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Flashcards in Cartilage And Bone Deck (25)
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Describe the composition of cartilage

Resiliant avascular connective tissue
Composed of chondrocytesand semisolid matrix
Mesenchymal origin - differentiate into chondrocytes
Secrete a matrix which surrounds cells in lacunae
Surrounded by pericondrium


Describe hyaline cartilage

Type 2 collagen
In resp pathways, articulating surface of long bone, anterior end of ribs, foetal skeleton
Flexible and smooth for movement
Avascular ( relies on diffusion)


Describe elastic cartilage

Type 2
Found in auditory tube, external ear, epiglottis
F - support,shape and extra flexibility
Has perichondrium
Avascular, matrix has elastic fibres


Describe fibrocartilage

Type 1 collagen
Found in intervertebral discs, menisci, pubic symohysis
f - support and rigidity, weight bearing
No perichondium
Associated to joint where need resistance to compression


Relate anatomical location of hyaline cartilage to its function

Firm and flexible support - respiratory passageways


Relate anatomical location of elastic cartilage to its function

Flexibility and support - auditory tubes, ear, epiglottis


Relate anatomical location of fibro cartilage to its function

Verystrong and resistant to compression - intervertebral discs, part of tendons


Describe the characteristic features of bone

Can withstand compression, stress and deformation
Dynamic - responds to stress and strains by growth
Supplied with blood, lymph vessels and nerves
Contains cells, fibres and ground substance


What is the function of bone

Support, protection, mineral storage, haemopoisis
Vascular connective tissue


Describe compact (dense) bone

Concentric lamellae with central nuerovascular (haversian canal) which communicate via volkmanns canals
Osteon (haversian) system of interconnecting canals


Describe spongy (cancellous) bone

Each trabeculum has Numerous osteocytes within irregular lamellae
Osteoblasts and osteoclasts remodel bone surfaces


Describe the composition of bone matrix

Collagen, water and non-collagen
Calcium phosphate and carbonate
Hardness due to interaction between inorganic salts and collagen
Calcium and phosphate stores can be released if levels fall
Ca2+ required for muscle contraction, blood cosgulation, cell membrane permeability, nerve impulse transmission
Pth stimulates osteoclasts to reabsorb bone matrix
Calcitonin released to inhibit osteoclasts


What is the role of osteoblast cells?

Synthesise the organic components of cells, making bone, produce osteoid matrix


What is the function of osteocytes

Found in lacunae cavities, maintain bone. Formed when osteoblasts are entombed to produce osteocytes


What are the function of osteoclasts

Large multinucleate cells from monocytes that digest bone


Describe the microstructure of i mature bone

Immature bone, is the first type of bone to appear in development and repair replaced by mature
Collagen fibres are arranged in a random interwoven fashion
More cells and less minerals


Describe the structure of compact bone

Series of haversian systems (osteons) consisting of concentric lamellae of bone around a central canal containing blood vessels, spaces inbetween haversian systems filled with bony lamellae


Describe the structure of spongy bone

Forms network of trabecullae filled with marrow


How does cartilage become bone?

Via endochondrial ossification
Cartilage is resorbed and replaced
Begins at primary centre in the diaphysis snd later at each end (ephysis)
Growth in length at epihysial growth plate


How does loose connective tissue/mesenchyme via intramembrous ossification

Bone begins as highly vascularised loose connective tissue
Mesenchymal cells differentiate into osteoblasts surrounded by collagen fibres and ground substance
They secrete uncalcified matrix (osteoid) and become osteocytes


Describe the remodelling of bone

Osteoblasts and osteoclasts release and incorporate calcium into and from the matrix


Describe fracture repair

1) site of injury filled with blood (haemotoma)
2) broken ends of bone become necrotic
3) blood coagulates forming a clot - invaded by macrophages and osteoclasts that remove dead tissue and bone
4) from pro-callus of blood clot and fibrous tissue (primary)
5) calcified to form secondary bone
6) bone remodelled by osteoclasts


Why is the extracellular matrix of cartilage highly highdrated?

Allows transient movement of water within the matrix to withstand varying pressure


What is special about hyaline articular cartilage

At the articulating surface of long bone the hyaline cartilage does not have a perichondrium, as it is soft and would be worn away


How are chondrocytes arranged in fibrocartilage?

In rows or as isogenous groups