A&P I Ch 7 Chapter Review

Steps in fracture repair.

1. fracture hematoma 2. fibrocartilage -soft- callus forms 3. a hard -bone- callus forms 4. the bone is remodeled

Interstitial Growth: 1. Chondrocytes housed within lacunae stimulate to undergo mitotic cell division 2. two cells occupy a single lacuna now called chondroblasts

3. chondroblasts begin to synthesize and secrete new cartilage matrix and are pushed apart 4. cartilage contains to grow in internal regions as chondrocytes cont. to produce more matrix

Steps involved in endochondral ossification: 1. fetal hyaline cartilage model develops 2. cartilage calcifies and a periostealbone collar forms 3. primary ossification center forms in diaphysis

4. secondary ossification center forms in the epiphysis 5. bone replaces almost all cartilage except the articular cartilage and epiphyseal cartilage 6. lengthwise groove cont. until the epiphyseal plates ossify and form epiphyseal lines

Compare and Contrast interstitial growth versus oppositional growth of cartilage.

Both use chondrocytes to produce more matrix and both use chondroblasts to produce and secrete new cartilage matrix. Interstitial begins with chondrocytes and appositional begins with stem cells; appositional is external while interstitial is internal.

Describe the microscopic anatomy of compact bone.

Composed of osteons which has a central canal, concentric lamellae, osteocytes, lacunae, and canaliculi other structures include perforating canals, circumferential lamellae, interstitial lamellae

Functions of the cartilage

Cartilage provides support for soft tissue, cartilage forms the initial model in endochondral ossification, cartilage provides a smooth gliding surface at the end of the bones in freely movable joints

Describe the structure of a typical long bone.

Greater in length than width, elongated-cylindrical shaft (diaphysis); most common bone shape; found in upper and lower limbs

Discuss the effects of exercise on bone.

Involved in bone remodeling; bone strength increases due to mechanical stress

Describe the general function of both osteoblast and osteoclast activity.

Osteoblasts form from osteoprogenitor stem cells, synthesize and secrete the initial semisolid organic form of bone matrix called osteoid. Osteoclasts are large multinuclear phagocytic cells, located within or adjacent to a depression or pit on bone surface called a resorption lacuna, involved in breaking down in an important process called bone resorption.

Explain how parathyroid regulates blood plasma calcium concentrated.

PTH is secreted and released by parathyroid to reduce blood calcium levels; The removal of calcium from bone the decrease in loss of calcium from the kidney and increase in calcium absorption from the gastrointestinal tract result in elevating blood calcium returning it to normal range

Why is spongy bone able to withstand stress in an area such as the expanded end of the long bone?

Trabeculate forms a meshwork of crisscrossing bars and plates of small bone pieces; provides great resistance to stresses applied in many directions by distributing the stress throughout the framework

Which of the five zones in the epiphyseal plate cartilage are specifically responsible for bone growth in length?

Zone 2: zone of proliferating cartilage as chondrocytes undergo mitotic cell division. Zone 3: zone of hypertonic cartilage as chondrocytes hypertrophy both enlarge size

Apposition Growth: 1. undiffererniated stem cells at internal edge of the perichondrium begin to divide 2. new undiffereniate stem cells and committed cells that differeniate into chondroblasts located at periphery of old cartilage

produce and secrete new cartilage matrix 3. chondroblasts push apart become chondrocytes with each in own lacuna; cartilage cont. to grow and produce more matrix