Chapter 6 Bone Tissue KS Lecture PDF

Chapter Opener 6 Colored scanning electron micrograph showing osteoclasts in bone lacunae. © 2019 Pearson Education, Inc. Figure 6.1 Functions of the skeletal system. Protection: Skeleton protects vital...

Chapter Opener 6 Colored scanning electron micrograph showing osteoclasts in bone lacunae. © 2019 Pearson Education, Inc. Figure 6.1 Functions of the skeletal system. Protection: Skeleton protects vital organs such as the brain. Brain Mineral storage and acid-base homeostasis: Bone stores minerals such as Ca2+ and PO43–, which are necessary for electrolyte and acid-base balance. Blood cell formation: Red bone marrow is the site of blood cell formation. Forming blood cells in red bone marrow Fat storage: Yellow bone marrow stores triglycerides. Fat in yellow bone marrow Movement: Muscles produce body movement via their attachment to bones. Muscle attached across joint Support: The skeleton supports the weight of the body. © 2019 Pearson Education, Inc. Figure 6.1-1 Functions of the skeletal system. Protection- Bone is one of the strongest substances in the body and provides a good “shell” to protect organs such as the brain, heart and lungs Protection: Skeleton protects vital organs such as the brain. Brain © 2019 Pearson Education, Inc. Figure 6.1-2 Functions of the skeletal system. Mineral Storage-Bone is a storehouse for minerals for calcium, phosphorus, and magnesium. These minerals are found in the blood as electrolytes, acids and bases Mineral storage and acid-base homeostasis: Bone stores minerals such as Ca2+ and PO43–, which are necessary for electrolyte and acid-base balance. © 2019 Pearson Education, Inc. Figure 6.1-3 Functions of the skeletal system. Blood Cell Formation-Bones house red bone marrow. This is the site for hematopoiesis(making blood) Blood cell formation: Red bone marrow is the site of blood cell formation. Forming blood cells in red bone marrow © 2019 Pearson Education, Inc. Figure 6.1-4 Functions of the skeletal system. Fat Storage-contains adipocytes and stored triglycerides. Can be used for release and used by the cell for fuel if needed. Fat storage: Yellow bone marrow stores triglycerides. Fat in yellow bone marrow © 2019 Pearson Education, Inc. Figure 6.1-5 Functions of the skeletal system. Movement-serve as attachment sites for most skeletal muscles. When muscles contract, the pull on bones which generates movement around a joint. Movement: Muscles produce body movement via their attachment to bones. Muscle attached across joint © 2019 Pearson Education, Inc. Figure 6.1-6 Functions of the skeletal system. Support-structural framework Support: The skeleton supports the weight of the body. © 2019 Pearson Education, Inc. Figure 6.2 Classification of bones by shape. Five general bone shapes Sternum Humerus (c) Flat bone—bone is broad, flat, and thin. Vertebra (a) Long bone—bone is longer than it is wide. (d) Irregular bone—bone’s shape does not fit into other classes. Trapezium (carpal bone) Patella (b) Short bone—bone is about as long (e) Sesamoid bone—round, flat bone as it is wide. found within tendon. © 2019 Pearson Education, Inc. Figure 6.3 Structure of long bones. Hyaline (articular) cartilage Epiphyseal lines Red bone Epiphysis marrow Endosteum Nutrient Medullary cavity artery Compact bone Periosteum Diaphysis Perforating fibers Nutrient Yellow bone foramen marrow Spongy bone Epiphysis (a) External structure of long bone (b) Sectioned long bone © 2019 Pearson Education, Inc. Figure 6.3a Structure of long bones. Hyaline (articular) cartilage Structure of a long bone ❑ Periosteum-membrane Epiphysis that covers bone surface supplied with blood vessels and nerves Periosteum ❑ Diaphysis-shaft ❑ Epiphysis-the ends of the long bone covered Diaphysis with articular cartilage Perforating fibers Nutrient foramen Epiphysis (a) External structure of long bone © 2019 Pearson Education, Inc. Figure 6.3b Structure of long bones. Hyaline (articular) cartilage Epiphyseal lines Medullary Cavity- hollow cavity within Red bone Epiphysis marrow the diaphysis. This is Endosteum where marrow is Medullary cavity Nutrient housed artery Compact Compact Bone- bone hard, dense outer bone that resists majority of stresses Diaphysis Spongy Bone-inner honeycomb-like bone forms framework of boney struts-resists stresses and place Yellow bone marrow for bone marrow to reside Spongy bone Endosteum- Epiphysis membrane lining spongy bone (b) Sectioned long bone © 2019 Pearson Education, Inc. Figure 6.4 Structure of short, flat, irregular, and sesamoid bones. Structure of Short, Irregular, and Sesamoid-two thin layers of compact bone and a middle layer of spongy bone housing bone marrow Periosteum Perforating fibers Compact bone Spongy bone or diploë (with red bone marrow) Compact bone Periosteum In flat bones the spongy bone is called the diploe(fold) © 2019 Pearson Education, Inc.  Red and Yellow Bone Marrow Red Bone Marrow-reticular fibers supporting islands of blood forming cells Can see red bone marrow in the pelvis, humerus, femur, vertebrae, ribs, clavicle and scapula Yellow Bone Marrow-stores triglycerides consists mostly of blood vessels and adipocytes. Infants and young children-most bone marrow is red Approximately age 5- yellow bone marrow starts to replace some of the red. Adulthood-most bone marrow is yellow. © 2019 Pearson Education, Inc. Bone Marrow Transplant Diseases of the blood leukemia, sickle-cell anemia, aplastic anemia Process-hematopoietic cells from red bone marrow are removed from a matching donor and given to a recipient Figure 06.9-2 Structure of compact bone. Osteons-series of cylindrical subunits which are closely arranged in compact bone tissue. Lamellae- the “rings “ or our miniature trees are very thin layers of bone. Most osteons contain 4-20 lamellae and this structure enhances its Osteons strength. Circumferential Interstitial lamellae lamellae Interstitial lamellae-remnants of resorbed osteons. Circumferential lamellae-outer and inner rings of lamellae are present just deep to the periosteum and superficial to spongy bone. © 2019 Pearson Education, Inc. Figure 06.9-3 Structure of compact bone. Volkmann’s canals-aka perforating channels allow blood vessels to enter the bones from periosteum Haversian canals-aka central canal is a passage for blood cells, lymph vessels and nerves © 2019 Pearson Education, Inc. Figure 06.9-4 Structure of compact bone.  Compact bone Spongy bone Spongy Bone-resists forces from many directions. These functions are performed by branching ribs of bone called Trabeculae trabeculae which project into the marrow © 2019 cavity. Pearson Education, Inc.  Lacunae with Canaliculi- osteocytes lacunae are connected to one another. Canaliculi Osteocytes have cytoplasmic extensions that extend through the canaliculi Trabecula Osteoblasts of the endosteum Lamellae Osteoclast © 2019 Pearson Education, Inc. Figure 6.5b The importance of bone matrices. Inorganic Bone Matrix-predominant ingredient is calcium salts and phosphorous. Most salts exist as hydroxyapatite crystals. This gives bone strength and resist compression. 65% of total bone weight Normal bones Remove inorganic matrix (b) Bone without its inorganic matrix (minerals) cannot resist compression. © 2019 Pearson Education, Inc. Figure 6.5a The importance of bone matrices. Organic bone matrix-aka Osteoid consists of protein fibers predominantly collagen which form crosslinks to help bone resist twisting and tensile forces. They also align with hydroxyapatite crystals to enhance hardness 35 % of total bone weight. Remove organic matrix (a) Bone without its organic matrix (collagen) is brittle and shatters easily. Normal bones © 2019 Pearson Education, Inc. Figure 6.6 Types of bone cells. Bone Endosteum LM (345×) Osteoblast Osteocyte Osteoclast Nuclei © 2019 Pearson Education, Inc. Figure 6.7-1 Functions of osteoblasts and osteocytes. Osteogenic cell Collagen Osteogenic cells fibers differentiating into osteoblasts Osteoblasts-derived from flattened cells Periosteum called osteogenic cells when stimulated by chemical signals. Osteoblasts- bone deposition 1 Osteogenic cells differentiate into osteoblasts. © 2019 Pearson Education, Inc. Figure 6.7-2 Functions of osteoblasts and osteocytes and osteocytes. Osteocytes- Osteoblasts Osteoblasts are becoming surrounded and surrounded by trapped by secreted bone matrix bone matrix in a small cavity called a lacunae. Secreted bone matrix Bone matrix 2 Osteoblasts deposit bone until they are trapped and become osteocytes. © 2019 Pearson Education, Inc. Figure 6.7-3 Functions of osteoblasts and osteocytes and osteocytes. Osteocytes Bone ECM Extracellular fluid in lacuna Osteocytes secreting chemicals required for bone maintenance 3 Osteocytes maintain the bone extracellular matrix (ECM). © 2019 Pearson Education, Inc. Figure 6.8 Function of osteoclasts. Osteoclast-large and multi-nucleated derived from fusion of cells forms in the bone marrow. They reside in shallow depressions on internal or external surfaces of bone. Osteoclast Collagen fibers of the periosteum Osteoclast Nuclei Enzyme Sugar Amino Ruffled border acid Bone Bone Enzymes and H+ Components of the bone degrade the bone ECM. ECM enter the osteoclast. (a) An osteoclast on the surface of bone (b) The process of bone resorption by an osteoclast Secrete hydrogen ions and enzymes from the ruffled border. This creates an acid environment Dissolves inorganic and breakdown © 2019 Pearson Education, Inc. organic Figure 6.8a Function of osteoclasts. Collagen fibers of the periosteum Osteoclast Nuclei Ruffled border Bone (a) An osteoclast on the surface of bone Osteoclast-responsible for bone resorption © 2019 Pearson Education, Inc. Figure 6.8b Function of osteoclasts. Osteoclast Enzyme Sugar Amino acid Bone Enzymes and H+ Components of the bone degrade the bone ECM. ECM enter the osteoclast. (b) The process of bone resorption by an osteoclast The liberated minerals, amino acids, and sugars enter the osteoclast and eventually delivered to the blood or © 2019 Pearson Education,excreted. Inc. Osteopetrosis- Marble Bone Disease Defective osteoclasts that do not properly degrade bone this causes increase in bone mass and weak and brittle bones © 2019 Pearson Education, Inc. This Photo by Unknown Author is licensed under CC BY  Structure of Compact Bone- resembles a forest of small tightly packed trees. Each tree is called an osteon This Photo by Unknown Author is licensed under CC BY-SA-NC © 2019 Pearson Education, Inc. Figure 6.9 Structure of compact bone. Central canal Nerve Vein Artery Osteons Lamellae Circumferential Interstitial lamellae lamellae Lacunae with osteocytes Canaliculi Collagen fibers in lamellae Periosteum: Outer fibrous layer Inner layer Osteon containing osteoblasts Blood vessels Canaliculi Central canal in periosteum Compact Lacunae with bone Spongy Perforating osteocytes bone fibers Perforating canals with blood vessels and nerves Central canals with blood vessels and nerves Lamellae TEM (620×) © 2019 Pearson Education, Inc. Figure 6.9-2 Structure of compact bone. Lamellae- the “rings “ or our miniature trees are very thin layers of bone. Most osteons contain 4-20 lamellae and this structure enhances its strength. Osteons Circumferential Interstitial lamellae lamellae Interstitial lamellae-remnants of resorbed osteons. Cirumferential lamellae-outer and inner rings of lamellae are present just deep to the periosteum and superficial to spongy bone. © 2019 Pearson Education, Inc. Figure 6.9-1 Structure of compact bone. Compact bone Spongy bone © 2019 Pearson Education, Inc. Figure 6.9-3 Structure of compact bone. Spongy bone Perforating canals with blood vessels and nerves Central canals with blood vessels and nerves © 2019 Pearson Education, Inc. Figure 6.9-4 Structure of compact bone. Central canal Central canal-contains blood vessels and nerves Nerve to supply the osteon Vein Artery Lamellae Lacunae with osteocytes Canaliculi Collagen fibers in lamellae Osteon © 2019 Pearson Education, Inc. Figure 6.10-1 Structure of spongy bone. Compact bone Spongy bone Spongy Bone-resists forces from many directions. These functions are performed by branching ribs of bone called trabeculae Trabeculae which project into the marrow cavity. © 2019 Pearson Education, Inc. Figure 6.10-2 Structure of spongy bone. Canaliculi-lacunae Lacunae with are connected to osteocytes one another. Osteocytes have Canaliculi cytoplasmic extensions that extend through the canaliculi Trabecula Osteoblasts of the endosteum Lamellae Osteoclast © 2019 Pearson Education, Inc. Bone Formation The process of bone formation is called ossification or osteogenesis. It begins during the embryonic period and for some bones continues through childhood. There are two types of ossification Intramembranous-built on starting material known as a model made of a membrane of embryonic connective tissue Endochondral- built on a model made of hyaline cartilage The first bone formed by both types of ossification is immature bone called primary bone or woven bone. It consists of irregularly arranged collagen bundles, abundant osteocytes and little inorganic matrix Secondary bone-lamellar bone-consists of higher percentage of inorganic material which contributes to strength. © 2019 Pearson Education, Inc. Figure 6.11 The process of intramembranous ossification. Frontal bone of fetal skull Mesenchymal Osteoblasts secreting Uncalcified Calcium salts in organic matrix Early compact cells Osteogenic Collagen organic the calcified Trabeculae of early bone cells fibers matrix bone Early spongy spongy bone bone Osteocytes Blood vessel Osteoblasts Osteocytes Primary ossification center Developing periosteum Periosteum 1 Osteoblasts develop in the 2 Osteoblasts secrete organic 3 Osteoblasts lay down trabeculae 4 Osteoblasts in the periosteum primary ossification center matrix, which calcifies, and of early spongy bone, and some lay down early compact bone. from mesenchymal cells. trapped osteoblasts become of the surrounding mesenchyme osteocytes. differentiates into the © 2019 Pearson Education, Inc. periosteum. Figure 6.11-1 The process of intramembranous ossification. Frontal bone of fetal skull Intramembranous Ossification-many flat bones including skull and clavicles. The inner Mesenchymal Osteoblasts secreting spongy bone forms Uncalcified Calcium salts in cells Osteogenic Collagen organic organic matrix before the outer the calcified cells fibers matrix bone compact bone beginning at a place known as primary ossification center. Osteocytes Osteoblasts Primary ossification center 1 Osteoblasts develop in the 2 Osteoblasts secrete organic primary ossification center matrix, which calcifies, and from mesenchymal cells. trapped osteoblasts become osteocytes. © 2019 Pearson Education, Inc. Figure 6.11-2 The process of intramembranous ossification. Osteoblasts continue to lay down new bone forming the trabeculae. The trabeculae enlarge and merge.. Some of the mesenchyme differentiates into periosteum. Matrix becomes more heavily calcified and structure is remodeled to become immature compact bone. Osteoblasts secreting organic matrix Early compact bone Trabeculae of early Early spongy spongy bone bone Blood vessel Osteocytes Developing periosteum Periosteum 3 Osteoblasts lay down trabeculae 4 Osteoblasts in the periosteum of early spongy bone, and some lay down early compact bone. of the surrounding mesenchyme differentiates into the periosteum. © 2019 Pearson Education, Inc. Figure 6.12 The process of endochondral ossification (Part 1 of 2). All bones besides the skull and clavicles are formed by endochondral ossification. Most bones complete ossification by 7yr. Hyaline cartilage model Perichondrium Periosteum Developing Bone collar periosteum Osteocyte Osteoblasts Chondrocytes secreting Perichondrium Calcified organic matrix Chondroblasts cartilage Osteogenic Calcium salt cells Periosteum Developing Dying Osteoblasts periosteum chondrocyte 1 The chondroblasts in the perichondrium differentiate 2a Osteoblasts build the bone collar on the 2b Simultaneously, the internal cartilage into osteoblasts. bone’s external surface as the bone begins to calcify and the chondrocytes die. begins to ossify from the outside. © 2019 Pearson Education, Inc. Figure 6.12 The process of endochondral ossification (Part 2 of 2). Articular cartilage Epiphyseal blood vessel Spongy bone Secondary ossification Epiphyseal plate centers Calcified Compact bone cartilage Primary ossification Medullary cavity center Early spongy bone Osteoclasts enlarging Osteoblasts medullary secreting cavity organic matrix Osteocytes Calcified Medullary cartilage cavity 3 In the primary ossification center, osteoblasts replace the 4 As the medullary cavity enlarges, the remaining cartilage calcified cartilage with early spongy bone; the secondary is replaced by bone; the epiphyses finish ossifying. ossification centers and medullary cavity develop. © 2019 Pearson Education, Inc. Figure 6.12-1 The process of endochondral ossification. Hyaline cartilage Endochondral model ossification Perichondrium consists of chondrocytes Developing and cartilage periosteum ECM. The chondroblasts in the perichondrium differentiate into osteoblasts Chondrocytes Perichondrium Chondroblasts Osteogenic cells Osteoblasts Developing periosteum 1 The chondroblasts in the perichondrium differentiate into osteoblasts. © 2019 Pearson Education, Inc. Figure 6.12-2 The process of endochondral ossification. The bone ossifies from the outside. Periosteum Osteoblasts Bone collar build a bone collar and internal cartilage begins to calcify Osteocyte Osteoblasts secreting organic matrix Calcified cartilage Calcium salt Periosteum Dying chondrocyte 2a Osteoblasts build the bone collar on the 2b Simultaneously, the internal cartilage bone’s external surface as the bone begins to begins to calcify and the chondrocytes die. ossify from the outside. © 2019 Pearson Education, Inc. Figure 6.12-3 The process of endochondral ossification. Epiphyseal blood vessel Secondary ossification Osteoblasts centers replace the Calcified calcified cartilage cartilage with early spongy Primary bone. ossification center Early spongy bone Osteoblasts secreting organic matrix Calcified cartilage 3 In the primary ossification center, osteoblasts replace the calcified cartilage with early spongy bone; the secondary ossification centers and medullary cavity develop. © 2019 Pearson Education, Inc. Figure 6.12-3 The process of endochondral ossification. Articular cartilage Spongy bone Osteoclasts etch a hole in the bone Epiphyseal plate collar and allows blood vessels and Compact bone bone cells to enter primary ossification Medullary cavity center. Medullary cavity enlarges. The space becomes filled with bone marrow Osteoclasts enlarging medullary cavity Osteocytes Medullary cavity 4 As the medullary cavity enlarges, the remaining cartilage is replaced by bone; the epiphyses finish ossifying. © 2019 Pearson Education, Inc. Unnumbered Figure 6.1_page 197 Osteoporosis-inadequate inorganic matrix in the ECM. Causes include dietary, female, lack of exercise, hormonal factors, genetic factors and diseases of skin, digestive and urinary system SEM (15×) SEM (15×) Normal bone in vertebra Osteoporitic bone in vertebra © 2019 Pearson Education, Inc. Unnumbered Figure 6.1_page 198 Epiphyseal plates of long bones Carpal bones are largely not visible because they have not completed endochondral ossification. Hand of a young child © 2019 Pearson Education, Inc. Figure 6.13 Structure of the epiphyseal plate. Epiphyseal plate contains five different zones of cells. Diaphyseal side Diaphysis Osteoblasts and calcified Zone of ossification cartilage Dead chondrocytes Zone of calcification Epiphysis Zone of hypertrophy and maturation Chondrocytes in lacunae Zone of proliferation Zone of reserve cartilage LM (110×) Epiphyseal side Zone of reserve cartilage closest to epiphysis and not involved in © 2019 Pearson Education, Inc. bone growth Figure 6.14 Growth at the epiphyseal plate. Newly formed bone 4 Calcified cartilage is Zone of Calcified replaced with bone. ossification cartilage 3 Chondrocytes die and Calcium their matrix calcifies. Zone of calcification salts Humerus Epiphyseal 2 Chondrocytes that Zone of Enlarged plate reach the next zone chondrocyte hypertrophy enlarge and mature. and maturation in larger lacunae 1 Chondrocytes divide in the zone of proliferation. Cartilage ECM Zone of proliferation Dividing Direction of chondrocyte bone growth © 2019 Pearson Education, Inc. Figure 6.13-1 Growth at the epiphyseal plate. Longitudinal growth continues at the epiphyseal plate as long as mitosis is happening in the Humerus zone of proliferation. 12-15 years the rate of mitosis slows. Epiphyseal 18-21 years old- the plate zone of proliferation completely ossifies © 2019 Pearson Education, Inc.  Growth in Width All bones grow in width Appositional Growth-process in which osteoblasts between the periosteum and the bone surface lay down new bone. This initially results in new circumferential lamellae is formed. In actively growing bones, compact bone of the diaphysis thickens. Medullary cavity enlarges due to osteoclast activity. © 2019 Pearson Education, Inc. Role of Hormones in Bone Growth Growth Hormone-produced by the anterior pituitary gland and secreted throughout life. It enhances protein synthesis and cell division in nearly all tissues. An increase in the rate of mitosis of chondrocytes in the epiphyseal plate resulting in longitudinal growth Increase in activity of osteogenic cells Stimulate osteoblasts in the periosteum triggering appositional growth Testosterone-increases appositional growth depositing calcium salts and longitudinal growth by increasing rate of mitosis at the epiphyseal plate. Estrogen-increases the rate of longitudinal bone growth and inhibits osteoclasts Both estrogen and testosterone accelerates closure of the epiphyseal plates © 2019 Pearson Education, Inc.  Gigantism Excess growth hormone is secreted in childhood before closure of epiphyseal plate. © 2019 Pearson Education, Inc. This Photo by Unknown Author is licensed under CC BY-SA  Acromegaly growth hormone secretion occurs after closure of epiphyseal plate results in enlargement of bone, cartilage and soft tissue in the skull, face, hands and feet. This Photo by Unknown Author is licensed under CC BY-SA-NC This Photo by Unknown Author is licensed under CC BY-SA © 2019 Pearson Education, Inc. Unnumbered Figure 6.3_page 202 Bone remodeling-bone is dynamic and undergoes a continual process of formation and loss Osteocytes in newly Osteoclasts Osteoblasts deposited bone breaking down bone depositing bone Bone deposition Bone resorption © 2019 Pearson Education, Inc. © 2019 Pearson Education, Inc. Bone Deposition-carried out by osteoblasts in both periosteum and endosteum. They secrete proteoglycans and glycoproteins that bind to calcium ions and secrete vesicles Process of which bind to collagen fibers and their calcium ions eventually crystalize beginning Bone calcification. Remodeling Bone Resorption-osteoclasts secrete H+(hydrogen ions) from ruffled borders onto the bone ECM. This acidic environment breaks down hydroxyapatite crystals in inorganic matrix Bone Response to Forces Compression (squeezing or pressing together)-bone deposition occurs in proportion to these forces. An athlete who trains extensively with weights and places compressive forces on his/her bones deposits more bone tissue and results in higher bone mass. Tension (stretching force)- stimulates osteoblast activity and bone deposition occurs Pressure-(continuous downward force)- osteoclasts are stimulated and bone resorption occurs © 2019 Pearson Education, Inc.  Factors Influencing Bone Remodel Hormones Estrogen and Testosterone Age-Growth hormone decrease w/age. Calcium ion intake Vitamin D intake-acts on intestines to promote calcium ion absorption Vitamin C intake-required for synthesis of collagen Vitamin K intake- aids in production of calcium io-binding glycoproteins by osteoblasts Protein intake-necessary for osteoblasts to synthesize collagen fibers. © 2019 Pearson Education, Inc. Figure 6.16 Factors that influence bone remodeling. Compressional load or exercise Estrogen Inadequate exercise Continuous pressure placed Tension placed on bone Calcitonin Inadequate dietary intake of on bone Testosterone Increase in blood calcium ion calcium or vitamins C, D, or K Parathyroid hormone Adequate dietary intake of concentration Decrease in blood calcium ion calcium and vitamins C, D, and K concentration Increased osteoblast activity Decreased osteoclast activity Decreased osteoblast activity Increased osteoclast activity Increased bone deposition Increased bone resorption Osteoblast Osteoclast Bone Bone © 2019 Pearson Education, Inc. Figure 6.15 Maintaining homeostasis: response to low blood calcium ion level by a negative feed back loop. Calcium ion Homeostasis STIMULUS Blood Ca2+ decreases below normal range. Normal range EFFECTOR/RESPONSE RECEPTOR IN HOMEOSTATIC RANGE Osteoclasts Kidneys Intestines As blood Ca2+ returns to Parathyroid gland cells resorb bone. retain Ca2+. absorb Ca2+. normal, feedback stops detect a low blood effector responses. Ca2+ level. Osteoclast Ca2+ Normal range Ca2+ Ca2+ Ca2+ Bone Parathyroid CONTROL CENTER glands Parathyroid gland cells release PTH into the blood. PTH © 2019 Pearson Education, Inc.  Simple-aka (closed)- skin and tissue around the fracture remain intact Fracture Compound-aka(open)- damage around the fracture © 2019 Pearson Education, Inc. Table 6.1 Types of Fractures Table 6.1 Types of Fractures Fracture Fracture Type Description Type Description Fracture resulting from twisting forces applied to Fracture in which the bone is crushed under the Spiral the bone Compression weight it is meant to support; common in the elderly and those with reduced bone mass Comminuted Fracture in which the bone is shattered into multiple Avulsion Fracture in which a tendon or ligament pulls off fragments; difficult to repair a fragment of bone; often seen in ankle fractures [kom-ih- [ah-VUL- NOOT-’d] shun] Greenstick Fracture in which the bone breaks on one side but Epiphyseal Fracture that involves at least part of the only bends on the other side, similar to the break plate epiphyseal plate; occurs only in children and observed when a young (“green”) twig is bent; young adults; may interfere with growth common in children, whose bones are more flexible © 2019 Pearson Education, Inc. Avulsion Fracture © 2019 Pearson Education, Inc.  Compression fracture © 2019 Pearson Education, Inc. This Photo by Unknown Author is licensed under CC BY-SA-NC Figure 6.17 The process of fracture repair. Compact Medullary bone cavity Blood Periosteum vessels Fibroblasts Damaged blood vessel Chondroblasts Blood cells Collagen fibers Pieces of Hematoma broken bone Soft Regrowing callus blood vessel Blood vessel 1 A hematoma fills the gap between the bone fragments. 2 Fibroblasts and chondroblasts infiltrate the hematoma, and a soft callus forms. Bone callus of primary bone Repaired blood vessel Central canal Primary bone Osteoblasts Osteoblasts building secreting secondary organic matrix bone Osteoclast degrading Osteoblasts primary Lamellae in periosteum bone 3 Osteoblasts build a bone callus. 4 The bone callus is remodeled and primary bone is replaced with secondary bone. © 2019 Pearson Education, Inc. Figure 6.17-1 The process of fracture repair. 1) Hematoma fills in the gap. This cuts the blood supply to damaged area and bone cells surrounding area die. Compact Medullary bone cavity Blood Periosteum vessels Fibroblasts Damaged blood vessel Chondroblasts Blood cells Collagen fibers Pieces of Hematoma broken bone Soft Regrowing callus blood vessel Blood vessel 1 A hematoma fills the gap between the bone fragments. 2 Fibroblasts and chondroblasts infiltrate the hematoma, and a soft callus forms. 2) Fibroblasts and blood vessels invade hematoma. Fibroblasts secrete collagen fibers and form connective tissue bridge gap between bone. © 2019 Pearson Education, Inc. Figure 6.17-2 The process of fracture repair. 3) Osteoblasts in the periosteum lay down collar of primary bone called bone callus Bone callus of primary bone Repaired blood vessel Central canal Primary bone Osteoblasts Osteoblasts building secreting secondary organic matrix bone Osteoclast degrading Osteoblasts in primary periosteum Lamellae bone 3 Osteoblasts build a bone callus. 4 The bone callus is remodeled and primary bone is replaced with secondary bone. 4) Bone callus is re-modeled and primary bone is resorbed and replaced with secondary bone. © 2019 Pearson Education, Inc. Fracture Primary treatment is immobilization Closed Reduction-bone ends are brought into contact by simply manipulating the body part. treatment Open Reduction-severe fractures are fixated surgically with plates, wires and screws © 2019 Pearson Education, Inc. What classification in shape is the pelvic bone? A A. Sesamoid Bone B B. Irregular Bone C C. Flat Bone D D. Long Bone E E. Short bone Where is much of the marrow in a long bone housed? A A. Periosteum B B. Spongy Bone C C. Compact Bone D D. Medullary Cavity E E. None of These Which cells are responsible for the process of bone resorption? A A. Osteogenic cells B B. Osteoblasts C C. Osteocytes D D. Osteoclasts E E. None of these What structure connects lacunae? A A. Canaliculi B B. Osteocytes C C. Lamellae D D. Haversian canal E E. None of these What disease develops as a result of inadequate inorganic matrix in the ECM? A A. Osteopetrosis B B. Osteoporosis C C. Achondroplasia D D. Acromegaly E E. None of these Which zone of the epiphyseal plate contains cells that are not directly involved in bone growth? A A. Zone of Reserve Cartilage B B. Zone of Proliferation C C. Zone of Hypertrophy D D. Zone of Calcification E E. Zone of Ossification Which is not an effect that growth hormone has on bone tissue? A A. Increase rate of mitosis of chondrocytes B in epiphyseal plate C B. Increase activity of osteogenic cells D C. Stimulate osteoblasts in periosteum D. Accelerates epiphyseal plate closure