Biochem - Connective Tissue Flashcards by Jasmine Sappor

Types of connective tissue diseases

Sarcoma
Autoimmune
Congenital
Acquired

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Examples of autoimmune connective tissue diseases

RhA

SLE

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Examples of congenital connective tissue diseases

OI
Ehlers Danlos syndrome
Marfans

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Examples of acquired connective tissue diseases

Scurvy
OA
Tendinitis

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Characteristics of connective tissue

Highly specialised 
Mechanical support, movement 
Contains blood vessels, nerves
Arena for fighting infection 
Regulates cell behaviour

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Connective tissue components

Fibres
‘Ground substance’
Matricelluar proteins
Spp cells

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Connective tissue fibres

Collagen

Elastic fibres

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‘Ground substance’

Everything except collagen e.g. proteoglycans

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Spp cells found in skin, tendons and ligaments

Fibroblasts

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Spp cells found in cartilage

Chondrocytes

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Spp bones found in bone

Osteocytes (osteoclasts and osteoblasts)

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Structure of elastic fibres

Heavily cross linked

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Components of elastic fibres

Elastin
Fibrillins (1-3)
Fibulins
Matriculates Associated Glycoproteins (MAGP)

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Roles of elastic fibres

Structure

Regulation (growth factor signalling)

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Conditions caused by defects in elastin

Cutis laxa
Wiliams syndrome
Supravalvular aortic stenosis

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Conditions caused by defect in Fibrillin-1 (fibrillinopathies)

Marfan syndrome
Acromelial dysplasia
Stiff skin syndrome
Progeroid syndrome

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What is proteoglycan important for

Connective tissue material properties

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Features of proteoglycan

Variable in size
Confer viscoelastic properties
Hold water in tissue
Interact w. cells, cytokines and collagen

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Main structural component of connective tissue

Collagen fibrils

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Structure of collagen fibrils

3 alpha chains arranged in triple helix secreted into ECM

Each alpha chain is a single gene product

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Types of collagen

Type I
Type II
Type III
Type IV
Type V

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Type I collagen

Approx 90% of the collagen in the body is type I
Main component of bone, dermis, tendons and ligaments
Utilised in wound healing

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Type II collagen

Formed of copolymers

Main component of cartilage and is also found in the cornea and vitreous humour

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Type III collagen

Found in arteries and hollow organs, often in combination with type I
Also called reticular fibres

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Type IV collagen

Forms basement membrane

Type V collagen

Found in cell surfaces, placenta and hair | Helps organise type I collagen in the dermis

EDS is associated with a mutation in which type of collagen

Scurvy

Vit C deficiency | Shows importance of collagen hydroxylation

Presentation of scurvy

``` Bleeding gums Loss of teeth Skin lesions, bruises Poor wound healing Joint pain and weakness ```

What differs in each type of connective tissue

Collagen composition and organisation

Collagen composition in skin

60% Type I collagen | 30% Type II collagen

Organisation of collagen in skin

Meshwork of fibres

Collagen composition in tendon/ligaments

90% Type I collagen | 5% Type II collagen

Organisation of collagen in tendon/ligaments

Parallel fibres

Collagen composition in bone

90% Type I | 2% Type II

Organisation of collagen in bone

Sheets (lamella)

Collagen composition in cartilage

95% Type II collagen

Organisation of collagen in cartilage

Meshwork of fibres

Structural and biomechanical changes in OA cartilage

Loss of proteoglycans Collagen 'fibrillation' Enzymatic degradation

Common site of tendon pathology

Enthesis/ insertion as it is a region of stress conc

Common syndromes affecting enthesis

Tennis elbow Golfer's elbow Jumpers knee Osgood-Schlatters

Tendinopathy

``` A degenerative condn Loss of collagen organisation and reduced fibril diabetes Changes I collagen content Vascular (and nerve) infiltration Failure to repair ```

What mostly causes OI

Defects in Type I collagen genes

Type I OI

Mildest and most common form Quantitative defect Half the amounts of normal type I collagen

Type II OI

Most severe - death in utero Qualitative defect - missense mutation Abnormal Type I collagen

EDS types

``` Classical Benign hyper mobility Vascular Kyphoscoliosis Arthrochalasia Dermatosperaxis ```

Dx of EDS (& other genetic condns)

``` Detailed clinical and family hx Physical examination Skin biopsy and histology Biochemical analysis e.g. culture and urine analysis Molecular analysis of spp genes(s) ```

Treatment of EDS and connective tissue disorders

Vascular damage is most important complication Control risk factors Drugs

Controlling risk factors as treatment for connective tissue disorders

Healthy lifestyle Protection (bandages, splints, padding) Avoidance of contact sports and heavy exercise Supplementation of vitamin c

Drugs to treat connective tissue disorders

Beta blockers may reduce aortic dilation

Why should NSAIDs and aspirin be avoided when treating connective tissue disorders

Platelet function and clotting

What is EDS

A rare autosomal ctd that is primarily characterized by skin hyperextensibility, abnormal wound healing/atrophic scars and joint hypermobility. 90% of pts have all criteria listed.

Clinical symptoms of Marfan's

``` Scoliosis Chest deformities Arachnodactyly (long fingers) Tall, thin Joint hypermobility Craniofacial abnormalities Cardiovascular defects Ocular defects ```

Developmental problems of collagen

Chondrodystrophies | Collagenopathies

Structural problems of collagen

OI EDS Marfan’s

Condns associated with collagen maintenance and repair

Osteoporosis OA Tendinopathy

Ligaments vs tendons

Tendons attach muscle to bone but ligaments attach bone to bone

Function of tendons

Tendons are slightly elastic, allowing to transmit forces from muscle to bone

Function of ligaments

Help stabilise a joint by restricting excess movement and minimising risk of injury

Structure of tendons

Collagen fibril --> subfasicle --> fascicle ---> tertiary fibre bundle

Endotenon

Connective tissue separating fascicles | Facilitate gliding of bundles independently against one another during movement

Epitenon

Found outside tertiary fibre bundles

Types of entheses

Fibrocartiliginous | Fibrous

Zones in fibrocartilaginous entheses

Fibrous connective tissue (the tendon) Uncalcified fibrocartilage Calcified fibrocartilage Bone

Sharpey's fibres

Where calcified fibrocartilage interdigitates with bone

Fibrous entheses

Tendons merge with the periosteum before attaching by fibrous tissue to the bone