What type collagen are tendons and ligaments mainly composed of
```
Type I
Type III (small amounts)
```
33
Why do tendons and ligaments have proteoglycans
Provide lubricant to allow collagen fibres to move over each other + Regulate fibre diameter
34
What cell produces collagen and in what form are they produced as
Fibroblasts as procollagen (it is modified to collagen in the ECM)
35
How does the amount of elastin in tendons and ligaments differ when they differ in function at different parts of the body
Little elastin in tendons and extremeity ligaments
Loads present in ligaments supporting the spine (e.g. ligamentum flavium)
36
Role of ligamentum flavium
Protects spinal nerve roots
| Needed for spine stability
37
Ligament vs Tendons (4)
Ligaments connect bone to bone vs Tendons connect bone to muscle
Ligaments have less collagen I (90% of dry weight) vs Tendons have more collagen I (95%)
Ligaments have more elastic content vs Tendons have less elastic content
Ligaments fibre organisation is random vs tendon fibre organisation is highly organised
38
Describe the blood supply of tendons and ligaments
Where they are surrounded by paratenon, they have vascular blood supply
Where they are surrounded by a tendon sheath, they are avascular and receive oxygen via simple diffusion from neighboring tissues
39
What is enthesis
Insertion of a tendon or ligament to a bone
40
What are the two types of insertions we can have?
Fibrous
| Fibrocollagenous
41
WHat receptors do places of insertion have
Pain and proprioceptive receptors
42
What are fibrous insertions
Formed through intramembranous ossification (anchorage by sharpey fibres onto a bone)
43
What are fibrocartilage insertions
Gradual change form collagenous ligaments to fibrocartilage and then to mineralised cartilage onto a bone
44
What are fibrocartilage insertions formed through
Endochondral ossification
45
What does tensile load on ligaments and tendons result in
Results in elongation of the ends of the tissue
46
What does compressive load on ligaments and tendons result in
Contraction between the ends of the tissue
47
Describe the load-elongation curve
1. Small increase in load as crimpled collagen fibres straighten
2. Linear region fibres straighten and stiffness increases rapidly with loading
3. Maximum deformation and tensile strength of tissue. After this, collagen fibres begin to fail (Pmax)
4. Complete failure of tissue to support load
48
Is Pmax usually achieved during normal activity
No - 30% of it is achieved
49
Describe the load-elongation curve of ligaments such as ligamentum flavum that have high elastin content
Elongation increases exponentially with load
50
What is the ligamentum flavum connected to
Laminae to adjacent vertebrae
51
How does age affect mechanical properties of ligaments and tendons
Up to 20: - Increased number + quality of cross-links between collagen molecules = Increased tensile strength
- Increased collagen fibril diameter = Increased tensile strength
Aging: Decreased collagen content = decreased tesile strength
52
How does pregnancy affect strength of ligaments and tendons
Decreased tensile strength due to hormones
53
How does physical training affect tendon and ligament strength
Increased tendon tensile strength
| Ligaments become stiffer and stronger as collagen fibres increase in diameter
54
How does immobilisation affect tendon and ligament strength
Decreased tensile strength of ligaments, more elongation and less stiff
Decreased cross-links
NOTE: It takes months to recover strength after weeks of immobilisation
55
Outline the phases of tendon and ligament repair after injury
```
Short-term inflammatory phase (days)
Proliferative phase (weeks)
Remodelling and maturation phase (months)
```
56
How does repaired tendon compare with the original tendon we had before the injury
It will be a lot weaker even years after injury.
57
What are three functions of joints
1. Provide movement in three dimensions
2. Weight-bearing
3. Transfer load evenly to the MSK system
58
Define 'structural classification' of joints
Joints classified by the degree of movement they allow
59
Define the 'functional classification' of joints
By the components/tissues that hold the joints together
60
Name the three main types of structural joints
1. Fibrous
2. Cartilaginous
3. Synovial
61
Name the three main types of functional joints
1. Synarthroses (immovable joints)
2. Amphiarthroses (Slightly moveable joints)
3. Diarthroses (Freely moveable joints)
62
Where are synarthroses found?
Skull sutures
63
What do amphiarthroses mostly consist of
Mostly cartilaginous
64
What do diarthroses consist of
Synovium
65
What are skull sutures
Interdigitating adjacent bone
| Junction filled with short tissue fibres
66
Why do we need skull joints
To allow the growth of the skull after birth
67
What happens to the fibrous tissue between skull bones once growth has stopped
Forms bone sutures
68
What are syndesmoses
Fibrous joint - Bones connected by a cord or sheet of fibrous tissue
69
What affects the amount of movement of syndesmoses
Length of the fibre
70
What is an example of syndesmoses
Interosseous membranes
71
What type of joint are gomphoses
Fibrous joints
72
Where are Gomphoses found
In tooth articulation as a plug in socket joint
73
What type of joint are synchondioses
Connection of bone via hyaline cartilage
74
Are joints of synchondioses moveable
Yes
75
What is an example of synchondioses
Costal cartilage of ribs
76
What type of joint are symphysis
Connecting cartilage is a pad or plate of fibrocartilage
77
Where can symphysis be found
At the spinal cord
78
What category of joints do suture, syndesmosis and gomphosis lie under
Synarthrosis - Fibrous
79
What category do synchondrosis and symphysis lie under
Amphiarthrosis - Cartilaginous
80
What are synovial joints
Where articulating bones are separated by a fluid-filled cavity
81
What are the most common joints in the body
Synovial joints
82
What are the five properties of synovial joints
1. Articular cartilage
2. Joint Capsule - Inner Layer is synovial membrane
3. Joint Cavity - A space filled with synovial fluid
4. Synovial Fluid
5. Reinforcing Ligaments
83
What are two other structures found in knee joints (which are also synovial but have other components to normal joints)
1. Bursae
| 2. Menisci
84
What are bursae
Fluid-filled sacs lined by synovial fluid
85
What are menisci
Discs of fibrocartilage
86
What are five properties of hyaline cartilage
1. Frictionless Surfaces
2. Resists compressive loads
3. High Water content
4. Low cell content
5. No blood supply
87
What three important substances are found in the cartilage
Water, proteoglycans and collagens
88
Why is hyaline cartilage so important
1. Acts as a shock absorber to protect bones during joint movement
2. Provides smooth, frictionless surface for movement
89
Describe the layers of hyaline cartilage
1. Superficial Zone
2. Intermediate Zone
3. Deep Zone
4. Calcification of bone
5. Subchondral bone
90
What is synovial fluid
Joint lubricant
91
How does synovial fluid work
1. Covers articulating surfaces with a thin film
2. Modified from plasma by synoviocytes
3. Fluid, proteins + charged sugars that bind to water
4. Results in slimy fluid
5. Reduces friction durinng articulation
92
Where is the synovial membrane located
On the joint capsule + encloses synovial cavity
93
How thick is the synovial membrane
Once or two cells thick
94
What is the role of the synovial membrane and what feature of the synovial membrane allows this to be effective
Secretion of synovial fluid components and has villi projections to increase SA
95
What is the first class lever system
Fulcrum in the middle with force at one end and resistance at the other end
E.g. Triceps is the force
Elbow is fulcrum
Resistance is a weight being pulled
96
What is the second class lever system
Fulcrum is at one end, resistance in the centre and force at the other end
E.g. Temperomandibular joint - Force
Resistance = Muscles attached to coracoid process
97
What is the third class lever system
Fulcrum at one end
Force at the middle
Resistance at other end
E.g. Biceps and elbow
98
Where can hinge joints be found
Elbow
99
Where can condyloid joints be found
Interphalangeal joints
100
Role of condyloid joints
Allow flexion, extension, abduction, adduction and circumduction
101
Where can gliding joints be found
Carpal bones
102
Role fo gliding joints
The bones can slide past each other in any direction
103
Where can saddle joints be found
Carpometacarpal joints
104
What is the saddle joint close in function to
Condyloid joints
105
What is the role of saddle joints
Flexion, Extension, Adduction, Abduction and circumduction - HOWEVER NO AXIAL ROTATION
106
Where can pivot joints be found
Spinal cord - Intervertebral discs
107
What join are pivot joints close in function to
Hinge joint
108
Define Inversion and Eversion
Inversion is the inwards rotation of the foot
| Eversion is the outwards rotation of the foot
109
Define dorsi-flexion
Movement of foot upwards
110
Define plantar-flexion
Downward movement of foot
111
What are the three main stabilising ligaments of the hip joint
Iliofemoral
Ischiofemoral
Pubofemoral
112
What are the main stabilising ligaments of the shoulder
Glenoidal labrum
Coracohumeral
Three glenohumeral ligaments
Transverse humeral
113
What are the two tendons that stabilise the shoulder
Long head of biceps
| Rotator cuff muscles
114
What type of joint is present between the femur and tibia
Condyloid
115
What type of joint is present between the femur and patella
Gliding
116
What type of joint is found between the humerus and ulnar
Hinge
117
What type of joint is present between the humerus and radius
Gliding
118
What does a molecule of purine consist of
A pyramidine ring
| An Imidazole ring
119
Is purine water-soluble
Yes
120
How can we obtain purines in food
Meat
121
What two ways can purines be excreted by the body
Urine
| Gut
122
How is guanine metabolised
1. Nuclease frees guanine nucleotide
2. Nulceotidase creates guanosine
3. Phosphorylase convertes guanosine to guanine
4. guanase converts guanosine to guanine
5. Guanase converts guanine to xanthine
6. Xanthine oxidase oxidises xanthine to uric acid
123
How is Adenine metabolised
1. Nuclease frees nucleotide
2. Adenosine -> Inosine
3. Inosine -> hypoxanthine
4. hypoxanthine -> Xanthine via Xanthine Oxidase
5. Xanthine -> Uric Acid
124
Where is the uric acid excreted
Kidneys
125
Name some sources of purines in the diet
```
Meat
Offral (heart, liver and kidneys)
Seafood (muscles)
Fish (sardines)
Oatmeal
Fructose
```
126
What are some risk factors for gout
```
Obesity
Raised Temperature
Raised blood pressure
Coronary heart disease
Diabetes
```
127
Can alcohol increase risk of gout
Only in excess - fine in moderation
128
How can I manage gout without medication
Rest
Ice pack
Elevate affected joint
129
How can I manage gout with medication
NSAIDs
Colchicine
Steroids
130
What are three advice we should give to patients at risk from gout
Lose weight
Avoid purine-rich food
Reduce alcohol intake
131
How does allopurinol prevent gout
Stops Xanthine Oxidase from working so no Xanthine is produced caused no uric acid production
132
What are three complications of gout
1. Damage to joints
2. Secondary Infections
3. Nerve Damage
133
What is a consequence of high uric acid conc.
Formation of urate crystals
134
What are two major consequences of increased turnover rates of purines
1. Malignant tissue growing
| 2. Increased tissue breakdown
135
What happens to uric acid in some organisms
Converted to allantoin via urate-oxidase enzyme (not in humans)
136
Why is allantoin production a thing
Because allantoin is more water-soluble than uric acid so is more easily excreted in the urine
137
Define Hyperuricemia
Over production or under excretion of uric acid
138
Name four type of purines
Adenine
Guanine
Hypoxanthine
Xanthine
139
How does excersise affect the strength of the skeleton
Increases it
140
Is the change in skeleton strength environmental or genetic
Environmental only
141
What happens to the bone when I place a force on it
Minor deformation
142
What is strain
Change in length / Original Length
143
What are customary strains
Strains that the bone is already used to
144
What happens if there is a force exerted on the bone that is greater than customary strain
We will have bone formation
145
What happens if force exerted on a bone becomes less than the customary strain
Bone loss
146
What factors affect bone strain
Magnitude
Rate At which load is added and removed
Frequency of strain exerted
Dwelling of the strain (how long it remains for)
Number of cycles (least important factor)
147
Does duration of physical activity affect bone mass efficiently
Nope - It's not a very large influence
148
Define customary strain stimulus
Customary strains that are influenced by magnitude, frequency, duration and rest periods
149
What has the greatest impact on skull strain, smiling, cheqing or walking
Smiling
150
Define specific site customary strain stimulus
Customary strains that are influenced by magnitude, frequency, duration and rest periods AND that the same load can have different impacts of strain at different parts of the skeleton
151
What four non-force factors can affect strength of the bone
Sex
Age
Biochemicals
Drugs
152
Is compression of bone the only way bone strength can increase
No, can also increase when bone is stretched (e.g. when monkeys swing from trees)
153
What is the relationship between muscle and bone during excersise
An increase in cross-sectional surface of muscle also sees an increase in bone strength
154
How many cycles of strain a day will bones respond to
Only two
155
Excersise in the previous how many hours will increase response to subsequent loading
4 hours
156
How long does the mechanical load need to be exerted to cause a response in bones
BRIEF mechanical load
157
How does rest influence bone strengthening
Increases effort by bones to increase in strength
158
What two cells respond to bone loading
Osteoblasts and osteocytes
159
When are osteoblasts and osteocytes activated
When loading takes place
160
Where are osteoblasts activated
Periosteum
161
At what stage in life is response to excersise greatest
Growth
162
What is the dominant influence on bone strength
Loading
163
What property of the load results in the highest strain rate on the bones
Magnitude of the load
