Bone and Cartilage

Question 1

Bone and Cartilage Differences

Answer 1

Bone matrix mineralizes; cartilage mineralization leads to degeneration
Cartilage is avascular; bone is vascular
Cartilage lacks innervation
Cartilage growth is appositional and interstitial; bone grows appositionally

Question 2

hyaline cartilage

Answer 2

Most common
Type II collagen
Lacunae & isogenous groups
Perichondrium
Nutrition
Growth

Question 3

elastic cartilage

Answer 3

Locations
Elastic fibers
Type II collagen
Lacunae & isogenous groups
Perichondrium
Nutrition

Question 4

fibrocartilage

Answer 4

Locations
Type I collagen
Lacunae & isogenous groups
No perichondrium

Question 5

cartilage

Answer 5

Cells reside in lacunae

Few mitochondria

Typical Golgi, r-er, etc

Chondroblasts: Active cells

Chondrocytes: Quiescent or relatively inactive

Question 6

Cartilage matrix

Answer 6

60-80% water
Proteoglycan aggrecan:
Lot of chondroitin sulfates, keratan sulfates, & heparan sulfates covalently bound to a protein backbone

Hyaluronic acid:
Helps form proteoglycan aggregates
Extremely hydrophilic: binds Na+, water and produces a stiff gel

Chondronectin: (important)
Adhesive glycoprotein
Multiple binding sites: type II collagen; chondroitin-4 and -6 sulfates; integrins of chondroblasts and chondrocytes

Question 7

General Characteristics of bone

Answer 7

Dynamic
Structural support
Calcium reservoir
Morphology
Cell types
Matrix
Periosteum
Innervation and vascularization

Question 8

Osteoblasts

Answer 8

Synthesis of organic matrix (osteoid)
Deposition of inorganic components
Located on bone surfaces
‘epithelioid’ appearance
Basophilic and cuboidal to columnar
Cellular processes maintain contacts
Typical organelles for protein synthesis and secretion
Surface receptors for parathyroid hormone (PTH)
Osteoblasts bind PTH
Release ‘osteoclast stimulating factor’

Question 9

Osteocytes

Answer 9

Surrounded by matrix
Reduced protein synthesis
Maintenance of matrix and regulation of calcium
Death of osteocytes results in resorption of matrix
Lacunae
Canaliculi
Cells communicate via gap junctions
Cell-cell coordination
Nutrient transfer

Question 10

Osteoclasts

Answer 10

Large, multinucleated cells
Responsible for bone resorption
Monocyte heritage
Amitotic
Abundant lysosomes

Numerous cell processes

Ruffled border
Where osteoclast lies against bony surface

Question 11

Osteoclast Ruffled Border

Answer 11

Membranes pump H+ into sub-osteoclastic compartment

lowers pH and mineral is liberated

Minerals enter osteoclast and are then delivered to nearby capillaries