Nature of connective tissues Flashcards
What are connective tissues?
Biological tissues that supports, separates and connects tissues and organs
Maintains the form of the body and its organs
What are types of connective tissues?
Fibrous
Muscle
Bone
What are the three main components of connective tissues?
Fibres
Ground substance
Cells
What is the ground substance?
Clear colourless solution containing GAGs and proteoglycans
Fix body water and fibers within ECM
What makes up the ECM?
Body fluid and ECM
Can fibers be non-fibrous?
Yes
Blood and adipose tissue are non-fibrous fibers
What are the two types of cells of connective tissues?
Resident
Fluctuating
Examples of resident cells in connective tissues
Fibroblasts Adipocytes Osteoclasts Osteoblasts Mesenchymal stem cells
Examples of fluctuating cells in connective tissues
Macrophages
Lymphocytes
Mase cells
What is Mesengenesis?
Genesis of resident mesenchymal cells in bone and cartilage
What do mesenchymal stem cells undergo upon activation?
Proliferative and commitment events
Progeny into distinct lineages - bone, cartilage, cardiac
Terminal differentiation into ultimate phenotypes - osteocytes, chondriac, myocytes
What is the basement membrane?
Thin sheet-like network
Formed by two layers:
Basal lamina
Reticular connective tissue
What are the functions of the basement membrane?
Physical support
Developmental control
Filtering functions
What is the ECM?
Highly organised, complex arrangement of molecules filling intracellular spaces
What creates the ECM?
Resident local cells
Secrete proteins and assemble outside the cell
What determines the shape of the ECM?
Amount of ECM components
Organisation of the ECM components
What types of cells make up the ECM?
Structural insoluble proteins - collagen
Hydrostatic soluble fibrillar polymers - GAGs and PGs
Substrate adhesion molecules - laminin, fibronectin
Cytokine and GF binding proteins
What is the role of insoluble fibers?
Resist tensile forces
What is the role of soluble fibrillar polymers?
Inflate fibrous network and provide resistance to compression
What is the role of non-collagenous adhesive glycoproteins?
Bridges between matrix and basement membrane
Describe the structure of collagen
Triple helix
Three chain wrap around each other in rope-liek fashion
28 members in a family
Six classes - fibrillar = most abundant
What percentage total body collagen does collagen I compose?
90%
Structure of GAGs
Oligosaccharides and glycans attached to polypeptide chains
Carbohydrates attached to proteins by glycosylation
Examples of common GAGs
Hyaluronic acid
Chondroitin sulphate
Heparan sulphate
Dermatan sulphate
GAGs are important components of ground substance
TRUE or FALSE
TRUE
Role of Hyaluronate
Important GAG
Chief component of ECM
Important in cell migration/ proliferation
Increases viscosity of synovial fluid
Important in tissue repair
What are substrate adhesion molecules?
Proteins that mediate cell adhesion to ECM
Enhance integrin-expressing cell binding
Contrcact ECM to allow cells to bind
What are integrins?
Transmembrane receptor proteins that bridge cell-cell and cell-ECM interactions
What happens when integrins become activated?
Trigger intracellular signal transduction pathways
