10. Cartilage and Bone Flashcards
What do the large amounts of hyaluronic acid in the extracellular matrix of cartilage assist with?
With resilience to repeated application of pressure.
What do large ratios of glycosaminoglycans to type II collagen in cartilage permit?
Ready diffusion of substrates between chondrocytes and blood vessels surrounding the cartilage.
How many glycosaminaglycan units make up a proteoglycan monomer?
About 100.
What are the three types of cartilage?
Hyaline cartilage, elastic cartilage and fibrocartilage.
What is the composition of hyaline cartilage matrix?
Proteoglycans, hyaluronic acid and type II collagen. The hyaluronate proteoglycan aggregates are bound to the fine collagen matrix fibres.
What is the composition of elastic cartilage matrix?
Proteoglycans, hyaluronic acid, type II collagen and many elastic fibres and lamellae.
What is the composition of fibrocartilage matrix?
Proteoglycans, hyaluronic acid, type II collagen and abundant type I collagen fibres.
What cells do hyaline cartilage contain?
Chondrocytes only. Either singly or as isogenous groups, small clusters.
What is hyaline cartilage a precursor to in foetal development?
Bonds which develop by endochondral ossification.
Where does some hyaline cartilage remain after early foetal development?
At articulating surfaces of long bones.
Where can hyaline cartilage be found?
In the nose, articulating surfaces of joints, trachea, bronchi and in the rib cage.
What type of growth does hyaline cartilage have?
Appositional growth, growth from the periphery
What’s between the dense connective tissues and growing cartilage in hyaline cartilage?
Perichondrium.
When is perichondrium not lining hyaline cartilage?
At articulating surfaces and at epiphyseal growth plates.
Where can elastic cartilage be found?
External ear, external acoustic meatus (ear canal), the epiglottis and the Eustachian tube.
What are the cell types in fibrocartilage?
Chondrocytes and fibroblasts.
Does fibrocartilage have surrounding perichondrium?
No.
Where can fibrocartilage be found?
In intervertebral discs, articulate discs of the sternoclavicular and temperomandibular joints, the meniscus of the knee joint and in the pubic symphysis.
How are chondrocytes arranged in fibrocartilage?
In rows or as isogenous groups.
What can be seen in a section of compact bone?
Osteonal artery in the centre of osteons. Interstitial lamellae between osteons. Haversian canal joined by Volkmann’s canal. Periosteum at one end and endosteum at the other.
How are osteocytes arranged in immature and mature bone?
Immature: randomly arranged
Mature: arranged in concentric lamellae of osteons.
What two things are present in compact bone but not cancellous bone?
Haversian canals and Volkmann’s canals.
Describe the initial action of osteoclasts in bone modelling.
They bore a tunnel through the bond and release H+ ion and lysosomal enzymes.
What is the composition of bone?
65% mineral, 23% collagen, 10% water and 2% non-collagen proteins.
What are the four steps of fracture repair?
1) haematoma formation - blood clots formed in which granulation tissue arises.
2) fibrocartilaginous callus formation - procallus of granulate tissue is replaced by a fibrocartilaginous callus in which bony trabeculae are developing.
3) bony callus formation - endochondral and intermembraneous ossification give rise to a bony callus of spongy bone.
4) bone remodelling - cancellous bone is replaced by compact bone until remodelling is complete.
What is the purpose of bone banks?
To supply viable bone for grafting.
What is an autograph?
When the donor is the recipient.
What is a homograft?
When the donor is a different human.
What is a heterograft?
When the donor is of a different species.
What is cartilage made up of?
Extracellular matrix with chondrocytes.
