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Chapter 6 Bone & Skeletal Tissue

The Skeletal System  

Discuss the components and functions of the skeletal system.

  • Hyaline, elastic, & fibrocartilage help form the skeletal system

  • support: provide framework that supports body

  • protection: the shape of some bones help protect delicate organs

  • movement: anchor to each other & to muscle to move

  • mineral & growth factor storage: calcium & phosphate, release into blood to distribute all over

  • blood cell formation: hematopoiesis occurs in bone marrow

  • triglyceride (fat) storage: fat stored in yellow bone marrow in long bones

  • hormone production: osteocalcin helps regulate insulin secretion, glucose balance, & energy

Discuss the basic anatomy of long and flat bones.

  • long bone: longer than wide, limb bone

  • flat bone: thin, flat, slightly curved

  • short bone: cubic, sesamoid, reduce friction

  • irregular: complicated shapes

Describe the histological features of compact and spongy bone tissue.

  • spongy bone: internal layer of a bone (trabecular) & has mesh of bony spines called trabeculae

  • compact bone: external layer of a bone

  • osseous tissue (obvi), also contain nervous tissue, cartilage in articular cartilage, dense connective tissue covering external surrounding, & muscle & epithelial in the blood vessels

Compare and Contrast intramembranous ossification and endochondral ossification.

  • both processes develop bone,

  • endochondral ossification:

    1. bone collar forms around diaphysis of hyaline cartilage model (surrounded by perichondrium), mesenchymal cells turn into osteoblasts so perichondrium →periosteum, osteoblasts secrete osteoid to encase the hyaline cartilage diaphysis, chondrocytes within shaft hypertrophy (primary ossification center)

    2. cartilage calcified in center & develops cavities, chondrocytes ossify surrounding cartilage matrix & die, so matrix deteriorates, which opens up cavities, causing cartilage model to elongate

    3. periosteal bud invades internal cavities & spongy bone forms, in month 3, cavity is invaded by periosteal bud (contains nutrients artery & vein, red marrow stuff, osteoprogenitor cells (which turns to osteoclast), osteoclasts), osteoclasts fill remaining fragments of hyaline cartilage, earliest version of spongy bone is formed

    4. diaphysis elongates & medullary cavity forms, secondary ossification center appears in epiphysis

    5. epiphysis ossify, hyaline cartilage remains in epiphyseal plate & articular cartilages

  • Intramembranous ossification: forms bones of skull & clavicle

    1. ossification centers are formed when Mesenchymal cells cluster & become osteoblasts

    2. osteoid is secreted, then calcified. osteoblasts continue to secrete osteoid which clarifies in a few days (trapped osteoblasts become osteocytes)

    3. woven bone is formed when osteoid is laid down around blood vessels resulting in trabeculae. outer layer of woven bone forms periosteum

    4. lamellar bone replaces woven bone & red marrow appears

Define interstitial and appositional bone growth.

  • interstitial growth:

    • needs the epiphyseal cartilage

    • 5 zones: resting, proliferation, hypertrophic, calcification, & ossification

  • appositional growth: bone growth in width that occurs thru life

    • thickens the bone in response to body changes (weight, increased stress from muscle activity)

    • more building than breaking, so leads to thicker & stronger bone

Describe the process of bone remodeling and fracture repair.

  • Bone remodeling: both bone deposit & resorption

    • surfaces of periosteum & endosteum

    • osteoblasts (bone deposit) & osteoclasts (bone resorption)

  • fracture repair: begins w/ reduction (4 steps)

    1. Hematoma formation: blood vessels hemorrhage, forming hematoma (swollen, painful, inflamed cuz bone cells are deprived)

    2. Fibrocartilaginous callus forms: new blood vessels become clot, phagocytic cells clear debris and reconstruction has begun

    3. Bony callus forms: osteoblasts begin rebuilding spongy bone (done in 1 week) then callus is turned into hard callus (to continue for 2 months until firm union)

    4. Bone remodeling: begins during step 3 & lasts several months, excess material is removed, compact bone is placed to reconstruct shaft so the final product resembles the original

Classify the principal types of bones on the basis of shape and location.

  • Long bones are longer than wide & include limb bones (tibia, ulna)

  • Short bones are cubed & sesamoid. vary in size & #, but alter direction of pull of tendon & reduce friction (talus, scaphoid)

  • Flat bones are thin, flat, & curved (parietal, scapula)

  • Irregular bones are complicated shapes (pelvis, vertebrae)

Discuss selected bone diseases and common fractures.

Bone Tissue

Gross bone structure, anatomy and difference of long, short, irregular, and flat bones. 

Microscopic view, cells of bone tissue, and maturation of cells.

Bone development and bone growth starting in postnatal stage through childhood and adolescences, chemical composition, and growth/importance of the epiphyseal plate.