Define connective tissue
Forms a continuum throughout the body linking muscle, nerve and epithelial tissue in a structural way, but always providing support in metabolic and physical ways
Name the 5 types of connective tissue
1) Fibrocollagenous (loose, dense regular and dense irregular)
What are the main components of connective tissue?
1) Extracellular fibres
2) Amorphous ground substance
3) Cells Organic components only
What are the resident cell types found in connective tissue and their function?
1) Macrophage - ingest foreign material
2) Fibroblasts - Secrete collagen and components of extracellular matrix
3) Mesenchyme - Undifferentiated cells that maintain extracellular matrix
What are the visitant cell types found in connective tissue and their function?
Adipocytes - Storage, insulation, shock absorb
Plasma cells - derived from lymphocytes
Leukocytes - derived from blood vessels, production of immunocompetent cells
Mast cells - surround blood vessels, contain granules of heparin and histamines
What are the main differences between loose and dense connective tissue?
Loose has higher ratio of cells and ground substance compared to fibres whereas dense has fewer cells and less ground substance and is more densely packed with fibres
What are the three types of fibre found in connective tissue?
3) Reticular (type III collagen)
Where is dense regular connective tissue found?
Tendons and ligaments
What is the purpose of dense irregular connective tissue in he dermis of the skin?
Can withstand and counteract the multidirectional forces applied to the tissue
Name 3 types of loose connective tissue
1) Mucous connective tissue (Wharton's jelly)
Of what embryonic origin is connective tissue derived from?
What is amorphous ground substance?
Gel-like matrix in which the fibres and cells are embedded in. The tissue fluids diffuse through. Composed of glycosaminoglycans, proteoglycans and glycoproteins
Where is mucous connective tissue ( Wharton's jelly) found?
Only found in the umbilical cord and subdermal connective tissue of the embryo
Where is areolar connective tissue found?
This is found:
- Deep under the skin
- In a layer beneath the epithelia of mucous membranes
- The submucosa
- Below the mesothelium of the peritoneum
- Associated with adventitia of blood vessels
- Surrounding the parenchyma of glands
What type of collagen is found in reticular fibres?
Where is dense irregular connective tissue found?
- Dermis of skin
- Deep fascia of muscles
- Dura mater
Describe dense irregular connective tissue
Interwoven bundles of collagen, which criss-cross each other in many directions.
This counteracts multi-directional forces to which the tissues are subjected.
The tissue is mostly collagen with small components of elastic and reticular fibres
Describe systemic sclerosis
All organs have excessive accumulation of collagen (fibrosis). This occurs in skin, digestive tract, muscles and kidneys - hardening and functional impairment
Describe scurvy (Vitamin C deficiency)
Defective collagen synthesis leading to degeneration of connective tissue. Periodontal ligament (with a high collagen turnover) is affected in scurvy, lessening of teeth in their sockets with subsequent loss (bleeding gums)
Describe Marfan's syndrome
Genetic defect (autosomal dominant) in chromosomes that code for fibrillin, which affects elastic fibres (undeveloped). Large elastic arteries (Eg aorta) rupture because of high blood pressure
Describe Ehlers Danlos disease
Deficiency in collagen type III (reticular fibres) causing ruptures in tissues containing high reticulin content
What cells secrete cartilage matrix?
What is an entrapped chondroblasts termed?
What type of collagen makes up hyaline cartilage?
What type of collagen makes up elastic cartilage?
What type of collagen makes up fibrocartilage?
Where is hyaline cartilage located?
- Respiratory passageway
- Articulate surfaces (ends) of long bones
- Anterior ends of the ribs Flexible and smooth to allow movement of tissues
Where is elastic cartilage found?
- Auditory tubes
- External ear
- Epiglotis Provides support and maintains the shape of structures
Where is fibrocartilage found?
- Intervertebral disc
- Pubic symphysis
- Portions of the tendons Support and rigidity as it is the strongest cartilage
What is the clinical relevance of hyaline cartilage, particularly with age?
- Can calcify/ossify in old age and disease
- Increased size/number of chondrocytes with age