Cartilage and Bone Flashcards
What does cartilage consist of
Ground substance
-Chondroitin (leads to more firm ECM)
-sulphates
Fibres
-Collagen
-Elastin
Cells
-Chrondroblasts (secrete)
-Chondrocytes (maintain)
Additional feature of cartilage
Avascular - no blood vessels present, therefore heal very poorly and all exchange of nutrients and waste occur by diffusion
What is the most common type of cartilage
Hyaline Cartilage
-abundant ground substance lubricates joints
-contains collagen fibres (stain easily)
-connects ribs to sternum
-contains articular cartilages, (lines bones where we form joints)
Made up of:
Perichondrium
Chondrocytes
Chondroblasts (inner layer of perichondrium)
Articular cartilage
Formation of chondrocytes
once chondroblasts become embedded in matrix they cease synthesis and become chondrocytes (mature form of chondroblasts)
chondrocytes are found in the lacunae
What are the properties of elastic cartilage
-Highly flexible
-Avascular
-provide support and resistance to compression
-similar to hyaline cartilage
-contains collagen fibres particularly in perichondrium
-elastin fibres (show up as black) are conc around lacunae
Found in the outer ear/epiglottis not very common
what is the most durable cartilage
Fibrocartilage
-little ground substance
-dominated by collagen fibres
-chondrocytes arranged in rows
Form pads between spinal vertebrae
2 parts of the skeleton
Appendicular - provide attachment sites for muscle, facilitate movement
Axial - head, vertebrae and ribs, protect organs
what is the perichondrium
dense fibrous connective tissue, surrounds hyaline cartilage, attaches cartilage to various other tissues. has an inner cellular layer involved in growth and maintenance of cartilage. Not present in articular cartilage.
Which component of cartilage is responsible for conferring significant compression strength
Chondroitin sulphate
What do the ground substance of bone and cartilage have in common
Chondroitin sulphate
what type of collagen is most abundant in bone
Type 1
Collagen and ground substance form what un-mineralised component of ECM in bone
Osteoid (28%)
What makes up 2% of bone
Cells
-osteoblasts (synthesise and secrete osteoid/ECM)
-osteocytes
-osteoclasts
-osteogenic
Deposition of hydroxyapatite leads to what
osteoid is mineralised
What gives bone its strength
Hydroxyapatite and collagen together
-by itself hydroxyapatite is very brittle but with collagen fibres as a framework for the crystals producing a hard but flexible tissue
Are bones organs
Yes
Bones consist of tissue and….
CT proper (periosteum)
Adipose tissue (fatty marrow)
Blood vessels
Nervous tissue
Articular cartilage (lines external surface)
How many conformations of bone exist
2 - compact (cortical) bone
- spongy (trabecular) bone
What are the names of the cells found in bone tissue
All of same lineage but at different maturities except osteoclasts:
Osteogenic/osteoprogenitor
-bone cell precursor
-gives rise to osteoblasts
Osteoblast
-synthesise and secretes bone tissue (osteoid)
-gives rise to osteocytes, once they become encased
Osteocyte
-maintains mineralised bone tissue
Osteoclast
-resorbs bone
-derived from monocyte/macrophage lineage
where are osteogenic cells found
inner osteogenic layer of the periosteum
What are lamellae
layers of bone tissue
what is an osteon
functional units of compact bone, each unit of concentric lamellae
where are the central canals and what purpose do they serve
in the centre of an osteon, run longitudinally through entire length of bone containing network of blood vessels, nerves and lymphatics
what provides the bone tissue with nutrients
perforating (Volkmann’s) canal
where are the circumferential lamellae
They run around entire circumference directly beneath periosteum
What lies in between each osteon
remnants of old osteons, interstitial lamellae
Osteons are constantly being reformed, how
osteoclasts migrate into weakened areas of bone tissue and resorb and recycle a large channel into bone tissue forming new blood vessels and bone tissue to form a new osteon potentially replacing multiple older, weaker ones which in turn become interstitial lamellae.
what are canaliculi
branches off an osteocyte lacuna allowing osteocytes to reach out and remain in direct contact with each other to communicate and receive nutrients instead of relying on diffusion which isn’t possible due to presence of hydroxyapatite
structure of spongy Bone
-Contains lamellar bone (bone arranged in layers)
-no osteons
-spaces between trabeculae occupied by red and yellow marrow, nerves, blood vessels and lymphatics
-lined externally by endosteum
Another word for bone formation
Osteoblastogenesis
Influences on bone remodelling
Growth
Mechanical stresses
Hormonal - calcium homeostasis
Immunological
A lack of vitamin D can also affect bone remodeling as it prevents the uptake of calcium
What is periodontitis
A destructive inflammatory disease characterised by loss of periodontal attachment in the alveolar bone leading to gingival recession (desrtuction of host tissues due to an increase in osteoclastogenes (bone resorption))
Bone resorption is out of balance with bone formation
Types of arthritis
Rheumatoid arthritis
outer covering of joint first affected by swelling. Inflammation can change joint shape. significantly less bone volume than in osteoarthritis
Osteoarthritis
decreases mobility around the joint, severe loss of cartilage leads to bone on bone which can alter the shape of the joint, tendons and ligaments working much harder.
Osteomalacia (rickets in children) can be associated with what dental abnormalities
Enamel hypoplasia - not enough enamel (no strength)
Delayed tooth eruption
Caused by the failure of osteoid to mineralise adequately and therefore bones are weakened and prone to fracture
What percentage (approx) of hydroxyapatite makes up the enamel
95% making it the hardest substance in the body
What physiological process drives osteoclastogenesis in conditions such as periodontitis and rheumatoid arthritis?
Inflammation
