Structure and Biochemistry of Connective Tissue Flashcards
What embryological tissue is connective tissue derived from?
Mesoderm
What properties define connective tissues?
Cells positioned far apart, surrounded by extra-cellular matrix
What is the major cell type found in most connective tissues?
Fibroblasts
What extra-cellular matrix is produced by fibroblasts?
Fibres containing collagen and elastin
Ground substance
What makes up ground substance?
Water and proteoglycans and metabolites
Where are osteocytes found?
Bone
Where are chodrocytes found?
Cartilage
Where are adipocytes found?
Fat
Which connective tissue cell type proliferates in response to injury?
Fibroblasts (immature)
What are mesenchymal cells?
Undifferentiated stem cells
What is the function of adipocytes and what are the two types, and from which cell do they develop?
Adipocytes synthesise and store lipids
Unilocular adipocytes = White cells
Multilocular adipocytes = Brown cells (high in neonates)
Develop from mesenchymal cells
Name the two types of soft connective tissue?
Loose (low collagen)
Dense (high collagen)
Name the subdivisions of loose connective tissue?
Areolar (gas exchange)
Adipose
Reticular (lymph/liver/spleen)
Synovial
Describe synovial fluid?
High in blood plasma, it contains hyaluronan and glycoproteins (proteoglycan aggregates)
Name the subdivisions of dense connective tissue?
Irregular - dermis of skin
Regular (high in collagen and vit C) - including tendons/ligaments/fibrous capsule
Name and describe the three types of skeletal connective tissue?
Bone - haversian/woven
Cartilidge - hyaline/elastic/fibrocartilage
Dental - Dentine/enamel
Describe osteoarthritis?
Acts on hyaline cartilage
Slow degeneration
Wear and tear
Describe rheumatoid arthritis?
Acts on synovial membrane/hyaline cartilage
It is an autoimmune disorder
It is aggressive in progression
Tendonitis of the lateral epicondyle is commonly referred to as?
Tennis elbow
Tendonitis of the medial epicondyle is commonly referred to as?
Golfer’s elbow
Where is type I collagen found?
Ubiquitous (everywhere) - including bone
Where is type II collagen found?
Main component in cartilage formation
Vitreous humour of the eye
Where is type VI collagen found?
Basal laminae
In hyaline cartilage what do proteoglycans provide?
Flexibility and resilience to compression
In hyaline cartilage what do collagen fibres provide?
Rigidity and tensile strength
Where and how does hyaline cartilage obtain nutirents?
Comes from the synovial fluid and subcondral bone
Via accelerated diffusion
What does accelerated diffuse dependent upon?
Mobilisation of the joint
How does osteoarthritis lead to chondrocyte matrix breakdown?
Relieves the set constant pressure that the chonrocytes require to maintain their structure
What substances is collagen made up of?
Glycine
Proline/hydroxyproline
Hydroxylysine
Pro-collagen is converted via pro-collagen peptides into what?
Tropo-collagen
Defects in the pro-collagen peptides can lead to which condition?
Ehlers-Danlos syndrome type VII
What secondary protein structure makes up collagen?
Type II - trans helix (with hydrogen bonds)
Vit C deficiency can lead to which condition?
Scurvy
Collagen is structurally stabilised via lysine residue reactions and lysyl oxidase, a defect in lysyl oxidase leads to what conditions?
Ehlers-Danlos syndrom type V
SCAD
What is the protein to carbohydrate ratio in proteoglycans?
10:90
Name the type of proteoglycan primarily found in cartilage?
Aggrecan
Name the and describe the short glycosaminoglycan (GAG) chains found on aggrecan?
Keratan-sulphate
Galactose-GlucNac
Every other sugar has a negative charge
Name the and describe the long glycosaminoglycan (GAG) chains found on aggrecan?
Chondroitan-6-sulphate
Glucoronic acid-GlucNac
Every sugar is negatively charged
What part of the proteoglycan interacts with hyluronan and via which type of chemical bond?
G1 N-terminal
Ionic bond
How do proteoglycan aggregates present in the extracellular matrix?
Multimolecular aggregates with very high negative charge
What is the function of proteoglycan aggregates?
Retention of water in the extracellular matrix
Describe the term ‘swelling pressure’?
Proteoglycans are restrained from swelling by the tight collagen meshwork, creating a pressure
Describe the ‘dampening effect’?
Bottle-brushes of proteoglycans sliding past each other causing a large frictional drag - the cartilage deforms slowly and gradually under the load
