Transcript Chapter 6: Osseous Tissue and Bone Structure

Unit
2
Support and Movement
Fundamentals of
Anatomy & Physiology
Frederic H. Martini
PowerPoint® Lecture Slides prepared by
Professor Albia Dugger, Miami–Dade College, Miami, FL
Professor Robert R. Speed, Ph.D., Wallace Community College, Dothan, AL
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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.
2.
3.
Support
Storage of minerals (calcium)
Storage of lipids (yellow marrow)
5
Functions of the
Skeletal System
4.
5.
6.
Blood cell production (red marrow)
Protection
Leverage (force of motion)
6
How are bones classified?
7
Classification of Bones
 Bones are identified by:
 shape
 internal tissues
 bone markings
8
Bone Shapes
1.
2.
3.
4.
5.
6.
Long bones
Flat bones
Sutural bones
Irregular bones
Short bones
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 6–1f20
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 25
6–2a
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 29
6–2b
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, 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
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 39
of 4)
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 42
of 4)
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 44
of 4)
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
Osteoclasts
 Secrete acids and protein-digesting enzymes
Figure 6–3 (4 46
of 4)
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 osteoblasts) 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 6–550
Osteon
 The basic (smallest) 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 6–654
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 6–758
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.
2.
3.
Isolate bone from surrounding tissues
Provide a route for circulatory and nervous supply
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
PLAY
Endochondral Ossification
Figure 6–9 (Step 90
2)
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 95
6–12
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 D3 (cholecalciferol)
108
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
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 6–2111
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
 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
 Exercise and nutrition keep bones strong
121
What are the types
of fractures, and
how do they heal?
122
Fractures
 Fractures:
 cracks or breaks in bones
 caused by physical stress
 Fractures are repaired in 4 steps
123
Fracture Repair: Step 1
Figure 6–15 (Step 1)124
Fracture Repair: Step 1
 Bleeding:
 produces a clot (fracture hematoma)
 establishes a fibrous network
 Bone cells in the area die
125
Fracture Repair: Step 2
Figure 6–15 (Step 2)126
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
127
Fracture Repair: Step 3
Figure 6–15 (Step 3)128
Fracture Repair: Step 3
 Osteoblasts:
 replace central cartilage of external callus
 with spongy bone
129
Fracture Repair: Step 4
Figure 6–15 (Step 4)130
Fracture Repair: Step 4
 Osteoblasts and osteocytes remodel the fracture for up
to a year:
 reducing bone calluses
PLAY
Steps in the Repair of a Fracture
131
The Major Types of Fractures
 Pott’s fracture
Figure 6–16 (1 of132
9)
The Major Types of Fractures
 Comminuted fractures
Figure 6–16 (2 of133
9)
The Major Types of Fractures
 Transverse fractures
Figure 6–16 (3 of134
9)
The Major Types of Fractures
 Spiral fractures
Figure 6–16 (4 of135
9)
The Major Types of Fractures
 Displaced fractures
Figure 6–16 (5 of136
9)
The Major Types of Fractures
 Colles’ fracture
Figure 6–16 (6 of137
9)
The Major Types of Fractures
 Greenstick fracture
Figure 6–16 (7 of138
9)
The Major Types of Fractures
 Epiphyseal fractures
Figure 6–16 (8 of139
9)
The Major Types of Fractures
 Compression fractures
Figure 6–16 (9 of140
9)
What are the effects of aging
on the skeletal system?
141
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%
142
Effects of Bone Loss
 The epiphyses, vertebrae, and jaws are most affected:
 resulting in fragile limbs
 reduction in height
 tooth loss
143
Osteoporosis
 Severe bone loss
 Affects normal function
 Over age 45, occurs in:
 29% of women
 18% of men
144
Hormones and Bone Loss
 Estrogens and androgens help maintain bone mass
 Bone loss in women accelerates after menopause
145
Cancer and Bone Loss
 Cancerous tissues release osteoclast-activating factor:
 that stimulates osteoclasts
 and produces severe osteoporosis
146
SUMMARY (1 of 5)
 Bone shapes, markings, and structure
 The matrix of osseous tissue
 Types of bone cells
147
SUMMARY (2 of 5)
 The structures of compact bone
 The structures of spongy bone
 The periosteum and endosteum
148
SUMMARY (3 of 5)
 Ossification and calcification
 Intramembranous ossification
 Endochondrial ossification
149
SUMMARY (4 of 5)
 Blood and nerve supplies
 Bone minerals, recycling, and remodeling
 The effects of exercise
150
SUMMARY (5 of 5)
 Hormones and nutrition
 Calcium storage
 Fracture repair
 The effects of aging
151