Connective Tissue Histology Flashcards
4 basic classifications of tissue
- Muscle
- Epithelia
- Connective tissue
- Nervous tissue
What does connective tissue have roles in?
- Structural support
- Tensile strength
- Binding tissues together
- Immune defence
- Metabolism and energy storage
- Cushioning
- Elasticity
What is connective tissue proper?
Non-specialised connective tissue
2 forms of connective tissue proper
- Loose connective tissue
- Dense connective tissue
Components of connective tissue
- Cells
- Extracellular matrix
What makes up the extracellular matrix?
- Ground substance
- Fibres
What is the ground substance made of?
- Glycosaminoglycans
- Proteoglycans
- Water
What are the fibres in the extracellular matrix?
- Collagen
- Elastin
- Reticular
What is the main cell type in non-specialised connective tissue?
Fibroblasts
What is the function of fibroblasts?
Produce and maintain the extracellular matrix
Fixed cells in connective tissue and their functions
- Fibroblast
- Fibrocytes (inactive fibroblasts)
- Adipocytes (fat cells)
- Macrophages (phagocytic)
What are wandering connective tissue cells?
Immune cells that can move into connective tissue when required
Examples of wandering connective tissue cells (and their function)
- Plasma cells (produce antibodies)
- Eosinophils (consume foreign substances)
- Neutrophils (phagocytic)
- Lymphocytes
- Mast cells (inflammatory, histamine production)
What glycosaminoglycan often is the backbone of ground substance?
Hyaluronic acid
What do glycosaminoglycans contain that affects pH and what is the effect?
- Negative side chains
- Makes it acidic
Benefits of ground substance being hydrophilic and binding water
- Makes it strong to resist compressive forces
- Provides volume
- Allows good diffusion
General structure of elastin
Thin and branched
What is the precursor of elastin and how is it turned into elastin?
- Tropoelastin
- Polymerised to elastin
What is required for the formation of elastin?
Fibrillin scaffold
What is fibrillin?
Glycoprotein produced by fibroblasts
Function of elastin
Allows stretch and recoil to maintain shape
Where are elastin fibres found in the body?
- Skin
- Ears
- Arteries
- Lungs
- Bladder
Structure of collagen
- Triple alpha helix
- Thick with no branching
Types of collagen (and where they are found)
- Type I (bone, skin, tendons, ligaments)
- Type II (cartilage)
- Type III (reticular fibres)
- Type IV (basement membrane)
Function of reticular fibres
Form framework of organs/glands and blood vessels
What is basement membrane?
Specialised extracellular matrix that usually underlies epithelial cells
Where else can basement membrane be found?
- Surrounding some cells
- Separating 2 sheets of cells
Make up of loose connective tissue (no. of cells, amount of ground substance, no. and arrangement of fibres)
- Many cells
- Mostly ground substance
- Some fibres, loosely + randomly arranged
Function(s) of loose connective tissue
- Binds structures
- Diffusion
Make up of dense irregular connective tissue (no. of cells, amount of ground substance, arrangement of fibres)
- Fewer cells
- Less ground substance
- More fibres, randomly arranged
Function(s) of dense irregular connective tissue
Withstand pressure from different directions
Make up of dense regular connective tissue (no. of cells, amount of ground substance, arrangement of fibres)
- Fewer cells
- Less ground substance
- More fibres, arranged in parallel
Function(s) of dense regular connective tissue
Resist forces in one direction (tensile strength)
Types of adipose tissue
- White
- Brown
Lipid droplet arrangements in the different adipose tissues
- White = 1 big droplet
- Brown = multiple small droplets
Where are the different adipose tissues typically found?
- White = adults
- Brown = newborns, adult around kidney
What is brown adipose tissue rich in and what is its function?
- Mitochondria and capillaries
- Thermogenesis
Symptoms of Ehlers Danlos Syndrome and what causes it?
- Fragile, extra elastic skin and hypermobile joints
- Mutation of type I, III or V collagen
Symptoms of Marfan’s Syndrome and what causes it?
- Long digits + arms and tissues rich in elastic fibres (eg. aorta - risk of aneurysm) affected
- Mutation of fibrillin
Symptoms of osteogenesis imperfecta and what causes it?
- Brittle bones/malformations
- Mutation of type I collagen
Symptoms of chondrodysplasia and what causes it?
- Cartilage defects and joint abnormalities
- Mutation of type II collagen
