Joints and joint disease Flashcards
what is connective tissue made up of?
Connective tissue split into:
1) cellular component
2) ECM
ECM further split into:
Fibrous proteins (Elastin and Collagen)
Ground substance
Ground substance made up of proteoglycan, glycoprotein and water.
What are the three types of collagen and where are they found?
What is collagens main property?
Type 1 collagen - think TOUGH, forms tendons, ligaments, bones, dermis and encapsulates organs.
Type 2 collagen - forms HYALINE and ELASTIC cartilage
Type 3 - RETICULAR fibres forms the structural FRAMEWORK of SPLEEN / LIVER / LYMPH / SM/ ADIPOSE tissue
Collagen has TENSILE strength -> resist tensile forces
What is the purpose of elastin?
- Has ELASTIC strength, inherent stretchability and recoil.
- often mixed with collagen to prevent overstretch
- Found in large arteries, lungs, skin
What are the three types of connective tissue?
- Loose irregular -> tends to form underneath structures (e.g lamina propria, under pleural etc.)
- Dense irregular -> forms at regions that need to be tougher, resist forces from all directions. e.g. organ capsules and dermis
- Specialised connective tissue = dense regular -> e.g. tendons/ ligaments/ cartilage
Describe properties of loose irregular CT and where it forms
- High cellular content:
- macrophages
- mast cells
- fibroblasts
- adipose cells
- Loose arrangement of fibres (elastin/ collagen/ reticular fibres).
- abundant ground substance and EC fluid
- has blood vessels and nerves contained within it
- Forms at:
- glands
- underneath skin
- lamina propria of GI/ Resp
- Tunica adventitia
- underneath pleura/ peritoneum/pericardium
Describe the properties of Dense Irregular Connective tissue
where is it found
- Dense irregular made up of:
- low cellular content
- high fibre content, collagen arranged randomly to resist forces from all directions
- elastic fibre network
- Found at:
- Organ capsules
- dermis
- nerve sheaths
describe properties of specialised connective tissue:
dense regular CT
where is it found?
Other types of specialise CT
- Forms ligaments/ tendons/ aponeurosis
- High fibre content, collagen arranged in PARALLEL
- Other tissues:
- Cartilage
- Adipose tissue
- haematopoetic tissue –> lymph glands, blood, bone marrow
Describe structure of cartilage:
ECM
Outer layer
Blood supply
Cartilage formed of ECM and fibrous proteins collagen and elastin.
ECM formed of proteoglycan and GAG’s v hydrated -> resist compressive forces
Covered in outer connective tissue layer called PERICHONDRIUM. Formed of outer FIBROUS layer and inner CELLULAR layer.
Perichondrium absent at articulating surfaces to allow friction free movement.
Cartilage nourished by DIFFUSION assisted by compression, is AVASCULAR therefore slow to heal.
Origin of cartilage cells?
mesenchymal stem cell –> chondroblast (present in periochondrium) –> chondrocyte (mature cell formed after secretion of ECM, sits in own lacuna)
Cartilage growth and repair?
Growth:
1) appositional growth: occurs by chondroblasts in the perichondrium, adds surface layers of cartilage (not at articular surfaces)
2) interstitial growth (at articulating surfaces and endochondral ossification) : chondroblasts grow, divide, secrete ECM, spread out from each other, occupy own lacunae and become chondrocytes.
Repair: poor unless in children
cartilage often replaced by dense regular connective tissue. (ligaments/ tendons/ aponeurosis).
Three types of cartilage?
- Hyaline
- Elastic
- Fibrocartialge
Describe the three types of cartilage
-
Hyaline:
- most common and weakest
- has perichondrium but not at articulating surfaces.
- Formed of short dispersed TYPE 2 collagen fibres plus large amounts of PROTEOGLYCAN
- Present at articulating surfaces, costal cartilage and growth plates.
-
Elastic:
- strong, flexible and resilient
- at regions where deformation and recoil required
- elastic fibres and TYPE 2 collagen
- perichondrium present
- external ear
- epiglottis
- larynx
-
Fibrocartilage:
- strongest form
- thick parallel bundles of TYPE 1 collagen
- alternates with hyaline cartilage matrix
- found in regions of significant forces
- NO PERICHONDRIUM
- insertion points ligaments/ tendons
- IV discs
- joint capsules
- knee menisci
- pubic symphysis
- TMJ
What is a joint?
what different types of joint exist with different movement ability?
Joint = where two or more bones articulate
- synarthroidal -> no movement
- amphiarthroidal -> slightly moveable
- diarthroidal -> freely movable
Breakdown the different types of joint
1) synovial
2) fibrous joint -> sutures and syndesmoses
3) cartilaginous joint –> primary cartilaginous joint (growth plates, costal cartilage) and secondary cartilaginous joint (symphysis, IV discs, manubriosternal joint )
What fibrous joints are there?
sutures -> between flat bones of skull, immovable (synarthroidal)
syndesmoses -> interosseous membrane between tibia and fibula/ radius and ulna, slightly moveable (amphiarthroidal)
Joint mainly collagen no cartilage.