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 by Professor Albia Dugger, Miami–Dade College, Miami, FL Professor Robert R. Speed, Ph.D., Wallace Community College, Dothan, AL 1

Chapter 6: Osseous Tissue and Bone Structure 2

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

What are the functions of the skeletal system? 4

Functions of the Skeletal System 1. Support 2. Storage of minerals (calcium) 3. Storage of lipids (yellow marrow) 5

Functions of the Skeletal System 4. Blood cell production (red marrow) 5. Protection 6. Leverage (force of motion) 6

How are bones classified? 7

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

Bone Shapes 1. Long bones 2. Flat bones 3. Sutural bones 4. Irregular bones 5. Short bones 6. Sesamoid bones 9

Long Bones Figure 6–1a 10

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

Flat Bones Figure 6–1b 12

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

Sutural Bones Figure 6–1c 14

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

Irregular Bones Figure 6–1d 16

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

Short Bones Figure 6–1e 18

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

Sesamoid Bones Figure 6–1f 20

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

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

Bone Markings Table 6–1 (1 of 2) 23

Bone Markings Table 6–1 (2 of 2) 24

Long Bones The femur Figure 6–2a 25

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

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

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

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

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

What are the types and functions of bone cells? 31

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

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

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

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

Matrix Minerals 2/3 of bone matrix is calcium phosphate, Ca 3 (PO 4 ) 2 : reacts with calcium hydroxide, Ca(OH) 2 to form crystals of hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 which incorporates other calcium salts and ions 36

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

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

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

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

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

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

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

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

Osteoprogenitor Cells Are located in inner, cellular layer of periosteum (endosteum) Assist in fracture repair 45

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

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

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

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

Compact Bone Figure 6–5 50

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

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

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

Spongy Bone Figure 6–6 54

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

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

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

Weight–Bearing Bones Figure 6–7 58

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

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

Periosteum Figure 6–8a 61

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

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

Functions of Periosteum 1. Isolate bone from surrounding tissues 2. Provide a route for circulatory and nervous supply 3. Participate in bone growth and repair 64

Endosteum Figure 6–8b 65

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

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

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

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

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

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

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

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

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

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

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

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

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

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

How does bone form and grow? 80

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

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

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

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

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

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

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

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

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

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

What are the characteristics of adult bones? 91

Epiphyseal Lines Figure 6–10 92

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Calcitriol The hormone calcitriol: is made in the kidneys helps absorb calcium and phosphorus from digestive tract synthesis requires vitamin D 3 (cholecalciferol) 108

Vitamins Vitamin C is required for collagen synthesis, and stimulates osteoblast differentiation Vitamin A stimulates osteoblast activity Vitamins K and B 12 help synthesize bone proteins 109

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

Hormones for Bone Growth and Maintenance Table 6–2 111

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

Chemical Composition of Bone Figure 6–13 113

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

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

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

Parathyroid Hormone (PTH) Figure 6–14a 117

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

Calcitonin Figure 6–14b 119

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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