Nyki's Ch. 06 PPT updated F2020 (1).ppt

Chapter 06 Skeletal System: Bones and Bone Tissue See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes and animations. 6-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6.1 Functions of the Skeletal Sys...

Chapter 06 Skeletal System: Bones and Bone Tissue See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes and animations. 6-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6.1 Functions of the Skeletal System • Support. Bone is hard and rigid; cartilage is flexible yet strong. Cartilage in nose, external ear, thoracic cage and trachea. Ligaments- bone to bone • Protection. Skull around brain; ribs, sternum, vertebrae protect organs of thoracic cavity • Movement. Produced by muscles on bones, via tendons. Ligaments allow some movement between bones but prevent excessive movement • Storage. Ca and P. Stored then released as needed. Adipose tissue stored in marrow cavities • Blood cell production. Bone marrow that gives rise to blood cells and platelets 6-2 Components of Skeletal System • Bone • Cartilage: three types – Hyaline – Fibrocartilage – Elastic • Tendons and ligaments 6-3 6.2 Cartilage • Consists of specialized cells that produce matrix – Chondroblasts: form matrix – Chondrocytes: surrounded by matrix; are lacunae • Matrix. Collagen fibers for strength, proteoglycans for resiliency • Perichondrium. Double-layered C.T. sheath. Covers cartilage except at articulations – Inner. More delicate, has fewer fibers, contains chondroblasts – Outer. Blood vessels and nerves penetrate. No blood vessels in cartilage itself • Articular cartilage. Covers bones at joints; has no perichondrium • Growth – Appositional. New chondroblasts and new matrix at the periphery – Interstitial. Chondroblasts within the tissue divide and add more matrix between the cells. 6-4 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Perichondrium Appositional growth (new cartilage is added to the surface of the cartilage by chondroblasts from the inner layer of the perichondrium) Chondroblast Lacuna Chondrocyte Interstitial growth (new cartilage is formed within the cartilage by chondrocytes that divide and produce additional matrix) Nucleus Chondrocytes that have divided Matrix LM 400x © Ed Reschke Fig. 6. 1; Slide # 6-5 6.3 Bone Histology • Bone matrix. Like reinforced concrete. Rebar is collagen fibers, cement is hydroxyapatite – Organic: collagen and proteoglycans – Inorganic: hydroxyapatite. CaPO4 crystals • If mineral removed, bone is too bendable • If collagen removed, bone is too brittle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) Without mineral (b) Without collagen (c) a-c: © Trent Stephens •Fig. 6. 2; Slide # 6-6 • Osteoblasts Bone Cells – Formation of bone through ossification or osteogenesis. Collagen produced by E.R. and golgi. Released by exocytosis. Precursors of hydroxyapetite stored in vesicles, then released by exocytosis. – Ossification: formation of bone by osteoblasts. Osteoblasts communicate through gap junctions. Cells surround themselves by matrix. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone surface Osteoblast (a) Connecting cell processes New bone matrix Osteocyte (b) Fig. 6. 3 (a), (b); Slide # 6-7 Bone Cells • Osteocytes. Mature bone cells. Stellate. Surrounded by matrix, but can make small amounts of matrix to maintain it. – Lacunae: spaces occupied by osteocyte cell body – Canaliculi: canals occupied by osteocyte cell processes – Nutrients diffuse through tiny amount of liquid surrounding cell and filling lacunae and canaliculi. Then can transfer nutrients from one cell to the next through gap junctions. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. New bone matrix Osteocyte (b) Canaliculus Cell process Osteocyte Nucleus Lacuna Bone matrix (c) LM 1000x © Bio-Photo Assocs/Photo Researchers, Inc. Fig. 6. 3 (c), (d); Slide # 6-8 Bone Cells • Osteoclasts. Resorption of bone – Ruffled border: where cell membrane borders bone and resorption is taking place. – H ions pumped across membrane, acid forms, eats away bone. – Release enzymes that digest the bone. – Derived from monocytes (which are formed from stem cells in red bone marrow) – Multinucleated and probably arise from fusion of a number of cells • Stem Cells. Mesenchyme (Osteochondral Progenitor Cells) become chondroblasts or osteoblasts. 6-9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nuclei Osteoclast Acidic vesicles Podosomes H+ pump Ruffled border Bone Sealed compartment Fig. 6. 4; Slide # 6-10 Spongy Bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Trabeculae Compact bone Spongy bone Spaces containing bone marrow and blood vessels (a) Trabeculae Lines of stress Osteoblast Osteoclast Osteocyte Trabecula Lamellae Canaliculus © Robert Caladine/Visuals Unlimited (b) • Trabeculae: interconnecting rods or plates of bone. Like scaffolding. – Spaces filled with marrow. – Covered with endosteum. – Oriented along stress lines Fig. 6. 5 (a), (b); Slide # 611 Compact Bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Concentric lamellae Central canal Osteon Periosteum Blood vessel within the periosteum Blood vessels within a perforating canal Blood vessels within a central (haversian) canal Canaliculi LM 400x (a) Canaliculi Lacunae (b) Blood vessel connecting to a central canal between osteons a: © Trent Stephens Osteocytes in lacunae • Central or Haversian canals: parallel to long axis • Lamellae: concentric, circumferential, interstitial • Osteon or Haversian system: central canal, contents, associated concentric lamellae and osteocytes • Perforating or Volkmann’s canal: perpendicular to long axis. Both perforating and central canals contain blood vessels. Direct flow of nutrients from vessels through cell processes of osteoblasts and from one cell to the next. Fig. 6.7; Slide # 6-12 Compact Bone • Osteons (Haversian systems) – Blood vessel-filled central canal (Haversian canal) – Concentric lamellae of bone surround central canal – Lacunae and canaliculi contain osteocytes and fluid • Circumferential lamellae on the periphery of a bone • Interstitial lamellae between osteons. Remnants of osteons replaced through remodeling 6-13 Circulation in Bone • Perforating canals: blood vessels from periosteum penetrate bone • Vessels of the central canal • Nutrients and wastes travel to and from osteocytes via – Interstitial fluid of lacunae and canaliculi – From osteocyte to osteocyte by gap junctions 6-14 6.4 Bone Anatomy Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Flat bone (parietal bone from roof of skull) Irregular bone (sphenoid bone from skull) Long bone (femur, or thighbone) Short bone (carpal, or wrist, bone) • Long – Ex. Upper and lower limbs • Short – Ex. Carpals and tarsals • Flat – Ex. Ribs, sternum, skull, scapulae • Irregular – Ex. Vertebrae, facial Fig. 6.8; Slide # 6-15 Structure of a Long Bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Diaphysis – Shaft – Compact bone • Epiphysis – End of the bone – Spongy bone • Epiphyseal plate: growth plate – Hyaline cartilage; present until growth stops • Epiphyseal line: bone stops growing in length • Medullary cavity: In children medullary cavity is red marrow, gradually changes to yellow in limb bones and skull (except for epiphyses of long bones). Rest of skeleton is red. Diaphysis Articular cartilage Epiphysis Epiphyseal plates in juveniles Epiphyseal lines in adults Spongy bone Compact bone Medullary cavity (contains red marrow in juveniles and yellow marrow in adults) Diaphysis Periosteum Endosteum Young bone (a) (b) Adult bone Fig. 6.9 (a), (b); Slide # 616 Structure of a Long Bone • Periosteum – Outer is fibrous – Inner is single layer of bone cells including osteoblasts, osteoclasts and osteochondral progenitor cells – Fibers of tendon become continuous with fibers of periosteum. – Sharpey’s fibers: some periosteal fibers penetrate through the periosteum and into the bone. Strengthen attachment of tendon to bone. • Endosteum. Similar to periosteum, but more cellular. Lines all internal spaces including spaces in spongy bone. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteons (haversian systems) Endosteum Inner layer Periosteum Outer layer Compact bone Central canals Spongy bone With trabeculae Connecting vessels Medullary cavity (c) Adult bone Fig. 6.9 (c); Slide # 6-17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. TABLE 6.1 Gross Anatomy of a Long Bone Part Description Part Description Diaphysis Shaft of the bone Epiphyseal plate Epiphysis Part of the bone that develops from a center of ossification distinct from the diaphysis Area of hyaline cartilage between the diaphysis and epiphysis; cartilage growth followed by endochondral ossification results in growth in bone length Periosteum Double-layered connective tissue membrane covering the outer surface of bone except where articular cartilage is present; ligaments and tendons attach to bone through the periosteum; blood vessels and nerves from the periosteum supply the bone; the periosteum is where bone grows in diameter Spongy bone Bone having many small spaces; found mainly in the epiphysis; arranged into trabeculae Compact bone Dense bone with few internal spaces organized into osteons; forms the diaphysis and covers the spongy bone of the epiphyses Medullary cavity Large cavity within the diaphysis Endosteum Thin connective tissue membrane lining the inner cavities of bone Red marrow Connective tissue in the spaces of spongy bone or in the medullary cavity; the site of blood cell production Articular cartilage Thin layer of hyaline cartilage covering a bone where it forms a joint (articulation) with another bone Yellow marrow Fat stored within the medullary cavity or in the spaces of spongy bone 6-18 Structure of Flat, Short, and Irregular Bones • Flat Bones Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. – No diaphyses, epiphyses – Sandwich of spongy between compact bone • Short and Irregular Bone Compact bone Spongy bone – Compact bone that surrounds spongy bone center; similar to structure of epiphyses of long bones – No diaphyses and not elongated • Some flat and irregular bones of skull have sinuses lined by mucous membranes. Fig. 6.10; Slide # 6-19 6.5 Bone Development • Intramembranous ossification – Takes place in connective tissue membrane • Endochondral ossification – Takes place in cartilage • Both methods of ossification – Produce woven bone that is then remodeled – After remodeling, formation cannot be distinguished as one or other 6-20 Intramembranous Ossification • • • • • Takes place in connective tissue membrane formed from embryonic mesenchyme Forms many skull bones, part of mandible, diaphyses of clavicles When remodeled, indistinguishable from endochondral bone. Centers of ossification: locations in membrane where ossification begins Fontanels: large membrane-covered spaces between developing skull bones; unossified 6-21 Intramembranous Ossification Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteoblast Osteocyte Bone matrix of trabecula LM 250x LM LM500x 500x 1 A cross section of a newly formed trabecula shows the youngest bone in this series of photomicrographs. Osteocytes are surrounded by bone matrix, and osteoblasts are forming a ring on the outer surface of the trabecula. As the osteoblasts lay down bone, the trabeculae increase in size. 2 A lower magnification shows older bone than in step 1. Spongy bone has formed as a result of the enlargement and interconnections of many trabeculae. Connective tissue Parietal bone Periosteum Ossification center Developing compact bone Frontal bone Superior part of occipital bone Inferior part of occipital bone Red bone marrow Ethmoid bone Nasal bone Maxilla Temporal bone Vertebrae Styloid process 12 weeks Trabeculae LM 50x Zygomatic bone Mandible 3 A lower magnification than in step 2, with a Cartilage different stain that makes the bone appear of mandible blue, shows the oldest bone in this series. Within the spongy bone are trabeculae (blue) Sphenoid bone and developing red bone marrow (pink). Beneath the periosteum is an outer layer of developing compact bone. (1): © Victor Eroschenko; (2): © Dr. Richard Kessel/Visuals Unlimited; (3): © Victor Eroschenko Fig. 6.11; Slide # 6-22 Endochondral Ossification • Bones of the base of the skull, part of the mandible, epiphyses of the clavicles, and most of remaining bones of skeletal system • Cartilage formation begins at end of fourth week of development • Some ossification beginning at about week eight; some does not begin until 18-20 years of age 6-23 Endochondral Ossification Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Uncalcified cartilage Uncalcified cartilage Perichondrium Calcified cartilage Periosteum Uncalcified cartilage Calcified cartilage Calcified cartilage Perichondrium Calcified cartilage Periosteum Primary ossification center Bone collar Blood vessel Blood vessel Periosteum Spongy bone Bone collar Blood vessel to periosteum Open spaces forming in bone Medullary cavity Perichondrium Perichondrium Bone collar Cartilage 1 Chondroblasts produce a cartilage model that is surrounded by perichondrium, except where joints will form. 2 The perichondrium of the diaphysis becomes the periosteum, and a bone collar is produced. Internally, the chondrocytes hypertrophy, and calcified cartilage forms. 3 A primary ossification center forms as blood vessels and osteoblasts invade the calcified cartilage. The osteoblasts lay down bone matrix, forming spongy bone. 4 The process of bone collar formation, cartilage calcification, and spongy bone production continues. Calcified cartilage begins to form in the epiphyses. A medullary cavity begins to form in the center of the diaphysis. Fig. 6.13; Slide # 6-24 Endochondral Ossification Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Articular cartilage Articular cartilage Epiphysis Spongy bone Epiphyseal line Diaphysis 7 Spongy bone Secondary ossification center Space in bone Blood vessel Compact bone Medullary cavity Medullary cavity 6 The original cartilage model is almost completely ossified. Unossified cartilage becomes the epiphyseal plate and the articulazr cartilage. Uncalcified cartilage Blood vessel Calcified cartilage Spongy bone Epiphyseal plate Compact bone In a mature bone, the epiphyseal plate has become the epiphyseal line, and all the cartilage in the epiphysis, except the articular cartilage, has become bone. Spongy bone Periosteum Bone collar Blood vessel Medullary cavity 5 Secondary ossification centers form in the epiphyses of long bones. Fig. 6.13; Slide # 6-25 6-26 6.6 Bone Growth • Growth in length occurs at the epiphyseal plate • Involves the formation of new cartilage by – Interstitial cartilage growth – Appositional growth on the surface of the cartilage • Closure of epiphyseal plate: epiphyseal plate is ossified becoming the epiphyseal line. Between 12 and 25 years of age • Articular cartilage: does not ossify, and persists through life • Appositional growth only – Interstitial growth cannot occur because matrix is solid – Occurs on old bone and/or on cartilage surface 6-27 Zones of the Epiphyseal Plate Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epiphyseal side 1 2 3 New cartilage is produced on the epiphyseal side of the plate as the chondroblasts divide and form stacks of cells. 1 Chondroblasts Mature and enlarge. 2 Matrix is calcified, and chondrocytes die. 3 4 The cartilage on the diaphyseal side of the plate is replaced by bone. 4 LM400x (c) Diaphyseal side Fig. 6.14 (c); Slide # 6-28 Growth in Bone Length Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Femur Patella Epiphysis Epiphyseal plate Diaphysis (a) Length of bone increases. 1 1 New cartilage is produced on the epiphyseal side of the plate as the chondroblasts divide and form stacks of cells. 2 Chondroblasts Mature and enlarge. 3 Matrix is calcified, and chondrocytes die. 4 The cartilage on the diaphyseal side of the plate is replaced by bone. Thickness of epiphyseal Plate remains unchanged. Epiphyseal plate Chondrocytes divide and enlarge. 2 3 Bone is added to diaphysis. Calcified cartilage . is replaced by bone. Boneof diaphysis (b) 4 a: © Ed Reschke/Peter Arnold, Inc./Getty Images; b: © Bio-Photo Assocs/Photo Researchers, Inc. Fig. 6.14 (a), (b); Slide # 6-29 Growth at Articular Cartilage • Increases size of bones with no epiphyses: e.g., short bones • Chondroblasts/cytes near the surface of the articular cartilage similar to those in zone of resting cartilage 6-30 Growth in Bone Width Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Periosteum Osteoblast 1 Osteoblasts beneath the periosteum lay down bone (dark brown) to form ridges separated by grooves. Blood vessels of the periosteum lie in the grooves. Ridge Groove Blood vessel Periosteum 2 The groove is transformed into a tunnel when the bone built on adjacent ridges meets. The periosteum of the groove becomes the endosteum of the tunnel. Endosteum Osteoblast Tunnel Concentric lamella 3 4 Appositional growth by osteoblasts from the endosteum results in the formation of a new concentric lamella. The production of additional concentric lamellae fills in the tunnel and completes the formation of the osteon. Osteon Fig. 6.16; Slide # 6-31 Factors Affecting Bone Growth • Size and shape of a bone determined genetically but can be modified and influenced by nutrition and hormones • Nutrition – Lack of calcium, protein and other nutrients during growth and development can cause bones to be small – Vitamin D • Necessary for absorption of calcium from intestines • Can be eaten or manufactured in the body • Rickets: lack of vitamin D during childhood • Osteomalacia: lack of vitamin D during adulthood leading to softening of bones – Vitamin C • Necessary for collagen synthesis by osteoblasts • Scurvy: deficiency of vitamin C • Lack of vitamin C also causes wounds not to heal, teeth to fall out 6-32 Factors Affecting Bone Growth • Hormones – Growth hormone from anterior pituitary. Stimulates interstitial cartilage growth and appositional bone growth – Thyroid hormone required for growth of all tissues – IGFs (Insulin-like Growth Factors) • Stimulated by HGF from Ant. Pituitary and produced by the liver. • Very Important during childhood growth – Sex hormones such as estrogen and testosterone • Cause growth at puberty, but also cause closure of the epiphyseal plates and the cessation of growth 6-33 Factors Affecting Bone Growth Fig. 6.18; Slide # 6-34 6.7 Bone Remodeling • Involved in bone growth, changes in bone shape, adjustments in bone due to stress, bone repair, and Ca2+ ion regulation • Relative thickness of bone changes as bone grows. Bone constantly removed by osteoclasts and new bone formed by osteoblasts. • Formation of new osteons in compact bone – Osteoclasts enter the osteon from blood in the central canal and internally remove lamellae. Osteoblasts replace bone – Osteoclasts remove bone from the exterior and the bone is rebuilt 6-35 6.7 Bone Remodeling Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Articular cartilage Epiphyseal growth Growth in cartilage surrounding epiphysis Cartilage replaced by bone Epiphyseal line Bone remodeled Growth in length Cartilage growth in epiphyseal plate Cartilage replaced by bone Bone remodeled Bone reabsorption Growth in diameter Bone addition Bone reabsorption Adult bone Growing bone Fig. 6.19; Slide # 6-36 Mechanical Stress and Bone Strength • Stress causes bone remodeling to: – Increase bone mass (density) – Align trabeculae with stress • Changes caused by: – Osteoblast activity increases due to the electrical changes caused by the mechanical stress • Increases with stress 6-37 6.8 Bone Repair 1. 2. Hematoma formation. Localized mass of blood released from blood vessels but confined within an organ or space. Clot formation. Callus formation. Callus: mass of tissue that forms at a fracture site and connects the broken ends of the bone. – – Internal- blood vessels grow into clot in hematoma. • Macrophages clean up debris, osteoclasts break down dead tissue, fibroblasts produce collagen and granulation tissue. • Chondroblasts from osteochondral progenitor cells of periosteum and endosteum produce cartilage within the collagen. • Osteoblasts invade. New bone is formed. External- collar around opposing ends. Periosteal osteochondral progenitor cells  osteoblasts and chondroblasts. Bone/cartilage collar stabilizes two pieces. 6-38 Bone Repair 3. Callus ossification. Callus replaced by woven, spongy bone 4. Bone remodeling. Replacement of spongy bone and damaged material by compact bone. Sculpting of site by osteoclasts 6-39 Bone Repair Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Compact bone Medullary cavity Woven bone Periosteum External callus: Hematoma Woven bone Dead bone Cartilage Broken humerus Dead bone Hematoma formation Callus around broken humerus (at arrow) (a) 1 Blood released from damaged blood vessels forms a hematoma. Internal callus: Fibers and cartilage Woven bone Callus formation 2 The internal callus forms between the ends of the bones, and the external callus forms a collar around the break. Compact bone at break site Callus ossification 3 Woven, spongy bone replaces the internal and external calluses. Bone remodeling 4 Compact bone replaces woven bone, and part of the internal callus is removed, restoring the medullary cavity. a : © Andrew F. Russo Fig. 6.20; Slide # 6-40 Calcium Homeostasis • Bone is major storage site for calcium • The level of calcium in the blood depends upon movement of calcium into or out of bone. – Calcium enters bone when osteoblasts create new bone; calcium leaves bone when osteoclasts break down bone – Two hormones control blood calcium levelsParathyroid Hormone (PTH) and Calcitonin. • Decrease in blood [Ca2+] stimulates parathyroid glands to secrete PTH. • Increase in blood [Ca2+] stimulates thyroid glands to secrete Calcitonin. 6-41 Calcium Homeostasis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Decreased blood Ca2+ Increased blood Ca2+ 5 1 Posterior aspect of thyroid gland Kidney Parathyroid glands 1 Decreased blood Ca2+ stimulates PTH secretion from parathyroid glands. Thyroid gland 2 PTH stimulatesosteoclasts to break down bone and release Ca2+ into the blood. 3 In the kidneys, PTH increases Ca2+ reabsorption from the urine. PTH also stimulates active Vitamin D formation. 3 PTH Calcitonin 2 6 Stimulates osteoclasts Vitamin D Inhibits osteoclasts Bone 4 Osteoclasts promote Ca2+ uptake from bone. 4 Vitamin D promotes Ca2+ absorption from the small intestine into the blood. 5 Increased blood Ca2+ stimulates calcitonin secretion from the thyroid gland. 6 Calcitonin inhibits osteoclasts, which allows for enhanced osteoblast uptake of Ca2+ from the blood to deposit into bone. Ca2+ Osteoblasts promote Ca2+ deposition in bone. Small intestine Ca2+ Blood Fig. 6.21; Slide # 6-42 6.10 Effects of Aging on Skeletal System • Bone matrix decreases. More brittle due to lack of collagen; but also less hydroxyapatite. • Bone mass decreases. Highest around 30. Men denser due to testosterone and greater weight. African Americans and Hispanics have higher bone masses than Caucasians and Asians. Rate of bone loss increases 10 fold after menopause. spongy bone lost first, then compact. • Increased bone fractures • Bone loss causes deformity, loss of height, pain, stiffness – Stooped posture – Loss of teeth 6-43 Bone Fractures • Open (compound)- bone break with open wound. Bone may be sticking out of wound. • Closed (simple)- Skin not perforated. • Incomplete- doesn’t extend across the bone. Complete- does • Greenstick: incomplete fracture that occurs on the convex side of the curve of a bone • Hairline: incomplete where two sections of bone do not separate. Common in skull fractures • Comminuted fractures: complete with break into more than two pieces 6-44 Bone Fractures • Impacted fractures: one fragment is driven into the spongy portion of the other fragment. • Classified on basis of direction of fracture • Linear • Transverse • Spiral • Oblique • Dentate: rough, toothed, broken ends • Stellate radiating out from a central point. 6-45 Bone Fractures Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Comminuted Impacted Linear Spiral Incomplete Oblique Complete Transverse Fig. 6B; Slide # 6-46 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diaphysis of femur Fractured epiphyseal plate Epiphysis of femur Joint cavity Epiphyseal plate Diaphysis of tibia © J. M. Booher 6-47 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diseases and Disorders TABLE 6.3 Skeletal System Condition Description Tumors May be malignant or benign and cause a range of bone defects Growth and Developmental Disorders Gigantism Abnormally small body size due to improper growth at the epiphyseal plates Dwarfsm Abnormally small body size due to improper growth at the epiphyseal plates Osteogenesis imperfecta Brittle bones that fracture easily due to insufficient or abnormal collagen Rickets Growth retardation due to nutritional deficiencies in minerals (Ca2+) or vitamin D; results in bones that are soft, weak, and easily broken Bacterial Infections Osteomyelitis Bone inflammation often due to a bacterial infection that may lead to complete destruction of the bone Tuberculosis Typically, a lung bacterium that can also affect bone Decalcification Osteomalacia Softening of adult bones due to calcium depletion; often caused by vitamin D deficiency Osteoporosis Reduction in overall quantity of bone tissue; see Systems Pathology Go to www.mhhe.com/seeley10 for additional information on these pathologies. 6-48 6-49 Ch. 6 Learning Objectives After reading this chapter, students should be able to: • List the components of the skeletal system. • Explain the functions of the skeletal system. • Describe the structure of hyaline cartilage. • Explain the types of cartilage growth. • Describe the components of the extracellular matrix, and state the function of each. • List each type of bone cell, and give the function and origin of each. • Describe the structure of woven and lamellar bone. • Explain the structural differences between compact and spongy bone. 6-50 Ch. 6 Learning Objectives • Classify bones according to their shape. • Label the parts of a typical long bone. • Explain the differences in structure between long bones, and flat, short, and irregular bones. • Outline the process of intramembranous ossification. • Describe the steps of endochondral ossification. • Outline the processes of bone ossification, growth, remodeling, and repair. • Demonstrate an understanding of bone growth in length and width, and at the articular cartilage. • Describe the factors that affect bone growth. • Explain the need for bone remodeling, particularly in long bones. • Discuss how mechanical stress affects bone remodeling and bone strength. 6-51 Ch. 6 Learning Objectives • Outline and explain the steps in bone repair. • Explain the role of bone in calcium homeostasis. • Describe how parathyroid hormone and calcitonin influence bone health and calcium homeostasis. • Describe the effects of aging on bones. 6-52