Chapter 6 Pearson Bones and Skeletal Tissues

Skeletal Cartilage

Exhibits chondrocytes housed in lacunae (cavities) within extracellular matrix (ground substance and fibers). It contains large amounts of water (which accounts for resilience), lacks nerve fibers, is avascular, and is surrounded by a fibrous perichondrium that resists expansion

Hyaline cartilage

Appear glassy; the fibers are collagen. They provide support with flexibility and resilience and are the most abundant skeletal cartilage, accounting for the articular, costal, respiratory, and nasal cartilages

Elastic Cartilage

Abundant elastic fibers, in addition to collagen fibers, more flexible than hyaline cartilages. Support outer ear and epiglottis

Fibrocartilages

Contain thick collagen fibers, are the most compressible cartilages and are resistant to stretch. They form vertebral discs and knee joint cartilages.

Appositional growth

Surrounding cells in perichondrium secrete new matrix on outside

Interstitial Growth

The lacunae-bound chondrocytes divide and secrete new matrix, expanding the cartilage within. Ends during adolescence.

Long Bones

Limbs, longer than they are wide

Short Bones

roughly cube shaped; Wrist and ankle bones

Sesamoid bones

Special short bone that form in a tendon. Patella

flat bone

Thin flattened, and usually a bit curved. Sternum, scapular, ribs, and skull bones

Irregular bones

Complicated shapes.Vertebrae and hip bones

Functions of Bones

Bones give the body shape, protect and support body organs, provide levers for muscles to pull on, store calcium and other minerals, and are the site of blood cell production

Diaphysis

shaft forms along axis of bone. Contains thick collar of compact bone that surrounds medullary cavity.

Medullary Cavity

Marrow cavity. Contains yellow bone marrow.

Epiphyses

Bones ends. Contains spongy bone

Epiphyseal line

Remnant of Epiphyseal plate.

Epiphyseal plate

Disc of hyaline cartilage that grows during childhood to lengthen bone.

Periosteum

white, double layered membrane covering bone. Outer fibrous layer is dense irregular connective tissue. Inner osteogenic layer, consists of osteoblasts and osteoclasts.

Nutrient Foramen

Nerve fibers, lymphatic vessels, and blood vessels enter vie foramen

Endosteum

Covers trabecuale of spongy bone and lines canal cavities has both osteoblasts and osteoclasts.

Red marrow

Hematopeitic tissue is found within the diploe of flat bones and occasionally within the epiphyses of long bones. In infants red marrow is in medullary cavity.

Osteon or Haversian System

Cylinder, weight bearing pillars. Group of hollow tubed of bone matrix

Lamella

Each tube in bone matrix of osteon

Lammalar bone

compact bone

Central Haversian canal

Runs through core of Osteon has small blood vessels and nerve fibers for cells.

Perforating or Volkmann's canals

Connect blood and nerve supply of the periosteum to the central canals

Lacunae

Junctions of lamellae, contain osteoctyes

Canaliculi

Hairlike canals connect lacunae together

Bone matrix

osteoid, organic substances produced by osteoblasts and give the bone tensile strength and give the bone tensile strength. Inorganic hydroxyapatites (Ca salts) make the bone hard

Intramembranous ossification

Forms cranial bones and clavicles.

1. An ossification center appears in the fibrous connective tissue membrane

2. Bone matrix is created within fibrous membrane

3. Woven bone and Periosteum form

4. Bone collar of compact bone forms and red marrow appears

Endochondral ossification

Uses hyaline cartilage bones as models.

1. Formation of bone collar around hyaline cartilage model

2. Cavitation of the hyaline cartilage within the model

3. Invasion of internal cavities by the periosteal bud and spongy bone formation

4. formation of the medullary cavity as ossification continues; appearance of secondary ossification in the epiphyses

5. ossification of the epiphyses when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilage.

Bone remoldeling

New bone continually being deposited and reabsorbed in response to hormonal and mechanical stimuli.

Bone deposit

Osteoid seam appears then Ca salts are deposited a few days later

Osteoclasts

Release lysosomal enzymes and acids on bone surface. The dissolved products are released to extra cellular matrix

Hormonal control of Ca levels

Blood Ca declines, PTH is released and stimulates osteoclasts to digest bone matrix. Blood Ca levels rise, calcitonin releases, stimulated removal of Ca from blood.

Stages of Healing a Bone Fracture

1. Hematoma formation

2. Fibrocartilage callus formation

3. Bony Callus formation

4. Bone remodeling

Osteomalacia / Rickets

Caused by inadequate minerals. The bones become soft and deformed. Often inadequate Vitamin D.

Osteoporosis

Any condition in which the bones breakdown outpaces bone formation, causing bones to become weak and porus.

Pagets Disease

Excessive and abnormal bone remodeling