Cartilage Flashcards
What are the three features of cartilage
Avascular tissue
Have extensive extracellular matrix
Contain chondrocytes - produce and maintain extracellular matrix
What are the three main types of cartilage?
Hyaline (most common)
Elastic
Fibrocartilage
What are the features of hyaline cartilage?
Chondrocytes
Hyaluronic acid
Type 2 collagen
Hyaline cartilage is a precursor for bone formation by _______________________
Endochondrial ossification - of long bones
Where is hyaline cartilage found?
Articulating surfaces - ear, nose, joints, rib cage (costal), trachea, bronchi
Also foetus
And epiphyseal growth plate of long bones until growth ceases
What is appositional growth of cartilage?
Cartilage grows in thickness from the periphery due to addition of more extracellular matrix by new chondroblasts that develop from the perichondrium
What is interstitial growth of hyaline cartilage?
Chondrocytes deeper in cartilage continuously divide causing deposition of further matrix which results in growth in length
What is a lacuna?
Small space surrounding a chondrocyte
What is present at the epiphyseal growth plate?
Contains hyaline cartilage
No perichondrium
Between epiphysis (spongy bone) and metaphysis
What are the features of elastic cartilage?
Like hyaline cartilage but with (many) elastic fibres
Where is elastic cartilage found?
External ear
Epiglottis
Eustachian tube
What are the features of fibrocartilage?
Contains chondrocytes and fibroblasts
Combination of dense regular connective tissue and hyaline cartilage
Abundant in type 1 collagen fibres
Where is fibrocartilage located?
Present between tendon and bone - enthesis
Intervertebral discs
Articular discs of sternoclavicular and temporomandibular joints
Pubic symphysis
Menisci of knee joint
What is the function of an osteoblasts?
Form new bone by laying down extracellular matrix containing type 1 collagen
What bones develop from intramembranous ossification?
Flat bones - skull, pelvis, clavicle
What is an osteoclast?
Large, multinuclear cell involved in remodelling/reabsorbing bone
What is cancellous bone?
“Spongy” - forms a network of fine bony plates to combine strength and lightness. Spaces are filled with bone marrow.
What is compact bone?
Cortical - external surface if bone - makes up ~ 80% skeletal mass
What is a haversians canal?
Carries blood and lymph vessels and nerves. Lie vertical through osteons - concentric lamellae around it
What is a volkmanns canal?
Horizontal - lie through concentric lamellae
Carry blood vessels, lymph vessels and nerves
What’s the difference in arrangement of osteocytes in immature and mature bone?
Immature - randomly arranged osteocytes
Mature - osteocytes arranges in the concentric lamellae of osteons
Which direction do reabsorption canals run?
Parallel with osteons long axis in mature bone
What’s the structure of trabeculae?
Similar to that of compact bone - no osteocytes lying between lamellae, numerous osteocytes embedded in irregular lamellae. No haversians and volkmanns canals. Osteoblasts and osteoclasts on surface for remodelling.
What cells lie in cavities between interconnecting trabeculae of cancellous bone?
Adipose and haemopoietic cells
What are the four stages of fracture repair?
Haematoma formation
Soft callus (fibrocartilagenous callus)
Bony callus
Bone remodelling
What is osteoporosis?
Metabolic bone disease - decreased mass of bone - no longer provides mechanical support, increased susceptibility to fracture
Reflects enhanced bone reabsorption relative to formation.
What are some of the factors associated with osteoporosis?
Bone mass peaks aged 25-35 starts to decline in 50s/60s.
Postmenopausal woman - increased osteoclasts number due to oestrogen withdrawal
Name 5 osteoporosis risk factors
Genetic - peak bone mass higher in black people
Insufficient calcium uptake
Insufficient calcium and vit D absorption
Immobilisation of bone - accelerated bone loss
Cigarette smoking
