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Flashcards in MidTerms 1 Deck (385):
1

When does the cartilaginous model begin ossifying

8 weeks

2

How come bone can repair itself

Due to high vascularisation

3

Is bone made of mostly ECM or mostly cells

ECM

4

What are the 2 types of extracellular components of bone

- organic
- inorganic

5

How much of ECM is organic?

6

How much of ECM is inorganic?

2/3

7

What is the organic component of ECM made of?

Collagen embedded in ground substance (proteoglycans)

8

How are the collagen fibres aligned in organic ECM

aligned in certain ways depending where forces coming from and to resist tension

9

What's in the ground substance of the organic component?

Proteoglycans

10

Function of organic component

Resist tension

11

What happens if organic component is removed?

Brittle/breaks easily

12

What is the inorganic component of bone made of

hydroxyapatite (mineral salts)

13

What gives the bone hardness

Hydroxyapatite

14

Function of inorganic component of bone

Resist compression

15

What happens if inorganic component removed

Too flexible = not good for support and movement

16

Role of OB

Build ECM

17

Role of OCytes

OB get trapped in ECM and mature into Octets
- mature bone cells
- important for COMMUNICATION in the remodelling process

18

Role of OC

break down ECM

19

Characteristics of OC

- multinucleated
- giant

20

What does compact bone look like at gross level

- outer surfaces seem impenetrable
- foramina/holes: nutrient foramen - provide blood (nutrients) to cells trapped in the compact bone at the microscopic level
- thickest in shaft
thin round head
for load bearing

21

What is compact bone for

Load bearing

22

Microscopic structure of compact bone

- osteon
- lamellae
- central canal
- lacunae
- canaliculi
- periosteum
- subperiosteal surface of bone

23

Function of Osteon

maintain Ocytes by providing nutrients
- need to bring blood from outside the bone in the gross level to Ocytes

24

Structure of osteon

longitudinal cylinder within compact bone
- foramen on outer surface of bone at gross level which gives opening for blood vessels and nerves to get into osteon systems

25

Function of lamellae

- resist forces
- resist tensile forces
- can resist tensile forces no matter which direction the force is coming from

26

Structure of lamellae

Tubes of ECM with collagen fibres aligned to resist forces
- form a series of cylinders running longitudinally down shaft = osteon
- sheaths of lamella = tubes of ECM
⅓ is collagen
- collagen fibres aligned different ways in each concentric tube to resist tensile forces

27

Central canal

Blood vessel and nerves

28

Lacunae

Lakes of OCytes

29

Function of canaliculi

Channels for Octets through ECM
- nutrient get between lakes
- allow cellular chemical communication between the octets, for the ocytes to communicate to OB and OC that remodelling of that osteon needs to occur
- penetrate lamella

30

Periosteum

Outer surface of bone

31

Structure of periosteum

Fibrous connective tissue sheath go around all surfaces of bone
- does not cover the ends where bones end to form a joint
- inserted into bone with fibres
- blood vessel goes through periosteum before it goes through the bone and into the osteon system

32

How is periosteum inserted into bone

with fibres

33

Subperiosteal surface of bone

where blood vessel penetrates

34

General overview of remodelling of compact bone (maintenance of normal, mature compact bone)

- osteoclastic front (multinucleate)
- break down ECM
- come through by blood as OCytes has communicated that remodelling needs to occur so OC come in
- OC destroy ECM
- left with void
- OB come and build ECM
- sheets of lamella formed by OB
- OB gets trapped in ECM and between sheets of lamella
sit within lacuna and aided in maintenance and survival by central canal that brings blood and nutrients diffused between lacuna by canaliculi

35

Where is cancellous bond found

At bone ends

36

Describe trabeculae

Struts of lamella bone
- sheets of ECM formed together and form honey comb network of trabecular

37

What fills the cavities in cancellous bone

Marrow
- red marrow fill gaps and form RBC

38

How are OCytes fed in trabeculae

Through direct communication with blood
- by blood that is formed and blood vessels penetrating the areas at the ends of the bones

39

Where are OCytes in spongy bone

Housed in lacuna on surfaces of trabeculae

40

How are OCytes arranged in spongy bone

Not arranged in concentric circles but the lacunae and OCytes are found in a lattice-like network of matrix spikes called trabecular
- each trabecular forms along lines of stress to provide strength to the bone
- the spaces in some spongy bones contain red marrow, protected by the trabecular, where hematopoiesis occurs.

41

Where are trabeculae found

More shock absorption

42

How are spongy bone and medullary cavity nourished

Receive nourishment from arteries that pass through the compact bone
- the arteries enter through the nutrient foramen
the OCytes in spongy bone are nourished by blood vessels of the periosteum that penetrate spongy bone and blood that circulates in the marrow cavities.


There are no blood vessels within the matrix of spongy bone, but blood vessels are nearby in the marrow spaces.
- exchange of nutrients, gases etc occurs between the capillaries in the marrow and the interstitial fluid of the marrow.
- the interstitial fluid extends into the canaliculi and thereby supplies the OCytes.

43

Are there blood vessels within matrix of spongy bone

NO

but blood vessels are nearby in the marrow spaces.
- exchange of nutrients, gases etc occurs between the capillaries in the marrow and the interstitial fluid of the marrow.
- the interstitial fluid extends into the canaliculi and thereby supplies the OCytes.

44

Organisation of trabeculae

- resist compression nada shock absorption
- trabeculae aligned in certain ways to diffuse those forces.

45

What is the zone of weakness

On the superior part of neck
- strengthening on inferior of neck to resist forces, but leaves area with less trabeculae

= area where trabecular do not cross at right ankles - less reinforcement by trabeculae = more potential for injury.

46

Human Tissue Act 2008

- bodies come from bequests, not condemned criminals or unclaimed bodies
- informed consent
- voluntary donation
- deceased person's wishes can be overridden by objections of surviving spouse or relative
- no referente to how long can keep body parts
- avoid unnecessary mutilation of body

47

What is the ECM made of

Water
proteins
proteglycans

48

Do tendons stretch during flexion

no

49

Does epithelial tissue have lots of or little matrix

Very little

50

Does connective tissue have lots of or very little matrix

Lots of ECM, containing fibres
- sparse cells

51

Role of nervous tissue

Conducting and supporting
- communication and coordination between body parts

52

Why are unicellular organisms limited in the types of environments they can successfully inhabit

Because their immediate surroundings must supply the appropriate nutrients and conditions

53

Conditions for life (unicellular)

- nutrients
- solute conc
- temperature
- pH
- toxins (including own wastes)
- lack of predators

54

What is the internal environment

ECF

55

Difference between ECF and ECM

The ECM comprises a complex system of non-living matter that is important to sustaining the life of the organism.

Extracellular fluid (ECF) bathes cells, and comprises the fluid component of the ECM

56

What does the external environment provide?

- source of nutrients
- site for waste disposal
- changeable
- pathogens

57

Proportion of ICF of total body water

2/3

58

Proportion of ECF of total body water

1/3

59

How much of ECF is ISF?

4/5

60

How much of ECF is plasma

1/5

61

What does ECF supply

Correct temp, pH, route for nutrient delivery and waste disposal etc

62

What does ECF also contain

Transcellular fluids contained within an epithelial lined spaces

eg synovial fluid in joints, ocular fluid in eye, CSF

63

Eg of transmembrane fluid

Synovial fluid in joints

64

Define homeostasis

The maintenance of relatively constant conditions in the internal environment (ECF) in the face of external (or internal) change

65

4 statements about homeostasis

1. In our bodies there are mechanisms that act to maintain constancy
2. any tendency toward change automatically meets with factors that resist change
3. there are co-operating mechanisms which act simultaneously or successively to maintain homeostasis
4. homeostasis does not occur by chance, but is the result of organised self-government

66

Main extracellular cation

Na+

67

Main intracellular cation

K+

68

Function of Na+

- determines ECF vol
- influences BP
- people with high BP shouldn't eat too much salt as ECM will inc. Part of ECM is plasma.
- important in AP generation in nerve and muscle tissue
- Na+ must come through specific channels


- ECF vol and therefore BP
- AP generation in nerve and muscle tissue

69

Normal conc of Na+ in ECF

135-145 mmol/L

70

Function of Ca2+

- impt structural component of bone and teeth
- involved in neurotransmission and muscle contraction
- essential for blood clotting
- regulates enzyme function (Ca2+ as a cofactor)
- muscle contraction

71

Which ion for AP generation in nerve and muscle tissue

Na+

72

Which ion for neurotransmission and muscle contraction

Ca2+

73

Which ion for blood clotting

Ca2+

74

Which ion as cofactor

Ca2+

75

Total plasma conc of Ca2+

2.2-2.6mmol/L

76

Function of glucose

- used by cells (Esp neutrons) to produce ATP. Neurons are particularly affected by low glucose levels
- high blood glucose causes other problems (both acute and chronic)

77

Fasting glucose conc

3.5-6mmol/L

78

Non-fasting glucose conc

3.5-8mmol/L

79

Function of K+

main determinant of RMP
- particularly important in excitable tissue i.e. nerve and muscle

80

Normal conc in ECF of K+

3.5-5mmol/L

81

Osmolarity of ECF and ICF

275-300 mosmol/L

82

normal pH range

7.35-7.45

83

What pH results in coma

below 6

84

Acidosis effect

- depresses nervous system
- neuronal function dec
- consciousness dec

85

Alkalosis effect

- "overexcitability" of nerve and muscle
- pins and needles
- muscle spasms
- convulsions

86

Core body temp

36 - 37.5°C

87

What is core body temp

Chest and head

88

How does oral and axillary temp differ from rectal (core) temp

0.5°C less than rectal

89

What happens at higher body temps

proteins denature

90

What happens at lower body temps

Chemical reactions slow down, preventing normal cell function

91

Body temp vicious cycel

As cells of nervous system become compromised, the ability to thermoregulate is lost -> viscious cycle. Detrimental positive feedback loop
- eg cold = neutrons can't properly control temp = colder etc

92

What does diffusion result from

the random movement of individual molecules as a consequence of their thermal energy

93

Relationship between distance travelled and time for diffusion

Distance travelled is proportional to square root of time
- four times as long to diffuse twice as far

- therefore diffusion is very rapid over short distances within cells and between cells and capillaries

94

Is diffusion effective within cells

Very rapid over short distances within cells and between cells and capillaries

95

Substances that can diffuse directly through the lipid bilayer of our cells

O2
CO2
Steroid hormones
Anaesthetic agents

96

3 types of channels

Leak
Ligand gated
Voltage gated

97

Example of carrier-mediated passive transport

Glucose entry into cells when insulin present
- glucose too large to get across cell membrane

98

What type of entry is glucose into cells when insulin is present

Carrier-mediated passive transport

99

What does the Na+-K+ pump maintain

- ionic gradients
- helps regulate cell volume

100

Eg of exocytosis

Secretion of insulin by beta cells of pancreas

101

Eg of endocytosis

Phagocytosis of microbes by neutrophils

102

When does osmosis stop

when water conc on both sides are equal. No net movement of water

103

Osmotic pressure

the pressure required to stop osmosis

104

How does water move in regards to osmotic pressure

Move from low osmotic pressure to a region of high osmotic pressure

105

What can differences in solute concentration across cell membrane cause

- fluid shifts
- and create pressure that can damage cells

106

Differences in solute concentrations across cell membranes can cause fluid shifts and create pressure that can damage cells

.

107

Osmolarity

Measure of the total number of solutes per litre of solution

108

Units of osmolarity

osmol/L

109

Osmolarity of ECF and ICF

275-300mosmol/L

110

Tonicity

the effect that solution has on cell volume

111

C and C tonicity and osmolarity

Osmolarity is a property of a particular solution (independent of any membrane)
- tonicity is a property of a solution with reference to a specific membrane

112

Spacial orientation of ICF, ISF and Plasma

ICF
ISF
Plasma

113

Osmolarity of ICF, ISF and Plasma

275-300mosmol/L

114

What happens if intravenous = water

Dilute plasma
- set up osmotic grad
- allow water to move into ISF = dilute ISF
- allow water into cells, through aquaporins, until equilibrium reached (osmolarity in all 3 compartments is the same)

115

Conc of normal saline

0.9%

116

Assumptions for calculating osmolarity

- NaCl completely dissociates
- particules move in the way we predict

117

What conc of normal saline is isosmotic and isotonic

0.9%

118

Is 300mosmol/L urea isosmotic and isotonic

Urea has conc equal to the solute conc inside cell = ISOSMOTIC
- but urea can diffuse across the plasma membrane (via transporters) because there is not much of the substances inside the cell (diffuse down its own conc grad)
- water will follow and enter the cell
- solution = hypotonic because its effect on cells is to cause them to swell
- but ISOTONIC

119

RMP

-70mV

-inside of a ell neg charged cf external surface

120

What does the RMP result from

the sep of a small number of oppositely charged ions across the lipid bilayer
- overall concentrations of ions in ICF and ECF are not significantly affected

- due to different concentrations of ions on each side of the membrane and their respective permeabilities to it.

121

What ion is the major determinant of RMP

K+

122

Why is K the major determinant of RMP

as the cell membrane is normally much more permeable to K+ than other ions

123

When is the RMP established

When the amount of K+ leaving the cell down its conc grad is balanced by that moving back in due to the electrical gradient.

eg start with cell with K+ inside only
- conc grad cause K+ to leave the cell
- electrical grad attracts K+ back in

124

What must the membrane potential do for excitable tissues (nerve and muscle)

The membrane potential must change in order for them to function
- occurs via opening or closing of specific channels

125

How does membrane potential change

via opening or closing of specific channels

126

Two diseases where excitable tissues can't function normally

- cardiac arrhythmias
- muscle weakness

127

What is the reference range

values of the regulated variable within acceptable limits

128

Why a reference range exists

For most physiological variables, body cells are
healthy over a range of values

• Within that range, predominantly gene.c factors determine different set points in different individuals (inter!individual varia%on)
• Varia%on may also occur within an individual (intra! individual varia%on)
" variables fluctuate around the set point in response to normal ac%vity (within the acceptable range)
- e.g. core body temperature, blood glucose, BP, etc

129

How is the reference range established

- healthy group of people
- values within 2SD of the mean are considered "normal"
- 95%
- 5% of healthy people may fall outside reference range

130

Interindividual variation

Genetic factors eg males vs females
age

131

Intraindividual variation (2)

- in response to normal activity (within the acceptable range)
- eg core body temp, blood glucose, BP

- in response to biological rhythms
eg hormones (but blood glucose isn't a biological rhythm)

132

Components of negative feedback

1. Sensor
2. Integrator
3. Effector
4. Communication pathways

133

Sensor

monitors actual value of the regulated variable

134

Integrator

- compares actual and set point values
- generates an "error signal" if any discrepancy between these
- determines and controls the response
- sensor and integrator can be the same cell

135

Effector

produce the responses that restores the regulated variable to its "set point"

136

Communication pathways

carries signals between components

137

Two physiological communications pathways

1. Neuronal
2. Hormonal

138

Neuronal Pathway

- involves AP in axons and neurotransmitter release at synapses
- electrical impulse travel down axon and release neurotransmitter at axon terminal. Bind to receptors on target tissues and bring response
- FAST
- SPECIFIC: bring response to a specific group of cells
- good for when conditions are changing rapidly and where an immediate response is required to prevent tissue damage or loss or homeostatic control
- good for brief responses

139

Hormonal pathway

- endocrine cell = any cell that produces hormones
- hormones released into blood (or ECF)
- targets ANY cells that have receptors specific (bind to receptors) for the particular hormone, so one hormone can potentially affect several tissues or organs
- good for widespread, sustained responses eg fluid volume regulation

140

Which pathway is good for widespread, sustained responses

Hormonal

141

What pathway is good for fast and specific responses

Neuronal

142

Where is the thermoreceptor/integrator

Hypothalamus

143

Responses for cold

Cold receptors in the skin detect decreased external temperature and then hypothalamus compares predicted value with set point = feed forward
- decreased core temp detached by the hypothalamus in the brain

- nerve impulses to muscles = shivering = generate heat = inc body temp
- nerve impulses to blood vessels in skin = vasoconstriction
- muscle = piloerection = hair follicles stand.

144

Responses for hot

- vasodilation - bring warm blood to surface = lose heat
- sweat (evaporate)
- conduction
- convection
- radiation

145

Effective heat loss mechanisms when environmental temp > body temp

Radiation, conduction, convection are NOT effective heat loss mechanisms when environmental temp > body temp
- only method of heat loss is sweating.

146

Feedforward

Involves detection or anticipation of external (or internal) conditions or situations that COULD alter a regulated variable (or disrupt homeostasis) if some sort of PRE-EMPTIVE ACTION was not taken
- integration center establishes a future "predicted value" for the regulated variable, compares this with the "set-point" and makes anticipatory corrections


eg cold receptors in skin detect decreased external temp and then hypothalamus compares predicted value with set point = feed forward

147

Two types of feedforward

- behavioural eg putting on a jacket
- physiological eg goosebumps

148

Positive feedback

- moves controlled variable further away from the "set point"
- vicious cycle
- useful when there is a specific end point or purpose

- must be carefully controlled to prevent inappropriate activation and to limit outcome

149

Examples of positive feedback

- childbirth: end point when baby born
- blood clotting: platelets sticking = release stuff that attract more platelets. Needs to be very well controlled to not clot bloodstream
- must be carefully controlled to prevent inappropriate activation and to limit outcome

150

Why does the body lose heat faster to water than air

Water has a much greater specific heat than air, so can absorb far greater quantities of heat.
- heat conductivity in water is very great in comparison with air.

- consequently the body loses heat to water faster than to air AND it is virtually impossible for the body to heat a thin layer of water next to the skin to form an "insulating zone" as occurs in air.

151

How long can skeletal muscle cells be

up to 40mm

152

How are muscle cells arranged

- parallel
- cylindrical
- striated - protein arrangement (form a repeated alignment of contractile proteins)
- sheath formed by TYPE 1 COLLAGEN: useful to create huge forces

153

Properties of muscle cells

Multinuclear
- cells merged
- nuclei pushed aside from the cells otherwise would be in the way of contractile mechanisms.

154

Structures of muscle

- myofilaments in sarcomere = thick and thin proteins
- myofibril
- myofibre/myocyte
- sarcomere (= protein arrangement)
- sarcolemma
- sarcoplasmic reticulum
- sarcomere
- muscle fibre bundle
- muscle belly
- fascia: summative term for all connectives between muscles. Can be extended to tendons.
- tendons consist of the same type of substructure as fascia
- bone also consist of type I collagen (protein)

155

Muscle sheaths

- single muscle fibre wrapped by endomysium
- fibre bundle wrapped by perimysium
- epimysium wrap the entire muscle (belly) all the way around

156

Importance of perimysium

Blood vessels and nerves

157

Sarcomere

- contractile unit
- 2 µm
- actin and myosin fibres: actin frame each of the sarcomeres, cannot be changed in overall length
- end-on-end along myofibril length
- Z - line
- boundaries of sarcomere
- link actin filaments

158

2 key proteins of muscle

actin and myosin
- jointly function to enable contraction

159

2 key metabolites for contraction

ATP and Ca2+

- active sites carry ATP and have small arms
- under the use of ATP, help muscle fibres to contract

160

Is myosin the thick or thin filament

Thick

161

Z line I line and A line

Z - connection between one sarcomere and the next
I - in polarised light looks same irrespective of how you look at it. Have actin only
A line - in middle from one end of myosin to another. Consist of end of actin and myosin

162

Function of muscle

- movement
- heat production: shiver = skeletal muscles 20-30Hz. Create a huge amount of heat for heating up body
- posture
- communication

163

frequency of muscle shivering

20-30Hz

164

What happens in muscle shortening

Thin drawn towards each other over thick
- Z lines move closer together (1µm apart)

165

Important factors for muscle contraction

- actin and myosin interdigitate
- actin and myosin retain their length: shortening come from actin moving relative to myosin
- process consumes energy
- Ca2+ essential

166

Muscle form determines function (3)

1. length of muscle fibres
2. number of muscle fibres
3. arrangement of muscle fibres

167

length of muscle fibres

- fibre can shorten up to 50% of resting length
- large ROM required means long muscle fibres needed

- length -> ROM

168

Number of muscle fibres

- tension (= force) is directly proportional to CSA
- greater number of fibres = greater CSA = grater tension
- origin at proximal
- insertion at distal

169

Arrangement of muscle fibres

Fibres oblique to muscle tendon
= pennate

- more fibres into same space
- reduced shortening but increased CSA
= FIBRE PACKING

170

Anatomical vs physiological CSA

- anatomical: cut muscle in standard anatomical plane = not representative of the max force the muscles can exert
- physiological CSA: muscles aligned to oblique = more force due to CSA = contract obliquely

- Anatomical CSA of straight and pennate are the same but physiological is different.
- higher for pennate

171

Do pennate fibres have more or less shortening and CSA

LESS shortening
MORE CSA

172

Pennate arrangement

- oblique to line of pull (uni-, bi-, multi-). Multi eg scapula eg rectus abdomens
- PSA for uni and bi and multipennate allows more fore than arranged longitudinally

173

Muscle tone

Even relaxed muscles are slightly active
- nerve impulses activating muscle fibres
- does NOT produce movement
- without nerves innervating muscles, can become hypertrophic or even atrophic
- synapses release ACh, which helps to depolarise the muscle cell to liberate Ca2+, thereby helping contraction

174

Function of muscle tone

Keeps muscles firm and healthy
- help stay metabolically active
- eg taking off cast = loss of proteins in muscle.
- become hypertrophic

- helps stabilise joints and maintain posture

175

Process of Synaptic transmission

1. Action potential reaches the end of the motor neuron
2. ACh released into the NMJ/synapse, which depolarises the muscle cell
3. ACh diffuses across synaptic cleft and binds to ACh receptors on the motor endplate of the muscle fibre
4. ACh receptors regenerate action potential (by allowing entry of Na+)
5. AP propagates into the T-tubules
6. Depolarisation of the T-tubule triggers Ca2+ release from the sarcoplasmic reticulum

176

2 fibre types

Fibre type I
Fibre type II

177

Fibre type I

- high enzyme activity
- aerobic, slow twitching: require O2 to stay active at all times
- eg for posture
- marathon runners

178

Fibre type II

- low enzyme activity
- anaerobic, fast twitching
- many contractions in a short time frame
- sprinters.

179

When does cartilage being to turn into bone

8 weeks

180

What is the process of transforming cartilage to bone called

Ossification

181

What does the cranial vault bones ossify from

Membranes, not cartilage

182

Where is the primary centre of ossification

Diaphysis

183

Where is the secondary centre of ossification

Epiphysis

184

Which centre ossifies first?

Epiphysis

185

Can there be more than one secondary center

yes

186

Function of secondary center

Bones meet at the ends at the joints
- those parts undergo different forces as we grow and move
- therefore need to develop separately to the primary centre

187

Epiphyseal plates

- made of cartilage
- as the bone grows in length, growth plate is continually turned into bone tissue
- at the top of growth plate = purely cartilage
- in the middle towards bottom, cartilage cells being transformed and destroyed by OB as OB's job is to reproduce bone tissue, so OB form more bone tissue below themselves (At the the bottom of growth plate)
- therefore, at bottom = bone
- as you go up its transforming into bone
- at top = cartilage
- in tibia, growth = upwards
- at distal end = downwards
- in xray, more bone can be seen (As cartilage doesn't show up)

188

Process of ossification (known..)

- known rate
- known sequence

- for estimating age
- for seeing if growth is normal
- eg which epiphyses should have been ossified at a certain age
- but difficult for different pop's due to different growth standards in different countries etc

189

How does bone grow in length

- occurs through childhood
- through epiphyseal plates
- during adolescence, hormonal surge = growth spurt
- drop in hormonal surge at the end of adolescent support = growth plates transform completely into bone

If bones just grow longer, then bone would be thin so the shafts of the long bones must also grow thicker at the same time they are getting longer -> moulding.

190

Growth in width/moulding

OB in periosteum inc width
- OB lay down new bone to the outside of the shaft at the sub-periosteal surface (surface under the periosteum)
- on inner layer of periosteum, there are OB -> lay down new bone tissue on outside of shaft

OB from endosteum mood the bone shape and form the medullary cavity
- remove bone where it needs to be removed
- inside of diaphysis
- in endosteum


Dead bone = empty cavity.
- shaft = tube of thick compact bone
- in adults, filled with yellow marrow
- in children = filled with red marrow (entire bone is filled with red marrow) due to rapid and continual growth in length and width and moulding. Need high vascularisation to allow the bone to continue to grow

191

Epiphyseal fusion

fusion of the epiphyses to diaphyses (After growth is complete)
- occurs at a known rate and sequence
- can use for estimating age in skeletal populations and forensics
- measuring whether growth is normal

192

Late fusing epiphyses

- medial clavicle
- pelvis (Esp impt for females, into early twenties)
- all growth complete mid-twenties

193

bone pathology

an imbalance of OB or OC activity

194

How is bone homeostasis maintained

- diet high in Ca2+
- moderate exercise
- Ca2+ homeostasis maintained by OC and OB etc

195

Osteoporosis

OC take over OB
- OC take away more bone than OB can produce

196

Process of osteoporosis

1. Compact bone become thinner and porous
- more vulnerable to fracture

2. Cancellous bone has a loss of volume
- COMPRESSION FRACTURES of vertebrae
- spine hunched as it is anterior

- trabeculae thinner as OC remove bone tissue
- fewer trabeculae

197

What happens to trabeculae in osteoporosis

- thinner as OC remove bone tissue
- fewer trabeculae

198

Causes of osteoporosis

- ageing- loss of estrogen, esp post-menopausal women
- lack of exercise: exercise stimulates bone cells to keep remodelling. Lack of exercise = don't get signals to continue remodelling. Astronauts -> atrophy
- nutritional factors: diet high in Ca2+
- peak bone mass - bone as a bank

199

Stage 1 fracture healing

Vascular damage initiates the highly regulated process

Lots of bleeding due to high vascularisation
Soft tissue damage
- haematoma (immediately)
hepatoma quickly becomes "organised", develops a firkin mesh, and transforms into a soft mass of granulation tissue containing inflammatory cells, fibroblasts, bone and cartilage forming cells and new capillaries.
- capillaries invade site and bring phagocytes
- phagocytes clean up debris

200

Stage 2 fracture healing

Been ends must be spliced so soft callus doesn't break. Correct alignment
- FB (can differentiate into other cells)
- chondroblasts (differentiated from fibroblasts)
- fibrocartilaginous callus ( pro callus). Helps to anchor the ends of the fractured bone more firmly, but offer no structural rigidity for weight bearing.
- approx 3 weeks

201

Stage 3 fracture healing

- bony callus. 6 weeks for OB top turn cartilage into bone
- OB invade cartilaginous callus
- bony callus lasts for 3-4 months

202

How long does it take for OB to turn cartilage into bone

6 weeks

203

How long does the bony callus last for

3-4 months

204

How long does the soft callus last for

3-4 weeks

205

Stage 4 of fracture healing

- remodelling
- back into osteon network of mature bone
- take a few weeks

- 6 months for complete remodelling

206

Can see bony callus?

Not in children. In adults, process slowed down = can see lump.

207

Pseudoarthroses

False joint
- ends of bones continue to move on each other if not fixed

208

Closed, simple

- minimal soft tissue damage
- not a lot of movement of bones on each other

209

Open, compound

- displacement of bone ends
- bone can penetrate skin = lots of soft tissue damage (muscles, nerves)
- if bone goes outside of skin = prone to infection

210

Greenstick

- not a complete discontinuation of the bone
- more common in children as their bones not as mineralised
- can get fractures though epiphyseal plate.

211

Intramembranous ossification

A few flat bones are formed within fibrous membrane, rather than cartilage, in the process of intramembranous ossification

212

Endochondreal Ossification

- The cartilage model of a typical long bone, such as the tibia, can be identified early in embryonic life
- the cartilage model then develops a periosteum that soon enlarges and produces a ring, or collar, of bone.
- bone is deposited by OB, which differentiate from cells on the inner surface of the covering periosteum.
- soon after appearance of the ring of bone, the cartilage begins to calcify, and a primary ossification centre forms when a blood vessel enters the rapidly changing cartilage model at the midpoint of the diaphysis
- endochondral ossification progresses from the diaphysis toward each epiphysis, and the bone grows in length
- the process is called INTERSTITIAL GROWTH
- eventually, secondary ossification enters appear in the epiphyses, and bone growth proceeds toward the diaphysis from each end.

until bone growth in length is complete, a layer of the cartilage, known as the epiphyseal plate, remains between each epiphysis and the diaphysis.
- during periods of growth, proliferation of epiphyseal cartilage cells brings about a thickening of this layer.
- ossification of the additional cartilage nearest the diaphysis follows, that is, osteoblasts synthesise organic bone matrix, and the matrix undergoes calcification
- as a result, the bone becomes longer.
- it is the epiphyseal plate that allows the diaphysis of a long bone to inc in length.

213

Epiphyseal plate structure

4 layers:
- cells closest to epiphysis is composed of "resting" cartilage cells. These cells are not proliferating or undergoing change. This layer serves as a point of attachment firmly joining the epiphyses to the shaft
- proliferating zone: composed of cartilage cells that are undergoing active mitosis. As a result to mitotic division and increased cellular activity, the layer thickens and the plate as a whole increases in length.
- zone of hypertrophy: composed of older, enlarged cells that are undergoing degenerative changes associated with calcium deposition
- ossification zone: thin layer composed of dead or dying cartilage cells undergoing rapid calcification. As the process of calcification progresses, this layer becomes fragile and disintegrates. The restyling space is soon filled with new bone tissue, and the bone as a whole grows in length.

214

Direction of length inc of epiphyseal plate activity

Grows upwards at the proximal end
- grows downwards at distal end.

215

Process of bone remodelling

- the first osteons formed in lamellar bone are called primary osteons.
- to form a primary osteon, OC in the endosperm that surrounds a blood vessel first demineralise a cone or tube around a blood vessel.
- this leaves a cavelike hollow filled with collagenous fibres and lined with endosperm
- OB in the endosperm then form layer upon layer (lamellae) along the inside wall of the tube, trapping OCytes between the lamellae.
- eventually, the concentric lamella run out of space to mineralise - leaving only the central canal with its tightly packed blood vessels, nerves and lymphatic vessels
- as bone develops, primary osteons are later replaced through the same process with secondary osteons.

Bones grow at their outer margins by the ossification of fibrous tissue by OB
- long bones grow in diameter by the combined action of OB and OC
- OC enlarge the diameter of the medullary cavity by eating away the bone of its walls
- at the same time OB from the periosteum build new bone around the outside of the bone.
- by this dual process, a bone with a larger diameter and larger medullary cavity is produced from a smaller bone with a smaller medullary cavity.

216

What is important in homeostasis of blood Ca2+ levels

- remodelling activity of OC and OB

217

What two processes balance each other out

Ossification and reabsorption proceed concurrently.
- these opposing processes balance each other during the early to middle years of adulthood.
- the rate of bone formation equals the rate of bone destruction.

During childhood and adolescence, ossification occurs at a faster rate than bone reabsorption. therefore bone grow larger


Older:
- bone gain occurs slowly at the outer, or periosteal surfaces of bones
- bone loss at endosteal surfaces and takes place at a somewhat faster pace.

218

Remodelling of trabecula

under mechanical stress, cancellous bone remodels its trabecular in different directions and thicker diameters to better withstand the stress.

219

Remodelling in compact bone

formation of new (secondary osteons) when bones are stressed.
- the higher the mechanical load on a bone, the narrower the tube hollowed out by OC as they prepare for new osteon.
- thus the bones that bear the greatest weight have the narrowest osteons.
- these narrower osteons also have denser mineralisation
the dense mineralisation along with more numerous, narrower osteons gives the bone great strength to resist the stress.

220

What is a joint

- hold bones together
- where bones meet = articulation
- involves bone shapes and soft tissues
- allow free movement/or control movement

221

Soft tissues associated with joints

- have no inorganic component
- cartilage:
1. fibrocartilage
2. hyaline/articular cartilage
- find hyaline cartilage between ends ribs and sternum, and cartilage model that the skeleton begins growing from
- growth plate is also hyaline cartilage

222

What type of cartilage is the cartilaginous model

Hyaline

223

What type of cartilage is growth plate

Hyaline cartilage

224

General cartilage composition

- collagen fibres in a ground substance. Collagen = protein. In FIBRES
- chondrocytes (produce ECM) live in lacuna
- nutrients diffused through by matrix by JOINT LOADING- i.e. not vascular

- osteon unit distribute nutrients to bone. Done by vascularisation
- for cartilage, only way nutrients can get diffused to the chondrocytes is by loading into the cartilage -> i.e. by normal movement of the body
- not vascular -> need to push tough tissue to stay alive. Can't regenerate like bone can.

225

Which cartilage has amorphous structure

Hyaline

226

Compare collagen fibre arrangement in hyaline vs fibro

In hyaline - collagen fibres barely visible
In fibrocartilage - collagen fibres form bundles throughout matrix

227

Which cartilage have more collagen

Hyaline has less collagen than fibrocartilage

228

How is collagen fibres aligned in fibrocartilage

- orientation of fibres aligns with stresses

229

Which type of cartilage has high water content in matrix

Hyaline

230

Function of hyaline cartilage

- resist compression only DUE TO HIGH WATER CONTENT
- resist compression ONLY, not tension (whereas fibrocartilage does resist compression)
- provide frictionless surface for movement of bones in synovial joints

231

Function of fibrocartilage

- resist compression (due to ground substance)
- resist tension AS WELL

232

Example of fibrocartilage

Meniscus of knee joint = concave discs of fibrocartilage
- deepens articulation at knee
- can adapt its shape to stresses on joint in movement

233

how does hyaline cartilage attach

Moulds to surface of the bones where they articulate

234

How does hyaline cartilage degrade

- degrades with age (lose water content, becomes friable and brittle) -> osteoarthritis
- degrades with trauma

235

Bony congruence

sum of the bone surfaces that form an articulation
- less BC = more soft tissue support
eg femoral head's entire head is covered by hip socket = less soft tissue support needed
- eg in shoulder, very shallow bony articulation = less bony congruence cf hip = more vulnerable to injury. Most of the support is from muscles

236

Meniscus of the knee location

Sit on top of the hyaline cartilage that's sitting on top of the bone

237

What is the meniscus

- concave discs of fibrocartilage
- deepen the articulation at the knee joint
- where femur articulates with knee is flat, therefore deepening of the articulation help stabilise knee joint
- can adapt shape to stresses on joint in movement
- anchored to bone on outer surface
- more loose on inside, able to move

238

Can the meniscus adapt shape to stresses on joint in movement

Yes

239

Inside of meniscus vs outside

- anchored to bone on outer surface
- more loose on inside, able to move

240

Force distribution over meniscus

- forces from above, through knee down tibia and into foot
- presence of meniscus = diffuse forces from above over a wider area over the tibia -> resist compression
- if removed = no cushioning, forces come into a smaller area of tibia = articular cartilage more likely to be damaged -> osteoarthritis

241

Cartilage in intervertebral disc

- cartilaginous joint
- anchored onto bone by a small ligament
- rings show how collagen is aligned = can resist tensile forces from all directions
- nucleus pulposus = fell-like, squishy ball bearing.
- can be compressed and can move with the movement of torso.

242

What is a slipped disc

Nucleus purposes gets squished out
- if tear is posterior, then impact on spinal cord
- if lateral, can impact on spinal nerves

243

What are ligaments and tendons made of

DFCT

244

DFCT

fibres as main matrix element.
- type 1 collagen
- crowded between collagen fibres are rows of fibroblasts that generate fibres.
- form strong, rope-like structures eg tendons and ligaments

245

How is collagen aligned in DFCT

in one direction

246

What are the cells that make up DFCT

Fibroblasts(cites) that mature into firbocytes.
- embedded in matrix

247

Function of ligaments and tendons

resist tension

248

Is there vascularity in ligaments and tendons

Some vascularity but minimal compared to bone
- therefore very slow healing compared to bone which is highly vascularised

249

Ligaments

Bone to bone

250

Function of ligaments

Restrict movement (inside and around joints)
- movement is restricted away from itself
- eg lateral restricts adduction
- eg medial restricts abduction
eg ankle: weight through ankle. Don't want ankle to move medially or laterally.

251

Do ligaments stretch

No.
- placed in such a way that restricts movement

252

How long for ankle repairmen (of ligament)

3 months to repair 50% of normal strength of ligament
- up to a year for 90%

253

Tendons

Muscle to bone

254

Function of tendons

On outside of muscle belly has fibrous sheath. Sheet merges into DCFT of tendon.
- tendon inserts into bone
- contraction of bone -> shortens -> pulls on tendon -> tendon pulls on bone. Occur because made of DFCT which will not lengthen if pulled on as it is to resist tension

Function = facilitates and controls movement
- contraction

255

Do tendons stretch

No
- it resists tension

256

How does over adduction affect ligament

Ligament pull away from bone = damage to bone as well
- evulsion fracture.

257

Another name for fibrous joints

Synarthroses

258

Another name for cartilaginous joints

Amphiarthroses

259

Another name for synovial joints

Diarthroses

260

What tissue makes up fibrous joints

DFCT
- function of DFCT is to resist tension

261

What tissue makes up cartilaginous joints

Fibrocartilage
- resists compression and tension

262

What tissue makes up synovial joints

All of the tissues
- hyaline cartilage
- fibrocartilage
- DFCT

263

What is the structure of fibrous joints

Ligament
- goes directly between 2 bones and articulates them and joins them together

264

What is the structure of synovial joints

- articular cartilage
- subchondral bone is smooth

265

Function of fibrous joints

limited movt/stability

266

Function of cartilaginous joints

Some movement
- special functions and various structures
- find where compressive forces and some movt between the bones

267

Function of synovial joints

Free-moving
- most limb joints

268

example of fibrous joints

- cranial suture (principal function is to protect the brain)
- distal tibiofibula joint (weight of body going through ankle -> don't want tibia and fibula to move apart = more vulnerable to injury
- between roots of teeth and jaw bone

269

Example of cartilaginous joints

- intervertebral disc = structure
- pubic symphysis = joint. Anterior of pelvic girdle
- need some movement because all forces go through posterior part of pelvic girdle, but still go to the anterior part. If had fibrous joint that does not allow any movement = more vulnerable to injury

270

Example of synovial joints

hip
knee

271

Structure of Synovial joints

- complex association of tissues and structures
- facilitation of free movement AND control of movement
- bone ends determine the range of motion at a knee joint


hip vs knee
- hip: lots of bony congruence due to hip socket = stable Less soft tissue support needed
- knee: fibrocartilage meniscus deepen the articulation and make up for lack of bony congruence. Lots of soft tissue support

- articular cartilage covers bone ends where they articulate AND move over each other
- subchondral bone is smooth (cf roughed areas where ligaments and muscles attach)

272

Capsular ligament/joint capsule function

Hold bones together
- go around and insert into the other bone

273

Structure of joint capsule

- tight and thick where more support is required
- thickening of capsule where more support is required
- losse and thin on sides where movement is allowed
- collateral ligaments of knee
- eg knee: thick tight ligaments on medial and lateral. Don't want tibia to move side to side on femur, but thin and loose on posterior and anterior aspects to allow flexion and extension.
- very thin and loose on shoulder joint, therefore support must come from other structures -> muscles

- potential space
- not a real space. If there is a space: due to trauma or synovial fluid being produced in response to trauma.

- synovial membrane lines the inner surface of the capsule and secretes synovial fluid = lubrication of joint

274

Collateral ligaments of knee

Medial restricts abduction
Lateral restricts adduction

eg phalanges also have collateral ligaments (part of joint capsule)

275

Function of intracapsular ligaments

- restricts movement between bones
- stop femur from moving anteriorly or posteriorly on the tibia
- eg going up stairs, femur slide off posteriorly tibia
going down, femur slide off anterior off tibia

276

Eg of intracapsular ligaments

- cruciate ligaments
- arise form tibia and insert into femur
- ACL restricts posterior displacement of femur
- PCL restricts anterior displacement of femur
- can be damaged from external forces: fixation of tibia but rest of body still moves eg skiing

277

What is meniscus made of

Fibrocartilage
- deepening articulation between femur and tibia
- diffuse compressive forces

278

Structural difference between fibrous joint and synovial joint

Fibrous joint and cartilaginous joints: tissues glue bones together to either stop movement entirely or allow some movement
Synovial - capsule goes from one bone to another. Leaves bone ends free to move over each other.

279

What is the reference range

The values of a controlled variable that is within an acceptable range

280

Where are hormonal signals transmitted

Via the blood stream

281

Type I diabetes mellitus

When the patient cannot produce insulin in response to stimuli

282

When does the diaphysis fuse to the epiphyses, hence ceasing vertical growth?

Adolescence

283

Does fibrocartilage have a high water content to resist compression

NO
hyaline does

284

Cells of DFCT

Fibrocytes/fibroblasts

285

Why is there a reference range rather than a single correct value

- within that range, genetic factors can determine different set points in different individuals
- set point may change in a regular way in response to biological rhythm
- body cells are healthy over a range of values
- variables fluctuate around the set point in response to normal activity (within an acceptable range)

NOT because different individuals have different levels of homeostatic strength

286

How does the hormonal communication systems work

Targeting by expression of specific receptors on target cells

287

What's the time frame for soft callus formation

3 days to 2 weeks

- fibroblasts differentiate into chondroblasts to form a fibrocartilaginous callus

288

What happens in remodelling of bone in middle-aged adult?

Ossification proceeds concurrently with resorption at equal rates.

289

How do OCytes in cancellous bone receive blood and nutrients

normal blood supply because OCytes are not embedded in a hard matrix

290

Purpose of menisci

To inc bony congruence in the joint
help with normal movement of the joint
to help stabilise the joint
to distribute weight over a large area

291

Function of T tubules

To conduct impulses into the muscle cell

292

In mid swing, the knee starts to extend. It is INITIALLY controlled by

Gravity

293

During mid stance what MAIN role does the quadriceps femoris play?

Stabilising

294

When human run, what is it called when both feet are on the ground?

No time when both feet are on the ground

295

Double stance

when both feet are on the ground

296

What mainly helps to keep us stable when standing (i.e. not falling over flat on our face)

Soleus

297

Two factors that determine peripheral skin temperature?

Room temperature and clothing

298

Muscle structure

- myofilaments in sarcomere (thick and thin)
- myofibrils
- myocyte
- sarcoplasmic reticulum
- sarcolemma
- muscle bundle
- muscle belly
- fascia

299

Epimysium

around entire muscle

300

perimysium

around muscle fibre bundles

301

important of perimysium

key structure to supply vascular supply and nerve supply to muscles
- allowing sliding of the muscle fascicles one relative to the other
- otherwise will have "shear off" phenomena and mechanical muscle destruction whenever contracts.

302

Endomysium

connect sheath around muscle fibre

303

Is myosin thicker than actin

yes

304

What is the human mscuoloskeletal system and its motion mainly based on

proteins
- muscle
- ligaments
- tendons
Not all of these proteins are contractile, but allow for locomotion.

305

What is muscle function largely driven by

nerves

306

Where do nerves that drive an excitation that causes a contraction sit?

at the ventral root of spinal cord
- must travel axon all the way down

307

How far does the axon go? (muscle)

only go as far as the proximal insertion of a muscle begins
- as proximal as possible
- to inc velocity of signal transduction
- to save material (to save material of axon)

308

What is the feedback of the NMJ provided by

- feedback provided by the spinal root and root ganglion (which sits slightly outside spinal cord)
- receives feedback of how the muscle is situated in space
- signals integrated from tendons and muscles are integrated via the nerves that are situated in the spinal root ganglion.

309

Transformation of signals

Electrical -> chemical -> electrical.

310

motor endplates

Com from axons of neurons
- for skeletal muscles, those axons are myelinated

311

Chemical signal diffusion

Diffusion signal takes a long time
- therefore at the outer surface of axon, have an electrical signal (time-saving mechanism)

312

Transformation of signal

Signal from spinal cord to the terminals of axons electrically
- electrical stimuli transmitted into neurotransmitters -> Ash (also for smooth muscle contractions as well)
- ACH in synaptic cleft can also become the site of neurological diseases -> myasthenia graves
- muscle cells, due to ACH, retransfers the chemical signal back to electrical, to twitch up to 30Hz

313

Cellular components involved in contraction

NMJ
Sarcolemma
T tubules (transport Ca2+ and make available in the muscle fibres so they can contract simultaneously)
SR
Ca2+

314

Why is Ca2+ so important for contraction?

Ca2+ is responsible for the ends of the myosin to make a movement to allow contraction
- movement of the ends of the myosin proteins (hundreds)
- Ca2+ bound in the ER when not contracting, but released upon contraction.

- tropomyosin between actin strands, which makes available myosin binding sites
- which cannot be attached unless Ca2+ is liberated

315

What does ATP and Ca2+ do?

Under the influence of ATP and Ca2+, the proteins, without changing length, approach each other, allowing muscle shortening.

316

What is the motor unit

all the muscle fibres being innervated by a single nerve fibre

- motor neuron
- axon
- branches
- plus ALL the muscle fibres it innervates

- size varies

317

Precise vs forceful contractions due to motor unit size

Eye muscles
- capable of making small, tiny movements
- tiny movements possible by a few fibres being innervated by a single motor neurone
- max of 30 fibres/motor neuron
- refined

Quadriceps femoris
- huge motor units
- up to 2000 fibres/unit
- forceful and powerful contraction
- huge force to ground and to joints

318

Myasthenia gravas

Neuromuscular disease
- auto antibodies act against receptors of ACh
- cannot open their eyes properly
- due to the eye of the muscles around the eye (huge number of muscle fibres) are using and wasting ACh within the synaptic cleft
- diplopia - seeing 2 images at the same time
- can't contract diaphragm -> being unable to breathe by themselves.

319

Displayed activation of fibres

Motor unit displays ALL or NONE activation of fibres
- different sizes of motor units = graded range of contraction
- how is the force of contraction of whole muscle then graded?

320

How is the force of contraction of whole muscle graded

- not only by the number of excitations from the nerve fibres
- also come from the number of fibres being excited to get a muscle contracted

321

What does the force of contraction of whole muscle depend on (3)

1. characteristics of muscle fibres: length, number, arrangement
2. characteristics of motor units: size, number, rate of firing that the motor neurone in the spinal cord generates
3. muscle attachments: size, number, rate of firing

322

Anatomical lever

bone = lever
- bones do not independently move without muscle
- for arm flexion, the ulna and radius are the bones that act as levers

joint = pivot

load = external or internal eg just your hand

muscle contraction = pull

323

Type I lever

pivot in middle between force and resistance

324

Type one lever function

Stabilise joint position
- prevent head drooping
- force of gravity on opposite side compared to muscle contraction

325

Type 2 lever

Axis -> resistance -> force

326

Type 2 lever function

effective at overcoming loads
- axis of motion is distant compared to both resistance and force
- resistance between axis and force

eg standing on tip toes
- balls of feet = axis
- achilles tendon = force
- ankle = resistance

327

Type 3 lever

Axis -> force -> resistance

328

Type 3 lever function

- large range of movement and speed
- force between resistance and axis
- huge lever

329

What allows a muscle to be lengthened

An opposing muscle or gravity
eg extension at elbow from a flexed position
- in most cases, an eccentric muscle or a neutralisation of a joint position is taking place by gravity
- eg jaw TMD drops during talking due to gravity, but contract actively back up.

330

Which muscle action involves the muscle being active and developing tnsion

Concentric
Static/isometric
Eccentric

331

Which muscle action involves a change in joint position

Concentric and eccentric

isometric does NOT result in a change in joint position

332

How does muscle length change for each of the muscle actions

Shortened in concentric
No change for isometric
Lengthened for eccentric.

333

Which type of lever allows for a large range of movement and speed

type 3

334

Agonist

- exert a certain movement at a certain joint position
eg BB shortens
- act concentrically

335

Antagonist

- opposes agonist
- supported by muscles on the opposite side on the relative joint
- TB -> lengthens
- act eccentrically

336

Stabiliser

- when a muscle is active to hold a joint STILL

eg holding a heavy book
BB = stabiliser
BB = isometric
no change in the length of BB

eg quads when standing
- do not have to sit on either side of the joint
- guide movement

- save energy

337

Neutraliser

Muscle eliminates an unwanted movement caused by another muscle
- can eliminate unwanted movement by another muscle (stabilising)
- but can also restore initial joint position without acting on the joint with large force

eg BB
- drinking from a glass
- flexion - yes
- supernation - no
"pronator" muscle neutralise supinating effect of BB

338

Functions of the skeleton

1. support
2. movement
3. protection
4. storage
5. RBC formation

339

Where is compact bone found

WHere strength and load bearing needed

340

Where is cancellous bone found

Where shock absorption is needed

341

Function of long bones

levers for movt

342

Function for short bones

weightbearing/shock absorption

343

Function of flat bones

protection - cranial bones
muscle attachemnt - scapula

344

Structure of long bone

longer than wide
diaphysis and epiphyses
thicker compact bone in shaft

345

Structure of short bones

near equal width and length
mostly cancellous bone

346

Structure of flat bones

thin plates of compact bone - some cancellous

347

Axial skeleton

Skull:
- cranium: frontal, parietal, occipital, temporal
- facial bone
- mandible

Vertebral column
- cervical (7)
- thoracic (12)
- lumbar (5)
- sacrum (5 fused)
- coccyx (2-5 fused)

Rib cage
- ribs
- sternum

348

Appendicular skeleton

- limbs
- regions: arm, forearm, thigh, leg

349

What is the upper limb designed for

Manipulation

350

What is the lower limb designed for

Stability and locomotion

351

Structure of limbs

single proximal long bone
two distal long bones
hands and feet

352

Attachment

pectoral girdle: clavicle and scapula
pelvic girdle: hip bones (2) and sacrum

353

Bones of forearm

radius and ulna

354

bones of leg

tibia
fibula

355

bones of hand

carpals (8)
metacarpals (5)
phalanges (3x 4 + 2)

356

Bones of foot

tarsals (7)
metatarsals (5)
phalanges (3)

357

Bursae

Synovial membrane and enclosed products.
if fully enclosed and independent of the joint, but still provides cushioning = bursae

- if it communicates = recess

358

Homeostasis of glucose

Pancreas: (Receptor/Controller)
Receives input (glucose level) and releases appropriate hormone

Liver (also muscle and body cells): (Effector)
Liver and muscle cells store or release glucose as appropriate, other body cells can take up excess glucose for use in respiration but can't store it

Blood system:
Transports hormones from pancreas, throughout body to liver, muscle and body cells



When we eat food, carbohydrates are digested and broken down into glucose.

This increases our blood glucose level
So the pancreas releases the hormone insulin, which allows the glucose to move from the blood into cells where the glucose is converted into ATP in the mitochondria (respiration), or converted to glycogen in the liver (and muscles) for storage.
Blood glucose drops, insulin production stops, no more glucose leaves the blood.


When we haven't eaten for a while or exercise, glucose is used up in cellular respiration.

This decreases our blood glucose level
So the pancreas releases the hormone glucagon, which allows to break down of glycogen in the liver and muscle cells into glucose which is released into the blood.
Blood glucose increases, glucagon production stops, no more glucose enters the blood.

359

What do growth plates allow

Provide a convenient means of allowing growth of a long bone without distorting the intricate shape at the joint surface.

360

Where does bone thickening and bone removal occur

Thickening of bone occurs at subperiosteal surface
Bone removed/resorbed by OC at the endosteal surface

361

How is bone removed

OC remove bone by releasing lysosomes and acid
- enzymes break down the organic part of bone tissue, and acid breaks down the inorganic part.

362

Factors predisposing to osteoporosis

Lack of biomechanical stress (lack of exercise, reduced gravity, paralysis)

Diet lacking in Ca2+

Cigarette smoking

Use of corticosteroids

Interference with oestrogen production

363

When does stage 1 occur

0 -3 days

364

When does stage 2 occur

3 days to 2 weeks

365

What is the soft callus made of

Fibrocartilage

366

how is the soft callus formed

Fibroblasts enter, produce collagen fibres
- some cells differentiate into chondroblasts

367

When does stage 3 occur

3-4 weeks

368

What happens in stage 3

OB transforms the fibrocartilage callus into a bony callus

369

What bone makes up the bony callus

cancellous bone

370

When does stage 4 occur

2-3 months

371

How long may remodelling take

up to 2 years

372

What influences final shape of bone

quality of "setting"
reduction of fracture

373

Does the thickness of epiphyseal plate change when bone lengthens

No.
- bottom layer of calcified cartilage becomes bone.
- bone added to diaphysis

374

Features of quadrupelda standing

Base of support
legs flexed at several joints
energetic expenditure

375

Features of biepdal standing

Relatively small area of contact
plantar surface of feet
energy efficient

376

Where is the line of gravity in relationship to hip, ankle and knee

Posterior to hip
anterior to ankle
anterior to knee

377

What happens to hip joint when standing

Joint pushed into extension
- extension = ligaments are tight = LOCKED
- capsular ligaments of the hip joint are spiral -> don't need contraction of quads or iliopsoas just when standing = prevent from falling back

378

Is the hip joint locked when standing

yes

379

What happens to the knee when standing

Joint pushed into extension
extension = ligaments are tight = LOCKED

380

IS THE KNEE JOINT LOCKED WHEN STANDING

YES

381

What happens to the ankle when standing

falls into dorsal extension
NOT LOCKED
plantar flexors stabiliser
energy consumed

382

Is the ankle joint locked when standing

NO

383

Is energy consumed at the ankle joint when standing

yes

384

bipedal stadngin summary

feet form base of support but insufficient size to provide only balance solution

- standing achieved with very little muscle effort - mot at ankle joint

- gait is characteristics

- gait is learnt.

385

when does primary ossification occur

when a blood vessel enters the cartilage model at the diaphysis