cartilage and bone Flashcards
what is the function of skeletal muscle tissues?
to provide a strong framework to support and protect our body and to provide movement
what are the two parts of the skeleton?
appendicular and axial
which bones does our appendicular skeleton contain?
bones of our limbs
what is the function of the appendicular skeleton?
these bones provide attachment sites for our muscles- the muscles contract and pull on the bone, facilitating movement
what bones does our axial skeleton contain?
bones of our head, vertebrae and ribs
what are the two classes of connective tissue?
loose and dense
what are the three types of cartilage called?
hyaline, fibro and elastic
what are features common to all three cartilage types?
- ground substance- predominantly chondroitin sulphates, proves resistance to compression
- collagen and elastin fibres
- chondroblast and chondrocyte cells which secrete and synthesis/maintain the ECM
- firm glassy ECM due to chondroitin sulphates in GS
- avascular- no blood vessels, leads to poor healing
- waste occurs via diffusion
describe hyaline cartilage
- most common type of cartilage
- includes articular cartilage
- lines joints and connects ribs to sternum
- abundant ground substance gives it its smoothness
- it is tough and flexible with good compression strength
- packed full of collagen fibres
- surrounded by perichondrium
- contains lacunae
what are lacunae?
small chambers in the matrix occupied by one or more chondrocyte
what is perichondrium?
- not present in articular cartilage
- dense fibrous connective tissue
- outer layer functions to attach the cartilage to various other tissues
- cellular inner layer involved in growth and maintenance of cartilage
- chondroblasts in the inner layer synthesise and secrete cartilage matrix, becoming embedded where they become chondrocytes and maintain the matrix
describe elastic cartilage
- rare
- flexible, avascular
- provides support and resistance to compression
- histologically similar to hyaline cartilage (perichondrium,chondrocytes and lacunae present)
- has lots more elastic fibres (stained black by van gieson stain) present- more flexible
- the elastin fibres are concentrated around the lacunae
- collagen fibres are also present
describe fibrocartilage
- very durable and tough
- very little ground substance
- dominated by dense irregular collagen fibres
- chondrocytes arranged in rows
- found in pads between vertebrae, limiting spine movement
describe the histological components of bone tissue
ground substance, fibres and cells
what is the ground substance of bone tissue made up of?
chondroitin sulphate and hyaluronic acid
what type of fibres are in bone tissue?
type 1 collagen
what is the osteoid of bone tissue?
unmineralised organic component of ECM made up of ground substance and fibres (28% hydroyapetite 70% fibres)
what cells are found in bone tissue?
osteoblasts, osteocytes and osteoclasts (make up 2%)
what do bones consist of?
- bone tissue
(- connective tissue) - adipose tissue
- blood vessels
- nervous tissue
- articular cartilage
what are the two different conformations of bone tissue?
spongy and compact
describe spongy bone conformation
(trabecular)
- honeycomb structure inside bone
describe compact bone structure
(cortical)
- dense tough outer layer
what are the cells in bone?
- osteogenic cells
- osteoblasts
- osteocytes
- osteoclasts
what are osteogenic cells?
- bone cell precursor cells
- give rise to osteoblasts
- capable of cell division
what are osteoblasts?
- synthesise and secrete osteoid (bone tissue)
- give rise to osteocytes
what are osteocytes?
- maintain mineralised bone tissue
what are osteoclasts?
- phagocytic bone cells
- resorb bone
- derived from immune cell linage
what are lamellae?
layers of bone (both spongy and compact bone tissue) arranged in lamellae
what is an osteon?
(harvesian system)
- functional units of compact bone made up of concentric lamellae
- central canal at the centre of each called an aversion canal
- each osteon contains a network of blood vessels, nerves and lymphatics
what are volksman’s canals?
(perforating canals)
- smaller canals which connect the central canals with the periosteum, supplying the bone tissue with nutrients
what is the periosteum?
- connective tissue around the outside of the bone
- inner layer (cambium) contains osteoblasts
- outer layer is elastic fibrous material containing blood vessels and nerves
what is circumferential lamellae?
- lies directly beneath the periosteum
- layers of bone which run around the entire circumference of the bone
what is interstitial lamellae?
- parts of compact bone which lie between osteons
- made up of remnants of old osteons which have weakened overtime which are partially reabsorbed and remodelled by osteoclasts
what are canalicui?
- small canals through which osteocytes can reach out to their neighbours
- through direct contact, osteocytes can maintain contact and communication and nutrients with their neighbours
what is the histological structure of spongy bone?
- contains lamellar bone
- no osteons
- spaces between trabeculae (small beams of supportive bone) are occupied by red and yellow nerves, blood vessels and lymphatics- lined externally by endosteum
what is another phrase for bone formation?
osteoblast genesis
what is another name for bone resorption?
osteoclast genesis
describe bone remodelling
in healthy bone, osteoblast genesis is coupled with osteoclast genesis
- bone remodelling can be influenced by: growth, mechanical stress, hormones and immunological factors
- some diseases are characterised by unbalanced osteoclastogenic activity
what is periodontitis?
- destructive inflammatory disease which destroys alveolar bone which leads to tooth loss
- chronic immune response to oral bacteria leads to destruction of host tissue
- gingival recession- loss of attachment to periodontal ligament
- immune generated- increases osteoclast genesis
describe arthritis
- osteoarthritis (most common)- affects the smooth cartilage around joints, changing shape of joint as protective cartilage on joints wears down
- rheumatoid arthritis- autoimmune- body attacks its own tissue- synovium (outer joint) is first affected then spreads changing joint shape
describe osteomalacia
- ‘rickets’ in children
- failure of osteoid to mineralise adequately
- caused by a lack of calcium/vit D/ phosphate
- bones become weak and prone to fracture
- associated with dental abnormalties eg enamel hypoplasia, delayed tooth eruption
- hydroxyapatite is most affected
