cartilage and bone

Question 1

what is the function of skeletal muscle tissues?

Answer 1

to provide a strong framework to support and protect our body and to provide movement

Question 2

what are the two parts of the skeleton?

Answer 2

appendicular and axial

Question 3

which bones does our appendicular skeleton contain?

Answer 3

bones of our limbs

Question 4

what is the function of the appendicular skeleton?

Answer 4

these bones provide attachment sites for our muscles- the muscles contract and pull on the bone, facilitating movement

Question 5

what bones does our axial skeleton contain?

Answer 5

bones of our head, vertebrae and ribs

Question 6

what are the two classes of connective tissue?

Answer 6

loose and dense

Question 7

what are the three types of cartilage called?

Answer 7

hyaline, fibro and elastic

Question 8

what are features common to all three cartilage types?

Answer 8

• 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

Question 9

describe hyaline cartilage

Answer 9

• 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

Question 10

what are lacunae?

Answer 10

small chambers in the matrix occupied by one or more chondrocyte

Question 11

what is perichondrium?

Answer 11

• 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

Question 12

describe elastic cartilage

Answer 12

• 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

Question 13

describe fibrocartilage

Answer 13

• 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

Question 14

describe the histological components of bone tissue

Answer 14

ground substance, fibres and cells

Question 15

what is the ground substance of bone tissue made up of?

Answer 15

chondroitin sulphate and hyaluronic acid

Question 16

what type of fibres are in bone tissue?

Answer 16

type 1 collagen

Question 17

what is the osteoid of bone tissue?

Answer 17

unmineralised organic component of ECM made up of ground substance and fibres (28% hydroyapetite 70% fibres)

Question 18

what cells are found in bone tissue?

Answer 18

osteoblasts, osteocytes and osteoclasts (make up 2%)

Question 19

what do bones consist of?

Answer 19

• bone tissue
  (- connective tissue)
• adipose tissue
• blood vessels
• nervous tissue
• articular cartilage

Question 20

what are the two different conformations of bone tissue?

Answer 20

spongy and compact

Question 21

describe spongy bone conformation

Answer 21

(trabecular)
- honeycomb structure inside bone

Question 22

describe compact bone structure

Answer 22

(cortical)
- dense tough outer layer

Question 23

what are the cells in bone?

Answer 23

• osteogenic cells
• osteoblasts
• osteocytes
• osteoclasts

Question 24

what are osteogenic cells?

Answer 24

• bone cell precursor cells
• give rise to osteoblasts
• capable of cell division

Question 25

what are osteoblasts?

Answer 25

- synthesise and secrete osteoid (bone tissue) - give rise to osteocytes

Question 26

what are osteocytes?

Answer 26

- maintain mineralised bone tissue

Question 27

what are osteoclasts?

Answer 27

- phagocytic bone cells - resorb bone - derived from immune cell linage

Question 28

what are lamellae?

Answer 28

layers of bone (both spongy and compact bone tissue) arranged in lamellae

Question 29

what is an osteon?

Answer 29

(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

Question 30

what are volksman's canals?

Answer 30

(perforating canals) - smaller canals which connect the central canals with the periosteum, supplying the bone tissue with nutrients

Question 31

what is the periosteum?

Answer 31

- connective tissue around the outside of the bone - inner layer (cambium) contains osteoblasts - outer layer is elastic fibrous material containing blood vessels and nerves

Question 32

what is circumferential lamellae?

Answer 32

- lies directly beneath the periosteum - layers of bone which run around the entire circumference of the bone

Question 33

what is interstitial lamellae?

Answer 33

- 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

Question 34

what are canalicui?

Answer 34

- 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

Question 35

what is the histological structure of spongy bone?

Answer 35

- 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

Question 36

what is another phrase for bone formation?

Answer 36

osteoblast genesis

Question 37

what is another name for bone resorption?

Answer 37

osteoclast genesis

Question 38

describe bone remodelling

Answer 38

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

Question 39

what is periodontitis?

Answer 39

- 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

Question 40

describe arthritis

Answer 40

- 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

Question 41

describe osteomalacia

Answer 41

- '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