WEEK 1

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WEEK 1
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Lecture Plan

• Introduction (subject details)
• Tissues of the body
• Response of Tissues to loading
• Joints

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Introduction

• Rita Hardiman
• ritahardiman44_at_hotmail.com
• 0408 374 021

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Assessment

• Written assessment 60
• Multiple choice in-lecture tests 10
• Flagrace 30

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You should have

• These notes!
• Timetable
• Prac notes for week 1 and 2
• Aims and Objectives

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Tissues of the Body

• Subcutaneous tissue
• Deep fascia
• Muscles
• Tendons ligaments
• Bone
• Cartilage

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Subcutaneous tissue

• Loose areolar tissue
• Some muscular tissue
• fat

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Deep Fascia

• Varying degrees of development
• Spread of infection
• Muscle attachment

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Ligaments

• Inflexible and flexible
• Arranged not to be subjected to prolonged strain

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Tendons

• Collagen
• Cylindrical or flat
• Synovial sheaths

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Cartilage

• Hyaline
• Elastic
• fibrocartilage

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Muscles

• Unipennate
• Bipennate
• Multipennate

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Normal Bone Tissue.

• Osteoblasts, osteoclasts, osteocytes
• Bone matrix (collagen, hydroxy-apatite)
• Blood vessels.
• Cortical and Trabecular bone

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Functions

• protection
• mineral storage
• Movement
• Support

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Types of Bone

• cortical (approx. 10 porosity)
• Trabecular (approximately 80 porosity)
• Type of bone tissue present is closely linked
  with function

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Wolffs Law

• ...bone is laid down where needed and resorbed
  where not needed.
• - Dr. J. Wolff, 1892

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Myths

• Bone is
• Slow to react to damage
• A hard, rigid structure
• Relatively avascular

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Realities

• Bone is
• Highly vascular
• Quick to respond to stimuli
• Flexible
• Dynamic in its response to forces

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Bone Throughout Life

• Formation
• During growth
• Increasing bone mass
• Maintenance
• Maintaining skeletal tissue (repairing damage)
• Involution
• Decreasing bone mass
• Decreased ability for maintenance

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Bone Mass
Time
45 years
13 years
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Bone Mass

• The overall amount of tissue present in bones

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Bone Mass

• Environmental
• Genetic
• Physical activity

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Osteoporosis
Genetic Factors
PEAK BONE MASS
Menopause
Aging
Osteoporosis
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Response to Damage

• Signal reaches cells
• Cells respond to signal
• Remodeling/apposition/involution

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Remodeling

• Excavation by osteoclasts
• Lag period
• Bone deposition by osteoblasts

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Physical Activity

• Exercise must be weightbearing
• Weight lifting is useful
• Anything which places a stress on the bones

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Research

• Age-related
• Sex related
• mechanics

• Macroscopic
• Microscopic
• Molecular biology

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Studying Bone

• Fixed or not fixed
• Specimen location
• Storage
• Physiological loading
• Invasive testing
• Ethics

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Testing Bone Strength

• Composition
• Mechanical tests

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Composition

• Porosity
• ash percentage

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Finally
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Collagen Fibre Response

• Longitudinal fibres resist tension
• Horizontal fibres resist compression

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Next

• Vibration plates fuelled by space research
• Clinton Rubin
• 90 Hz
• The FASEB Journal 10 minutes per day of
  vibration therapy promoted near-normal rates of
  bone formation in rats that were prevented from
  bearing weight on their hind limbs during the
  rest of the day

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Considerations

• Loading of tissue / immobilisation of tissue.
• Wolffs Law applies not only to bone tissue.
• Your body is trying to save energy.
• Rate of adaptation depends on tissue metabolism.

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Response of Tissues to Loading
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Order of Adaptation

• muscle
• tendon
• ligament
• cartilage
• bone

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Types of Adaptation

• Training (hypertrophy)
• Immobilisation (atrophy)
• Remobilisation (?)

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Tendon

• Collagen (65-75 dry mass), elastin (2 dry mass)
  in a proteoglycan-water matrix
• Fibroblasts
• Exercise increases tensile strength, elastic
  stiffness and total weight.
• Increased proteoglycan-matrix and collagen
  synthesis.

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Tendon

• Collagen fibres increase in number and
  cross-links
• Three-dimensional arrangement moves into line
  with stress direction.
• Metabolic turnover of tendon is slower than muscle

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TIME and TRAINING
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Ligament

• Similar structure to tendons
• Training produces increased tensile strength,
  elastic stiffness and total weight
• Also improves the biomechanical properties of the
  ligament-bone junction

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Cartilage

• Remember no vessels or nerves
• Joint motion MAY accelerate nutrient distribution
  and waste removal
• Regularly repeated, slowly progressing exercise
  causes
• Enlargement of cells (chondrocytes)
• Proteoglycan content increases
• Cartilage thickness increases

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Cartilage

• If the training is too strenuous or
  biomechanically unfavourable
• Thinner and softer
• Proteoglycan content decreases
• Chondrocyte number decreases
• This degenerative change can be caused even by
  minor injury.

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Bone

• Low bone mass is a risk factor for fractures
• Maintenance of bone mass is a balance between
  bone formation and bone resorption- called
  remodeling
• Peak bone mass depends on genetic, mechanical,
  endocrine, and nutritional factors

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Bone Mass Maintenance

• Factors are interdependent
• Absence of physical training, nutritional input
  is useless
• Absence of nutritional input, training is useless
• Radius of tennis players
• Training has to be regular, long term and
  continuous- remodeling cycle is very long

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Immobilisation
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Tendon

• Immobilisation causes a slow atrophy
• Metabolic rate
• Collagen fibres become thinner and disorganised
• Cross-links become smaller in size and number
• Biosynthesis decreases

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Ligament

• Much the same as tendon
• Separation force generally declines
• Most studies focus on the anterior cruciate
  ligament

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Cartilage

• Alterations in fluid dynamics
• Decrease in water and proteoglycan content
• Soft chondral surface
• Chondrocyte cell death
• Periarticular osteophytes
• Early changes are reversible

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Bone

• Stimulation of resorption
• Depression of formation
• Bone mass decreases (volume)
• Hypercalcaemia
• Hypercalciuria
• Calcium loss 2 per month

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Bone

• 30 loss due to increased resorption
• 70 due to decreased formation
• Unoposed resorption
• Cortex becomes thinner
• Haversian canals increase in size
• Trabecular bone volume increases

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Conclusion

• Low initial loading is best for increasing
  adaptive changes
• Changes first seen in tissues with a high
  metabolic rate
• Energy conservation
• Initial changes are reversible

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Joints
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Types

• Fibrous
• Cartilaginous
• Primary
• Secondary
• Synovial joints

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Fibrous joints

• Surfaces joined by fibrous tissue
• Lower end of tibia and fibula for example

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Cartilaginous

• Primary bone and hyaline cartilage (epiphyses)
• Immobile and strong
• Secondary hyaline cartilage and fibrous tissue
  (symphysis)

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Synovial

• Synovial membrane
• Joint cavity
• Synovial fluid
• Hyaline cartilage
• Intra-articular fibro-cartilages

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