Copyright © 2010 Pearson Education, Inc. Figure 4.8g Connective tissues. (g) Cartilage: hyaline Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress. Location: Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx. Photomicrograph: Hyaline cartilage from the trachea (750x). Costal cartilages Chondrocyte in lacuna Matrix Pg 135 Chondroblast -> Chondrocyte (Lacunae) Firm ground substance (chondroitin sulfate and water) Collagenous and elastic fibers No BV or nerves Perichondrium (dense irregular) Thickness? Metabolism?

Copyright © 2010 Pearson Education, Inc. Figure 6.1 The bones and cartilages of the human skeleton. Axial skeleton Appendicular skeleton Hyaline cartilages Elastic cartilages Fibrocartilages Cartilages Bones of skeleton Epiglottis Larynx Trachea Cricoid cartilage Lung Respiratory tube cartilages in neck and thorax Thyroid cartilage Cartilage in external ear Cartilages in nose Articular Cartilage of a joint Costal cartilage Cartilage in Intervertebral disc Pubic symphysis Articular cartilage of a joint Meniscus (padlike cartilage in knee joint) Pg 175 Support Smooth surface Cushions

Copyright © 2010 Pearson Education, Inc. Figure 4.8g Connective tissues. (g) Cartilage: hyaline Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress. Location: Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx. Photomicrograph: Hyaline cartilage from the trachea (750x). Costal cartilages Chondrocyte in lacuna Matrix glassy Pg 135

Copyright © 2010 Pearson Education, Inc. Figure 4.8h Connective tissues. (h) Cartilage: elastic Description: Similar to hyaline cartilage, but more elastic fibers in matrix. Function: Maintains the shape of a structure while allowing great flexibility. Location: Supports the external ear (pinna); epiglottis. Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800x). Chondrocyte in lacuna Matrix Pg 135

Copyright © 2010 Pearson Education, Inc. Figure 4.8i Connective tissues. (i) Cartilage: fibrocartilage Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate. Function: Tensile strength with the ability to absorb compressive shock. Location: Intervertebral discs; pubic symphysis; discs of knee joint. Photomicrograph: Fibrocartilage of an intervertebral disc (125x). Special staining produced the blue color seen. Intervertebral discs Chondrocytes in lacunae Collagen fiber Pg 136 Tough! Forms discs and pads

Copyright © 2010 Pearson Education, Inc. Figure 6.7 Microscopic anatomy of compact bone. Endosteum lining bony canals and covering trabeculae Perforating (Volkmann’s) canal Perforating (Sharpey’s) fibers Periosteal blood vessel Periosteum Lacuna (with osteocyte) (a) (b)(c) Lacunae Lamellae Nerve Vein Artery Canaliculi Osteocyte in a lacuna Circumferential lamellae Osteon (Haversian system) Central (Haversian) canal Central canal Interstitial lamellae Lamellae Compact bone Spongy bone Pg 182 Support Protection Blood formation Storehouse Movement Hydroxyapatite (calcium salts) Bone Cells -osteoblast -osteocyte -osteoclast Periosteum (dense irr.) 2 types of bone osteoblast Osteoblasts & clasts

Copyright © 2010 Pearson Education, Inc. Proximal epiphysis (b) (c)(a) Yellow bone marrow Endosteum Epiphyseal line Articular cartilage Periosteum Spongy bone Compact bone Medullary cavity (lined by endosteum) Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries Diaphysis Distal epiphysis Figure 6.3 The structure of a long bone (humerus of arm). Pg 178 Spongy = Cancellous Spaces contain marrow Trabeculae -Ends of long bones -Shaft of young bones -In flat, short and irregular bones 8 days/20%

Copyright © 2010 Pearson Education, Inc. Figure 6.7 Microscopic anatomy of compact bone. Endosteum lining bony canals and covering trabeculae Perforating (Volkmann’s) canal Perforating (Sharpey’s) fibers Periosteal blood vessel Periosteum Lacuna (with osteocyte) (a) (b)(c) Lacunae Lamellae Nerve Vein Artery Canaliculi Osteocyte in a lacuna Circumferential lamellae Osteon (Haversian system) Central (Haversian) canal Central canal Interstitial lamellae Lamellae Compact bone Spongy bone Pg 182 Compact forms shaft of long bones and a shell over spongy bone

Copyright © 2010 Pearson Education, Inc. Figure 4.8j Connective tissues. (j) Others: bone (osseous tissue) Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. Function: Bone supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis). Location: Bones Photomicrograph: Cross-sectional view of bone (125x). Lacunae Lamella Central canal Pg 137

Copyright © 2010 Pearson Education, Inc. Figure 6.2 Classification of bones on the basis of shape. (a)Long bone (humerus) (b)Irregular bone (vertebra), right lateral view (d)Short bone (talus) (c)Flat bone (sternum) Pg 176

Copyright © 2010 Pearson Education, Inc. Figure 6.3a The structure of a long bone (humerus of arm). Proximal epiphysis (a) Epiphyseal line (plate) Articular cartilage Periosteum Spongy bone Compact bone Medullary cavity (lined by endosteum with clasts & blasts) Diaphysis Distal epiphysis Pg 178 Red-> Yellow

Formation of bony skeleton Intramembranous: cranial bones, mandible, part of clavicle Endochondral: Most bones of the body

Bone is only deposited in an area with less highly specialized connective tissue. Intramembranous mesenchyme -> Dense Irr. -> Spongy -> Compact C.T. Bone Bone (inside)

© 2013 Pearson Education, Inc. Figure 6.9 Intramembranous ossification. 1 Ossification centers appear in the fibrous connective tissue membrane. Selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center that produces the first trabeculae of spongy bone. Mesenchymal cell Collagen fibril Ossification center Osteoid Osteoblast Osteoid Osteocyte Newly calcified bone matrix Mesenchyme condensing to form the periosteum Trabeculae of woven bone Blood vessel 2 Osteoid is secreted within the fibrous membrane and calcifies. Osteoblasts begin to secrete osteoid, which calcifies in a few days. Trapped osteoblasts become osteocytes. 3 Woven bone and periosteum form. Accumulating osteoid is laid down between embryonic blood vessels in a manner that results in a network (instead of concentric lamellae) of trabeculae Called woven bone. Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum. Fibrous periosteum Osteoblast Plate of compact bone Diploë (spongy bone) cavities contain red marrow 4 Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears. Trabeculae just deep to the periosteum thicken. Mature lamellar bone replaces them, forming compact bone plates. Spongy bone (diploë), consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow. Pg 185

Copyright © 2010 Pearson Education, Inc. Figure 6.5 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone. Compact bone Trabeculae Spongy bone (diploë) Layers? Pg 177

Bone is only deposited in an area with less highly specialized connective tissue. Intramembranous mesenchyme -> Dense Irr. -> Spongy -> Compact C.T. Bone Bone (inside) Endochondral mesenchyme -> Hyaline -> Spongy -> Compact Cartilage Bone Bone

Copyright © 2010 Pearson Education, Inc. Figure 6.9 Endochondral ossification in a long bone Bone collar forms around hyaline cartilage model. Cartilage in the center of the diaphysis calcifies and then develops cavities. The periosteal bud invades the internal cavities and spongy bone begins to form. The diaphysis elongates and a medullary cavity forms as ossification continues. Secondary ossification centers appear in the epiphyses in preparation for stage 5. The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages. Hyaline cartilage Area of deteriorating cartilage matrix Epiphyseal blood vessel Spongy bone formation Epiphyseal plate cartilage Secondary ossification center Blood vessel of periosteal bud Medullary cavity Articular cartilage Childhood to adolescence Birth Week 9 Month 3 Spongy bone Bone collar Primary ossification center Pg 184

Copyright © 2010 Pearson Education, Inc. Figure 6.11 Long bone growth and remodeling during youth. Bone growth Bone remodeling Articular cartilage Epiphyseal plate Cartilage grows here. Cartilage is replaced by bone here. Cartilage grows here. Bone is resorbed here. Bone is resorbed here. Bone is added by appositional growth here. Cartilage is replaced by bone here. Pg 186 In Length: Until end of puberty Endochondral In Width (appositional): occurs throughout life Achondroplasia

Hormonal Control of Skeletal System Growth Hormone -Anterior Pituitary Gland -Stimulates mitosis of cartilage at epiphyseal plates and growth of bones in length -Giantism, Acromegaly, Pituitary Dwarfism Thyroxine -Thyroid Gland -Works with Growth Hormone to regulate bone growth and regulates osteoblast activity. Sex Hormones (Estrogen and Testosterone) -Ovary and Testes -Stimulates bone growth in adolescence (surge closes plates) -Stimulates bone maintenance in adulthood.

© 2013 Pearson Education, Inc. Figure 6.12 Parathyroid hormone (PTH) control of blood calcium levels. Calcium homeostasis of blood: 9–11 mg/100 ml BALANCE Stimulus Falling blood Ca 2+ levels Thyroid gland Parathyroid glands Parathyroid glands release parathyroid hormone (PTH). Osteoclasts degrade bone matrix and release Ca 2+ into blood. PTH IMBALANCE Pg 188 Calcitonin ?

© 2013 Pearson Education, Inc. Clicker Question: In a patient whose parathyroid glands have been removed, you would expect that person's blood calcium levels to _______. A. decrease B. increase C. stay the same D. increase twofold

Osteoporosis Estrogen -Reduced with menopause -Loss of bone mass Calcium Vitamin D Exercise

Copyright © 2010 Pearson Education, Inc. Figure 6.16 The contrasting architecture of normal versus osteporotic bone. Pg 192

fibrous

Copyright © 2010 Pearson Education, Inc. Figure 6.15 Stages in the healing of a bone fracture. Hematoma External callus Bony callus of spongy bone Healed fracture New blood vessels Spongy bone trabecula Internal callus (fibrous tissue and cartilage) 1 A hematoma forms. 2 Fibrocartilaginous callus forms. 3 Bony callus forms. 4 Bone remodeling occurs. Pg 191 Intramembranous & Endochondral Osteoclasts & Osteoblasts