Musculoskeletal Flashcards

1
Q

What are the 2 double meanings of bone?

A

Organ and tissue

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2
Q

What are the 6 functions of the skeletal system?

A

Support, protection, movement, calcium and phosphorus storage, haemopoiesis, fat storage

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3
Q

What percentage of the body’s calcium is found in bone?

A

90%

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4
Q

Where is the majority of red bone marrow located?

A

Around the axial skeleton

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5
Q

Where is the majority of yellow bone marrow located?

A

Around limbs/further from the centre of the body

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6
Q

What is the main function of the axial skeleton?

A

Support, protection and haemopoiesis

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7
Q

What is the main function of the appendicular skeleton?

A

Movement and fat storage

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8
Q

What are the 3 regions of long bones?

A

Epiphysis, metaphysis and diaphysis

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9
Q

How many axial bones are there?

A

80

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9
Q

How many named bones are there in the body?

A

206

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10
Q

How many appendicular bones are there?

A

126

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11
Q

What are the layers of bone from outer to inner in the diaphysis?

A

Periosteum, compact bone, endosteum

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12
Q

What are the layers of bone from outer to inner in the epiphysis?

A

Articular cartilage, compact bone, spongy bone

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13
Q

What is the centre of bone called?

A

Medullary cavity

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14
Q

What is spongy bone made of and what covers it?

A

Trabeculae, completely covered by endosteum

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15
Q

What connects the periosteum to the compact bone?

A

Perforating/Sharpays fibers

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16
Q

What 2 components make up ECM?

A

Fibres and ground substance

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17
Q

What type of fibres are found in bone?

A

Collagen

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18
Q

What do collagen fibres resist in bone?

A

Tension (stretching/pulling)

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19
Q

What is the ground substance in bone made up of?

A

Hydroxyapatite

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20
Q

What are the 4 cells that makeup bone in order from youngest to oldest?

A

Osteogenic cell, osteoblast, osteocyte, osteoclast

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20
Q

What does the ground substance in bone resist?

A

Compression (squeezing/crushing)

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21
Q

Where are osteogenic cells located?

A

On the surface of bone in the periosteum and endosteum, also found in central canals of compact bone

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22
Q

What is the function of osteogenic cells?

A

Normally dormant but can divide and supply developing bone with osteoblasts

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23
Q

Where are osteoblasts located?

A

In the layer under the periosteum or endosteum - wherever new bone is being formed

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24
Q

What is the function of osteoblasts?

A

Synthesis, deposition and calcification of osteoid (the ECM)

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25
Q

What is calcification?

A

When the osteoid becomes infiltrated with bone salts (hydroxyapatite)

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25
Q

What is the osteoid, and what does it consist of?

A

The ECM of bone/precursor matrix mainly consists of collagen (70%), also proteoglycans, proteins and water

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26
Q

Where are osteocytes located?

A

Within lacunae

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27
Q

What is the function of osteocytes?

A

Bone tissue maintenance, repair, Ca2+ exchange

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27
Q

Where are osteoclasts located?

A

At sites where bone resorption is occurring

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28
Q

What is the function of osteoclasts?

A

Secrete acids and enzymes, dissolve the mineral and organic components of bone

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29
Q

What does the medullary cavity contain?

A

Bone marrow

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30
Q

What is the endosteum?

A

Thin, inner fibro cellular layer lining the medullary cavity and trabeculae

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31
Q

What does the periosteum contain?

A

Blood vessels and nerves

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31
Q

What is the periosteum?

A

Outer, fibro cellular sheath which surrounds bone

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32
Q

What is the diaphysis made of?

A

Periosteum, compact bone, endosteum and medullary cavity

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33
Q

What type of force are trabeculae arranged to resist?

A

Perpendicular force

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34
Q

What is the epiphysis made up of?

A

Articular cartilage, compact bone, spongy bone, endosteum

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34
Q

What are perforating/sharpays fibres made of?

A

Thick bundles of collagen

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35
Q

What are the 2 components of all connective tissue?

A

Cells and ECM

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36
Q

What is the organic component of bone connective tissue?

A

Fibres - collagen type 1

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37
Q

What is the inorganic component of bone connective tissue?

A

Ground substance - hydroxyapatite

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38
Q

What is the osteoid?

A

The organic ECM (collagen) of bone initially laid down by osteoblasts prior to calcification

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38
Q

Overall, what force does the ECM of bone resist?

A

Torsion

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39
Q

What percentage of the osteoid is collagen?

A

70%

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40
Q

What makes up the osteoid layer?

A

Collagen, proteoglycans, proteins and water

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41
Q

What is a lacunae?

A

Small space in bone containing osteocyte

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42
Q

What does the acid secreted by osteoclasts dissolve?

A

Mineral components of bone e.g. hydroxyapatite

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43
Q

What are canaliculi?

A

Small canals through which osteocytes communicate with neighbouring cells using their long cellular processes

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44
Q

How do osteocytes communicate with other cells?

A

Through cellular processes running thorugh canaliculi

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45
Q

In what order do osteoclasts dissolve bone (organic or inorganic first)?

A

Inorganic hydroxyapatite then collagen fibres

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46
Q

What do the enzymes secreted by osteoclasts dissolve?

A

Organic component of bone e.g. collagen

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47
Q

What is the name of the ‘pit’ formed under osteoclasts after the bone is dissolved?

A

Howships lacunae

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48
Q

What is the ‘clear zone’?

A

Area/microbiome under osteoclast that ensures acid doesn’t escape and helps to anchor the cell

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49
Q

How long do osteoclasts live for?

A

2-3 months

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50
Q

What is thicker - the endosteum or periosteum?

A

Periosteum

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51
Q

How does bone grow?

A

Via appositional growth

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52
Q

Describe the process of appositional growth

A
  • Signal triggers osteogenic cells to divide, resulting in some of the daughter cells being pushed into the matrix and becoming osteoblasts
  • Osteoblasts lay down osteoid and calcify it
  • Some osteoblasts become trapped in lacunae, eventually forming osteoclasts
  • When growth stops, osteoblasts convert back to osteogenic cells or die - peri/endosteum goes back into resting state
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53
Q

Describe the process of bone resorption.

A
  • Monocyte precuser cells leave BV and start to fuse on bone surface forming syncytium/osteoclase
  • Osteoclasts start dissolving bone
  • Osteoclasts eventually die via apoptosis
  • Blood vessels grow into newly formed space in bone
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54
Q

What is the other type of growth that occurs in the body that bone cannot undergo?

A

Interstitial growth

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55
Q

Why can bone not grow via interstitial growth?

A

Because it is required to resist deformation

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56
Q

What 2 processes make up ‘bone remodelling’?

A

Appositional growth and bone resorption

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57
Q

How do long bones grow in length?

A

Endochondral ossification

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58
Q

Why can the epiphysis not undergo appositional growth?

A

Because it is covered in articulate cartilage

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59
Q

Describe endochondral ossification

A
  • Chondrocytes in the hyaline cartilage in the epiphyseal plate divide (interstitial growth), growing the cartilage and pushing the epiphysis away from the metaphysis.
  • Cartilage eventually dies, and osteoblasts place new bone as the ossification rate catches up to the cartilage growth rate
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60
Q

Where is the epiphyseal plate located?

A

Between the epiphysis and metaphysis - closes during puberty

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61
Q

What are the 2 types of bone?

A

Immature/woven & mature/lamellar

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62
Q

What are the 2 classes of mature bone?

A

Spongy (cancellous/trabecular) and Compact (cortical)

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63
Q

When is immature/woven bone seen?

A

Fetus - 3 years old and when a bone is quickly regrown e.g. broken arm

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64
Q

How does immature bone differ from mature bone?

A

Lower cell count, less dense, irregular collagen fibres

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65
Q

How is bone arranged in mature bone?

A

In sheets/layers called lamallae

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66
Q

What is the max width of an osteon or trabecula?

A

0.4mm

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67
Q

What is the max width of circumferential lamellae?

A

0.2mm

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68
Q

What are the 3 different organisations of lamellae in compact bone?

A

Circumferential, concentric and interstitial

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69
Q

Where are concentric lamellae found?

A

Osteons

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70
Q

Where are circumferential lamellae found?

A

Around the outer edge of the bone

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71
Q

What is the canal in which blood vessels run from the periosteum to central haversian canals?

A

Perforating/volkmanns canal

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72
Q

What are the 2 layers that make up the periosteum?

A

Outer fibrous layer and inner osteogenic layer

73
Q

Where are interstitial lamellae found?

A

Between osteons

74
Q

Describe the formation of a primary osteon

A
  • Osteoblasts in active periosteum put down new bome forming ridges around blood vessels
  • Ridges fuse (periosteum now endosteum)
  • Osteoblasts build bone inwards towards the centre of the canal
  • Bone continues to grow outwards as osteoblasts place circumferential lamellae
75
Q

Describe the formation of a secondary osteon

A
  • Osteoclasts form and gather in an area that needs remodelling
  • Osteoclasts begin to bore through existing bone creating tunnel inside bone - cutting cone
  • Osteoblasts move into newly formed tunnel and deposit osteoid/build concentric lamellae layers slowly filling tunnel in - closing cone. Some osteoblasts are trapped and become osteocytes
  • Eventually tunnel is reduced to size of typical haversian canal and osteoblasts lining the tunnel either die or revert back to osteogenic cells making up resting endosteum
76
Q

What are the percentages of compact bone and spongy bone in long bones?

A

90% compact, 10% spongy

77
Q

What component of mature bone are osteoclasts often found on and why?

A

Trabeculae as spongy bone can grow 5x faster than compacts bone - good Ca2+ source

78
Q

Where is spongy bone predominantly located in long bones?

A

Epiphysis

79
Q

What is the main function of spongy bone?

A

Support stress from multiple directions

80
Q

Where is compact bone predominantly located in long bones?

A

Diaphysis

81
Q

What is the main function of compact bone?

A

Support and protection

82
Q

What is the location of blood supply for spongy bone?

A

Blood vessels between trabeculae

83
Q

What is the location of blood supply for compact bone?

A

Blood vessels running through volkmanns and haversion canals

84
Q

Why are not all osteons primary?

A

There are not enough blood vessels for osteons to form around

85
Q

What is the cement line?

A

Line between newly formed secondary osteon and old bone

86
Q

What is the rate of bone resorption of the cutting cone?

A

1mm/20 days

87
Q

Approximately what percentage of our skeleton do we replace every year?

A

10%

88
Q

What is the unit of spongy bone?

A

Trabeculae

89
Q

What is the direction of unit growth in spongy bone?

A

Outwards

90
Q

What is the unit of compact bone?

A

Osteon

91
Q

What is the direction of unit growth in compact bone?

A

Inwards

92
Q

What percentage of connective tissue in bone is crystallised mineral salts?

A

50-60%

93
Q

What do tendons connect?

A

Muscle to bone

94
Q

What do ligaments connect?

A

Bone to bone

95
Q

What are the 3 main functions of joints?

A

Movement

Force transmission

Growth

96
Q

What is a joint?

A

Any point at which 2 or more bones interconnect

97
Q

What are the 3 functional classifications of joints?

A

Synarthrosis, amphiarthrosis, diarthrosis

98
Q

What are synarthrosis joints?

A

Immovable, highly stable, common in axial skeleton, for growth and force transmission

99
Q

What are amphiarthrosis joints?

A

Slightly moveable, medium stability, common in axial skeleton, e.g. intervertebral disks, force transmission

100
Q

What are diarthrosis joints?

A

Freely moveable, low stability, common in the appendicular skeleton

101
Q

What percentage of diarthrosis joints are found in the appendicular skeleton?

A

80%

102
Q

What functional class of joint are synovial joints?

A

Diarthrosis

103
Q

What is the most common type of joint?

A

Synovial

104
Q

What are the 4 common features of synovial joints?

A

Articular cartilage, articular capsule, joint cavity, synovial fluid

105
Q

What is the thickness of articular cartilage?

A

1-7mm

106
Q

What type of cartilage is articular cartilage?

A

Hyaline (specialised)

107
Q

What percentage of articular cartilage is cells?

A

5%

107
Q

What is the articular cartilage attached to?

A

Bone

108
Q

What are the functions of articular cartilage?

A

Protect ends of bones, absorb shock, support heavy loads for extended time periods, provide smooth and frictionless surface when combined with synovial fluid

109
Q

What cells are found in articular cartilage?

A

Chondrocytes

109
Q

Describe the cells in articular cartilage

A

Chondrocytes which build, repair and maintain cartilage

Live in lacunae

Live by themselves or in nests (depending on zone)

Secrete ECM

110
Q

What percentage of articular cartilage is ECM?

A

95%

111
Q

What 3 components make up the ground substance of the ECM in articular cartilage?

A

Water (+soluble ions), GAGS and PGs

112
Q

What fibre is present in the ECM of articular cartilage

A

Collagen - type 2

112
Q

What makes up the fixed solid component of articular cartilage?

A

PGs and Collagen fibres

113
Q

What percentage of the wet weight of articular cartilage is water?

A

75%

113
Q

What percentage of the dry weight of articular cartilage is collagen?

A

75%

114
Q

What percentage of the dry weight of articular cartilage is PGs?

A

25%

115
Q

What provides the swelling and hydrating mechanism for the proper function of articular cartilage?

A

GAGs

116
Q

What are 3 of the common GAGs found in articular cartilage?

A

Hyaluronic acid, chondroitin sulphate, keratin sulphate

117
Q

What is the common PG found in articular cartilage?

A

Aggrecan

118
Q

What are the 3 zones that make up the functional zone of articular cartilage?

A

Surface, middle and deep zones

119
Q

What zone of articular cartilage has the lowest PG level?

A

Surface zone

120
Q

What zone of articular cartilage has the highest PG level?

A

Deep zone

121
Q

What are the infoldings of the synovial membrane called?

A

Vili

122
Q

What is the junction between calcified cartilage and subchondral bone called?

A

Osteochondral junction

123
Q

What are thicker sections of the fibrous capsule called?

A

Capsular ligaments

124
Q

How are the chondrocytes in cartilage nourished?

A

By diffusion

125
Q

Where is the nearest blood supply to the articular cartilage?

A

In the articular capsule

126
Q

What is unloaded equilibrium?

A

When the swelling force = the tension force

127
Q

What is loaded equilibrium?

A

When the cartilage stops shrinking after load has been placed on it

128
Q

What is the fluid loss out of cartilage due to load known as?

A

Creep

129
Q

What are the 2 layers of the synovial membrane?

A

Intima & subintima

129
Q

What are the 2 layers of the articular capsule?

A

Outer fibrous layer and inner synovial membrane

130
Q

What does the synovial membrane line?

A

All non-articular surfaces in joint cavity

131
Q

What is the synovial membrane made of?

A

Loose connective tissue

132
Q

What is the fibrous capsule made of?

A

Dense connective tissue (irregular & regular)

133
Q

What cells make up the intima layer of the synovial membrane?

A

Synoviocytes

134
Q

What do proprioceptors do?

A

Monitor stretch and help us know the positions of our joints

135
Q

What do synoviocytes secrete?

A

Hyaluronic acid and lubricating proteins

136
Q

What does synovial fluid consist of?

A

Ultrafiltrate of blood plasma, hyaluronic acid, lubricating proteins, free cells (mono, lymph, macro, synovio)

137
Q

What are the functions of synovial fluid?

A

Shock absorption, joint lubrication, chondrocyte metabolism, joint maintenance

138
Q

Which is the larger GAG: keratin sulphate or chondroitin sulphate?

A

Chondroitin (125 units)

138
Q

What is the max volume of synovial fluid in the joint cavity?

A

2ml

138
Q

What does the tide mark indicate?

A

The boundary between the deep zone and calcified cartilage

138
Q

What is the outer fibrous layer of the articular capsule continuous with?

A

Periosteum of bone

139
Q

What is the most vascular layer of the articular capsule?

A

Subintima of the synovial membrane

139
Q

What percentage of body mass is skeletal muscle?

A

40-50%

140
Q

What are the 5 main functions of muscle?

A

Movement, stability, communication, control of body passages and heat production

141
Q

What is the junction between bone and tendon called?

A

Osteotendinous junction

142
Q

What is the junction between muscle and tendon called?

A

Myotendinous junction

143
Q

What are the layers of skeletal muscle in order from outer to inner?

A

Epimysium -> perimysium -> fascicle -> endomysium -> myocyte -> sarcolemma -> sarcoplasm -> myofibril

144
Q

What does the epimysium surround?

A

The entire muscle

145
Q

What does the perimysium surround?

A

Fascicles

146
Q

What are the epimysium and perimysium both made of?

A

Dense irregular connective tissue

147
Q

What is a fascicle?

A

Buncle of myocytes

148
Q

What does the endomysium surround?

A

Myocytes

149
Q

What surrounds myocytes?

A

Endomysium

150
Q

What is endomysium made out of?

A

Loose, irregular CT

151
Q

What contains the nerve and blood vessels supplying myocytes?

A

Endomysium

152
Q

What does a myofibril contain?

A

Sarcomeres

152
Q

What does a myocyte contain?

A

Sarcolemma, sarcoplasm, myofibrils

153
Q

What is the thickness range of myocytes?

A

10um -> 100um

154
Q

What does the sarcoplasm contain?

A

Mitochondria, myoglobin, glycogen

155
Q

What are deeper walls of deep fascia called?

A

Investing fascia

156
Q

What is deep fascia between 2 bones called?

A

Interosseous membrane

156
Q

What is deep fascia between muscles called?

A

Intermuscular Septa

157
Q

What is deep fascia made of?

A

Dense irregular and regular CT

158
Q

What is the outermost layer of muscle?

A

Epimysium

159
Q

What is hypertrophy?

A

Increase in muscle size due to increased number of individual myofibrils inside myocytes

160
Q

What are anabolic steroids?

A

Synthesized variants of testosterone

160
Q

What are 2 ways hypertrophy can occur?

A

Resistance training and anabolic steroids

161
Q

What are some of the side effects of anabolic steroids?

A

Acne, hair loss/growth, liver failure, shrivelled testes, infertility, mood swings, increased risk of coronary artery disease

162
Q

What is atrophy?

A

Decrease in muscle size due to reduction of myofibrils in myocytes

163
Q

What causes atrophy?

A

Lack of stimulation of muscle by motor neurons

164
Q

At what age does muscle loss become accelerated?

A

50

165
Q

What percentage of muscle is lost by 80 years?

A

40%

166
Q

At what age does normal muscle loss begin?

A

20

167
Q

What is hypoplasia?

A

Myocyte loss

168
Q

How are myocytes created?

A

Fusion of many myoblasts during fetal growth

168
Q

Myocytes contain many nuclei so are a…….

A

Syncytium

169
Q

How are satellite cells made?

A

Formed from unfused myoblasts

170
Q

Where are satellite cells located?

A

Outside the sarcolemma but within the basement membrane of myocytes

171
Q

What is the role of satellite cells?

A

Divide upon signal and fuse to form new myocytes to repair damage

172
Q

What are the 4 functions of skeletal muscle CT?

A

Organisation/scaffolding

Medium for blood vessels and nerves

Prevent excessive stretching

Distribute forces generated by contraction

173
Q

What protein helps to align sarcomeres between myofibrils?

A

Desmin

174
Q

What is the role of desmin?

A

To align sarcomeres between adjacent myofibrils

175
Q

How do the Z lines of the outermost myofibrils attach to the sarcolemma, basement membrane and enomysium?

A

Via protein complexes

176
Q

What are the protein complexes in myocytes responsible for?

A

Attaching myocytes and surrounding connective tissue

Strengthing the sarcolemma