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MEDSCI 142 > Section 7: Musculoskeletal System > Flashcards

Section 7: Musculoskeletal System Flashcards

1
Q

Bone (organ)

A

Organs are made up of diff types of tissue

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2
Q

Bone (tissue)

A

One of the tissues found in bones of skeleton

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3
Q

What is found in bone

A 
CT
Smooth muscle
Nervous tissue
Cartilage
Bone tissue
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4
Q

Functions of skeletal system

A 
Support
Protection
Movement
Calcium and phosphorous reserve
Haemopoiesis (red marrow)
Fat storage (yellow marrow)
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5
Q

Tissues - soft or hard

A

Most tissues are soft and deformation, so need bone to hang and suspend the tissue

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6
Q

Muscle tissue

A

Soft tissue
Can shorten by ~1/3
Since they’re soft, they aren’t good at pulling on other tissues so attach to skeletal system –> allows movement

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7
Q

Functions of skeletal system: Calcium

A

Need to have a certain amount of Ca2+ in serum for organs to function properly
Determines muscle contraction
Important for APs

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8
Q

Where is Ca2+ found

A

~99% in body is skeleton, other 1% is dissolved in tissue fluid

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9
Q

Phosphorous is used a lot in…

A

Cellular structures

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10
Q

Functions of skeletal system: Haemopoiesis

A

Found inside bones that you make blood out of, e.g. RBC, WBC

Red

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11
Q

Functions of skeletal system: Fat storage

A

High fat content

Yellow

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12
Q

Adult skeleton =

A

Axial + Appendicular

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13
Q

Adult skeleton: Axial vs appendicular - no of bones

A

Axial: 80 (some paired)
Appendicular: 126 (all paired)

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14
Q

How many bones in total does the skeleton have

A

When born have ~270 centres of ossifications and eventually some fuse tgt
Adult skeleton ~206
As you get older (~30 years), some of the 206 bones will also fuse

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15
Q

Adult skeleton: Axial vs appendicular - found where

A

Axial: found on axis/core of body
Appendicular: upper and lower limbs

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16
Q

Adult skeleton: Axial vs appendicular - main regional differences in function

A

Axial:
Support / protection
Haemopoeisis

Appendicular:
Movement
Fat storage

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17
Q

Adult skeleton: Axial vs appendicular - bone marrow

A

Axial: most bone marrow is haemopoietic tissue (red)
Appendicular: most bone marrow is fat storage

Further from axial skeleton = more likely to find yellow marrow

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18
Q

Adult skeleton: All machinery needed to make body function is usually associated with…

A

The axial skeleton

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19
Q

Adult skeleton: Appendicular skeleton - environment

A

Sense environment
Manipulate environment
Move body through environment

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20
Q

Classic bone

A

Long bone

Means the bone is longer in one axis than it is in the other two

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21
Q

Ends of a long bone

A

Usually articulating with neighbouring bones at its ends

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22
Q

Parts of a long bone

A 
Epiphysis = ends
Diaphysis = length of bone
Metaphysis = properties of epiphysis and diaphysis
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23
Q

Long bone - forces

A

Epiphysis: Since bone is in contact with bone, most forces are transmitted through joint itself
Diaphysis: As forces get down to shaft, aren’t perpendicular with surface and now are running parallel with surface –> don’t need plates but instead have thicker walls to resist the force

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24
Q

Long bone: Diaphysis - shape

A

Cylinder-shaped - one of the strongest shapes for its weight

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25
Q

Long bone: Diaphysis - weight

A

Quite light, but very strong

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26
Q

Long bone: Diaphysis - wall

A

Compact bone forms the wall

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27
Q

Long bone: Diaphysis - medullary cavity

A

Where (mainly yellow) bone marrow is found

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28
Q

Do all bones have marrow in them

A

No, some don’t

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29
Q

Long bone: Diaphysis - periosteum

A

Surrounds bones - covers most of its outer surface

Important for health of bone

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30
Q

Peri

A

Perimeter / outer layer

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31
Q

Long bone: Diaphysis - Sharpey’s / perforating fibres

A

Anchors periosteum to bone - strong
Bundles of collagen that infuse into matrix of bones
Usually small but can get big when there’s a tendon or ligament that needs to attach to bone

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32
Q

Long bone: Diaphysis - Endosteum

A

Thin, inner fibro-cellular layer lining medullary cavity

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33
Q

Long bone: Epiphysis - spongy bone

A

Made up of trabeculae to support outer layer of bone

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34
Q

Long bone: Epiphysis - trabeculae

A

Unit of spongy bone

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35
Q

Long bone: Epiphysis - medullary cavity

A

Spaces between trabeculae
Quite small
Usually red marrow

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36
Q

Long bone: Epiphysis - blood vessels

A

Inside compact bone and medullary cavity

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37
Q

Long bone: Epiphysis - articular cartilage

A

Usually only found where bone comes in contact with other bone
Bone rubbing directly against bone is painful

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38
Q

Biggest bone in body

A

Femur

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39
Q

Femur - holes

A

Nutrient foramen - how blood vessels get in

Quite small and lots of them

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40
Q

Femur - amount of trabeculae

A

As you move from diaphysis to metaphysis to epiphysis, amount of trabeculae increases
Inside of epiphysis = lots

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41
Q

Femur: Trabeculae - arrangement

A

Not randomly arranged
Radiate away from side of bone and go out for support
Since weight is slightly offset from centre, there’s a bending force on head of femur, so some trabecular move out in that plane

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42
Q

Bone - anaesthesia

A

Bone has poor hydration factor, so anaesthesia doesn’t get into the centre of the bone

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43
Q

Bone is a _____ CT

A

Specialised

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44
Q

CT - common?

A

The most common tissue in body

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45
Q

CT tends to be used for…

A

Packaging

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46
Q

CT - diverse?

A

Diverse range of physical properties because diverse functions

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47
Q

What is CT made of

A

Made up of cells which secrete material around them - called ECM

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48
Q

ECM components

A 
Fibres
Ground substance (quite a lot of water)
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49
Q

CT - hydration

A

Most CT is quite hydrated

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50
Q

Nerves often act on…

A

Blood vessels

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51
Q

What are the fibres in the bone

A

Collagen

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52
Q

Bone: ECM - organic?

A

Fibres = organic (C-based)

Ground substance = inorganic

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53
Q

Bone: ECM - made up of?

A

Fibres: collagen fibres (type I)

Ground substance: hydroxyapatite (calcium and phosphorous)

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54
Q

ECM: Ground substance - hydroxyapatite

A

Typically only found in bone

Good at resisting compression –> gives bone its unique properties

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55
Q

ECM - resists what

A

Fibres = resist tension (stretch/pull)
Ground substance = resist compression (squeeze/crush)

So combination of them allows to resist torsion
i.e. tension + compression = torsion

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56
Q

ECM - weight

A

Fibres = 1/3 of dry weight

Ground substance = 2/3 of dry weight

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57
Q

ECM: What determines tension

A

How loose the fibre was to begin with determines how far apart you can move the points of attachment before they start resisting

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58
Q

What is found wherever tension needs to be resisted

A

Collagen

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59
Q

Collagen arrangement

A

Ligaments and tendons that have lots of powerful tension - all in same orientation
Tissues where there are multiple tension forces - randomly arranged to resist as many forces possible

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60
Q

Types of bone cells

A

Osteogenic cell (osteoprogenitor cell) ↔
Osteoblast ↔
Osteocyte

Osteoclast

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61
Q

Osteogenic cells - precursor

A

Unspecialised stem cells - found in bone marrow, left from mesenchyme embryonic CT and overtime divided/specialised

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62
Q

Osteogenic cells - location

A

Surface of bone under peri/endosteal fibres and wait, but under right cues will start to divide –> osteoblast
Also in central canals of compact bone

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63
Q

Osteoblast - precursor

A

Osteogenic cell

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64
Q

Osteoblast - location

A

Usually in a layer under the peri/endosteum (now active!)

Wherever new bone is being formed

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65
Q

Osteoblast - structure

A

Quite fat because they have organelles inside them designed for secretion

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66
Q

Osteoblast - secretion

A

Secrete osteoids, which are rich in organic components of bone

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67
Q

Osteoblast - osteoid

A

The organic ECM (70% collagen, 30% proteoglycans, proteins, water) of bone, synthesised by osteoblasts prior to mineral deposition

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68
Q

Osteoblast - osteoid - calcification

A

Where the precursor matrix is infiltrated with bone salts (hydroxyapatite)
Can usually calcify osteoid up to 70-80% in 3-4 weeks
Makes bone strong and dense - nutritive fluids can’t diffuse freely through it

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69
Q

Osteoid weight

A

Before mature bone only forms ~25% of wet weight

In mature bone forms ~70%

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70
Q

Osteoblast - osteoid - calcification rate

A

Quite fast to begin with, but as time goes on, water is displaced (needed to bring nutrients in and take waste out), so rates start to drop off quite significantly
Can take years to fully calcify bones since removing water

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71
Q

Bone - nutrient diffusion

A

Bone is quite poor in nutrient diffusion because low water count

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72
Q

Osteocyte - precursor

A

Osteoblast

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73
Q

Osteocyte - location

A

Trapped within lacunae inside bone
Can communicate with neighbouring cells through their long cellular processes inside canaliculi - helps maintain contact with neighbours and cells on surface

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74
Q

Osteocyte - function

A

Bone tissue maintenance:

  • live lattice inside bone that maintains microenvironment to make sure bones are healthy and can release signals
  • localised minor repair
  • rapid Ca exchange
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75
Q

What do osteocytes occupy

A

Occupy little spaces called lacunae

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76
Q

Osteoclast - precursor

A

Monocyte progenitor cells usually form WBCs, but can also move out of blood vessel (BV) and a collection of them can gather on surface of bone and fuse –> osteoclast

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77
Q

Osteoclast - location

A

At sites where bone resorption is occuring

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78
Q

Osteoclast - function

A 
Secretes acid (which dissolves mineral/hydroxyapatite of bone, exposing collagen) and enzymes (which dissolves organic components/collagen of bone)
These enzymes are inactive until they're exposed to the acid environment underneath the cell
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79
Q

Syncytium

A

A cell formed from fusion of other cells

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80
Q

Osteoclast - size

A

Big cell in comparison to others

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81
Q

Osteoclast - ruffled border

A

Very corrugated/convoluted membrane for absorption and secretion

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82
Q

Osteoclast - clear zone

A

Sucks cell onto surface and makes sure the acids and enzymes don’t get out and destroy other areas of body

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83
Q

Osteoclast - how can minerals / organic compounds get out of the clear zone

A

The only way is to be endocytosed into the cell and be neutralised
Then can get exocytosed out of cell
i.e. dissolves product and ejects it out the top of cell

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84
Q

Osteoclast - Howship’s lacunae

A

Like little pits

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85
Q

Osteoclasts are often found in…

A

Groups

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86
Q

Osteoclasts - nuclei

A

Multiple nuclei

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87
Q

Mineralised bone - structure

A

Lattice network

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88
Q

CT growth

A

A lot of CT undergoes interstitial growth, but bone can’t grow like this

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89
Q

CT - interstitial growth

A

Cells divide mitotically and secrete ECM which grows the tissue from within

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90
Q

How does bone grow

A

Via appositional growth

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91
Q

Bone: Appositional growth - where

A

Adds bone on outside

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92
Q

Bone: Bone resorption

A

Occurs in inner layer to decrease thickness

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93
Q

Bone remodelling

A

Overall mechanism of appositional growth and bone resorption

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94
Q

When is bone remodelling occuring

A

Constantly occurring throughout your life

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95
Q

Appositional growth - steps

A

Osteogenic cells get signals telling them to divide –> osteoblasts, some of which settle on surface where we want new bone –> secretes osteoid and calcifies it
Since layer has more than osteogenic cells, it’s now active
Some osteoblasts bury themselves and become trapped in lacunae, eventually becoming osteocytes
When growth stops, osteoblasts convert back into osteogenic cells or die
Osteoid is fully calcified and we are back to resting state (only osteogenic cells)

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96
Q

Appositional growth - net effect

A

We put down layers of bone on the outside and growth occurs outwards

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97
Q

Appositional growth - where

A

On existing surfaces

Mostly in periosteum, but can occur anywhere else

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98
Q

Lacunae - calcification

A

Walls of lacunae aren’t as calcified as central parts of tissue because osteocytes are exchanging with walls of lacunae

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99
Q

Osteocytes - how do they align

A

A lot of osteocytes tend to line up in rows

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100
Q

Bone resorption: Venules

A

Since blood is flowing slowly through them and the wall is thin, it’s easy for WBCs to wriggle through the wall

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101
Q

WBCs are ___ cells

A

CT

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102
Q

Bone resorption - steps

A

Messages from osteocytes cause monocyte precursor cells to leave BV and fuse on bone surface to form Howship’s lacunae (secretes acids and enzymes)
Once osteoclasts died, BVs grow into new area created by loss of bone - helps keeps cells alive

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103
Q

Osteoclasts - how long do they live

A

Relatively short-lived (2-3 months) and undergo apoptosis

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104
Q

Apoptosis

A

Self-destruction

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105
Q

Why can’t bone grow by interstitial growth

A

Bone tissue is too rigid; interstitial growth occurs in softer tissues that can deform
Bone is designed to resist deformation ,so can only grow by adding new bone onto existing surface (appositional growth)

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106
Q

Appositional growth and bone resorption occur ______ to each other

A

Independent

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107
Q

How do long bones grow in length

A

By a process called endochondral ossification

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108
Q

Long bones: Endochondral ossification

A

As cartilage plate gets thicker, the epiphysis moves away from the metaphysis
Cartilage in contact with metaphysis dies off –> gives osteoblasts the surface to put down bone and macrophages remove dead cartilage
Eventually rate at which cartilage grows is slower than rate of bone growth so epiphysis makes contact with metaphysis and the 2 surfaces fuse –> epiphyseal line

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109
Q

Is epiphysis fixed from bone to bone

A

No; a cartilage plate (made of hyaline cartilage) is found between it

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110
Q

Hyaline cartilage

A

Like a firm rubber, but can still undergo interstitial growth
Has chondrocytes in it that can divide and secrete more ECM

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111
Q

Why are males taller on average

A

During endochondral ossification, the fusion of the epiphysis and metaphysis usually ends earlier in females

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112
Q

Appositional growth and bone resorption - ratio

A

Baby: higher ratio of appositional growth
Our age: similar ratio
About age 30: rate of bone resorption starts to increase relative to appositional growth - this is why elderly have brittle bones

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113
Q

What affects how brittle your bones are when you’re older

A

How strong/dense they are in your younger years

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114
Q

2 main bone types

A

Woven/immature bone

Mature/lamellar bone

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115
Q

Woven bone - structure

A

Collagen fibres are wavy
Less densely packed and ECM is less dense
Not as strong as mature bone

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116
Q

Woven bone - babies

A

Born with woven bone because doesn’t need to be very strong when embryo
But when born and start crawling/walking, bone needs to strengthen
~3 years old, you’ve replaced all your woven bone with mature lamellar bone

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117
Q

When do we find woven bone in adults

A

When we break a bone

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118
Q

Mature/lamellar bone: What’s found between the fibres

A

Hydroxyapatite

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119
Q

Mature/lamellar bone: Bending

A

Inner surface is put under compression, whereas outer surface has tension

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120
Q

Mature/lamellar bone: Collagen arrangement

A

Typically put down in same direction within a layer, but can alternate up to 90° out of phase between layers
Enables bone to withstand forces from diff directions –> stronger
No matter which way you bend your bone, some fibres are going to be under tension

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121
Q

Types (subcategories) of mature/lamellar bone

A

Spongy bone

Compact bone

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122
Q

Spongy bone AKA…

A

Cancellous bone

Trabecular bone

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123
Q

How much of our skeleton is spongy bone

A

Usually 20% (less dominant)
But can change depending on where the bone is
e.g. long bone doesn’t have lots of compression; ~10%
Vertebrae ~40%

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124
Q

There is more spongy bone where there is more…

A

Compression

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125
Q

What are trabeculae covered in

A

Since they’re inside the bone, they’re covered in endosteum

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126
Q

What do you find on the surface of trabeculae

A

Osteoclasts

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127
Q

Spongy bone vs compact bone - SA

A

SA of spongy bone is significantly greater than SA of compact bone

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128
Q

Osteoporosis - females

A

One of the things that controls osteoclasts is oestrogen levels
Females go through menopause –> oestrogen levels drop –> decreased regulation of osteoclasts
Therefore females tend to be affected by this disease more

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129
Q

Osteoporosis - males

A

Males aren’t affected as much because testosterone and its derivatives help control osteoclasts

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130
Q

Osteoporosis - what happens / symptoms

A

Osteoclasts dissolve spongy bone in particular because high SA and high turnover
Makes bone look more porous/spongy

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131
Q

Spongy bone - direction of growth

A

Can only grow outwards, so newest lamellae is on the outer edge

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132
Q

Spongy bone - blood vessels

A

Blood vessels transport O2 and nutrients which are picked up by cells on surface of trabeculae

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133
Q

Spongy bone - narrowest dimension

A

0.4mm - can get quite a long/flat trabeculae as long as smallest dimension doesn’t exceed this length
Bone tissue is poorly hydrated so nutrients can’t move through tissue well
If trabeculae too thick, cells in centre won’t get enough nutrients

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134
Q

Compact bone AKA…

A

Cortical bone

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135
Q

Compact bone - thickness in diaphysis

A

Particularly thick

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136
Q

Spongy bone vs compact bone - thickness

A

Compact bone much thicker because it has blood vessels running through it which originate in periosteum

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137
Q

Compact bone - blood vessels

A

Originate in periosteum and send these branches through to Volkmann’s canals (perpendicular to surface)
Then link with other BVs that run parallel with surface (central/Haversian canal)

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138
Q

Compact bone: Haversian vs Volkmann’s canals

A

Haversian canals usually have concentric lamellae around them whereas Volkmann’s canals don’t

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139
Q

Compact bone: What do Haversian canals mark out

A

The centre of the unit that defines compact bone - the osteon

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140
Q

Osteon AKA…

A

Haversian system

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141
Q

Compact bone: Osteon - structure

A

Central canal with blood vessels running through

Concentric lamellae alternating between layers

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142
Q

Compact bone: Osteon - under force

A

If subjected to a common/predominant force that’s usually in one direction, collagen fibres between layers may be less extreme in alternation and line up better
If exposed to forces in diff directions, collagen fibres will become more at 90° to each other

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143
Q

Spongy bone vs compact bone - nutrient flow

A

Spongy bone: trabeculae had nutrient flow inwards

Compact bone: blood vessels are in centre so nutrient flow is outwards

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144
Q

Compact bone: Circumferential lamellae

A

Run around the perimeter of bone

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145
Q

Compact bone: Appositional growth in periosteum

A

Adds layers of circumferential lamellae

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146
Q

Compact bone: How are primary vs secondary osteons formed

A

Primary: Appositional growth
Secondary: Osteoclast activity

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147
Q

Compact bone: Formation of primary osteon - steps

A
  1. Osteoblasts in periosteum either side of a BV put down new bone, forming ridges
  2. As bone grows, the ridges come tgt and fuse –> tunnel around BV. Tunnel is now lined with endosteum
  3. Osteoblasts in endosteum build concentric lamellae onto walls of tunnel, which is slowly filled inward toward centre –> new osteon
  4. Bone continues to grow outward as osteoblasts in periosteum build new circumferential lamellae until you have a small hole just big enough to fit the BV and some soft tissue
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148
Q

Compact bone: Formation of primary osteon - how quickly is bone put down (in step 1)

A

Initially puts it down quite rapidly, but growth slows down when ridges form

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149
Q

Differences between periosteum and endosteum

A

Very similar

Main difference is periosteum is thicker because it’s needed for protection and attachment

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150
Q

Compact bone: Why do we need secondary osteons

A

Because there aren’t enough periosteal BVs to account for every osteon in compact bone
So, we need a way to develop an osteon in bone that’s already existing - secondary osteon does this

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151
Q

Compact bone: Where are secondary osteons created

A

Inside the existing bone

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152
Q

Compact bone: How do primary osteons differ from secondary osteons

A

Primary osteon: tunnel is created on surface of a bone it grows
Secondary osteon: tunnel is created inside the existing bone

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153
Q

Compact bone: Formation of secondary osteons - steps

A
  1. A group of osteoclasts bore a tunnel through existing bone - this area is called the ‘cutting cone’
  2. Osteoblasts move in behind the cutting cone, forming the new active endosteum, and start depositing osteoid onto wall of new tunnel. Osteoid layer is calcified –> new lamella. BV grows into newly formed tunnel to supply cells
  3. New lamellae slowly closes in tunnel - called the ‘closing cone’. Some osteoblasts are trapped in newly deposited lamellae –> osteocytes
  4. When tunnel is reduced to size of a typical Haversian canal, osteoblasts die, or form osteogenic cells –> resting endosteum
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154
Q

Compact bone: Formation of secondary osteons - the ‘cutting cone’ creates…

A

A tunnel inside the existing bone

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155
Q

Compact bone: Formation of secondary osteons - cement line

A

Sometimes at the end of the formation, a line can be seen at the junction between the outermost lamella of the new osteon and the pre-existing older bone

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156
Q

Compact bone: What happens if osteocytes detect damage in bone they can’t repair themselves

A

They release chemical cues that cause osteoclasts to move into the area

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157
Q

Compact bone: Formation of secondary osteons - what is the cutting cone

A

A collection of osteoclasts that act as a cellular drill

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158
Q

Compact bone: Formation of secondary osteons - what is the cutting cone under the control of

A

Under control of osteocytes already trapped in bone

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159
Q

Compact bone: Formation of secondary osteons - which area is most likely to be damaged

A

Cutting cone

160
Q

Compact bone: Formation of secondary osteons - cutting cone speed

A

Quite slow, moves about 1mm every 20 days

161
Q

Compact bone: Formation of secondary osteons - glycoproteins

A

The first layer the osteoblasts put down at the junction between old and new osteon quite often have lots of glycoproteins

162
Q

Compact bone: Formation of secondary osteons - collagen arrangement

A

As osteoblasts put down new layers, they alternate the collagen orientation

163
Q

Compact bone: Formation of secondary osteons - how are the trapped osteocytes connected to each other

A

Via canaliculi and lacunae

164
Q

Compact bone: Formation of secondary osteons - closing cone; appositional growth in ______

A

Endosteum

165
Q

Compact bone: Is primary or secondary osteon more common

A

Secondary

166
Q

Compact bone: Formation of secondary osteons - maixmum size

A

Osteon can’t be bigger than 0.4mm

167
Q

Compact bone: Interstitial lamellae

A

Not defined / old lamellae

168
Q

Why do osteocytes tend to line up in rows

A

Tend to find osteocytes where the lamina is changing direction - rows

169
Q

Spongy vs compact bone - osteons

A

By definition, osteons present = compact bone

No osteons = spongy bone

170
Q

Osteons and age

A

Osteons harden with age –> imprint smaller than new bone

171
Q

Bone: X-rays

A

Bone has to be at least ~50% calcified for X-rays not to pass through it

172
Q

New vs older bone - osteon appearance

A

Newer bone: osteon is more complete (circle)

173
Q

Arthro-

A

Joints

174
Q

What is a joint / articulation

A

Any point where two/more bones interconnect

175
Q

Joint - compromise

A

Compromise between need to provide support (stability) and need to remain mobile (movement)

176
Q

Joints - functions

A

Movement
Force transmission
Growth

177
Q

Functional classification of joints

A

Synarthrosis
Amphiarthrosis
Diarthrosis

178
Q

Functional classification of joints: Synarthrosis

A

Immovable joint
Highly stable, low movement
Axial skeleton

179
Q

Functional classification of joints: Amphiarthrosis

A

Slightly movable
Medium stability, medium movement
Axial skeleton

180
Q

Functional classification of joints: Diarthrosis

A

Freely movable
Low stability, high movement
Appendicular skeleton

181
Q

Can joints be trained

A

Yes

182
Q

Joints: Function - what can affect movement

A

Soft tissue around each joint has big effect on flexibility - can stretch to get more movement
Bulk of tissue
Genetics
Age

183
Q

Age and ability to repair tissue

A

As we get older, our ability to repair tissue is harder

184
Q

What is the weakest part of the skeleton

A

Joints

185
Q

Joints: Function - growth - why do we need joints

A

Since bones can’t undergo interstitial growth, need natural breaks in bones to create areas of soft tissue that can undergo interstitial growth

186
Q

Functional classification of joints: Synarthrosis - ankylosis

A

Where joints disappear and bones fuse

187
Q

Functional classification of joints: Amphiarthrosis - vertebral column

A

As you go down the vertebral column, you’re adding load, so amount of movement in each intervertebral disc reduces as you go down the column

188
Q

Functional classification of joints: Which joint is damaged the most

A

Diarthrosis

189
Q

What is the most common joint

A

Synovial joints

190
Q

Synovial joints - restriction

A

Unlike other types of joints, they aren’t restricted by properties of a specific tissue
Apart from articular capsule, ends of articulating bones in a synovial joint are mostly free

191
Q

What type of joint is a synovial joint

A

Diarthrosis

192
Q

Synovial joints: Common features

A

Articular cartilage
Articular capsule
Joint cavity
Synovial fluid

193
Q

Synovial joints: Articular cartilage - what is it

A

A specialised type of hyaline cartilage (type of CT)

194
Q

Synovial joints: Articular cartilage - function

A

Protect ends of bones that come tgt to form a joint
Absorb shock
Support heavy loads for long periods
Provide a near frictionless surface when combined with synovial fluid

195
Q

Synovial joints: Articular cartilage - structure

A

Thin layer - typically 1-7mm thick

Attached to bone

196
Q

Synovial joints: Articular cartilage - degradation

A

Degradation of articular cartilage leads to arthritis

197
Q

Synovial joints: Where is synovial fluid found

A

In the joint cavity

198
Q

How much fluid do joints have

A

Just enough to lubricate them and keep the cartilage alive, but not excessive amounts (would cause problems)

199
Q

Types of cartilage in body

A

Fibrocartilage
Hyaline cartilage
Elastic cartilage

200
Q

Can bone absorb shock

A

No - it is hard so can’t absorb shock

201
Q

Synovial joints: Articular cartilage - how is it different from other soft tissues

A

Unlike many other soft tissues, it can endure long periods of compression

202
Q

Synovial joints: Articular cartilage - CoF

A

Coefficient of friction
A measure of how much friction 2 surfaces have when rubbed tgt
Joints v frictionless

203
Q

Why are joints so frictionless

A

Due to design of cartilage and synovial fluid

204
Q

Chondro-

A

Cartilage

205
Q

Synovial joints: Articular cartilage - what is it composed of (%)

A

Cells ~5%

ECM ~95%

206
Q

Synovial joints: Articular cartilage - cells

A

Chondrocytes

207
Q

Synovial joints: Articular cartilage - where do cells live

A

In lacunae

208
Q

Synovial joints: Articular cartilage - cells - function

A

Build, repair, maintain cartilage

209
Q

Synovial joints: Articular cartilage - cells - found individually or in groups

A

Depending on zone, can occur by themselves or in groups called nests

210
Q

Synovial joints: Articular cartilage - ECM - ground substance - fluid component

A

Water (and soluble ions) ~75% WW

Can move in and out of tissue

211
Q

Synovial joints: Articular cartilage - ECM - ground substance - solid component

A

Glycosaminoglycans (GAG)
Proteoglycans (PG)
Fixed inside tissue
Provides swelling and hydrating mechanism

212
Q

Glycosaminoglycans (GAG) - example(s)

A

Hyaluronic acid
Chondroitin sulphate
Keratin sulphate

213
Q

Proteoglycans (PG) - example(s)

A

Aggrecan

214
Q

Synovial joints: Articular cartilage - ECM - fibres

A

Collagen (type II) ~75% DW
Fixed inside tissue
Provides structural integrity to tissue
Specific zonation patterns

215
Q

Glycosaminoglycans (GAG) are hydrophobic/hydrophilic

A

Hydrophilic

216
Q

Why must cartilage be able to resist force

A

It has multiple forces subjected to it

217
Q

Cartilage - types of forces

A

Expansion
Compression
Shear

218
Q

Articular cartilage: Expansion

A

Lifts surface of cartilage away from bone

219
Q

Articular cartilage: Shear forces

A

Under extreme load, one surface can slide against another in one or multiple planes

220
Q

Articular cartilage - zones

A

Surface zone
Middle zone
Deep zone
Calcified cartilage

221
Q

Articular cartilage: Surface zone - thickness

A

5-10% of total depth of functional cartilage

222
Q

Articular cartilage: Surface zone - collagen fibres

A

Very fine and arranged parallel with surface - resists shear forces
Very tightly packed

223
Q

Articular cartilage: Surface zone - chondrocytes

A

Don’t have lots of space –> flat

224
Q

Articular cartilage: Surface zone - proteoglycans

A

Very few

Poke up through surface - help lubricate surface –> reduces friction

225
Q

Articular cartilage: Middle zone - thickness

A

40-45% thickness

226
Q

Articular cartilage: Middle zone - collagen fibres

A

Much thicker and less tightly packed

Orientated ~45 degrees to surface

227
Q

Articular cartilage: Middle zone - chondrocytes

A

Have enough room to pump up –> chondrocytes slightly larger

Sit inside lacunae between bundles of collagen fibres

228
Q

Articular cartilage: Middle zone - proteoglycan

A

From here is where we start to see proteoglycan content increase

229
Q

Articular cartilage: Deep zone - collagen fibres

A

Strong bundles

Run perpendicular to surface

230
Q

Articular cartilage: Deep zone - chondrocytes

A

Form stacks called nests

Likely to be undergoing division

231
Q

Articular cartilage: Deep zone - interstitial growth

A

Chondrocytes divide and put more ground substance between each other –> gap between them separates and chondrocytes move up

232
Q

Articular cartilage: Deep zone - proteoglycans

A

Highest PG content

233
Q

Articular cartilage: Tide mark

A

Junction between functional cartilage and 4th zone (calcified cartilage)
i.e. mix of normal and calcified cartilage

234
Q

Articular cartilage: Functional cartilage - zones

A

Top 3 zones; surface, middle, deep

235
Q

Articular cartilage: Tide mark - collagen fibres

A

Collagen fibres continue through tide mark and calcified zone

236
Q

Articular cartilage: When/where do collagen fibres anchor

A

Anchor themselves onto subchondral bone at osteochondral junction

237
Q

Articular cartilage: Calcified cartilage - thickness

A

5-10% of thickness

238
Q

Articular cartilage: Calcified cartilage - chondrocytes

A

Chondrocytes sit inside calcified lacunae - secrete hydroxyapatite

239
Q

Articular cartilage: Calcified cartilage - why do we need it

A

If went straight from a deformable tissue to a non-deformable tissue, would put lots of strain on junction between them
Calcified cartilage has properties of both - helps distribute shear force over bigger surface

240
Q

Articular cartilage: Calcified cartilage - proteoglycans

A

Low in PG, high in hydroxyapatite

241
Q

Articular cartilage: Osteochondral junction

A

Boundary between cartilage and bone

242
Q

Articular cartilage: Osteochondral junction - collagen fibres

A

Don’t go through osteochondral junction

243
Q

Articular cartilage: Osteochondral junction - proteoglycans

A

Rich in cement-like proteoglycans –> cement line helps stick cartilage onto osteochondral junction

244
Q

Articular cartilage: Osteochondral junction - structure

A

Very convoluted - increases SA for adhesion and makes it less likely to delaminate the cartilage off the surface

245
Q

Articular cartilage - age

A

Functional layers get thinner as we get older

Healthy joint has ~5mm cartilage in a joint, but in elderly may be ~2mm

246
Q

Articular cartilage: Middle and deep zone - proteoglycans

A 
Rich in proteoglycans
Causes swelling (water moves into these areas) --> hydration
247
Q

Articular cartilage - numb

A

Cartilage is avascular and aneural –> numb tissue

Important because it’s getting compressed often

248
Q

Articular cartilage - blood vessels

A

There’s occasionally subchondral BVs that come up from bone, but they don’t go further than the calcified zone

249
Q

Articular cartilage: Chondrocytes are nourished by…

A

Diffusion only

250
Q

Articular cartilage: What is a glycosaminoglycan (GAG) made up of

A

Repeating disaccharide units

251
Q

Articular cartilage: Monosaccharide - charge

A

Often have carboxyl groups / sulphate groups on them, so when put in solution, end up with a -ve charge

252
Q

Articular cartilage: Aggrecan

A

A common proteoglycan found in cartilage

253
Q

Articular cartilage: GAG - charges

A

When GAG compresses = lots of resistance from -ve charges - fundamental trait of cartilage
If you remove the load, it acts like a molecular spring

254
Q

Articular cartilage: Proteoglycan (PG)

A

Many GAGs attached to a protein core

-ve charges repel each other, so GAGs stand out like bristles on a bottle brush

255
Q

Articular cartilage: Large proteoglycan complex

A

Proteoglycans attached to a long hyaluronic acid chain

Can attach to collagen fibres

256
Q

Articular cartilage: What zones are the -ve charges found

A

Middle and deep zone

Attracts +ve ions

257
Q

Articular cartilage: Loading cycle - steps

A
  1. Recently unloaded cartilage
  2. -ve charges on repeating disaccharide units attract +ve ions into cartilage from joint space
  3. Increased ionc conc creates an osmotic P/gradient –> draws water into matrix –> cartilage starts to swell –> surface zone moves away from subchondral bone
  4. As cartilage swells, collagen is placed under tension. Eventually swelling F = tension F, and cartilage stops swelling = unloaded equilibrium. Pre-stressed tissue
  5. When load is introduced, the fluid component is squeezed out of cartilage back into joint space - lubricates joint
  6. Loss of fluid reduces V of cartilage = creep. Pushes -ve charges close tgt. Eventually compressive load will be supported by solid component and repulsion of -ve charges. Cartilage stops shrinking = loaded equilibrium
  7. Back to start
258
Q

Articular cartilage: Loading cycle - fixed solid component

A

Proteoglycan complex in matrix

259
Q

Articular cartilage: Loading cycle - mobile fluid component

A

Ca2+
K+
Na+
H2O

260
Q

Articular cartilage: What happens if you cut the collagen fibres in the deep zone

A

The cartilage will continue to swell

So, collagen is important for stopping it getting to its full V

261
Q

Articular cartilage: Arthritic finger joint - osteophytes

A

Bone growing in ‘weird’ places with the aim to increase contact area to reduce loading

262
Q

Articular capsule: All synovial joints are surrounded / enclosed by a…

A

Joint capsule, which forms a sleeve around the joint, connecting the ends of the bones

263
Q

Articular capsule - tightness

A

Needs to be suitably loose to permit joint to function properly
Can become tight at extreme limits of natural range of joint movement - protects from damage by excessive movement

264
Q

Articular capsule: Perforated by?

A

Vessels and nerves, and may be reinforced by ligaments

265
Q

Ligaments

A

Dense regular CT connecting bone to bone

Poor blood supply –> takes a while to repair

266
Q

Articular capsule - parts

A

Comprised of an outer fibrous layer and an inner synovial membrane

267
Q

Articular capsule: Fibrous layer

A

Outer layer of dense CT (regular and irregular)

Variable in thickness

268
Q

Articular capsule: Fibrous layer - collagen fibres

A

Made up of parallel and interlacing bundles of collagen fibres that are continuous with periosteum of bone

269
Q

Regular vs irregular fibres

A 
Regular = orientated in one direction
Irregular = orientated in diff directions
270
Q

Articular capsule: Fibrous layer - capsular ligaments

A

Thicker sections of the capsule

Resists predominant and tensional forces and check excessive joint movement

271
Q

Articular capsule: Fibrous layer - function

A

Supports synovial membrane

Protects synovial membrane and whole joint

272
Q

Articular capsule: Fibrous capsule - vascular?

A

Poorly vascularised but is richly innervated

This is why it hurts to sprain your joints

273
Q

Articular capsule: Fibrous layer - what is it made of

A

Fibroblasts (secretes collagen)
Nerves (pain and proprioceptors)
Blood vessels (usually transitory)

274
Q

Articular capsule: Synovial membrane

A

Inner layer of loose CT

Variable thickness

275
Q

Articular capsule: Synovial membrane - where is it found

A

Lines all non-articular surfaces inside joint cavity, up to edge of articular cartilage

276
Q

Articular capsule: Synovial membrane - layers

A

Intima

Subintima

277
Q

Articular capsule: Synovial membrane - intima

A

Thin

Normally only 1-3 cells (synoviocytes) thick; completely absent in some joints

278
Q

Articular capsule: Synovial membrane - intima - synoviocytes

A

Secrete some components found in synovial fluid
e.g. hyaluronic acid and glycoproteins - lubricate
Important for specialising synovial fluid

279
Q

Articular capsule: Synovial membrane - subintima

A

Highly vascular

Helps maintain and protect articular capsule

280
Q

Articular capsule: Synovial membrane - number of villi

A

Increases as we get older

281
Q

Articular capsule: Synovial membrane - function

A

Makes it slippery

282
Q

Articular capsule: Synovial membrane - intima vs subintima - density

A

Subintima not as densely packed

283
Q

Articular capsule: Synovial membrane - subintima - blood vessels

A

Lots of BVs - important for health of cartilage because they’re the closest BVs to the avascular tissue
Leak out fluid and create synovial fluid
Constant exchange

284
Q

Articular capsule: Synovial membrane - adipocytes

A

Can vary from not there to giant fat pads

Act like little cushions around joint to help reduce V of joint and cushion capsule

285
Q

Synovial joints: Joint cavity

A

The small area between the articulating surfaces

286
Q

Synovial joints: Joint cavity - peripheral margins

A

Filled by the collapsing and in-folding of synovial membrane (villi)
Contains a small amount of synovial fluid

287
Q

Synovial joints: Joint cavity - amount of synovial fluid

A

In a healthy joint cavity rarely exceeds 2mL

288
Q

Synovial joints: Synovial fluid

A

A clear / slightly yellow fluid that is an ultrafiltrate of blood plasma

289
Q

Synovial joints: Synovial fluid - pathway

A

Leaks out of BVs into synovial membrane (subintima) into joint space

290
Q

Synovial joints: Synovial fluid - free cells

A

Found in low conc

Monocytes, lymphocytes, macrophages, synoviocytes

291
Q

Synovial joints: Synovial fluid - function

A

Joint lubrication
Shock absorption
Chondrocyte metabolism
Joint maintenance

292
Q

Synovial joints: Joint cavity acts like…

A

Peritoneum

293
Q

In any given joint, about ____ of the cartilage is in contact with the opposing cartilage

A

Half

Other half is likely to be in contact with synovial membrane of joint capsule

294
Q

Synovial joints: Joint cavity - Why do we want to keep the amount of fluid between capsule and cartilage as low as possible

A

To aid exchange between BVs and synovial membrane

295
Q

Synovial joints: What happens if there’s too much fluid

A

Nutrients become diluted

296
Q

Synovial joints: What structures help fill in crevices of cavity to make sure there’s not too much fluid

A

Villi and fat pads

297
Q

Bones and joints - passive

A

Can’t generate movement themselves

298
Q

Muscle - push or pull

A

Muscle can only pull - doesn’t push

299
Q

Does muscle always contract

A

No - it’s a contractile tissue but doesn’t always contract

300
Q

Muscle - function

A

Convert chemical energy (ATP) into mechanical energy

301
Q

Muscle: Function - stability

A

Stabilise joints and maintain posture

302
Q

Muscle: Function - communication

A

Muscles are used for facial expression, body language, writing and speech

303
Q

Muscle: Function - control of body openings and passages

A

Some sphincters help control admission of light, food and drink that enter our bodies
Elimination of waste

304
Q

Sphincters

A

Ring-like muscles

305
Q

Muscle: Function - heat production

A

Skeletal muscle can produce up to 85% of our body heat (biproduct)
Used to maintain body at 37 degrees

306
Q

How much of our body mass is muscle

A

~40-50%

307
Q

Origin vs insertion

A

Origin: attachment that moves the least during muscle contraction
Generally closer to axial skeleton and more proximal, but can change depending on action
Insertion: attachment that moves the most during muscle contraction
Generally closer to appendicular skeleton and more distal, but can change depending on action

308
Q

Skeletal muscle: What is the contractile component

A

Muscle belly

309
Q

Skeletal muscle: Muscle belly

A

An organ made up of multiple tissues, including muscle tissue
Pulls on bones via tendons

310
Q

Tendons connect…

A

Muscle to bone

311
Q

Skeletal muscle: Tendon

A

Dense regular CT

Poor blood supply

312
Q

Skeletal muscle: Tendon - function

A

Strong and good at resisting tension

313
Q

Skeletal muscle: Myotendinous junction (MTJ)

A

Between muscle belly and tendon

One of the weaker areas of muscle organ

314
Q

Skeletal muscle: Which part is most often damaged when the muscle is strained

A 
Myotendinous junction (MTJ)
You do damage the muscle belly when you overwork it, but its highly vascular so it repairs itself quite quickly
315
Q

Skeletal muscle: Osteotendinous junction (OTJ)

A

Between tendon and bone

Very strong because lots of collagen fibres in tendon blend with collagen matrix of bone (Sharpey’s fibres)

316
Q

Skeletal muscle: Osteotendinous junction (OTJ) - under stress

A

If under extreme stress, it’s often not the junction that breaks, but the bone that comes away

317
Q

Skeletal muscle: Biceps - primary function

A

Flex the arm

318
Q

Skeletal muscle: How many attachments do muscles have

A

Most muscles have 2 attachments (origin and insertion) but some can have more

319
Q

Skeletal muscle - fundamental unit

A

Myocyte

320
Q

Skeletal muscle: Myocyte - size/length

A

Can be from mm to cm long

Size: 10-fold difference from min to max

321
Q

Skeletal muscle: Myocyte - nuclei

A

Many nuclei - up to 100

Are a syncytium

322
Q

Skeletal muscle: Myocyte - cell membrane

A

Unique cell membrane called sarcolemma

Conducts APs very quickly

323
Q

Skeletal muscle: Myocyte - sarcoplasm

A

Inside cell

Has a lipid reserve and myoglobin

324
Q

Skeletal muscle: Myocyte - myoglobin

A

A protein that can store O2
Not as good as haemoglobin (~4x more) but still gives cells an O2 store
Can function anaerobically but less efficient

325
Q

Skeletal muscle: Myocyte - vascular?

A

Very vascular tissue

326
Q

Skeletal muscle: Myocyte - strength

A

Quite delicate

327
Q

Skeletal muscle: Myofibrils

A

Contractile organelles that run the length of the cell

328
Q

Skeletal muscle - contractile unit

A

Sarcomere

329
Q

Skeletal muscle: Myofibrils - structure

A

Have sarcomeres next to each other, each of which is defined in its boundary by a Z-disc/band/line

330
Q

Skeletal muscle: Myofibrils - sarcomere arrangement

A

All arranged in series

When contract –> pulls Z-discs closer tgt

331
Q

Skeletal muscle: Myofibrils - sarcomere bands

A

A band = dark band in middle of sarcomere

I band = has Z disc running through it, and is shared by neighbouring sarcomeres

332
Q

Myo-

A

Muscle

333
Q

Sarco-

A

Flesh

334
Q

Myofibril, myocyte, fascile and muscle

A 
Myofibril = many sarcomeres
Myocyte/myofibre = bundle of myofibrils
Fascicle = bundle of myocytes
Muscle = bundle of fascicles
335
Q

Skeletal muscle: Fascicle - no of myocytes

A

Variable - can be a few or hundreds depending on muscle

336
Q

Skeletal muscle: Fascicle - endomysium

A

Loose irregular CT
Runs around myocytes and packages them within the fascicle
Supporting tissue
Allows capillaries and motor neurons to run down cell

337
Q

Skeletal muscle: Fascicle - what puts down the endomysium

A

Fibroblasts

338
Q

Skeletal muscle: Fascicle - BM

A

Immediately outside the sarcolemma is a BM which is partly secreted by myocyte and fibroblasts
A thin, specialised CT that blends with endomysium

339
Q

Skeletal muscle: Muscle - no of fascicles

A

Highly variable

340
Q

Skeletal muscle: Muscle - perimysium

A

Dense irregular CT bundling fascicles tgt
Thicker bundles of collagen and more dense
Bigger vessels

341
Q

Skeletal muscle: Muscle - epimysium

A

Dense irregular CT

Surrounds perimysium and entire muscle

342
Q

Skeletal muscle: Muscle - continuum?

A

Structures blend with each other

343
Q

Skeletal muscle: Order of layers (superficial to deep)

A 
(skin)
(superficial fascia / subcutaneous layer)
(deep fascia)
Muscle
Epimysium
Perimysium
Fascicle
Endomysium
Myocyte
Sarcolemma
Sarcoplasm
Myofibril
344
Q

Skeletal muscle: What does the deep fascia cover

A

Most of your muscles

345
Q

Fascia

A

A collagenous sheet-like material found all over the body

Often has regional names

346
Q

Skeletal muscle: Where is the deep fascia particularly important

A

Appendicular skeleton

347
Q

Skeletal muscle: Superficial fascia / subcutaneous tissue

A

Fatty layer under skin

Acts like a cushion and thermal blanket

348
Q

Skeletal muscle: Deep fascia - intermuscular septa

A

Where deep fascia comes away from outer layer and goes deep

349
Q

Septa

A

Wall / partition

350
Q

Skeletal muscle: Deep fascia - interosseous membrane

A

A piece of fascia that links 2 bones

351
Q

Skeletal muscle: Deep fascia - investing fascia

A

Intermuscular septa and interosseous membranes
A continuation of the deep fascia that leaves the outer wall and goes deep
Usually anchors onto deeper structures (often bone)

352
Q

Skeletal muscle: Deep fascia - compartments

A

Muscle in a limb often divided into compartments

Groups muscles with some commonality

353
Q

Skeletal muscle: Deep fascia - compartment - specificity

A

Epimysium is specific to that muscle, whereas deep fascia isn’t specific to a tissue

354
Q

Skeletal muscle: Deep fascia and epimysium

A

In most areas the epimysium can move and glide under deep fascia
Sometimes deep fascia will blend with epimysium depending on muscle

355
Q

Skeletal muscle: Deep fascia - compartment - common function

A

If you have a compartment with a common function, the other side of the limb will have a compartment that are antagonists

356
Q

Skeletal muscle: Deep fascia - compartment - supply

A

Muscles in a compartment often have the same blood and nerve supply

357
Q

Skeletal muscle: What is fascia made of

A

Collagen, which doesn’t stretch easily so if muscles in compartment contract, the belly expands
Veins have valves so if mucles contract –> compress veins against compartment –> aids venous return back to heart

358
Q

Skeletal muscle: Deep fascia - compartment - swelling

A

If excessive swelling, veins may be compressed so hard against the wall that they get occluded –> still have arteriole supply but drainage is affected –> edema
Usually happens in trauma

359
Q

Skeletal muscle: Deep fascia - type of CT

A

Dense CT (regular and irregular)

360
Q

Skeletal muscle: Deep fascia - When investing fascia comes in contact with bone…

A

It fuses with the periosteum

361
Q

Skeletal muscle: In some areas, the deep fascia is part of the ______ and can act as a an attachment point

A

Muscle tendon

362
Q

Hyperplasia

A

When a tissue or organ increases in size due to an increase in cell no

363
Q

Does skeletal muscle undergo hyperplasia

A

Not typically; they usually undergo hypertrophy

364
Q

Skeletal muscle: Hypertrophy

A

Increase in muscle size is due to increases in size of individual myocytes as more myofibrils are packed into each muscle cell

365
Q

Skeletal muscle: What factors can stimulate skeletal muscle hypertrophy

A

Repetitive contraction of muscles to near maximal tension (heavy resistance training)
Anabolic steroids

366
Q

Skeletal muscle: Anabolic steroids

A

Variants of testosterone

367
Q

Skeletal muscle: Anabolic steroids - function

A

Increase protein synthesis through interactions with specific target tissues, e.g. skeletal muscle and bone

368
Q

Skeletal muscle: Anabolic steroids - side effects

A 
Removes regulatory process of testosterone levels -->
Acne
Hair loss
Excess hair gain in wrong places
Liver failure
Shrivelled testes
Infertility
Increased susceptibility to coronary disease
Mood swings
369
Q

Skeletal muscle: What were anabolic steroids originally designed for

A

To help people who had diseases that caused their muscles to waste away - retards this process by overstimulating cells that manufacture protein

370
Q

Skeletal muscle: Atrophy

A

When the muscle decreases in size due to reduction of myofibrils in myocytes

371
Q

Skeletal muscle: Atrophy - when does it occur

A

When muscles aren’t used or stimulated by motor neurons –> can result in paralysis
Also as part of diseases, e.g. heart failure, diabetes, cancer, AIDS

372
Q

Skeletal muscle: Atrophy - when does normal loss of muscle mass start

A

Age of 20 years
Rate is accelerated after age of 50
By 80, ~40% of our muscle mass will be lost

373
Q

Skeletal muscle: Atrophy - is it reversible

A

If atrophy is not permitted to proceed too far, it can often be reversed
But, hypoplasia is not reversible

374
Q

Skeletal muscle: Atrophy - what is muscle replaced by

A

Fat and CT

375
Q

Skeletal muscle: Atrophy - hypoplasia

A

Where muscle loss occurs due to the loss of myocyte

Difficult to reverse

376
Q

Skeletal muscle: How are myocytes created

A

By fusion of many myoblasts during embryonic stage of life = syncitium

377
Q

Skeletal muscle: Myocytes - division

A

Since they contain many nuclei and are v large cells, can’t divide by mitosis

378
Q

Skeletal muscle: Formation of satellite cells / myoblasts

A

During formation of myocytes, not all myoblasts fuse

Some remain as individual cells –> satellite cells

379
Q

Skeletal muscle: Satellite cells / myoblasts - where is it found

A

They lie beside the muscle fibres, outside the sarcolemma but within the same BM

380
Q

Skeletal muscle: Satellite cells / myoblasts - division

A

They are the only cells in muscle that can divide (mitosis) and fuse with each other and myocytes to repair damage

381
Q

Skeletal muscle: Satellite cells / myoblasts - limited ability?

A

Have a limited ability to replace muscle fibres that die from old age or injury

382
Q

Skeletal muscle: At what age do you start growing your muscles

A

~8 weeks

383
Q

Skeletal muscle: How many myocytes do you have when you’re born

A

About the number of myocytes for your life

384
Q

Skeletal muscle: What are myoblasts

A

Cells that put down / build your muscle

385
Q

Denervation of skeletal muscle

A

Since many muscles have a dual nerve supply, if you lose one supply, the other one can try pick it up –> some myocytes become overstimulated –> lose fine control of muscle

386
Q

Myostatin

A

Turns off satellite cells

387
Q

Skeletal muscle: Recruiting myocytes as we need them allows for…

A

Smoother action

388
Q

Collagen fibres at MTJ blend with…

A

Collagen in the endomysium

389
Q

Tendon is an extension of…

A

Fused endo, peri and epimysium of muscle

390
Q

Deep fascia groups…

A

Muscles with similar function tgt

391
Q

What is the most abundant cartilage

A

Hyaline cartilage

392
Q

Alignment of osteons is along…

A

Lines of physical stress on a long bone

393
Q

Intrinsic ligaments

A

Thicker part of fibrous layer

394
Q

Bone with large amount of osteoid is likely to be…

A

More flexible

395
Q

What type of joint is most likely used for growth

A

Synarthrosis

MEDSCI 142 (9 decks)

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