Larger osteoclasts resorbing bone at higher rate

Larger osteoclasts resorbing bone at higher rate
Newly deposited bone poorly formed
Most commonly affected bones:
pelvis, skull, vertebrae, femur, tibia
Symptoms of bone deformity and pain
Compact and Spongy Bone Microscopic Anatomy Figure 7.8a-b
Compact bone composed of osteons - Small cylindrical structures
Also known as Haversian systems
Basic functional and structural unit of mature compact bone
Oriented parallel to bone diaphysis
In cross section appears like bull’s-eye target
Components of osteons of compact bone Figure 7.7a - b

Central canal - cylindrical channel
lies at center of osteon and runs parallel to it
blood vessels and nerves traveling here
Concentric lamellae - rings of bone connective tissue
surround the central canal
contain collagen fibers
oriented at an angle 90 degrees from previous and next lamellae
give bone part of its strength and resilience
Osteocytes - mature bone cells
found in small spaces between concentric lamellae ( lacunae )
maintain bone matrix
Canaliculi - tiny interconnecting channels within bone connective tissue
extend from each lacuna
travel through lamellae
connect to other lacunae and central canal
house osteocyte projections permitting intercellular contact
allow travel of nutrients, minerals, gases, and wastes between blood vessels and osteocytes
Other components of compact bone
Perforating canals ( Volkmann canals ) - contain blood vessels and nerves
run perpendicular to the central canals
help connect multiple central canals within different osteons
Circumferential lamellae - rings of bone
run the entire circumference of bone
Interstitial lamellae - components of compact bone between osteons
may be partially resorbed osteons
look like a “bite” taken out of them
Components of spongy bone Figure 7.7c
Trabeculae - open lattice of narrow rods and plates of bones
bone marrow filling spaces between
form a meshwork of crisscrossing bars
provide great resistance to stresses
Structure of hyaline cartilage
Population of cells scattered through matrix of protein fibers
Embedded in a gel-like ground substance
includes proteoglycans but not calcium
Resilient and flexible
High percentage of water
Highly compressible and a good shock absorber
Avascular and contains no nerves
Chondroblasts - produce cartilage matrix
Chondrocytes - chondroblasts that have become encased within the matrix
occupy small spaces called lacunae
maintain the matrix
Perichondrium - dense irregular connective tissue
covers cartilage and helps maintain its shape
Comparison of Bone Connective Tissue & Hyaline Cartilage Connective Tissue (Table 7.1)
Cartilage Growth
Process of cartilage growth
Begins during embryologic development
Growth in length through interstitial growth
occurs within the internal regions of cartilage
Growth in width by appositional growth
occurs on cartilage’s outside edge

Steps of interstitial growth Figure 7.9a
1) A chondrocyte within a lacuna is stimulated to mitotically divide.