23: Cartilage And Bone Tissue Flashcards
What % of cartilage is water?
60-80%
Vascularization and innervation of cartilage
Avascular, not innervated
How do nutrients and gases get into cartilage?
Diffusion
Perichondrium composition
Dense irregular CT with two layers
Outer and inner layer of perichondrium
Outer fibrous layer: type I collagen + fibroblasts
Inner chondrogenic layer: mesenchymal SCs for growth and maintenance
Perichondrium function
Resists outer cartilage expansion when compressed
Ground substance of cartilage (3 components)
Hyaluronic acid, proteoglycans, water
ECM of cartilage: fibers
Type II collagen always, some have elastin or type I collagen
How are bones considered organs
Contain all four tissue types
Innervation and Vascularization of bone
Innervated + vascular
Where are nerves found in bone?
Periosteum
Five parts of a long bone
Epiphysis, diaphysis, metaphysis, periosteum, endosteum
Epiphysis
Knobby regions at ends of long bone, with compact bone superficially and trabecular deep to the surface
Diaphysis
Elongated shaft of long bone housing the marrow cavity
Metaphysis
Spongy bone between diaphysis and epiphysis
Periosteum tissue type
Dense irregular CT
Endosteum
CT lining all trabeculae and the marrow cavity
Cell types present in periosteum vs endosteum
Periosteum: osteoblasts, osteoprogenitors
Endosteum: osteoprogenitors, reticular cells of bone marrow
Organic vs inorganic osteoid compositions
Organic: type I collagen, proteoglycans
Inorganic: calcium phosphate, hydroxyapatite crystals
Two functions of long processes of osteocytes (found in canaliculi)
- Communication with other cells via gap junctions
2. Receive nutrients
Osteon
Concentric lamellae surrounding a central canal, running parallel to diaphysis
Cement line
Outer boundary of an osteon
Interstitial lamellae
Partial rings, remnants of previous concentric lamellae
Five zones of epiphyseal growth plate growth and what happens in each
- Resting zone: reserved chondrocytes
- Proliferation zone: chondrocytes proliferate + stack up
- Hypertrophic zone: older cartilage cells enlarge + secrete matrix
- Calcification zone: calcification occurs and cartilage cells die
- Ossification zone: where new bone forms
How often is trabecular bone replaced vs compact bone?
Trabecular: every 3-4 years
Compact: every 10 years
Two functions of bone remodeling
- Repair microdamage
2. Calcium metabolism
How much Ca can enter or leave the adult skeleton each day
500mg
Achondroplasia
Most common form of dwarfism with shortened long bones, small midface, and altered spinal curvature
Mutation in achondroplasia and genetic inheritance pattern
FGFR3 mutation; autosomal dominant
What does FGFR3 play a role in?
Chondroblast proliferation
Osteoporosis
Low bone mass due to bone resorption faster than deposition
Why is estrogen therapy for women controversial?
Increased risk of MI, CVA, CA
Vitamin D deficiency in adults vs children
Adults: osteomalacia
Children: rickets
Osteomalacia
Soft bones due to inadequate mineralization
Rickets
Weakened long bones, abnormal head and rib cage
