Ordinary Connective Tissue Flashcards
What are the functions of connective tissue? (5)
- Provides an extracellular matrix that connects and binds organs and cells within the body
- Gives support to the body (forms fascia, tendons, cartilages, bone)
- Facilitates cellular defence mechanisms
- Repair (scar tissue formation)
- Provides an avenue for communication.transportation
How is connective tissue supplied with oxygen and nutrients?
CT is directly supplied by blood and lymphatic vessels and nerve
What are the 2 classifications of CT?
Ordinary (CT proper)
Special CT
Name 3 types of ordinary connective tissue
- Loose, areolar connective tissue
- Dense irregular connective tissue
- Dense regular connective tissue
Name 6 types of special connective tissue
- Adipose tissue
- Cartilage
- Bone
- Dentin
- Haematopoietic tissue (lymphatic and myeloid)
- Endothelium
What are the 3 structural elements of connective tissue?
- Cells
- Fibres
- Ground substance
Name the three types of fibre that can be found in CT
- Collagen
- Elastic
- Reticular
Name the components of the ground substance
Highly hydrated gel comprised of glycosaminoglycans (GAGs), proteoglycans and glycoproteins
What 2 components make up the extracellular matrix?
Fibres and ground substance
What are the principle cells of CT?
Fibroblasts
What is the function of fibroblasts?
Produces fibres (collagen and elastic) and ground substances of CT
Describe the structure of a fibroblast
Irregular branched cytoplasm, extensive rough endoplasmic reticulum and well developed golgi apparatus
Describe the structure of reticular fibres
Branched, thin collagenous fibres tat form delicate networks
Do not form bundles
Describe the function and location of collagen type I
Function: provides tensile strength
Location: dermis, ligaments, tendons, bone, dentin
90% of total collagen in body
Where is collagen type II found?
Hyaline cartilage and elastic cartilage
Where is collagen type III found?
Reticulin (The first collagen secreted in wound healing), lymphoid organs
Where is collagen type IV found
Basal lamina
What is the function of collagen type VII?
Forms anchoring fibrils e.g. anchors the basal lamina of epidermis to underlying dermal fibres
What is the name of collagen synthesised when it is still inside the cell?
Procollagen
What is the structure of procollagen?
Three collagen molecules (α-polypeptide chains)
What happens when procollagen is secreted from the cell?
Proteolytic enzymes cleave polypeptides from procollagen to form tropocollagen
What is the name of procollagen after enzymatic cleavage?
Tropocollagen
How are tropocollagen molecules aligned?
Tropocollagen molecules aligned into linear arrays with a 67nm stagger to produce collagen fibrils
Describe collagen production and formation using a flow diagram
procollagen (inside cell) > tropocollagen (outside cell) > collagen fibril > collagen fibre > collagen bundle
What is the main component of elastic fibres
Elastin
Where are elastic fibres located?
Dermis, elastic arteries (aorta), lung, elastic cartilages
Describe the structure of an elastic fibre
An elastin core covered with fibrils made up of the glycoprotein FIBRILIN (fibrilin is important in the assembly and integrity of elastic fibres)
What is the main composition of reticular fibres?
Collagen type III
What is the function of reticular fibres
Provides a more intimate form of support
Name 2 collagen disorders
- Scurvy
2. Ehler-Danlos Syndrome
What causes scurvy?
Lack of vitamin C
Vitamin C is essential for collagen synthesis. This results in imperfect collagen production causing abnormal bone growth, fragile capillaries leading to bleeding gums and tooth loss
What is Ehler-Danlos syndrom caused by?
Caused by a defect in the structure, production or processing of collagen or proteins that interact with collagen
Characterised by skin extensibility, joint hypermobility and tissue fragility
Name and describe an ELASTIN disorder
Marfan syndrome
A defect in the FBN1 gene which encodes fibrillin-1, resulting in a lack of fibrillin in elastic fibres.
Affected individuals tend to be tall, thin, long limbs, large hands and sunken chest. Tend to have defects of the heart valves and aorta (prone to aortic rupture)
What is the main functions of ground substance?
Resists compressive forces on the matrix and provides mechanical strength
Functions as a molecular sieve where nutrients, metabolites and hormones diffuse between blood capillaries and cells
What is the ground substance comprised of?
Glycosaminoglycans (GAGs), proteoglycan and adhesive glycoproteins
Describe the structure of glycosaminoglycans (GAGs)
Unbranched polysaccharide chains composed of repeating disaccharide units
Very large and hydrophilic molecules
Describe the functions of GAGs
Maintain the tissue architecture: GAGs have a high viscosity and low compressibility
Rigid and turgor provides structural integrity to cells and
Provides passageways between cells, allowing for cell migration
Describe the fibrous composition and function of dense irregular CT
Predominance of collagen fibres, densely packed which run haphazardly
Offer resistance and protection in many directions
Name 4 locations of dense irregular CT
- Dermis
- Submucosa of digestive tract
- Periosteum and perichondrium
- Fibrous capsules of organs
Describe the fibrous composition and the function of dense regular CT
Predominance of collagen fibres that run in parallel
Maximum tensile strength in one direction/one plane
(have a poor blood supple so when damaged take time to regenerate)
Name 3 locations of dense regular CT
- Ligaments (connect to bone)
- Tendons (connect to muscle)
- Aponeurosis
Which of the 3 embryonic germ layers does CT originate from?
Mesoderm
Describe the structure and function of lose areolar CT
Pliable and mesh-like with widely dispersed collagen and fibroblasts and an abundance of ground substance
Provide a ‘packing’ framework for organ support
Name 3 location of lose, areolar CT
- Widely distributed below epithelia
- Forms lamina propria of mucosa
- Surrounds capillaries
