Week 7&8 Bone Structure 222 PDF

Because learning changes everything. ® Chapter 7 Lecture Outline Anatomy & Physiology AN INTEGRATIVE APPROACH Fourth Edition Michael P. McKinley Valerie Dean O’Loughlin Theresa Stouter Bidle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or d...

Because learning changes everything. ® Chapter 7 Lecture Outline Anatomy & Physiology AN INTEGRATIVE APPROACH Fourth Edition Michael P. McKinley Valerie Dean O’Loughlin Theresa Stouter Bidle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.1 Introduction to the Skeletal System 1 Components of the skeletal system: Bones of skeleton Cartilage Ligaments Other CT Bones Primary organs of the skeletal system Rigid framework of body Many other functions Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 2 7.1 Introduction to the Skeletal System 2 Types of bone: Compact bone Dense or cortical bone 80% of bone mass Spongy bone Cancellous or trabecular bone Located internal to compact bone Appears porous 20% of bone mass Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 3 7.1 Introduction to the Skeletal System 3 Cartilage Semirigid CT, more flexible than bone Types: Hyaline cartilage Attaches ribs to sternum, covers ends of some bones, within growth plates, model for bone formation Fibrocartilage Weight-bearing cartilage that withstands compression Intervertebral discs, pubic symphysis, menisci of knee Structures composed of dense regular CT Ligaments connect bone to bone, tendons connect muscle to bone Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 4  Distribution of Cartilage in the Adult and Juvenile Skeletons Figure 7.1 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 5 Section 7.1 What did you learn? 1. Compare the appearance of compact bone and spongy bone. 2. In what three locations of the body do you find fibrocartilage? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6 7.2a General Functions Bones perform several basic functions Support and protection Levers for movement Hematopoiesis Blood cell production Occurs in red bone marrow CT Storage of mineral and energy reserves Calcium and phosphate Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7 Medical Terminology Moment Hemato= Blood Poiesis= to make A =without, no,not Osseous= having to do with a bone Osteo= having to do with the bone Os: opening Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2b Classification of Bones Four classes of bone determined by shape Long bones Greater in length than width; for example femur, humerus Short bones Length nearly equal to width; for example carpals and tarsals Flat bones Flat, thin surfaces, may be slightly curved; for example cranial bones Irregular bones Elaborate, sometimes complex shapes; for example vertebrae Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 9  Classification of Bone by Shape Figure 7.2 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 10 Types of Bones (Slide 1 of 2) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What kind of bone is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What kind of bone is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. What kind of bone is this? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2c Gross Anatomy of Bones 1 Regions of a long bone Diaphysis Elongated, usually cylindrical shaft Provides leverage and weight support Compact bone with thin spicules of spongy bone extending inward Medullary (marrow) cavity Hollow, cylindrical space within the diaphysis Contains red bone marrow in children Contains yellow bone marrow in adults Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 15 Parts of a Long Bone (Slide 2 of 4) B: From White T: Human osteology, ed 2, Philadelphia, 2000, Academic Press. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Figure 7.3 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2c Gross Anatomy of Bones 2 Regions of a long bone (continued) Epiphysis Knobby region at each end of long bone Proximal epiphysis End of the bone closest to body trunk Distal epiphysis End farthest from trunk Composed of Outer thin layer of compact bone Inner region of spongy bone Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18 7.2c Gross Anatomy of Bones 3 Epiphysis (continued) Articular cartilage Covers the joint surface Thin layer of hyaline cartilage Reduces friction Absorbs shock in moveable joints Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19 7.2c Gross Anatomy of Bones 4 Regions of a long bone (continued) Metaphysis Region where bone widens and transfers weight between the diaphysis and epiphysis Epiphyseal plate Located within metaphysis Growth plate Thin layer of hyaline cartilage Provides for lengthwise bone growth In adults, the epiphyseal line, is the remnant of the epiphyseal plate Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20  Gross Anatomy of a Long Bone Figure 7.3a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 21 7.2c Gross Anatomy of Bones 5 Coverings and linings of bone Periosteum Tough sheath covering outer surface of bone Outer fibrous layer of dense irregular CT Protects bone from surrounding structures Anchors blood vessels and nerves to bone surface Attachment site for ligaments and tendons Inner cellular layer Includes osteoprogenitor cells, osteoblasts, osteoclasts Attached to bone by numerous collagen fibers Perforating fibers Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 22  Periosteum Figure 7.3c Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 23 7.2c Gross Anatomy of Bones 6 Coverings and linings of bone Endosteum Covers all internal surfaces of bone within medullary cavity Thin layer of CT containing osteoprogenitor cells, osteoblasts, and osteoclasts Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 24  Endosteum Figure 7.3b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 25 7.2c Gross Anatomy of Bones 7 Gross anatomy of other bone classes Short, flat, and irregular bones differ from long bones External surface composed of compact bone covered by periosteum Interior composed of spongy bone Diploë—spongy bone in flat bone of skull No medullary cavity Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 26  Flat Bones Within the Skull ©Susumu Nishinaga/Science Source Figure 7.4 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 27 Microscopic Structure of Bone B: Dennis Strete. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2c Gross Anatomy of Bones 8 Blood supply and innervation of bone Blood supply Bone highly vascularized, for example, in regions of spongy bone Vessels enter from periosteum Nutrient foramen Small opening or hole in bone Artery entrance and vein exit here Nerves that supply bone Accompany blood vessels through foramen Innervate bone, periosteum, endosteum, and marrow cavity Mainly sensory nerves Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 29 7.2d Bone Marrow 1 Bone marrow Soft CT of bone Red bone and yellow bone marrow Red bone marrow (myeloid tissue) Hematopoietic (blood cell forming) Reticular CT, developing blood cells, and adipocytes In children Located in spongy bone and medullary cavity of long bones In adults Located only in selected areas of axial skeleton Skull, vertebrae, ribs, sternum, ossa coxae, proximal epiphyses of humerus and femur Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 30 7.2d Bone Marrow 2 Yellow bone marrow Product of red bone marrow degeneration as children mature Fatty substance Located in medullary cavity Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 31  Red Bone Marrow Figure 7.5 (b) ©Dr. M. Laurent, University Hospitals Leuven, Belgium Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 32 Sections 7.2a-d What did you learn? 1 3. What two minerals are stored in bone, and what are their functions in the body? 4. What are several examples of flat bones in the body? 5. Draw a long bone, such as the humerus, and label the following features: diaphysis, medullary cavity, epiphysis, articular cartilage, periosteum, endosteum, epiphyseal line. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 33 Sections 7.2a-d What did you learn? 2 6. Which long bone structures are responsible for a growth in bone length? Which are responsible for a growth in bone width? 7. Where is red bone marrow found in the adult skeleton? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 34 7.2e Microscopic Anatomy: Bone Connective Tissue 1 Bone CT (osseous CT) Primary component of bone Bone is composed of cells and extracellular matrix Cells of bone Four types found in bone CT 1. Osteoprogenitor cells 2. Osteoblasts 3. Osteocytes 4. Osteoclasts Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 35 7.2e Microscopic Anatomy: Bone Connective Tissue 2 Cells of bone (continued) Osteoprogenitor cells Stem cells derived from mesenchyme Cellular division yields another stem cell and a “committed cell” Matures to become an osteoblast Located in periosteum and endosteum Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 36 7.2e Microscopic Anatomy: Bone Connective Tissue 3 Cells of bone (continued) Osteoblasts (Baby Bone Builders) Form from osteoprogenitor stem cells Synthesize and secrete osteoid Initial semisolid organic form of bone matrix Osteoid later calcifies Become entrapped within the matrix Differentiate into osteocytes Osteocytes Mature bone cells derived from osteoblasts Detect stress on bone; trigger new bone formation Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 37 Medical Terminology Moment Blast= baby cell Clast= something that breaks or destroys things Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2e Microscopic Anatomy: Bone Connective Tissue 4 Cells of bone (continued) Osteoclasts (Bone Chewers) Large, multinuclear, phagocytic cells Derived from fused bone marrow cells Ruffled border increases surface area exposed to bone Located within/adjacent to a depression/pit on bone surface Resorption lacuna Involved in bone resorption (breakdown of bone) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 39  Types of Cells in Bone Connective Tissue (c) ©Alvin Telser, Ph.D. Figure 7.6 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 40 Bone-Forming and Bone-Eroding Cells From Williams P: Gray’s anatomy, ed 38, Philadelphia, 1996, Churchill Livingstone. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2e Microscopic Anatomy: Bone Connective Tissue 5 Composition of the bone matrix Organic components Osteoid produced by osteoblasts, contains Collagen protein Semisolid ground substance of proteoglycans and glycoproteins Includes chondroitin Gives bone tensile strength by resisting stretching Contributes to bone flexibility Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 42 7.2e Microscopic Anatomy: Bone Connective Tissue 6 Inorganic components Salt crystals, calcium phosphate, Ca3(PO4)2 Interacts with calcium hydroxide Forms crystals, hydroxyapatite, Ca10(PO4)6(OH)2 Other substances incorporated into crystals for example, calcium carbonate, sodium, magnesium, sulfate, fluoride Crystals deposit around collagen fibers Harden matrix and account for rigidity of bones Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 43 7.2e Microscopic Anatomy: Bone Connective Tissue 7 Bone formation Begins with secretion of osteoid Calcification (mineralization) occurs, deposition of hydroxyapatite crystals Process requires Vitamin D—enhances calcium absorption from GI tract Vitamin C—required for collagen formation Calcium and phosphate for calcification Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 44 7.2e Microscopic Anatomy: Bone Connective Tissue 8 Bone resorption Bone matrix is destroyed by substances released from osteoclasts Proteolytic enzymes released from lysosomes within osteoclasts Chemically digest organic matrix components Calcium and phosphate dissolved by hydrochloric acid Freed calcium and phosphate ions enter the blood Occurs when blood calcium levels are low Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 45 7.2e Microscopic Anatomy: Bone Connective Tissue 9 Compact bone microscopic anatomy Composed of small cylindrical structures—osteons (Haversian systems) Basic functional and structural unit of mature compact bone Oriented parallel to bone diaphysis Appears as bull’s-eye target Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 46 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2e Microscopic Anatomy: Bone Connective Tissue 10 Osteon components Central (Haversian) canal Cylindrical channel at center of osteon and parallel to it Blood vessels and nerves extend through channel Concentric lamellae Rings of bone CT Surround central canal Collagen fibers 90 degrees from previous and next lamellae Gives bone strength and resilience Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 48 7.2e Microscopic Anatomy: Bone Connective Tissue 11 Osteon components (continued) Osteocytes Mature bone cells Found in small spaces between concentric lamellae (lacunae) Maintain bone matrix Canaliculi Tiny, interconnecting channels within bone CT Extend from each lacuna, travel through lamellae and connect to lacunae and central canal House osteocyte projections that allow intercellular contact Allow exchange of nutrients, minerals, gases, and wastes between blood vessels and osteocytes Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 49 7.2e Microscopic Anatomy: Bone Connective Tissue 12 Structures in long bone, not part of osteon Perforating (Volkmann) canals Perpendicular to central canals Connect central canals within different osteons Circumferential lamellae External—rings of bone run immediately internal to periosteum Internal—rings of bone run internal to the endosteum Both run the entire circumference of the bone Interstitial lamellae Components of compact bone between osteons or partially resorbed osteons Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 50  Components of Bone: Osteons Figure 7.7a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 51  Components of Bone: Compact Bone Figure 7.7b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 52 Practice Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7.2e Microscopic Anatomy: Bone Connective Tissue 13 Spongy bone Trabeculae Open lattice of narrow rods and plates of bones Bone marrow fills spaces Meshwork of crisscrossing bars Resistance to stresses Parallel lamellae Bone matrix Osteocytes between lamellae Canaliculi radiate from lacunae Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 54  Components of Bone: Spongy Bone Figure 7.7c Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 55  Microscopic Anatomy of Bone (a) ©Carolina Biological Supply Company/Phototake; (b) ©Andrew Syred/Science Source; (c) ©Biophoto Associates/Science Source Figure 7.8 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 56 7.2f Microscopic Anatomy: Hyaline Cartilage Connective Tissue 1 Structure of hyaline cartilage Cells scattered through matrix of protein fibers Embedded in a gel-like ground substance Includes proteoglycans but not calcium Resilient and flexible High percentage of water Highly compressible and a good shock absorber Avascular and contains no nerves Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 57 7.2f Microscopic Anatomy: Hyaline Cartilage Connective Tissue 2 Structure of hyaline cartilage (continued) Chondroblasts—produce cartilage matrix Chondrocytes Chondroblasts encased within the matrix Occupy small spaces, lacunae Maintain the matrix Perichondrium Dense irregular CT Covers cartilage and helps maintain its shape Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 58 Sections 7.2e-f What did you learn? 8. What are the functions of the osteoprogenitor cell, osteoblast, osteocyte, and osteoclast? 9. What organic and inorganic substances compose bone matrix? 10. List and describe the major components of an osteon. 11. What are the primary ways that hyaline cartilage tissue differs from bone tissue? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 59 7.3 Cartilage Growth Process of cartilage growth Begins during embryologic development Growth in length through interstitial growth Occurs within internal regions of cartilage Growth in width by appositional growth Occurs on cartilage’s outside edge Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 60  Formation and Growth of Cartilage: Interstitial Growth (Top) ©McGraw-Hill Education/Al Telser Figure 7.9a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 61  Formation and Growth of Cartilage: Appositional Growth (Top) ©McGraw-Hill Education/Al Telser Figure 7.9b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 62 Section 7.3 What did you learn? 12. Where do interstitial and appositional growth of cartilage occur? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 63 7.4 Bone Formation Ossification (osteogenesis) Formation and development of bone CT Begins in the embryo Continues through childhood and adolescence By 8th through 12th weeks of embryonic development Skeleton begins forming From intramembranous ossification Or endochondral ossification Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 64 7.4a Intramembranous Ossification 1 Intramembranous ossification Bone growth within a membrane Also called dermal ossification Produces: Flat bones of skull Some of the facial bones Mandible Central part of the clavicle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 65 7.4a Intramembranous Ossification 2 Steps of intramembranous ossification 1) Ossification centers form within thickened regions of mesenchyme beginning at the eighth week of development Some cells become osteoprogenitor cells Some cells become osteoblasts secreting osteoid 2) Osteoid undergoes calcification Calcium salts deposit onto osteoid and crystallize Entrapped cells become osteocytes Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 66 7.4a Intramembranous Ossification 3 Steps of intramembranous ossification (continued) 3) Woven bone and surrounding periosteum form At first, bone is immature and poorly organized Woven bone (primary bone) Mesenchyme surrounding woven bone forms periosteum 4) Lamellar bone replaces woven bone, as compact bone and spongy bone form Compact and spongy bone form from trabeculae Typical structure of a flat cranial bone Composed of two external layers of compact bone Layer of spongy bone in between Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 67  Intramembranous Ossification Figure 7.10 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 68 7.4b Endochondral Ossification 1 Endochondral ossification Begins with a hyaline cartilage model Produces most bones of skeleton, including Bones of upper and lower limbs, pelvis, vertebrae, ends of clavicle An example of this process is long bone development Steps of long bone development in a limb 1. The fetal hyaline cartilage model develops Chondroblasts secrete cartilage matrix During 8th to 12th week of development Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 69 7.4b Endochondral Ossification 2 Steps of long bone development in a limb (continued) 2. Cartilage calcifies, a periosteal bone collar forms Chondrocytes in the cartilage model produce holes in the matrix Matrix calcifies, and chondrocytes die Produces calcified cartilage shaft with large holes Blood vessels grow toward cartilage Osteoblasts develop and secrete osteoid Form a layer of osteoid around calcified cartilage shaft Periosteal bone collar formed Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 70 7.4b Endochondral Ossification 3 Steps of long bone development in a limb (continued) 3. Primary ossification center forms in diaphysis Periosteal bud extends from periosteum into cartilage shaft Growth of capillaries and osteoblasts Osteoids produce osteoid on calcified cartilage template Primary ossification center First major center of bone formation Most formed by 12th week of development Bone development extends in both directions toward epiphyses Bone CT displaces calcified, degenerating cartilage Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 71 7.4b Endochondral Ossification 4 Steps of long bone development in a limb (continued) 4. Secondary ossification centers form in epiphyses Hyaline cartilage calcifies and degenerates Blood vessels and osteoprogenitor cells enter Secondary ossification centers form Bone displaces cartilage Not all form at birth Osteoclasts resorb some bone matrix Creates hollow medullary cavity Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 72 7.4b Endochondral Ossification 5 Steps of long bone development in a limb (continued) 5. Bone replaces cartilage, except articular cartilage and epiphyseal plates 6. Lengthwise growth continues until epiphyseal plates ossify and form epiphyseal lines Lengthwise bone growth continues into puberty Growth continues until epiphyseal plate is converted to epiphyseal line Indicates bone has reached adult length Occurs between ages of 10 and 25 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 73  Endochondral Ossification 1 (Ten-week fetus) ©Biophoto Associates/Science Source; (Sixteen-week fetus) ©Tissuepix/Science Source; (Skeleton) ©MShieldsPhotos/Alamy Stock Photo; (Humerus) ©Bone Clones; (X-ray) ©Zephyr/ Science Source RF Figure 7.11 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 74  Endochondral Ossification 2 (Ten-week fetus) ©Biophoto Associates/Science Source; (Sixteen-week fetus) ©Tissuepix/Science Source; (Skeleton) ©MShieldsPhotos/Alamy Stock Photo; (Humerus) ©Bone Clones; (X-ray) ©Zephyr/ Science Source RF Figure 7.11 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 75 Section 7.4 What did you learn? 13. When does intramembranous ossification begin? What bones are formed from this method? 14. Briefly describe the process by which a long bone forms by endochondral ossification. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 76 7.5a Bone Growth 1 Interstitial growth-Long bone growing in length Dependent upon cartilage growth in epiphyseal plate Five zones of epiphyseal plate: 1. Zone of resting cartilage Zone nearest to epiphysis Small chondrocytes distributed throughout matrix Resembles mature hyaline cartilage Secures epiphysis to epiphyseal plate Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 77 7.5a Bone Growth 2 Five zones of epiphyseal plate (continued) 2. Zone of proliferating cartilage Chondrocytes undergo rapid mitotic division Align into longitudinal columns of flattened lacunae Columns parallel to diaphysis 3. Zone of hypertrophic cartilage Chondrocytes cease dividing Cells greatly enlarge (hypertrophy) Walls of lacunae become thin Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 78 7.5a Bone Growth 3 Five zones of epiphyseal plate (continued) 4. Zone of calcified cartilage Composed of 2 to 3 layers of chondrocytes Minerals are deposited between columns of lacunae Destroys chondrocytes 5. Zone of ossification Walls break down between lacunae in columns Spaces invaded by capillaries and osteoprogenitor cells New bone matrix deposited on the calcified cartilage matrix Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 79  Epiphyseal Plate (a) ©McGraw-Hill Education/Al Telser; Figure 7.12a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 80 7.5a Bone Growth 4 Interstitial growth (continued) Bone growth in length Occurs specifically within Zone 2 (proliferating cartilage) Zone 3 (hypertrophic cartilage) Pushes zone of resting cartilage toward epiphysis Epiphyseal plate Maintains thickness during childhood At maturity, rate of cartilage production slows Remnant is an internal thin line of compact bone Epiphyseal line- when growing stops Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 81  Colorized X-ray of a Child’s Hand (b) ©Yoav Levy/Medical Images Figure 7.12b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 82  Appositional Bone Growth- wider Occurs within the periosteum Bone matrix deposited within layers parallel to surface Osteoclasts resorb bone matrix along medullary cavity Figure 7.13 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 83 7.5b Bone Remodeling 1 Bone remodeling Continues throughout adulthood Occurs at periosteal and endosteal surfaces of a bone 20% of skeleton replaced yearly Dependent upon the coordinated activities of osteoblasts, osteocytes, and osteoclasts Influenced by hormones and mechanical stress Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 84 7.5b Bone Remodeling 2 Mechanical stress Occurs in weight-bearing movement and exercise Required for normal bone remodeling Detected by osteocytes and communicated to osteoblasts Increase synthesis of osteoid Increased bone mass From weight-bearing activities Decreased bone mass From removal of mechanical stress Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 85 7.5c Hormones That Influence Bone Growth and Remodeling 1 Hormones Molecules released from one cell into the blood Travel throughout the body to affect or cells Bind to cellular receptors of specific cells Initiate specific cellular changes Some alter rates of chondrocyte, osteoblast, and osteoclast activity Affect bone composition and growth patterns Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 86 7.5c Hormones That Influence Bone Growth and Remodeling 2 Growth hormone (somatotropin) Produced by anterior pituitary gland Stimulates liver to produce hormone called insulin-like growth factor (IGF), also called somatomedin Both directly stimulate growth of cartilage in epiphyseal plate Thyroid hormone Secreted by thyroid gland Influences basal metabolic rate of bone cells Regulates normal activity at epiphyseal plates Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 87 7.5c Hormones That Influence Bone Growth and Remodeling 3 Sex hormones Estrogen and testosterone Secreted in large amounts at puberty Dramatically accelerate bone growth Increases rate of cartilage growth and bone formation in epiphyseal plate Bone formation rate greater than cartilage growth Eventually cartilage replaced with bone (growth stops) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 88 7.5c Hormones That Influence Bone Growth and Remodeling 4 Glucocorticoids Group of steroid hormones-released to help us deal with stress Released from adrenal cortex Regulate blood glucose level High amounts increase bone loss Impairs growth at epiphyseal plate in children Must monitor if child receiving high doses of glucocorticoids (for example, in asthma) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 89 Section 7.5 What did you learn? 15. How does a bone grow in width? 16. What is bone remodeling, and how is it impacted by mechanical stress on bone? 17. Which hormones are responsible for bone growth and deposition? Which hormones may promote bone loss? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 90 7.6 Regulating Blood Calcium Levels Regulating calcium concentration in blood is essential Calcium is required for Initiation of muscle contraction Exocytosis of molecules from cells, including neurons Stimulation of the heart by pacemaker cells Blood clotting Two primary hormones regulate blood calcium Calcitriol Parathyroid hormone Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 91 7.6a Activation of Vitamin D to Calcitriol 1) UV light converts 7-dehydrocholesterol to vitamin D3 Cholecalciferol Released into the blood Absorbed from small intestine from diet 2) Vitamin D3 circulates throughout the body Converted to calcidiol by liver enzymes Both steps 1 and 2 occur continuously with limited regulation 3) Calcidiol circulates in the blood Converted to calcitriol by kidney enzymes Kidneys make it active!!! Parathyroid hormone (PTH) increases rate, so more calcitriol is formed Calcitriol stimulates absorption of calcium ions from small intestine into the blood Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 92  Calcitriol Production Figure 7.14 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 93 7.6b Parathyroid Hormone and Calcitriol Parathyroid hormone (PTH) Secreted and released by parathyroid glands in response to reduced blood calcium levels Accelerates conversion to calcitriol by kidney PTH and calcitriol interact with major organs Bone Act synergistically to increase release of calcium from the bone into the blood by increasing osteoclast activity Kidneys Stimulate the kidney to excrete less calcium in urine and increase calcium reabsorption Small intestine Only calcitriol increases absorption of calcium from small intestine into the blood Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 94  Effects of Parathyroid Hormone and Calcitriol on Blood Calcium Levels Figure 7.15 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 95 7.6c Calcitonin Calcitonin Aids in regulating blood calcium levels Less significant role than PTH or calcitriol Released from the thyroid gland in response to high blood calcium levels Also secreted in response to exercise Inhibits osteoclast activity Stimulates kidneys to increase loss of calcium in the urine Reducing blood calcium levels Greatest effect during greatest bone turnover for example, growing children Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 96 Section 7.6 What did you learn? 18. Make a flowchart that tracks the activation of calcitriol. List the molecules in each step and the location where activation of each new molecule occurs. 19. When are parathyroid hormone and calcitriol produced and/or secreted, and what organs respond to them? 20. How does calcitonin regulate blood calcium levels? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 97 7.8 Bone Fracture and Repair 2 Fracture healing Simple fracture—2 to 3 months to heal; compound— longer Four steps of fracture repair: 1) Fracture hematoma forms Blood vessels torn within periosteum 2) Fibrocartilaginous (soft) callus forms Fracture hematoma reorganized into a CT procallus Fibroblasts produce collagen fibers Chondroblasts form dense regular CT Procallus becomes fibrocartilaginous (soft) callus Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 98 7.8 Bone Fracture and Repair 3 Four steps of fracture repair (continued) 3) Hard (bony) callus forms Osteoblasts adjacent to callus produce trabeculae Replaces callus Forms a hard (bony) callus Continues to grow and thicken 4) Bone is remodeled Final phase of fracture repair Osteoclasts remove excess bony material Compact bone replaces primary bone Usually leaves a slight thickening of bone Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 99  Fracture Repair Figure 7.17 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 100 Section 7.8 What did you learn? 22. What are the four basic steps in fracture repair? Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 101  End of Main Content Because learning changes everything. ® www.mheducation.com Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.