Joints & Joint Disease Flashcards
What are the different components of connective tissue?
- Cells
- ECM:
- Fibrous proteins (collagen and elastin)
- Ground substance (proteoglycans, glycoproteins and water)
What determines a tissues physical properties?
ECM composition
What is collagen?
A fibre of connective tissue that is good at resisting tensile forces
What are the 3 types of collagen?
- Type I: bone, tendons, ligaments, dermis and organ capsules
- Type II: hyaline and elastic cartilage
- Type III (reticular fibres): structural framework of spleen, liver, lymph nodes, SM and adipose tissue
What is elastin?
The major component of elastic fibres that enables stretch and recoil of tissues found in a wide variety of structures e.g. walls of large arteries, lungs and skin (often mixed with collagen to prevent overstretch)
What are the 3 types of connective tissue?
- Loose irregular (areolar)
- Dense irregular
- Specialised
What is loose irregular connective tissue? Where is it found?
Contains lots of cells (fibroblasts, adipose cells, macrophages, mast cells + other cells responsible for immune/allergic reactions), loose arrangement of fibres (collagen, reticular + elastic), abundant ground substance and ECF - found below epithelial layer of resp. + GI tract (lamina propria - mucous membranes), below pleura, peritoneum + pericardium (serous membrane), below skin and associated with adventitia of blood vessels and glands
What is dense irregular connective tissue? Where is it found?
Contains lots of fibres, fewer cells, randomly arranged collagen (resists stress from all directions) and elastic fibres - forms the dermis of the skin, capsules of organs (kidneys, testes, ovaries, spleen + lymph nodes) and sheaths of nerves
What are the different types of specialised connective tissue?
- Dense regular connective tissue (tendons, ligaments and aponeuroses)
- Cartilage
- Adipose tissue
- Haemopoietic tissue (bone marrow + lymphoid tissue)
- Blood
What are the characteristics of cartilage?
- Strong, flexible and semi-rigid
- Withstands compression forces so can act as a shock absorber
- Smooth surface enables friction-free movement
What are the functions of cartilage?
- Forms articulating surface of bones
- Growth and development of bones (endochondral ossification)
- Supporting framework of some organs e.g. walls of airway
What are the features of cartilage extracellular matrix (ECM)?
- Contains aggrecan (proteoglycan) that has an osmotic effect thus, high water content and resists compressive forces
- Contains collagen and elastin fibres
What is the structure of the cartilage?
Cartilage in the centre ECM surrounded by perichondrium (outer fibrous and inner cellular layer) - avascular structure being supplied by diffusion
What are the different types of cartilage cells?
Mesenchymal stem cells produce chrondroblasts that are cartilage building cells sitting in the cellular layer. Chrondroblasts form chrondrocytes when they are trapped in ECM/lacuna.
How does cartilage grow in childhood and adolescence?
- Appositional growth: surface layers of matrix added by chrondroblasts in the perichondrium (inner cellular layer)
- Interstitial growth: chrondrocytes (now surrounded in ECM/lacuna) grow and divide laying down new matrix producing articular cartilage and endochondral ossification
How does cartilage repair?
Poor regeneration EXCEPT in children:
- Small defects are dealt with by chrondrogenic cells from the perichondrium that form new cartilage
- Large defects involve replacement with dense connective tissue
What are the 3 types of cartilage?
- Hyaline
- Fibrocartilage
- Elastic
What is hyaline cartilage?
The most common but weakest form of cartilage containing short and dispersed type II collagen fibres and large amounts of proteoglycans. It has a perichondrium layer (except on articular surfaces) and is found in articular joint surfaces, costal cartilages and epiphyseal growth plates.
What is fibrocartilage?
The strongest form of cartilage containing thick parallel bundles of type I collagen alternating with hyaline cartilage matrix and no perichondrium. It is found in places that need to resist significant force for example, insertion points of ligaments and tendons to bone, IV discs, joint capsules, knee menisci, pubic symphysis and TMJ.
What is elastic cartilage?
Strong, flexible and resilient cartilage containing elastic fibres and type II collagen fibres with a perichondrium. It is present in structures which require some degree of deformation but then rapidly regain their original shape for example, external ear, larynx and epiglottis.
What are joints?
Articulation of 2 or more bones
What are the 3 different joint types movement?
- Synarthrodial: fixed with no movement e.g. suture skull joints
- Amphiarthrodial: slightly moveable e.g. pubic symphysis
- Diarthrodial: freely moveable e.g. shoulder (glenohumeral)