L15 Skeletal Cartilage Flashcards
Where are chondrocytes found?
They occupy lacunae in cartilage
Why does cartilage heal slowly?
Cartilage is poorly vascularised, exchange of nutrients/waste occurs by diffusion
Cartilage is derived from which embryonic layer?
Mesoderm
The mesoderm gives rise to the mesenchyme. What develops from the mesenchyme?
Cartilage
Bone
Fibrous tissue
What separates cartilage from surrounding tissues?
Perichondrium
There are 2 layers:
1) outer fibrous irregular CT layer
2) inner cellular layer
What are the 3 major types of cartilage?
Hyaline cartilage
Elastic cartilage
Fibrocartilage
Hyaline is the most common type of cartilage, what is the matrix made of?
Densely packed collagen fibres form a translucent matrix.
Where can hyaline cartilage be found?
Connecting the ribs and sternum
Nasal cartilages and respiratory tract
Articulate cartilage (joints)
Where can you find elastic cartilage?
External flap of outer ear
Epiglottis
Larynx
What makes elastic cartilage so resilient and flexible?
The matrix contains many elastic fibres
What are the general uses of fibrocartilage?
Resist compression
Absorb shock
Prevent bone-to-bone wear
Where can fibrocartilage be found?
Between spinal vertebrae
Between public bones in pelvis
Around/within some joints and tendons
What are the two mechanisms of cartilaginous growth?
Interstitial growth (cartilage grows from within by chondrocyte division)
Appositional growth (new layers added to the surface, fibroblasts increase matrix)
What is endochondral ossification?
Development of bones from hyaline cartilage model. Bone replaces existing cartilage.
Begins near middle of shaft (primary ossification centre)
Centre of epiphyses (head) calcify (secondary ossification centre)
Forms weight bearing bones, such as femurs and vertebrae
What bones are formed by intramembranous ossification?
Flat bones (mandible, face bones, skull, clavicle)
How does intramembranous ossification occur?
Bone develops from the mesenchyme or connective tissue.
Mesenchyme cells cluster and secrete matrix
Calcification occurs: Stem cells differentiate into osteoblasts
Ossification begins (ossification centre)
1st spongy bone forms, then remodelling takes place to form compact bone.
Blood is supplied to the bones via the __1__ artery, and __2__ and __3__ vessels.
1) nutrient
2) metaphyseal
3) periosteal
What are the six bone types?
1) Long bones (e.g. femur, humerus)
2) Short bones (e.g. carpals, tarsals)
3) Flat bones (e.g. parietal, ribs, scapula)
4) Irregular bones (e.g. vertebrae, pelvis)
5) Sesamoid bones (e.g. kneecap)
6) Sutural bones
Which cells occupy lacunae in bone?
Osteocytes
How do osteoclasts regulate serum levels of calcium and phosphate?
Secrete acids and proteolytic enzymes to dissolve bone matrix (osteolysis)
What is osteopenia?
Thinning and weakening of the bones as they age. Caused when osteoclast activity overtakes osteoblasts activity and can lead to osteoporosis.
