Lecture 10: connective tissue Flashcards
Define what connective tissue is by defining its structure.
Made ground substance, fibre and cells
Give 3 functions of connective tissue.
- hold & support organs, skin
- shock absorber
- heat insulation
- protect the vital organs
- separate tissues
- transporting substances
- fuel + storage
Name some examples of the main connective tissue cells.
- chondrocytes
- osteoblasts/cytes/clasts
- fibroblasts
- stem cells/progenitor cells/BM/blood/adipocytes
- reticulocytes
- macrophages
- mast cells
What are the main products of connective tissue?
- fibres
- wax or gel-like substances
- GS
Name some examples of fibres you can find in connective tissue.
- elastin
- collagen 1-4
- reticulin
Name what ground substance (GS) is made out of and identify an example.
Proteoglycans: hyaluronic acid
Describe what these suffixes mean…
- blast
- cyte
- clast
Blast: create, grow, make…
Cyte: maintain, finished state…
Clast: destroy, break down…
Extracellular matrix is made of 2 (3) substances. What are they?
GS + fibre (+cells)
How can connective tissue be classified?
Loose/areolar connective tissue
Dense/fibrous/collagenous connective tissue: irregular or regular
Describe the structure of loose connective tissue.
Contains many types of cells: fibroblast, macrophages, adipocytes, mast cells, WBCs
Contains fibres: elastin & collagen
Blood vessels, cells, fibres lie in gel-like GS
What are some functions of connective tissue?
Holds vessels that will supply fluid Permits cell migration Becomes involved in the inflammatory pathways Packaging around organs Cushions and stabilises organs
Why are fibroblasts important in the immune system?
They are cells involved in healing process and responsible for scar formation.
How are myofibroblasts different to fibroblasts?
Myofibroblasts are modified fibroblasts that contain actin and myosin. This allows the healing cells to pull together; causing contraction of the wound to close.
What is the role of a macrophage?
They are monocyte derivatives that move in areolar loose tissue (not blood) which phagocytose and become APC to T lymphocytes.
What is the role of a mast cell?
Contain many granules: histamines, anticoagulants, cytokines.
They mostly react to allergens by crosslinking their IgE & allergen which releases the granules = oedema.
What are the different types of adipose tissue and give their functions?
White adipose = 1 lipid droplet with peripheral nucleus which acts as padding, shock absorber, insulation and energy store.
Brown adipose = >1 lipid droplet with central nucleus which provides insulation and energy storage. NOT PROTECTION.
Why would individuals have more brown than white adipose tissue?
Neonates/young children release more heat compared to adults. Brown adipose allows uncoupling of oxidative phosphorylation so more heat is generated and lipolysis is quicker. White adipose breakdown is slower so heat is only generated by shivering.
Collagen is the most common protein in the entire body & there are 4 types. Discuss each type and where you would find these collagen types.
Type 1: Fibrils->fibres->fibre bundles found in tendons, dermis, organs
Type 2: Thin proteins found only as fibrils in hyaline & elastic cartilage
Type 3: (AKA reticulin) Fibrils->fibres around muscle, nerve cells, tendons and within lymphatic tissues.
Type 4: 6 chain structure found in the basement membrane.
Out of all 3 fibres, which fibre is absent in areolar tissue?
Reticular fibres which would usually provide a supporting framework; not needed in loose tissue.
Knowing what mast cells’ function and secretions are, where would you not find them in the body and why?
Mast cells cause oedema and so you would not find these in the brain as this will cause serious damage due to pressure build up in the skull.
GS is made up of proteoglycans. What are proteoglycans made up of and how do they help the GS with its function?
They are macromolecules with core proteins bound to GAGs (glycosaminoglycans).
GAGs attract H2O as they are polysaccharides. Hence it forms a gel which resists compression.
What is the most famous GAG and how is its structure suited to its popular use in cosmetics?
Hyaluronic acid can form giant hydrophilic macromolecules which attract a lot of water. Therefore, it will retain a lot of water if applied to the skin.
Why would hyaluronate be present in GS of cartilage?
Cartilage undergoes a lot of pressure and stress. The hyaluronic acid will make the GS more gel-like so that the cartilage resists compression. Hence, less friction and damage will occur in the cartilage.
Describe the arrangement of irregular dense connective tissue. Try to relate the structure back to its role.
Many collagen bundles packed closely together due to little GS. The multidirectional packing allows the skin to withstand multidirectional tearing.
The elastin allows for some stretch (again prevent tearing) and for the skin to be restored to its original form after bending.