15 Cartilage And Bone Flashcards
What do all types of cartilage have in common?
All have matrix containing proteolycan and hyaluronic acid
All have chondrocytes
What are the 3 types of cartilage?
Hyaline
Elastic
Fibrocartilage
What cells are present in hyaline cartilage?
Chondrocytes (present in isogenous groups)
Perichondrial cells develop into chondroblasts
Chondroblasts divide into chondrocytes
What is hyaline cartilage’s role in Fetal development?
Precursor model of bones in fetus that develop by endochondral ossification
Proteoglycan structure in cartilage ground substance
Similar to other connective tissues
About 100 hyaluronate proteoglycan aggregates per collagen fibril
Makes stiff gel-like substance
Where is hyaline cartilage found?
Cartilage in nose
Articulate cartilage of joint
Costal cartilage
Larynx, trachea
What is the perichondrium?
Covers margin of hyaline cartilage
Dense connective tissue
Chondrocytes position
Lie in cartilage extracellular matrix which they produce and maintain
What is appositional growth?
Growth from the periphery inwards
What is interstitial growth?
Growth from the centre outwards
Layers of tracheal wall (out to in)
Adventitious (areolar CT)
Hyaline cartilage
Submucosa with possible seromucous glands
Mucosa
Lumen of trachea lined with pseudostratified ciliated epithelium
What cells are present in elastic cartilage?
Chondrocytes
Also contains elastic fibres
Where is elastic cartilage found?
Pinna of ear
Eustachian tube
Epiglottis
What cells are present in fibrocartilage?
Chondrocytes and fibroblasts
It is a combination of dense regular connective tissue and hyaline cartilage
No surrounding perichondrium
Where is fibrocartilage found?
Intervertebral discs
Meniscus of knee joint
Pubic symphysis
Can act as shock absorber and resist to shearing forces
Cartilage acts as template for bone formation
For developing long bones
Grow by endochondral ossification
Hyaline cartilage is model
Subsequently mineralises to form bone
Growth plates
Present at femur head and end
Separates epiphysis from diaphysis
Long bone development by endochondral ossification - embryo 5-6 weeks
Initial cartilage model
Miniature version of adult bone
Long bone development by endochondral ossification - embryo 6-8 weeks
Collar of periosteal (compact) bone appears at sides of shaft
Long bone development by endochondral ossification - fetus 8-12 weeks
Central cartilage calcifies
Nutrient artery penetrates, supplying bone-depositing osteogenic cells
Primary ossification centre formed
Long bone development by endochondral ossification - postnatal
Medulla becomes cancellous bone
Cartilage forms epiphyseal growth plates
Epiphyses develop secondary centres of ossification at either end of bone
Long bone development by endochondral ossification - prepubertal
Epiphyses ossify
Growth plates continue to move apart, lengthening bone
Long bone development by endochondral ossification - mature adult
Epiphyseal growth plates replaced by bone
Hyaline articular cartilage persists
Where are osteocytes?
In middle of bone
Where are osteoblasts?
On edge of bone
When surrounded by new osteoid, becomes osteocyte
They secrete substance of bone
Organic component of bone in matrix
Non-collagenous proteins stimulate osteoblasts to do their function - Osteocalcin - Osteonectin - Phosphoproteins - Bone sialoprotein - Bone morphogenic proteins They resist pulling and tensing forces
Osteoprogenitor
Undifferentiated cells - stem cells
Inner layer of endosteum and periosteum
Osteoblast
Intermediate cells that cannot divide
Inner layer of endosteum and spicules
Lay down new bone
Osteocyte
Terminally differentiated bone cell
Trapped within osteon
No longer lay down matrix - tissue maintenance
Osteoclast
Large cells with many nuclei Fused monocytes (WBCs) On surface of cortical bone (endosteum) Reabsorption of existing bone/breaks down bone
Compact bone
Osteon - layers of bone around osteocyte, have blood vessels and nerves
Lamellar of compact mineralised collagen
Send out filipodia to communicate with other osteocytes
Haversian canal are vertical blood vessels
Volkmanns canal are horizontal blood vessels
Osteoarthritis
Degeneration of bones
Mechanical failure of articular cartilage
Narrowing of joint space
Bone rubs against bone
Rheumatoid arthritis
Autoimmune disease
Inflammation of synovial membrane
Thickening of joint capsule
Both bone and cartilage disintegrate
Changes associated with rheumatoid arthritis
Osteoclasts degrade bone
Fibroblasts out down scar tissue
Macrophages digest bone
T cells recognise tissues as non-self
