Lecture 14 Flashcards
What are the three types of cartilage?
Hyaline- type 2 collagen
Ellastic
Fibrocartilage- type 1 collagen
What is common between all types of cartilage?
All have proteoglycan and hyaluronic acid containing matrix and chondrocytes
Can cartilage repair itself?
No, you get scar tissue instead of it
Difference between endochondral and intramembranous ossification?
Endochondral occurs from existing fetal cartilage.
What way are chondrocytes found?
In groups called isogenous groups that separate as they lay down matrix. Found in depressions called lacunae.
Where is cartilage left in long bones?
At the epiphyseal growth plate and articular surface (at the end of bone)
Why is hyaluronic acid important for the matrix of cartilage?
Attracts water which helps resist compression
What is the role of proteoglycans?
Bind with hyaluronic acid to form hyaluronate proteoglycan aggregates which forms a stiff gel like substance.
Where would you find hyaline cartilage?
The nose, trachea and forms the articular cartilage of joints.
What covers hyaline cartilage?
Perichondrium which is made of dense connective tissue
What are the two types of growth in cartilage?
Appositional from the periphery and interstitial from the centre
What is the difference between a chondrocyte and chondroblast?
A chondroblast is active or immature and then becomes a chondrocyte when it is inactive or mature.
What is the role of cartilage in rheumatoid arthritis?
Cartilage is broken down and cannot repair itself so fibroblasts from surrounding connective tissue lay down scar tissue which calcifies with age and flexibility is lost.
Where are the three places in the body where elastic cartilage is found?
Pinna of ear
Eustachian tube
Epiglottis
What cells are in elastic cartilage?
Just chondrocytes
What cells are in fibrocartilage?
Chondrocytes and fibroblasts. No perichondrium
What is fibrocartilage made of?
Dense connective tissue and hyaline cartilage combination. Dense connective tissue helps resist shearing forces.
Where would you find fibrocartilage?
The meniscus (pad like cartilage in knee joint) and intervertebral disks.
What are two common injuries seen by GP’ and orthopaedic surgeons?
Intervertebral disk (prolapse) and knee meniscus
What are the three main sections of long bone called?
Epiphysis, diaphysis and metaphysics in between where the growth plate is located
Describe the process of endochondral ossification
Begins with a hyaline cartilage model
Collar of periosteal bone appears in shaft.
Centre of cartilage than ossified and a nutrient artery enters supplying the new primary ossification centre with nutrients for the osteogenic cells.
Medulla becomes cancellous bone . Two epiphyseal growth plates and secondary ossification centres form.
The epiphyses ossify while the two growth plates continue to move apart which lengthens the bone
Eventually the growth plates are replaced by bone and and only hyaline articular cartilage persists.
How is the girth of a long bone extended?
Intramembranous ossification
What is the function of organic and inorganic components of bone?
Inorganic resist bending and compression. Organic resists pulling and tension.
How are bony spicules grown?
By osteoblasts which then become trapped and become osteocytes
What are the cells of bone?
Osteprogenitor cell which becomes an osteoblasts which becomes an osteocytes when trapped and mature and no longer lays down new tissue but rather maintains existing tissue.
What is compact bone structure?
Circular units called osteons made up of concentric lamellae with osteocytes between them that sit in lacunae and a haversian canal in the centre. Volkmans canals link Haversian canals. The osteoclasts are on the outside of compact bone at the periosteum.
What’s the main difference between osteoarthritis and rheumatoid arthritis?
Osteoarthritis involves breakdown of just cartilage whereas rheumatoid involves cartilage and bone. Pain in osteoarthritis caused by growth of bony spurs which osteoclasts cannot break down
What causes pain in rheumatoid arthritis?
Osteoclasts degrade bone and macrophages recruited to digest who then cause immune response and inflammation. Fibroblasts lay down scar tissue
