Chapter 6

Made of highly resilient, molded cartilage tissue that consists primarily of water

-layer of dense connective tissue -contains blood vessels for nutrient delivery to cartilage

-appositional growth -interstitial growth

-adding new cartilage or bone on top of pre-existing bone or cartilage (deposition) -life long but slows down when we get older -always occurs under a membrane with lots of blood vessels (chondrogenic or osteogenic)

-growth from within (inside out) -occurs in hyaline cartilage -in the bone and stops at ages 18-25

Cells that add bone (osteo-) or cartilage (chondro-)

-provide support, flexibility, and resilience -joints, ribs, larynx, nose tip -most abundant type

-contains elastic fibers -ear and epiglottis

-thick collagen fibers -menisci of knee and vertebral discs

-cartilage forming cells in perichondrium secrete matrix against external face of existing cartilage -new matrix laid down on surface of cartilage

-Chondrocytes within lacunae divide and secrete new matrix, expanding cartilage from within -New matrix made with cartilage

-support -protection -movement -mineral/growth factor storage -blood cell formation -triglyceride storage -hormone production

-needed for all cell activity -muscle contraction -nervous system *once absorbed extra calcium is put on the bone

-long axis of the body -skull, vertebral column, rib cage

-bones of upper and lower limbs -girdles attaching limbs to axial skeleton

Dense outer layer on every bone that appears smooth and solid

Made up of a honeycomb of small needle-like or flat pieces of bone called trabeculae *spaces between trabeculae are filled with red or yellow bone marrow

thin plates of spongy bone covered by compact bone

have a shaft (diaphysis), bone ends (epiphysis), and membranes

Tubular shaft that forms long axis of bone

Located between diaphysis and epiphysis

Ends of long bones that consist of compact bones externally and spongy bone internally

White double-layered membrane that covers external surfaces except joints

Outer layer consisting of dense irregular connective tissue consisting of Sharpey's fibers that secure to bone matrix

Inner layer abutting bone and contains primitive osteogenic stem cells that rise to all bone cells

-delicate connective tissue membrane covering internal bone surface -covers trabeculae of spongy bone

Red marrow found within trabecular cavities of spongy bone and diploe of flat bones such as the sternum

-osteogenic cells -osteoblasts -bone lining cells -osteoclasts -osteocytes

-called osteoprogenitor cells -mitotically active stem cells in periosteum and endosteum

bone forming cells that secrete unmineralized bone matrix called osteoid

Mature bone cells in lacunae that no longer divide

Flat cells on bone surfaces believed to also help maintain matrix

Derived from same hematopoietic stem cells that become macrophages

Structured unit of compact bone

Runs through core of osteon

Canals lined with endosteum that occur at right angles to central canal

Small cavities that contain osteocytes

Hair-like canals that connect lacunae to eachother and to central canal

-lamellae not part of osteon -Some fill gaps between forming osteons; others are remnants of osteons cut by bone remodeling

Deep to periosteum but superficial to endosteum, these layers of lamellae extend around surface of diaphysis

-osteogenic cells -osteoblasts -osteocytes -bone lining cells -osteoclasts -osteoid

Make up 1/3 of organic bone matrix, secreted by osteoblasts

-Hydroxyapatites (mineral salts) -responsible for hardness and resistance to compression

-Process of bone tissue formation -begins at 2 month -postnatal growth occurs until early childhood -bone remodeling/repair are lifelong

-forms essentially all bones inferior to base of skull except clavicle -breakdown of hyaline cartilage -begins at primary ossification center

-Begins with in fibrous connective tissue membranes formed by mesenchyme cells

-resting (quiescent) zone -proliferation (growth) zone -hypertrophic zone -calcification zone -ossification (osteogenic) zone

Area of cartilage on epiphyseal side of epiphyseal plate that is inactive

-area of cartilage on diaphysis side of epiphyseal plate that is rapidly dividing -new cells formed moving upward, pushing epiphysis away from diaphysis, cause lengthening

chondrocyte deterioration leaves long spicules of calcified cartilage at epiphysis-diaphysis junction

-about 5-7% bone mass is recycled each week -spongy: 3-4 yrs -compact: 10yrs -consists of bone deposit and bone resorption

packets of adjacent osteoblasts and osteoclasts coordinate remodeling process

produced by parathyroid glands in response to low calcium levels

Produced by parafollicular cells of thyroid gland in response to high levels of blood calcium levels

Active form of vitamin D

Bones grow or remodel in response to demands placed on them

breaking of bone *during youth-result from trauma *old age-due to bone thinning

-bone fragments in 3+ pieces -common in the age where bones are more brittle

-bone is crushed -common in porous bones

-ragged break occurs when excessive twisting forces are applied to a bone -common in sports

-epiphysis separates from the diaphysis along the epiphyseal plate -occurs where cartilage cells are dying and calcification of the matrix is occurring

-broken bone portion is pressed inward -typical of skull fracture

-bone breaks incompletely; one side of the shaft breaks while the other side bends -common in children whose bones have more organic matrix/flexibility

Realignment of broken bone ends

Physician manipulates to correct position

Surgical pins or wires secure ends

Cast or traction is needed for healing

-hematoma formation -fibrocartilaginous callus formation -bony callus formation -bone remodeling

-torn blood vessels hemorrhage forming mass of clotted blood -site is swollen, painful and inflamed

Callus is converted to bony (hard) callus of spongy bone

Final structure resembles original structure

-osteomalacia and rickets -Osteoporosis -Paget's disease

-bones are poorly mineralized -osteoid is produced, but calcium salts not deposited -soft, weak bones -pain upon bearing weight

-Otseomalacia of children -bowed legs due to enlargement bone ends -caused by vitamin D deficiency or insufficient dietary calcium

-group of diseases in which bone resorption exceeds deposit -matrix is normal; bone mass decline