S6 Connective Tissue Flashcards
What 3 components is connective tissue made of?
- Cells (fibroblasts, adipocytes and reticular cells)
- Fibres (collagen, elastin and reticular fibres)
- Ground Substance (proteoglycans - GAGs e.g. hyaluronic acid)
What makes up the extra cellular matrix?
Ground substance and fibres
What are the 6 functions of connective tissue?
- Binding and supporting
- Protecting
- Insulating
- Storing reserve fuel and cells
- Transporting substances within the body
- Separation of tissues
Examples of connective tissue binding and supporting?
Holding skin, gut, lung, etc. together
Examples of connective tissue protecting?
Bone protects vital organs and fat acts as a shock absorber
Example of connective tissue insulating?
Fat underlying skin
Examples of connective tissue storing reserve fuel and cells?
Bone marrow and fat tissue
Examples of connective tissue transporting substances around the body?
Blood and interstitium (space between tissues and organs of the body)
Examples of connective tissue separating tissues?
Fascia and tendons and cartilage
What is connective tissue proper?
General connective tissue - loose and dense (irregular/regular) connective tissue
What is loose connective tissue also known as?
Areolar tissue
What is another name for dense connective tissue?
‘Fibrous’ or collagenous tissue
What are 3 examples of loose connective tissue?
- LAMINA PROPRIA is part of the mucosa (under to basal lamina of epithelial cells, above muscularis mucosae)
- Surrounding capillaries, nerves and sinusoids
- Around glands
What are the two types of dense connective tissue?
- Irregular (fibres run in different directions)
2. Regular (fibres run parallel to each other)
What are the two main types of fibre in loose connective tissue?
Collagen and elastic
What are the main cell types in loose connective tissue?
- Fibroblasts
- Macrophages
- Other WBC
- Mast cells
- Adipocytes
What are fibroblasts?
Why are they important?
Cells that synthesise and secrete fibres that are in the ground substance.
Important in wound healing process - involved in formation of scar tissue.
What are myofibroblasts?
Fibroblasts that contain actin and myosin - responsible for wound contraction when tissue loss has occurred
What do mast cells contain?
Where are they found?
Contain granules:
histamine (increase blood vessel wall permeability) heparin (anticoagulant)
cytokines (attract eosinophils and neutrophils)
Found in loose connective tissue, near blood vessels (not found in CNS)
(look like basophils)
What do mast cells do?
Bind to IgE molecules (bind to allergens).
When an allergen binds to IgE on mast cell surface, granules are released.
What are adipocytes?
Fat storage cells
What is white adipose tissue?
Have only one lipid droplet per cell and a normal number of mitochondria.
Organelles squashed to side of cell.
Used for padding/shock absorber, insulation and as an energy reserve.
Found in adults.
Slow lipid breakdown.
What is brown adipose tissue?
Have more than one lipid droplet per cell and more mitochondria.
Organelles are squeezed to the centre of the cell.
Used for insulation and as an energy reserve.
Found in neonates and young kids.
Fast lipid breakdown.
Where can you find type 1 collagen?
E.g. tendons and skin dermis
Where can you find type 2 collagen?
E.g. hyaline and elastic cartilage
Where can you find type 3 collagen?
E.g. muscle and nerve cells, lymphatic tissues and organs (e.g spleen) and tendons
What is type 3 collagen called?
Reticulin
Where can you find type 4 collagen?
E.g. epithelial tissues
Which type of collagen’s fibrils don’t form fibres?
Type 2
Describe collagen…
… flexible with high tensile strength
Describe reticulin…
…provides a supporting framework/sponge
Describe elastin…
…allows tissues to recoil after stretch or distension
What sort of connective tissue don’t you find reticulin in?
Loose connective tissue
What is the role of loose connective tissue?
Prevents ingress of pathogens past epithelial surfaces (can undergo swelling during this, e.g. due to elastin)
What does ground substance look like?
It’s a viscous and clear substance that feels slippery (high water content)’
What is ground substance made up of?
PROTEOGYLCANS a large macromolecule with a protein centre which are covalently bound to glycosaminoglycans (GAGs) which are polysaccharides.
What do GAGs do?
Attract water to form a hydrated gel (allow for rapid diffusion but also resist compression)
What is an example of a GAG?
Hyaluronic acid
Where is dense irregular connective tissue found?
The dermis
Where do you find dense regular connective tissue?
In tendons
What happens at the myotendinous junction?
Skeletal muscle fibres and tendon collagen ‘interdigitate’ with each other - giving high strength
What substance are tendons mainly made of?
Water (68%)
What sort of collagen is in tendons? And how much of each?
70% collagen 1
30% collagen 3 (reticulin)
What is an advantage of irregular connective tissue in terms of resisting stress compared to regular dense?
It resists stresses in all directions compared to in only one direction.
What is fascia? And how many types are there?
A connective tissue that has 3 types:
- Superficial
- Deep
- Visceral/parietal
Collagen fibres arranged in wavy parallel pattern - can resist stress until wavy pattern is pulled straight.
What vitamin is needed for collagen production?
Vitamin C
What happens if a person has a vitamin C deficiency?
Can lead to scurvy (poor wound healing and impaired bone formation)
What are symptoms of scurvy?
- Gum disease
- Bruising of skin
- Bleeding
- Poor wound healing
What is Marfan’s syndrome?
An autosomal dominant disorder - expression of fibrilin 1 gene is affected, so elastic tissue is abnormal.
Symptoms of Marfan’s syndrome?
- Abnormally tall
- Arachnodactyly (longer fingers)
- Joint dislocation
- At risk of aortic rupture
What is osteogenesis imperfecta?
Also known as brittle bone disease.
Due to mutated collagen fibres that don’t “knit” together or not enough collagen is produced.
What are the symptoms of osteogenesis imperfecta?
- Weakened bones
- Short stature
- Blue sclera
- Hearing loss
- Hypermobility
- Poor teeth development
What is the primary component of elastic fibres?
Elastin
What is elastin surrounded by?
Fibrilin (microfibrils)
What are the 3 layer of an artery? And what is each layer made up of?
- Tunica intima (endothelial cell)
- Tunica media (elastin lamellae)
- Tunica adventitia (collagen)
