Презентация на тему: The Skeletal System

The Skeletal System The Skeletal System: A Dynamic System The Skeletal System Bones: Types Compact Bone Compact Bone High Magnification Spongy Bone Histology Trabeculae of Spongy Bone Cartilage:Types Hyaline Cartilage Fibrocartilage Figure 7.1 Ligaments and Tendons Bones The Skeletal System Bone Functions Bone Classification Long Bones Long Bones Short Bones Short Bones Flat Bones Flat Bones Irregular Bones Irregular Bones Figure 7.2 Gross Anatomy of Bones: Long Bones Long Bone Regions: Diaphysis Long Bone Regions: Medullary Cavity Long Bone Regions: Epiphysis Long Bone Regions: Epiphysis Figure 7.3a Humerus Bone Coverings Figure 7.3c Bone Coverings Figure 7.3b Gross Anatomy of Bones: Other Bones Figure 7.4 Blood Supply and Innervation of Bone Gross Anatomy of Bones: Bone Marrow Red Bone Marrow Yellow Bone Marrow Figure 7.5 Microscopic Anatomy of Bone: Cells of Bone Osteoprogenitor Cells Osteoblasts Osteocytes Figure 7.6a Osteoclasts Figure 7.6b Bone Matrix Composition Bone Matrix Composition Changes to Molecular Composition of Bone Bone Matrix Formation Bone Matrix Resorption Microscopic Anatomy of Bone: Compact Bone Figure 7.8a-b Figure 7.7a Figure 7.7b Microscopic Anatomy of Bone: Spongy Bone Figure 7.7c Microscopic Anatomy: Hyaline Cartilage Microscopic Anatomy: Hyaline Cartilage Comparison of Bone Connective Tissue and Hyaline Cartilage Connective Tissue (Table 7.1) Cartilage Growth Figure 7.9a Figure 7.9b Cartilage Growth Stages Bone Formation Intermembranous Ossification Figure 7.10 Endochondral Ossification Figure 7.11 The Skeletal System Bone Homeostasis: Bone Growth and Remodeling Bone Growth and Remodeling: Role of Bone Cells Bone Growth Figure 7.12a Figure 7.12b Bone Growth: Epiphyseal Plate Figure 7.13 Bone Growth and Remodeling: Role of Hormones Bone Growth and Remodeling : Mechanical Stress Blood Calcium Levels Figure 7.14 Regulating Blood Calcium Levels: Parathyroid Hormone and Calcitriol Blood Calcium Levels Figure 7.15 Effects of Aging on Bone Effects of Aging Effects of Aging Osteoporosis Bone Fracture and Repair Figure 7.16 Bone Fracture and Repair Figure 7.17
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Первый слайд презентации: The Skeletal System

Bone Structure and Function

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Слайд 2: The Skeletal System: A Dynamic System

The skeleton is more than a supporting framework The skeletal system is composed of dynamic living tissues It interacts with all other organ systems It continually rebuilds and remodels itself

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Слайд 3: The Skeletal System

Includes Bones Primary structure Compact bone Spongy bone Cartilage Hyaline Fibrocartilage Ligaments and Tendons

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Слайд 4: Bones: Types

Compact Bone also called dense or cortical bone relatively dense connective bone tissue appears white, smooth, and solid 80% of bone mass Spongy Bone also called cancellous or trabecular bone located internal to compact bone appears porous 20% of bone mass

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Слайд 5: Compact Bone

Osteons Central canals Perforating canals Interstitial lamellae

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Слайд 6: Compact Bone High Magnification

Osteon Central canal Osteocytes Lacunae Interstitial lamella Lamella Cement line Canaliculi

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Слайд 7: Spongy Bone Histology

Marrow Trabecula e Periosteum

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Слайд 8: Trabeculae of Spongy Bone

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Слайд 9: Cartilage:Types

Hyaline Cartilage attaches ribs to the sternum covers the ends of some bones cartilage within growth plates model for formation of most bones Fibrocartilage weight-bearing cartilage that withstands compression forms intervertebral discs forms pubic symphysis forms cartilage pads of the knees

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Слайд 10: Hyaline Cartilage

Chondrocytes Extracellular matrix Perichondrium Lacunae Nuclei of chondrocytes

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Слайд 11: Fibrocartilage

Chondrocytes Collagen fibers Ground substance Lacunae Nuclei of chondrocytes

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Слайд 12: Figure 7.1

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Articular cartilage Costal cartilage Articular cartilage Articular cartilage Epiphyseal plate Epiphyseal plate Cartilage of Intervertebral disc Pubic symphysis Articular cartilage Meniscus (padlike fibrocartilage in knee joint) Hyaline cartilage Fibrocartilage

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Слайд 13: Ligaments and Tendons

Covered in Chapter 9 Ligaments connect bone to bone ACL Tendons connect muscle to bone Achilles

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Слайд 14: Bones

206 bones is standard / typical (but nearly everyone has more/fewer )

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Слайд 15

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Слайд 16: Bone Functions

Support and Protection Body’s framework Protects from trauma Movement Sites of muscle attachment Hemopoiesis Production of red, white blood cells and platelets Storage of Mineral and Energy Reserves Calcium, Phosphorous Lipids

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Слайд 17: Bone Classification

Four classes determined by shape Long bones Short bones Flat bones Irregular bones

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Слайд 18: Long Bones

Greater in length than width Have elongated, cylindrical shaft (diaphysis) Most common bone shape Found in upper and lower limbs e.g., arm, forearm, fingers, thigh, leg, toes Vary in size

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Слайд 19: Long Bones

Arm Forearm Fingers Thigh Leg Toes

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Слайд 20: Short Bones

Length nearly equal to width C arpal bones (wrist bones) S esamoid bones, bones along tendons of muscles P atella (kneecap), largest sesamoid bone

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Слайд 21: Short Bones

Carpals Sesamoid bone of Hallux Sesamoid bone of Pollex Patella Tarsals

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Слайд 22: Flat Bones

Flat, thin surfaces, may be slightly curved Provide surfaces for muscle attachment Protect underlying soft tissues Form: T he roof of the skull T he scapulae T he sternum T he ribs

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Слайд 23: Flat Bones

Parietal bone Scapula Sternum Sternum and Ribs Frontal bone

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Слайд 24: Irregular Bones

Have elaborate shapes E.g., vertebrae, ossa coxae (hip bones) E.g., several bones in the skull ( ethmoid, sphenoid

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Слайд 25: Irregular Bones

Cervical vertebra Os coxae Ethmoid bone Sphenoid bone

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Слайд 26: Figure 7.2

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Flat bone (frontal bone) Irregular bone (vertebra) Long bone (femur) Short bone (tarsal bone)

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Слайд 27: Gross Anatomy of Bones: Long Bones

Regions of a long bone Diaphysis Medullary cavity Epiphysis

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Слайд 28: Long Bone Regions: Diaphysis

Elongated, usually cylindrical shaft Provides for leverage and major weight support Compact bone with thin spicules of spongy bone extending inward

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Слайд 29: Long Bone Regions: Medullary Cavity

hollow, cylindrical space within the diaphysis contains red bone marrow in children contains yellow bone marrow in adults

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Слайд 30: Long Bone Regions: Epiphysis

Knobby region at the ends of long bone P roximal epiphysis end of the bone closest to trunk D istal epiphysis end farthest from trunk C omposed of: outer thin layer of compact bone inner region of spongy bone J oint surface covered by thin layer of hyaline cartilage termed articular cartilage helps reduce friction and absorb shock in moveable joints

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Слайд 31: Long Bone Regions: Epiphysis

Metaphysis R egion of mature bone between diaphysis and epiphysis Epiphyseal plate I n metaphysis T hin layer of hyaline cartilage P rovides for continued lengthwise bone growth R emnant in adults termed the epiphyseal line

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Слайд 32: Figure 7.3a

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Proximal epiphysis Metaphysis Diaphysis Metaphysis Distal epiphysis (a) Humerus, anterior view Articular cartilage Spongy bone Articular cartilage Epiphyseal line Compact bone Spongy bone Medullary cavity (contains yellow bone marrow in adult) Endosteum Periosteum Perforating fibers Nutrient artery through nutrient foramen

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Слайд 33: Humerus

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Слайд 34: Bone Coverings

Periosteum Tough sheath covering outer surface of bone Outer fibrous layer of dense irregular connective tissue P rotects bone from surrounding structures A nchors blood vessels and nerves to bone surface A ttachment site for ligaments and tendons Inner cellular layer Includes osteoprogenitor cells, osteoblasts, and osteoclasts Attached to bone by numerous collagen fibers T ermed perforating fibers

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Слайд 35: Figure 7.3c

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (c) Periosteum Perforating fibers Periosteum Cellular layer Fibrous layer Osteocyte Compact bone Compact bone

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Слайд 36: Bone Coverings

Endosteum Covers all internal surfaces of bone within medullary cavity Incomplete layer of cells Contains osteoprogenitor cells, osteoblasts, and osteoclasts

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Слайд 37: Figure 7.3b

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endosteum Osteoprogenitor cell Osteoblasts Nuclei Osteoclast Osteocyte Spongy bone Medullary cavity (b) Endosteum Spongy bone Medullary cavity

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Слайд 38: Gross Anatomy of Bones: Other Bones

Short, flat, and irregular bones External surface composed of compact bone Interior composed of spongy bone also called diploë in flat skull bones Lack a medullary cavity

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Слайд 39: Figure 7.4

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. SEM 5x Flat bone of skull Periosteum Compact bone Periosteum Spongy bone (diploë) © Susumu Nishinaga/Photo Researchers, Inc.

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Слайд 40: Blood Supply and Innervation of Bone

Blood supply Bone highly vascularized, especially spongy bone Vessels entering from periosteum Nutrient foramen small opening or hole in the 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

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Слайд 41: Gross Anatomy of Bones: Bone Marrow

Soft connective tissue of bone Includes red bone marrow and yellow bone marrow

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Слайд 42: Red Bone Marrow

Also known as myeloid tissue Hemopoietic (blood cell forming) Contains reticular connective tissue, immature blood cells, and fat In children, located in the spongy bone and medullary cavity of long bones In adults, located in portions of axial skeleton located in proximal epiphyses of humerus and femur skull, vertebrae, ribs, sternum, ossa coxae

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Слайд 43: Yellow Bone Marrow

Product of red bone marrow degeneration Fatty substance May convert back to red bone marrow may occur during severe anemia condition with reduced erythrocytes (red blood cells) facilitates the production of additional erythrocytes

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Слайд 44: Figure 7.5

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Red bone marrow Yellow bone marrow (b) Head of femur, sectioned (a) Red bone marrow in the adult (b): Credit: Dr. M. Laurent, University Hospitals Leuven, Belgium. Image is available under a creative commons attribution license.

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Слайд 45: Microscopic Anatomy of Bone: Cells of Bone

Bone connective tissue Primary component of bone Also called osseous connective tissue Composed of cells and extracellular matrix Four types found in bone connective tissue Osteoprogenitor cells Osteoblasts Osteocytes Osteoclasts

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Слайд 46: Osteoprogenitor Cells

Stem cells derived from mesenchyme Produce cells that mature to become osteoblasts Located in periosteum and endosteum

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Слайд 47: Osteoblasts

Often positioned side by side on bone surfaces Synthesize and secrete osteoid initial semisolid form of bone matrix later calcifies Become entrapped within the matrix they produce

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Слайд 48: Osteocytes

Mature bone cells derived from osteoblasts Have lost bone forming ability Maintain bone matrix Detect mechanical stress on bone May trigger deposition of new bone matrix

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Слайд 49: Figure 7.6a

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteoprogenitor cells develop into osteoblasts. Some osteoblasts differentiate into osteocytes. (a) Bone cells Osteocyte (maintains bone matrix) Osteoblast (forms bone matrix)

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Слайд 50: Osteoclasts

Large, multinuclear, phagocytic cells Derived from fused bone marrow cells Ruffled border to increase surface area exposed to bone Often located within or adjacent to a depression or pit on bone surface termed resorption lacuna Involved in breaking down bone

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Слайд 51: Figure 7.6b

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Resorption lacuna Endosteum Osteoclast Nuclei Lysosomes Ruffled border (b) Osteoclast Fusing bone marrow cell

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Слайд 52: Bone Matrix Composition

Organic components Osteoid produced by osteoblasts collagen protein semisolid ground substance of proteoglycans glycoproteins Give bone tensile strength by resisting stretching Contribute to bone flexibility

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Слайд 53: Bone Matrix Composition

Inorganic components Made of salt crystals, primarily calcium phosphate, Ca3(PO4)2 Interacts with calcium hydroxide forms crystals of hydroxyapatite, Ca10(PO4)6(OH)2 Other substances incorporated into crystals e.g., calcium carbonate, sodium, magnesium ions Crystals deposited around collagen fibers Harden the matrix and account for relative rigidity of bones

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Слайд 54: Changes to Molecular Composition of Bone

Correct proportion allows optimal functioning Loss of protein resulting in brittle bones Insufficient calcium resulting in soft bones

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Слайд 55: Bone Matrix Formation

Begins with secretion of osteoid Proceeds with calcification, when hydroxyapatite crystals deposited calcium and phosphate ions precipitating out, forming crystals Process requires vitamin D enhances calcium absorption from gastrointestinal tract Requires vitamin C needed for collagen formation Requires calcium and phosphate for calcification

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Слайд 56: Bone Matrix Resorption

Bone matrix 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 May occur when blood calcium levels low

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Слайд 57: Microscopic Anatomy of Bone: Compact Bone

Osteon ( haversian system) is a tapered, cylindrical unit that makes up compact bone tissue Central canal Osteoblasts Lacuna Osteocytes Canaliculi ("tiny canals ") Lamellae (sing. lamella)

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Слайд 58: Figure 7.8a-b

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. SEM 1040x LM 75x Lacuna (with osteocyte) Osteon Central canal Concentric lamellae Canaliculi (a) Compact bone Osteon Central canal Lacunae (b) Compact bone (a): © Carolina Biological Supply Company/Phototake; (b): © Dr. Richard Kessel & Dr. Randy Kardon/Tissues and Organs/Visuals Unlimited;

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Слайд 59: Figure 7.7a

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) Section of humerus Perforating canals Central canal Trabeculae of spongy bone Interstitial lamellae Internal circumferential lamellae Diaphysis of humerus External circumferential lamellae Osteon Central canal Perforating fibers Fibrous layer Cellular layer Periosteum

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Слайд 60: Figure 7.7b

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Canaliculi Central canal Osteon Collagen fiber orientation Concentric lamellae Nerve Vein Artery Lacuna (b) Compact bone Osteocyte Canaliculi

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Слайд 61: Microscopic Anatomy of Bone: Spongy Bone

Trabeculae open lattice of narrow rods and plates of bones bone marrow filling spaces between form a meshwork of crisscrossing bars provide great resistance to stresses Parallel lamellae composed of bone matrix osteocytes resting between lamellae canaliculi radiating from lacunae

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Слайд 62: Figure 7.7c

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endosteum Osteoclast Parallel lamellae Osteocyte In lacuna (c) Spongy bone Canaliculi opening at surface Canaliculi opening at surface Osteoblasts aligned along trabecula of new bone Trabeculae Space for bone marrow Interstitial lamellae

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Слайд 63: Microscopic Anatomy: Hyaline Cartilage

Population of 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

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Слайд 64: Microscopic Anatomy: Hyaline Cartilage

Chondroblasts produce cartilage matrix Chondrocytes chondroblasts that have become encased within the matrix occupy small spaces called lacunae maintain the matrix Perichondrium dense irregular connective tissue covers cartilage and helps maintain its shape

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Слайд 65: Comparison of Bone Connective Tissue and Hyaline Cartilage Connective Tissue (Table 7.1)

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Слайд 66: Cartilage Growth

Process b egins during embryologic development Growth in length through interstitial growth occurs within the internal regions of cartilage Growth in width by appositional growth occurs on cartilage’s outside edge

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Слайд 67: Figure 7.9a

1 2 3 4 Perichondrium Hyalinecartilage (a) Interstitial Growth A chondrocyte within a lacuna begins to exhibit mitotic activity. Lacuna Chondrocyte Matrix Two cells (now called chondroblasts) are produced by mitosis from one chondrocyte and occupy one lacuna. Chondroblast Lacuna Each cell produces new matrix and begins to separate from its neighbor. Each cell is now called a chondrocyte. Cartilage continues to grow internally. Chondrocyte New matrix Chondrocyte Lacuna New matrix LM 320x Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © The McGraw-Hill Companies, Inc./Al Telser, photographer Matrix Chondrocyte in lacuna

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Слайд 68: Figure 7.9b

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 2 3 LM 320x Perichondrium Matrix Chondrocyte in lacuna Hyalinecartilage (b) Appositional Growth Mitotic activity occurs in stem cells within the perichondrium. Mesenchymal cells Dividing undifferentiated stem cell New undifferentiated stem cells and committed cells that differentiate Into chondroblasts are formed. Chondroblasts produce new matrixat the periphery. Undifferentiated stem cells Committed cells differentiating into chondroblasts Chondroblast secreting new matrix As a result of matrix formation, the chondroblasts push apart and become chondrocytes. Chondrocytes continue to produce more matrix at the periphery. Undifferentiated stem cells Chondrocyte secreting new matrix Mature chondrocyte Older cartilage matrix New cartilage matrix Perichondrium Perichondrium New cartilage matrix Older cartilage matrix New cartilage matrix Older cartilage matrix © The McGraw-Hill Companies, Inc./Al Telser, photographer

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Слайд 69: Cartilage Growth Stages

During early embryonic development interstitial and appositional growth occur simultaneously As cartilage matures interstitial growth declines rapidly cartilage is semi-rigid further growth primarily apositional After cartilage is fully mature new cartilage growth stops growth occurs only after injury limited due to lack of blood vessels

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Слайд 70: Bone Formation

Process is called ossification Begins in embryo 8-12 weeks Always starts with membrane or cartilage that turns to bone Intermembranous ossification Endochondral ossification

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Слайд 71: Intermembranous Ossification

Also known as dermal ossification Produces: flat bones of the skull some of the facial bones mandible central part of the clavicle Begins when mesenchyme becomes thickened with capillaires

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Слайд 72: Figure 7.10

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 2 3 4 Flat bone of skull Ossification centers form within thickened regions of mesenchyme. Osteoid undergoes calcification. Woven bone and surrounding periosteum form. Lamellar bone replaces woven bone, as compact and spongy bone form. Spongy bone Lamellar bone Compact bone Periosteum Mesenchyme condensing to form the periosteum Trabeculaof wovenbone Blood vessel Newly alcified bone matrix Osteoblast Osteocyte Osteoid Collagen fiber Mesenchymal cell Ossification center Osteoblast Spongy bone Lamellar bone Compact bone Periosteum Mesenchyme condensing to form the periosteum Trabecula of woven bone Blood vessel Newly calcified bone matrix Osteoblast Osteocyte Osteoid Collagen fiber Mesenchymal cell Ossification center Osteoblast Osteoid Osteoid

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Слайд 73: Endochondral Ossification

Begins with a hyaline cartilage model Produces most bones of the skeleton, including: bones of the upper and lower limbs pelvis vertebrae ends of the clavicle

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Слайд 74: Figure 7.11

Ten-week fetus, special staining highlights the cartilaginous models of the bones. Arrow points to the humerus. 8–12 weeks Perichondrium Hyaline cartilage Fetal hyaline cartilage model develops. Sixteen-week fetus, showing diaphyses of developing bones. Skeleton of a neonate. Fetal period Newborn to child Deteriorating cartilage matrix Epiphyseal blood vessels Epiphyseal blood vessel Periosteal bone collar Hyaline cartilage Cartilage calcifies, and a periosteal bone collar forms around diaphysis. Primary ossification center forms in the diaphysis. Secondary ossification centers form in epiphyses. Secondary ossification centers Calcified cartilage Developing compact bone Medullary cavity Periosteum Primary ossification center Blood vessel of periosteal bud Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (left): © Science VU/Visuals Unlimited; (middle): © Tissuepix/Photo Researchers, Inc.; (right): © MShieldsPhotos/Alamy 1 2 3 4

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Слайд 75

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6 5 Humerus from a 5-year-old child. Note the unfused epiphyses and diaphyses. X-ray of an adult humerus. Epiphyseal plates ossify and form epiphyseal lines. Epiphyseal line Medullary cavity Epiphyseal line (remnant of epiphyseal plate) Compact bone Periosteum Spongy bone Articular cartilage Articular cartilage Spongy bone Child Articular cartilage Spongy bone Epiphyseal plate Periosteum Compact bone Medullary cavity Epiphyseal plate Articular cartilage Bone replaces cartilage, except the articular cartilage and epiphyseal plates. Late teens to adult (left): © Bone Clones; (right): © ZEPHYR/SPL/Getty Images RF Figure 7.11

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Слайд 76: Bone Homeostasis: Bone Growth and Remodeling

Bone is never at rest Old bone is being destroyed New bone is being laid down Processes begin in embryo Bone growth in length Termed interstitial growth Bone growth in diameter Termed appositional growth

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Слайд 77: Bone Growth and Remodeling: Role of Bone Cells

Osteoblasts make new bone matrix (using Ca ++ from blood ) Osteoclasts ("bone breakers") dissolve bone matrix (releasing Ca ++ to blood)

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Слайд 78: Bone Growth

Interstitial growth Occurs in epiphyseal plate Increases bone length Appositional growth Occurs within the periosteum Increases bone diameter

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Слайд 79: Figure 7.12a

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. LM 70x Zone 1: Zone of resting cartilage Zone 2: Zone of proliferating cartilage Zone 3: Zone of hypertrophic cartilage Zone 4: Zone of calcified cartilage Zone 5: Zone of ossification © The McGraw-Hill Companies, Inc./Al Telser, photographer (a) Epiphyseal plate

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Слайд 80: Figure 7.12b

Epiphyses (b) X-ray of a hand Epiphyseal plates Epiphyseal plates Diaphysis Epiphyses Diaphyses Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Image Shop/Phototake

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Слайд 81: Bone Growth: Epiphyseal Plate

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Слайд 82: Figure 7.13

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone deposited by osteoblasts Bone resorbed by osteoclasts Periosteum Medullary cavity Compact bone Infant Child Young adult Adult Medullary cavity Compact bone Periosteum

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Слайд 83: Bone Growth and Remodeling: Role of Hormones

Calcitonin (CT; from thyroid) increases Ca ++ storage (out of blood ) Parathyroid hormone (PTH) gets Ca ++ out of storage (into blood ) Growth Hormone Thyroid Hormone Glucocorticoids Serotonin Estrogen/Testosterone

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Слайд 84: Bone Growth and Remodeling : Mechanical Stress

Weight bearing activity and exercise causes bone growth increased deposition of minerals salts and production of collagen fibers Benefits of weight-lifting, running Lack of weight bearing activity weakens bones astronauts

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Слайд 85: 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

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Слайд 86: Figure 7.14

1 2 3 Dietary intake (e.g., milk) OH Calcidiol Ultraviolet light or HO Precursor molecule (7-dehydrocholesterol) The precursor molecule is converted to Vitamin D 3 (cholecalciferol). Vitamin D 3 is converted to calcidiol in the liver (when an —OH group is added). Calcidiol is converted to calcitriol in the kidney (when another —OH group is added). HO CH 2 —OH —OH CH 2 OH HO CH 2 OH HO Calcitriol Vitamin D 3 (cholecalciferol) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Слайд 87: Regulating Blood Calcium Levels: Parathyroid Hormone and Calcitriol

Clinical View: Rickets Disease caused by vitamin D deficiency in childhood Characterized by deficient calcification of osteoid tissue Acquire bowlegged appearance Disturbances in growth, hypocalcemia, and tetany (cramps and twitches) caused by low blood calcium Continues to occur in some developing nations Incidence increasing in urban U.S. children

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Слайд 88: Blood Calcium Levels

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 Inhibits osteoclast activity in bone connective tissue less calcium released from bone into blood Stimulates kidneys to increase loss of calcium in the urine reducing blood calcium levels

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Слайд 89: Figure 7.15

5 4b 1 Ca 2 + EFFECTORS Calcitriol increases absorption of calcium from small intestine. 4c Small intestine PTH and calcitriol act synergistically to decrease calcium excreted in urine. PTH and calcitriol act synergistically to increase activity of osteoclasts. 4a Kidneys Bone Blood calcium levels rise and return to normal. This is regulated by a negative feedback mechanism. Ca 2 + STIMULUS Low blood calcium levels. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. HOMEOSTASIS RESTORED Too Low Homeostasis Too High Too Low Homeostasis Too High 3 2 RECEPTOR Parathyroid glands detect low blood calcium levels. Parathyroid glands CONTROL CENTER Parathyroid glands release parathyroid hormone. Parathyroid hormone release PTH + Calcitriol PTH Vitamin D converted to calcitriol, and then released from kidneys Calcitriol

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Слайд 90: Effects of Aging on Bone

More bone is made than is lost until age 25 (usually rapid until puberty, then slows ) About as much bone is made as is lost 25-50 (can vary ) More bone is lost than is made 50-120 Yellow marrow replaces red marrow, reducing total RBC production

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Слайд 91: Effects of Aging

Osteopenia Occurs slightly in all people with age Begins as early as age 35-40 Osteoblast activity declining; osteoclast activity at previous levels Vertebrae, jaw bones, epiphyses losing large amount of mass Women losing more of their skeletal mass every decade than men

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Слайд 92: Effects of Aging

Osteoporosis Reduced bone mass sufficient to compromise normal function Occurs in a significant percentage of older women Occurs in a smaller percentage of older men Reduced hormones with age Include growth hormone, estrogen, and testosterone Contributes to reduction in bone mass Reduced bone mass sufficient to compromise normal function

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Слайд 93: Osteoporosis

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Слайд 94: Bone Fracture and Repair

Breaks in bone Termed fractures Occur as result of unusual stress or impact Increased incidence with age due to normal thinning and weakening of bone

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Слайд 95: Figure 7.16

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Classification of Bone Fractures Description Fracture Avulsion Colles Comminuted Complete Compound (open) Compression Depressed Displaced Epiphyseal Greenstick Hairline Impacted Incomplete Linear Oblique Pathologic Pott Simple (closed) Spiral Stress Transverse Fracture is at right angles to the long axis of the bone Thin fractures due to repeated, stressful impact such as running (These fractures often are difficult to see on x-rays, and a bone scan may be necessary to accurately identify their presence.) Fracture spirals around axis of long bone; results from twisting stress Bone does not break through the skin Fracture is at the distal ends of the tibia and fibula Weakening of a bone caused by disease process (e.g., cancer) Diagonal fracture is at an angle Fracture is parallel to the long axis of the bone Partial fracture extends only partway across the bone One fragment of bone is firmly driven into the other Fine crack in which sections of bone remain aligned (common in skull) Partial fracture; one side of bone breaks—the other side is bent Epiphysis is separated from the diaphysis at the epiphyseal plate Fractured bone parts are out of anatomic alignment Broken part of the bone forms a concavity (as in skull fracture) Bone is squashed (may occur in a vertebra during a fall) Broken ends of the bone protrude through the skin Bone is broken into two or more pieces Bone is splintered into several small pieces between the main parts Fracture of the distal end of the lateral forearm bone (radius); produces a “dinner fork” deformity Complete severing of a body part (typically a toe or finger) (Top): © Mediscan/Visuals Unlimited; (middle): © ISM/Phototake; (bottom): © Wellcome Photo Library, Wellcome Images

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Слайд 96: Bone Fracture and Repair

Fracture healing Simple fracture about 2 to 3 months to heal Compound fracture longer to heal Generally becomes slower with age Some require surgical intervention to heal correctly

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Последний слайд презентации: The Skeletal System: Figure 7.17

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 2 3 4 Fibro- cartilaginous (soft) callus Medullary cavity Hematoma A fracture hematoma forms. Compact bone Periosteum A fibrocartilaginous (soft) callus forms. Regenerating blood vessels A hard (bony) callus forms. The bone is remodeled. Compact bone at fracture site Primary bone Hard callus

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