Osseous Tissue and Bone Structure PowerPoint Presentation

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Fundamentals of Anatomy & Physiology Frederic H. Martini Unit 2 Support and Movement Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint® Lecture Slides prepared byProfessor Albia Dugger, Miami–Dade College, Miami, FL Professor Robert R. Speed, Ph.D., Wallace Community College, Dothan, AL 1

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Chapter 6: Osseous Tissue and Bone Structure 2

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The Skeletal System Skeletal system includes: bones of the skeleton cartilages, ligaments, and connective tissues 3

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What are the functions of the skeletal system? 4

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Functions of the Skeletal System Support Storage of minerals (calcium) Storage of lipids (yellow marrow) 5

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Functions of the Skeletal System Blood cell production (red marrow) Protection Leverage (force of motion) 6

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How are bones classified? 7

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Classification of Bones Bones are identified by: shape internal tissues bone markings 8

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Bone Shapes Long bones Flat bones Sutural bones Irregular bones Short bones Sesamoid bones 9

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Long Bones Figure 6–1a 10

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Long Bones Are long and thin Are found in arms, legs, hands, feet, fingers, and toes 11

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Flat Bones Figure 6–1b 12

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Flat Bones Are thin with parallel surfaces Are found in the skull, sternum, ribs, and scapula 13

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Sutural Bones Figure 6–1c 14

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Sutural Bones Are small, irregular bones Are found between the flat bones of the skull 15

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Irregular Bones Figure 6–1d 16

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Irregular Bones Have complex shapes Examples: spinal vertebrae pelvic bones 17

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Short Bones Figure 6–1e 18

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Short Bones Are small and thick Examples: ankle wrist bones 19

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Sesamoid Bones Figure 6–1f 20

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Sesamoid Bones Are small and flat Develop inside tendons near joints of knees, hands, and feet 21

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Bone Markings Depressions or grooves: along bone surface Projections: where tendons and ligaments attach at articulations with other bones Tunnels: where blood and nerves enter bone 22

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Bone Markings Table 6–1 (1 of 2) 23

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Bone Markings Table 6–1 (2 of 2) 24

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Long Bones The femur Figure 6–2a 25

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Long Bones Diaphysis: the shaft Epiphysis: wide part at each end articulation with other bones Metaphysis: where diaphysis and epiphysis meet 26

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The Diaphysis A heavy wall of compact bone, or dense bone A central space called marrow cavity 27

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The Epiphysis Mostly spongy (cancellous) bone Covered with compact bone (cortex) 28

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Flat Bones The parietal bone of the skull Figure 6–2b 29

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Flat Bones Resembles a sandwich of spongy bone Between 2 layers of compact bone 30

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What are the types and functions of bone cells? 31

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Bone (Osseous) Tissue Dense, supportive connective tissue Contains specialized cells Produces solid matrix of calcium salt deposits Around collagen fibers 32

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Characteristics of Bone Tissue Dense matrix, containing: deposits of calcium salts bone cells within lacunae organized around blood vessels 33

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Characteristics of Bone Tissue Canaliculi: form pathways for blood vessels exchange nutrients and wastes 34

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Characteristics of Bone Tissue Periosteum: covers outer surfaces of bones consist of outer fibrous and inner cellular layers 35

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Matrix Minerals 2/3 of bone matrix is calcium phosphate, Ca3(PO4)2: reacts with calcium hydroxide, Ca(OH)2 to form crystals of hydroxyapatite, Ca10(PO4)6(OH)2 which incorporates other calcium salts and ions 36

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Matrix Proteins 1/3 of bone matrix is protein fibers (collagen) 37

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Bone Cells Make up only 2% of bone mass: osteocytes osteoblasts osteoprogenitor cells osteoclasts 38

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Osteocytes Mature bone cells that maintain the bone matrix Figure 6–3 (1 of 4) 39

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Osteocytes Live in lacunae Are between layers (lamellae) of matrix Connect by cytoplasmic extensions through canaliculi in lamellae Do not divide 40

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Osteocyte Functions To maintain protein and mineral content of matrix To help repair damaged bone 41

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Osteoblasts Immature bone cells that secrete matrix compounds (osteogenesis) Figure 6–3 (2 of 4) 42

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Osteoid Matrix produced by osteoblasts, but not yet calcified to form bone Osteoblasts surrounded by bone become osteocytes 43

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Osteoprogenitor Cells Mesenchymal stem cells that divide to produce osteoblasts Figure 6–3 (3 of 4) 44

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Osteoprogenitor Cells Are located in inner, cellular layer of periosteum (endosteum) The endosteum is a thin layer of connective tissue which lines the surface of the bony tissue that forms the medullary cavity of long bones. This endosteal surface is usually resorbed during long periods of malnutrition Assist in fracture repair 45

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Osteoclasts Secrete acids and protein-digesting enzymes Figure 6–3 (4 of 4) 46

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Osteoclasts Giant, mutlinucleate cells Dissolve bone matrix and release stored minerals (osteolysis) Are derived from stem cells that produce macrophages 47

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Homeostasis Bone building (by osteocytes) and bone recycling (by osteoclasts) must balance: more breakdown than building, bones become weak exercise causes osteocytes to build bone 48

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What is the difference between compact bone and spongy bone? 49

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Compact Bone Figure 6–5 50

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Osteon The basic unit of mature compact bone smallest unit of mature compact bone Osteocytes are arranged in concentric lamellae Around a central canal containing blood vessels 51

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Perforating Canals Perpendicular to the central canal Carry blood vessels into bone and marrow 52

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Circumferential Lamellae Lamellae wrapped around the long bone Binds osteons together 53

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Spongy Bone Figure 6–6 54

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Spongy Bone Does not have osteons The matrix forms an open network of trabeculae Trabeculae have no blood vessels 55

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Red Marrow The space between trabeculae is filled with red bone marrow: which has blood vessels forms red blood cells and supplies nutrients to osteocytes 56

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Yellow Marrow In some bones, spongy bone holds yellow bone marrow: is yellow because it stores fat 57

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Weight–Bearing Bones Figure 6–7 58

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Weight–Bearing Bones The femur transfers weight from hip joint to knee joint: causing tension on the lateral side of the shaft and compression on the medial side 59

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Periosteum and Endosteum Compact bone is covered with membrane: periosteum on the outside endosteum on the inside 60

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Periosteum Figure 6–8a 61

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Periosteum Covers all bones: except parts enclosed in joint capsules It is made up of: an outer, fibrous layer and an inner, cellular layer 62

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Perforating Fibers Collagen fibers of the periosteum: connect with collagen fibers in bone and with fibers of joint capsules, attached tendons, and ligaments 63

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Functions of Periosteum Isolate bone from surrounding tissues Provide a route for circulatory and nervous supply Participate in bone growth and repair 64

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Endosteum Figure 6–8b 65

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Endosteum An incomplete cellular layer: lines the marrow cavity covers trabeculae of spongy bone lines central canals 66

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Endosteum Contains osteoblasts, osteoprogenitor cells, and osteoclasts Is active in bone growth and repair 67

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What is the difference between intramembranous ossification and endochondral ossification? 68

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Bone Development Human bones grow until about age 25 Osteogenesis: bone formation Ossification: the process of replacing other tissues with bone 69

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Calcification The process of depositing calcium salts Occurs during bone ossification and in other tissues 70

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Ossification The 2 main forms of ossification are: intramembranous ossification endochondral ossification 71

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Intramembranous Ossification Also called dermal ossification: because it occurs in the dermis produces dermal bones such as mandible and clavicle There are 3 main steps in intramembranous ossification 72

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Intramembranous Ossification: Step 1 Figure 6–11 (Step 1) 73

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Intramembranous Ossification: Step 1 Mesenchymal cells aggregate: differentiate into osteoblasts begin ossification at the ossification center develop projections called spicules 74

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Intramembranous Ossification: Step 2 Figure 6–11 (Step 2) 75

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Intramembranous Ossification: Step 2 Blood vessels grow into the area: to supply the osteoblasts Spicules connect: trapping blood vessels inside bone 76

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Intramembranous Ossification: Step 3 Figure 6–11 (Step 3) 77

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Intramembranous Ossification: Step 3 Spongy bone develops and is remodeled into: osteons of compact bone periosteum or marrow cavities 78

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Endochondral Ossification Ossifies bones that originate as hyaline cartilage Most bones originate as hyaline cartilage 79

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How does bone form and grow? 80

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Endochondral Ossification Growth and ossification of long bones occurs in 6 steps 81

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Endochondral Ossification: Step 1 Chondrocytes in the center of hyaline cartilage: enlarge form struts and calcify die, leaving cavities in cartilage Figure 6–9 (Step 1) 82

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Endochondral Ossification: Step 2 Figure 6–9 (Step 2) 83

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Endochondral Ossification: Step 2 Blood vessels grow around the edges of the cartilage Cells in the perichondrium change to osteoblasts: producing a layer of superficial bone around the shaft which will continue to grow and become compact bone (appositional growth) 84

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Endochondral Ossification: Step 3 Blood vessels enter the cartilage: bringing fibroblasts that become osteoblasts spongy bone develops at the primary ossification center Figure 6–9 (Step 3) 85

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Endochondral Ossification: Step 4 Remodeling creates a marrow cavity: bone replaces cartilage at the metaphyses Figure 6–9 (Step 4) 86

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Endochondral Ossification: Step 5 Capillaries and osteoblasts enter the epiphyses: creating secondary ossification centers Figure 6–9 (Step 5) 87

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Endochondral Ossification: Step 6 Figure 6–9 (Step 6) 88

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Endochondral Ossification: Step 6 Epiphyses fill with spongy bone: cartilage within the joint cavity is articulation cartilage cartilage at the metaphysis is epiphyseal cartilage 89

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Endochondral Ossification Appositional growth: compact bone thickens and strengthens long bone with layers of circumferential lamellae Endochondral Ossification PLAY Figure 6–9 (Step 2) 90

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What are the characteristics of adult bones? 91

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Epiphyseal Lines Figure 6–10 92

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Epiphyseal Lines When long bone stops growing, after puberty: epiphyseal cartilage disappears is visible on X-rays as an epiphyseal line 93

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Mature Bones As long bone matures: osteoclasts enlarge marrow cavity osteons form around blood vessels in compact bone 94

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Blood Supply of Mature Bones 3 major sets of blood vessels develop Figure 6–12 95

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Blood Vessels of Mature Bones Nutrient artery and vein: a single pair of large blood vessels enter the diaphysis through the nutrient foramen femur has more than 1 pair 96

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Blood Vessels of Mature Bones Metaphyseal vessels: supply the epiphyseal cartilage where bone growth occurs 97

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Blood Vessels of Mature Bones Periosteal vessels provide: blood to superficial osteons secondary ossification centers 98

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Lymph and Nerves The periosteum also contains: networks of lymphatic vessels sensory nerves 99

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How does the skeletal system remodel and maintain homeostasis, and what are the effects of nutrition, hormones, exercise, and aging on bone? 100

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Remodeling The adult skeleton: maintains itself replaces mineral reserves Remodeling: recycles and renews bone matrix involves osteocytes, osteoblasts, and osteoclasts 101

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KEY CONCEPTS Bone continually remodels, recycles, and replaces Turnover rate varies If deposition is greater than removal, bones get stronger If removal is faster than replacement, bones get weaker 102

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Effects of Exercise on Bone Mineral recycling allows bones to adapt to stress Heavily stressed bones become thicker and stronger 103

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Bone Degeneration Bone degenerates quickly Up to 1/3 of bone mass can be lost in a few weeks of inactivity 104

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KEY CONCEPTS What you don’t use, you lose Stresses applied to bones during physical activity are essential to maintain bone strength and mass 105

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Effects of Hormones and Nutrition on Bone Normal bone growth and maintenance requires nutritional and hormonal factors 106

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Minerals A dietary source of calcium and phosphate salts: plus small amounts of magnesium, fluoride, iron, and manganese 107

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Calcitriol The hormone calcitriol: is made in the kidneys helps absorb calcium and phosphorus from digestive tract synthesis requires vitamin D3 (cholecalciferol) 108

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Vitamins Vitamin C is required for collagen synthesis, and stimulates osteoblast differentiation Vitamin A stimulates osteoblast activity Vitamins K and B12 help synthesize bone proteins 109

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Other Hormones Growth hormone and thyroxine stimulate bone growth Estrogens and androgens stimulate osteoblasts Calcitonin and parathyroid hormone regulate calcium and phosphate levels 110

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Hormones for Bone Growth and Maintenance Table 6–2 111

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The Skeleton as Calcium Reserve Bones store calcium and other minerals Calcium is the most abundant mineral in the body 112

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Chemical Composition of Bone Figure 6–13 113

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Functions of Calcium Calcium ions are vital to: membranes neurons muscle cells, especially heart cells 114

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Calcium Regulation Calcium ions in body fluids: must be closely regulated Homeostasis is maintained: by calcitonin and parathyroid hormone which control storage, absorption, and excretion 115

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Calcitonin and Parathyroid Hormone Control Bones: where calcium is stored Digestive tract: where calcium is absorbed Kidneys: where calcium is excreted 116

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Parathyroid Hormone (PTH) Figure 6–14a 117

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Parathyroid Hormone (PTH) Produced by parathyroid glands in neck Increases calcium ion levels by: stimulating osteoclasts increasing intestinal absorption of calcium decreases calcium excretion at kidneys 118

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Calcitonin Figure 6–14b 119

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Calcitonin Secreted by C cells (parafollicular cells) in thyroid Decreases calcium ion levels by: inhibiting osteoclast activity increasing calcium excretion at kidneys 120

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KEY CONCEPTS (1 of 2) Calcium and phosphate ions in blood are lost in urine Ions must be replaced to maintain homeostasis If not obtained from diet, ions are removed from the skeleton, weakening bones 121

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KEY CONCEPTS (2 of 2) Exercise and nutrition keep bones strong 122

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What are the types of fractures, and how do they heal? 123

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Fractures Fractures: cracks or breaks in bones caused by physical stress Fractures are repaired in 4 steps 124

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Fracture Repair: Step 1 Figure 6–15 (Step 1) 125

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Fracture Repair: Step 1 Bleeding: produces a clot (fracture hematoma) establishes a fibrous network Bone cells in the area die 126

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Fracture Repair: Step 2 Figure 6–15 (Step 2) 127

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Fracture Repair: Step 2 Cells of the endosteum and periosteum: Divide and migrate into fracture zone Calluses stabilize the break: external callus of cartilage and bone surrounds break internal callus develops in marrow cavity 128

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Fracture Repair: Step 3 Figure 6–15 (Step 3) 129

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Fracture Repair: Step 3 Osteoblasts: replace central cartilage of external callus with spongy bone 130

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Fracture Repair: Step 4 Figure 6–15 (Step 4) 131

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Fracture Repair: Step 4 Osteoblasts and osteocytes remodel the fracture for up to a year: reducing bone calluses Steps in the Repair of a Fracture PLAY 132

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Figure 6–16 (1 of 9) The Major Types of Fractures Pott’s fracture 133

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The Major Types of Fractures Comminuted fractures Figure 6–16 (2 of 9) 134

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The Major Types of Fractures Transverse fractures Figure 6–16 (3 of 9) 135

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The Major Types of Fractures Spiral fractures Figure 6–16 (4 of 9) 136

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Figure 6–16 (5 of 9) The Major Types of Fractures Displaced fractures 137

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Figure 6–16 (6 of 9) The Major Types of Fractures Colles’ fracture 138

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Figure 6–16 (7 of 9) The Major Types of Fractures Greenstick fracture 139

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Figure 6–16 (8 of 9) The Major Types of Fractures Epiphyseal fractures 140

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Figure 6–16 (9 of 9) The Major Types of Fractures Compression fractures 141

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What are the effects of aging on the skeletal system? 142

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Age and Bones Bones become thinner and weaker with age Osteopenia begins between ages 30 and 40 Women lose 8% of bone mass per decade, men 3% 143

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Effects of Bone Loss The epiphyses, vertebrae, and jaws are most affected: resulting in fragile limbs reduction in height tooth loss 144

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Osteoporosis Severe bone loss Affects normal function Over age 45, occurs in: 29% of women 18% of men 145

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Hormones and Bone Loss Estrogens and androgens help maintain bone mass Bone loss in women accelerates after menopause 146

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Cancer and Bone Loss Cancerous tissues release osteoclast-activating factor: that stimulates osteoclasts and produces severe osteoporosis 147

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SUMMARY (1 of 5) Bone shapes, markings, and structure The matrix of osseous tissue Types of bone cells 148

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SUMMARY (2 of 5) The structures of compact bone The structures of spongy bone The periosteum and endosteum 149

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SUMMARY (3 of 5) Ossification and calcification Intramembranous ossification Endochondrial ossification 150

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SUMMARY (4 of 5) Blood and nerve supplies Bone minerals, recycling, and remodeling The effects of exercise 151

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SUMMARY (5 of 5) Hormones and nutrition Calcium storage Fracture repair The effects of aging 152