Bones and Skeletal Tissues

Location of Bones and Cartilages © 2013 Pearson Education, Inc. Location of Bones and Cartilages

Types of Skeletal Cartilages © 2013 Pearson Education, Inc. Types of Skeletal Cartilages Three types 1. Hyaline cartilage Provides support, flexibility, and resilience Collagen fibers only; most abundant type Articular skeleton, costal (ribs), respiratory, nasal cartilage 2. Elastic cartilage Similar to hyaline cartilage, but contains elastic fibers External ear and epiglottis 3. Fibrocartilage Thick collagen fibers—has great tensile strength Menisci of knee; vertebral discs

© 2013 Pearson Education, Inc. Important Point! cartilage is not "turned into" bone, it is replaced by bone in a complicated process **hyaline cartilage forms the model for the bones in a developing embryo. Growth and reshaping occurs in two ways: interstitial growth and appositional growth.

Growth of Cartilage Appositional growth: Interstitial growth © 2013 Pearson Education, Inc. Growth of Cartilage Appositional growth: takes place "at the edge" of the cartilage mass Interstitial growth takes “in the middle" of the mass of cartilage. Calcification of cartilage- Depositing calcium Occurs during normal bone growth Youth and old age Hardens, but cacified cartilage is not bone!

Review Questions: pg 196 M.C 3, 4, 10, Short Answer: 15, 18, © 2013 Pearson Education, Inc. Review Questions: pg 196 M.C 3, 4, 10, Short Answer: 15, 18,

Classification of Bones © 2013 Pearson Education, Inc. 206 named bones in Adult skeleton Divided into two groups: See fig. 7.1 Axial skeleton and Appendicular skeleton

Classification of Bones by Shape © 2013 Pearson Education, Inc. Classification of Bones by Shape Long bones Longer than they are wide Limb, wrist, ankle bones Short bones Cube-shaped bones (in wrist and ankle) Sesamoid bones (within tendons, e.g., Patella) Vary in size and number in different individuals Flat bones Thin, flat, slightly curved Sternum, scapulae, ribs, most skull bones Irregular bones Complicated shapes Vertebrae, coxal bones

Figure 6.2 Classification of bones on the basis of shape. © 2013 Pearson Education, Inc. Flat bone (sternum) Long bone (humerus) Irregular bone (vertebra), right lateral view Short bone (talus)

Functions of Bones 1. Support: Standing upright, sitting 2. Protection: soft organs 3. Movement: muscles attached 4. Storage: fat, calcium, phosphorus 5. Blood Cell Formation: hematopoiesis 6. Hormone production Osteocalcin Regulates bone formation

Bones Are organs Three levels of structure © 2013 Pearson Education, Inc. Bones Are organs Contain different types of tissues Bone (osseous) tissue, nervous tissue, cartilage, fibrous connective tissue, muscle and epithelial cells in its blood vessels Three levels of structure Gross anatomy Microscopic Chemical

Gross Anatomy: Bone Texture © 2013 Pearson Education, Inc. Gross Anatomy: Bone Texture Compact and Spongy bone Compact Dense outer layer; smooth and solid Spongy: also called trabecular Less dense- open spaces

Structure of Short, Irregular, and Flat Bones © 2013 Pearson Education, Inc. Structure of Short, Irregular, and Flat Bones Thin plates of spongy bone covered by compact bone Plates sandwiched between connective tissue membranes Periosteum (outer layer) and endosteum (inner layer) No shaft or epiphyses Bone marrow throughout spongy bone; no marrow cavity

Long Bones Epiphyses Bone ends © 2013 Pearson Education, Inc. Long Bones Epiphyses Bone ends External compact bone; internal spongy bone Articular cartilage covers articular surfaces Between is epiphyseal line Remnant of childhood bone growth at epiphyseal plate Diaphysis Tubular shaft forms long axis Compact bone surrounding medullary cavity

© 2013 Pearson Education, Inc. Bone Membranes: Endosteum Periosteum

© 2013 Pearson Education, Inc. Review Questions: # 5, 21, 22

Hematopoietic Tissue in Bones © 2013 Pearson Education, Inc. Hematopoietic Tissue in Bones Red marrow Found within trabecular cavities of spongy bone and in flat bones (e.g., sternum) In medullary cavities and spongy bone of newborns Adult long bones have little red marrow Heads of femur and humerus only Yellow marrow can convert to red, if necessary

Table 6.1 Bone Markings (1 of 2) © 2013 Pearson Education, Inc.

Table 6.1 Bone Markings (2 of 2) © 2013 Pearson Education, Inc.

© 2013 Pearson Education, Inc. Cells of Bone Tissue

Anatomy of Compact Bone © 2013 Pearson Education, Inc. Osteon or Haversian system Structural unit of compact bone Hollow tubes of bone matrix called lamellae Collagen fibers in adjacent rings run in different directions Withstands stress – resist twisting

Figure 6.7 Microscopic anatomy of compact bone. Spongy bone © 2013 Pearson Education, Inc. Central (Haversian) canal Perforating (Volkmann’s) canal Endosteum lining bony canals and covering trabeculae Osteon (Haversian system) Circumferential lamellae Perforating (Sharpey’s) fibers Lamellae Periosteal blood vessel Periosteum Nerve Vein Lamellae Artery Central canal Canaliculi Osteocyte in a lacuna Lacunae Interstitial lamella Lacuna (with osteocyte)

Chemical Composition of Bone: Inorganic Components © 2013 Pearson Education, Inc. Chemical Composition of Bone: Inorganic Components Hydroxyapatites (mineral salts) 65% of bone by mass Mainly of tiny calcium phosphate crystals in and around collagen fibers Responsible for hardness and resistance to compression

Bone Fun Facts Half as strong as steel in resisting compression © 2013 Pearson Education, Inc. Bone Fun Facts Half as strong as steel in resisting compression As strong as steel in resisting tension Last long after death because of mineral composition Reveal information about ancient people Can display growth arrest lines Horizontal lines on bones Proof of illness - when bones stop growing so nutrients can help fight disease