Bone Tissues Flashcards
1
Q
What are the general tisses of the bone?
A
- Bone (osseous) tissue; 2. Dense connective tissue; 3. Epithelium; 4. Adipose tissue; 5. Nervous tissue
2
Q
Why is a bone considered an organ?
A
Because it is made up of multiple tissues
3
Q
What are the componenets of the skeletal system?
A
Bones; cartilage; ligaments; tendons
4
Q
Osteology
A
the study of bone structure and the treatment of bone disorders.
5
Q
What are the basic functions of the bone and the skeletal system?
A
- Support (structural framework of the body. Supports soft tissue and points of attachments for tendons). 2. Protection (protection of internal organs-pelvis/ribs; spine; skull) 3. Assistance in movement (provide a surface for muscular attachment; contraction of muscles will pull on bones to produce movement) 4. Mineral homeostasis (calcium & phosphorous storage) 5. Blood cell production (Red Marrow-Hematopoiesis) 6. Triglyceride storage (yellow marrow mainly adipose cells)
6
Q
Macroscopic Structure of A Long Bone
A
- Diaphysis 2. Epiphysis 3. Metaphysis 4. Articular Cartilage 5. Periosteum 6. Medullary Cavity 7. Endosteum
7
Q
Diaphysis
A
growing between; the shaft or body of the bone; main portion
8
Q
Epiphyses
A
growing over; singular epiphysis; proximal and distal ends of the bone
9
Q
Metaphysis
A
between; the region between the diaphysis and the epiphyses. In a growing bone will contain an epiphyseal plate (aka: growth plate) a layer of hyaline cartilage that allows the diaphysis to grow in length. A bone ceases to grow in length at about ages 14-24; hyaline cartilage is replaced by bone. The resulting bony structure is known as the epiphyseal line
10
Q
Articular Cartilage
A
Thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation joint with another bone.
11
Q
Articular Cartilage Functions
A
Thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation joint with another bone.
12
Q
Articular Cartilage Complication
A
lacks a perichondrium and blood vessel supply; any damage will have limited repair
13
Q
Periosteum
A
tough; connective tissue sheath and its associated blood supply; surrounds the bone surface whenever it is not covered by articular cartilage. Outer Fibrous layer: dense irregular connective tissue Inner Osteogenic Layer: cells;
14
Q
Functions of Periosteum
A
- Contains some cells allow bone growth (thickness only; NOT length) 2. Protection of the bone 3. Assists in bone tissue repair 4. Provides nourishment of the bone tissue 5. Attachment point for ligaments & tendons
15
Q
What are the attachments of the periosteum?
A
- Sharpey’s fibers (perforating fibers): thick bundles of collagen that extend from the periosteum into bone extracellular matrix. Function: attaches periosteum to underlying bone
16
Q
Medullary Cavity
A
Hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in adults.
17
Q
Medullary Cavity function
A
Function: minimizes weight of the bone; by reducing the dense bony material where it is least needed. The design of the long bone provides maximum strength with minimum weight.
18
Q
Endosteium
A
Within; thin membrane that lines the medullary cavity.
19
Q
Endosteium Components
A
Within; thin membrane that lines the medullary cavity.
20
Q
What is bone tissue made up of?
A
Crystallized mineral salts; collagen; water
21
Q
What does the hardness of bone depend on?
A
crystallized inorganic mineral salts
22
Q
What does the flexibility of a bone depend on?
A
depends on its collagen fibers & other organic molecules [gives tensile strength]
23
Q
Tensile Strength
A
resistance to being stretched or torn apart
24
Q
What are the four types of bone cells?
A
Osteoprogenitor cells; osteoblasts; osteocytes; and osteoclasts
25
Osteoprogenitor cells
Definition: Unspecialized bone stem cells derived from mesenchyme; a tissue almost all CT is derived from [Only bone cells to undergo cell division] Become osteoblasts
26
Osteoprogenitor cells location
1. Found along the inner portion of the periosteum; 2. In the endosteum; 3. Canals w/in bone that contain blood vessels
27
Osteoblasts
[Buds or sprouts] Definition: bone-building cells [No cell division]
28
Osteoblasts function
1. synthesize and secrete collagen fibers and other organic used to build the ECM of bone 2. initiate calcification 3. Osteoblasts surround themselves with the matrix. They will become trapped in their secretion and then become osteoclasts. Note: “-blast” This or any other connective tissue cell ending in blast means that the cell secretes extracellular matrix.
29
Osteocytes
[no cell division] Definition: mature bone cells that are the main cells in bone tissue
30
Osteocytes function
Function: maintain its daily metabolism [exchange nutrients and wastes in the blood;
Note: “-cyte” Bone or any other connective tissue cell ending in cyte means that the cell maintains & monitors the tissue
31
Osteoclasts
[break] Definition: huge cells derived from the fusion of many monocytes; concentrated in endosteum
32
Osteoclasts function
1. RESORPTION: 1. The side of the osteoclast facing the bone surface-The osteoclast plasma membrane will be deeply folded into a ruffled border. 2. The cells will release lysosomal enzymes and acids that digest protein and mineral components of the underlying extracellular bone tissue matrix. Note I: “-clast” cell breaks down extracellular matrix Note II: Resorption is a part of normal development; maintenance and repair of bone. 2. regulation of serum calcium (via hormone regulation)
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Mnemonic to help differentiate between osteoblasts and osteoclasts
osteoBlasts Build Bone; osteoClasts Carve out bone
34
Two types of bone
Compact and spongy
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Compact Bone
```
General Characteristics:
1. Few spaces
2. Strongest form of bone tissue
Location:
1. Found beneath periosteum
2. Forms the bulk of the diaphysis of long bones
```
36
Compact bone function
Function: 1. Support and protection 2. Resists the stresses produced by weight and movement
37
Compact bone components in histology
1. Osteons or Haversian Systems [Repeating structural units; each osteon contains the following:
a. Concentric Lamellae [resemble the growth rings of a tree; circular plates of mineralized extracellular matrix of increasing diameter; surrounding a small network of blood vessels and nerves located in the central canal]
b. Central canal (Haversian Canal)[tube-like; parallel cylinders that run parallel to the long axis of the bone
c. Lacunae [“little lakes.” Small spaces found between the concentric lamellae; contain the osteocytes]
d. Canaliculi [radiate in all directions from the lacunae; filled with extracellular fluid. Inside; there are slender finger-like processes projecting from osteocytes];
e. Osteocytes: communicated with each other via gap junctions
38
Compact bone integration
analiculi connect with each other; lacunae and with the central canals. This forms an intricate; miniature system of interconnected canals throughout bone.
Function: routes for nutrients and oxygen reach osteocytes; removal of wastes
39
Osteons
All osteons are aligned in the same direction and are parallel to the length of the diaphysis.
40
Benefit of osteons
shaft of the long bone has resistance in bending or fracturing; even with considerable stress applied to either end
41
What is the thickest part of the bone?
Compact bone is thickest in the part of the bone where stresses are applied in relatively few directions.
Lines of stress are not static.
1. They change as a person learns to walk and in response to repeated strenuous activities (weight training/exercise).
2. Can change due to fracture or physical deformity
As a result; osteon organization is not static; but changes over time in response to the physical demands placed on the skeleton.
42
Interstitial lamellae
Areas between neighboring osteons and lamellae. These are fragments of older osteons that have been partially destroyed during bone rebuilding or growth. These also have the following components: lacunae with osteocytes and canaliculi
43
Perforating Canals (Volkmann’s Canals)
Transversely found running from the periosteum and penetrate compact bone. These BV and nerves connect with those found in the medullary cavity; periosteum and central canals.
44
Circumferential Lamellae
Arranged around entire outer and inner circumference of the shaft of a long bone. These develop during initial bone formation.
Two types:
1. Outer circumferential lamellae: just deep to the periosteum. Connected to periosteum via Sharpey’s Fibers (perforating fibers)
2. Inner circumferential lamellae: line the medullary cavity
45
Spongy Bone
aka: trabecular or cancellous bone tissue
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Spongy Bone Characteristics
1. Does NOT contain osteons 2. Always covered by a layer of compact bone for protection 3. Contains marrow
4. Appears less organized; but it is very organized. The osteons are precisely oriented along lines of stress. This allows bone to resist stresses and transfer force w/o breaking. 5. Location: found in bones that are not heavily stress or where stresses are applied from many directions 6. Trabeculae are not fully formed until locomotion is fully learned. 7. Arrangement can be altered as lines of stress change secondary to fracture or deformity
47
Spongy Bone Location
ALWAYS located in the interior of a bone. It will be covered and protected by compact bone.
Fills most of the interior portion in the following type of bones: short; flat; sesamoid; irregularly shaped bones
In long bones: forms the core of the epiphyses and found beneath a paper thin layer of compact bone
48
Compontents of Spongy Bone
Trabeculae; Macroscopic spaces between the trabeculae fits with bone marrow; and bone marrow
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Trabeculae
‘little beams” [Lamellae arranged in irregular pattern of thin columns]
a. Each trabeculae contains:
i. Concentric lamellae
ii. Osteocytes in lacunae
iii. Canaliculi [radiate outward from lacunae]
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Macroscopic Spaces between the trabeculae fits with bone marrow
a. Red bone marrow in bones that produce blood cells
| b. Yellow marrow (adipose)-Other bones
51
Bone marrow
a. Both types have numerous small blood vessels that nourish osteocytes
52
How are spongy and compact bone different?
1. Spongy bone is light (reduces overall weight of the bone)
reduction in weight allows bone to move more readily when pulled on by a skeletal mm.
2. Trabeculae of spongy bone support and protect bone marrow
The following are the only sites where spongy bone is found; containing red marrow for hematopoiesis.
These are the only locations in the adult in which blood cell formation occurs in adults.
1. Hip bones
2. Sternum
3. Vertebrate
4. Proximal ends of the humerus and femur
53
Ateries
carry blood TO bone tissue
54
Periosteal Arteries
small arteries accompanied by nerves; enter diaphysis of the bone through perforating (Volkmann’s canals). Function: supply periosteum and outer part of compact bone.
55
Nutrient Arteries
found near the center of the diaphysis
Function: supply inner compact bone tissue of diaphysis and spongy bone tissue and red bone marrow as far as the epiphyseal plates Traverses: nutrient foramen [hole in compact bone]
Course: nutrient artery ? nutrient foramen ? medullary cavity; artery divides into proximal and distal branches and course toward each end of the bone
Variations: some bones have multiple nutrient arteries (femur) and some only have one (tibia).
(lines)
56
Epiphyseal Artery
Course: enter the epiphyseal
| Function: supply red marrow and the bone tissue of the epiphyses
57
Metaphyseal Artery
Course: enter the metapyses of a long bone (together with the nutrient artery)
Function: supply bone tissue of the metaphyses & red marrow
58
What supplies the ends of long bones with blood?
Metaphseal and epiphyseal arteries
59
Veins
carries blood away from bone tissue
60
Nutrient Veins
[one or two veins will accompany the nutrient artery and exit the diaphysis]
61
Numerous Epiphyseal and Metaphyseal Veins
accompany their respective arteries and exit through the epiphyses and metaphyses.
62
Many Periosteal Veins
accompany periosteal arteries and exit via the periosteum
63
Nerve
Nerves accompany BV that supply bones. Periosteum is rich in sensory nerves; some of which carry sensation of pain; a result of tearing or tension.
Severe pain can result when there is a fracture or bone tumor. There is also pain with a bone marrow biopsy.
64
Bone marrow biopsy
A bone marrow biopsy is a procedure in which a needle is inserted into the middle of the bone to withdraw a sample of red bone marrow to examine it for conditions such as leukemia; metastatic neoplasm (tumors); lymphoma; Hodgkin’s and aplastic anemia. Pain is only felt as the needle penetrates the periosteum. Once through; there is little pain.
65
Ossification
the process by which bone forms.
66
Osteogenesis
the process by which bone forms.
67
Principle Situations in which there is bone formation:
1. initial formation of bones in an embryo/fetus
2. growth of bones during infancy; childhood; and adolescence until adult sizes are reached
3. remodeling of bone [replacement of old bone by new bone throughout life]
4. repair of fractures [breaks in bone] throughout life
68
Bone formation in an embryo/fetus
Embryonic skeleton is composed of mesenchyme found in the general shape of bones. It is the site where cartilage formation and ossification will occur during the 6th week of embryonic development. Bone formation will occur in one of two patterns: endochondral ossification and intramembranous ossification. Bone formation involves the replacement of the preexisting connective tissue with bone. There will not be structural differences in mature bone; between these two types of bone formation. They are just different types of formation; which achieve the same result.
69
Intramembranous ossification
membrane [bone forms directly within mesenchyme; arranged in sheet-like layers resembling membrane]
70
Endochondral ossification
“cartilage” [bone forms w/in hyaline cartilage that develops from mesenchyme]
71
Steps in intramembranous ossification
Development of the ossification center; calcification; formation of trabeculae; development of periosteum
72
Development of the ossification center
1. Sites where bone formation is supposed to occur; chemical messengers will signal mesenchyme to cluster together and develop into osteoprogenitor cells; then osteoblasts. [aka: ossification center]
2. Osteoblasts secret organic extracellular matrix of the bone; until it surrounds them.
73
Calcification
3. Secretion of the ECM (extracellular matrix) stops. Cells are known as osteocytes. Osteocytes lie in lacunae and extend their narrow cytoplasmic processes into canaliculi; radiating in all directions.
4. w/in a few days; calcium and other mineral salts are deposited and ECM hardens or calcifies [aka: calcifications]
5. ECM hardens
74
Formation of trabculae
6. Bone ECM forms; it will develop into trabeculae that fuse with one another forming spongy bone around a network of BV in the tissue
7. CT associated with BV in the trabeculae differentiate into red bone marrow
75
Development of periosteum
8. Simultaneous with formation of trabeculae; mesenchyme condenses at the periphery of the bone and develops into periosteum.
9. Eventually a thin layer of compact bone replaces the surface layers of spongy bone; spongy bone remains in the center.
10. Much of this newly formed bone is remodeled (destroyed and reformed) as bone is transformed into its adult size and shape.
76
Location of intramembranous ossification
flat bones of the skull; most facial bones; mandible (lower jawbone); medial clavicle (collar bone); “soft spots” that allow fetus to exit via the birth canal; will harden through this type.
77
Steps in endochondral ossification
Development of the cartilage model; growth of the cartilage model development of the primary ossification center; development of the medullary (marrow) cavity; development of the secondary ossification center; and formation of articular cartiliage and the epiphyseal plate
78
Location of endochondral ossification
mast of the bones in the body best observed in a long bone
79
Primary ossification center
a region where bone tissue will replace most of the cartilage. Located near the middle of the model. Osteoblasts begin to deposit bone ECM over the remnants of calcified cartilage; forming spongy bony trabeculae.
80
Secondary ossification center
spongy bone remains in the interior epiphyses; ossification proceeds outward from the center of the epiphyses toward the outer surface of the bone.
81
During infancy; childhood; and adolescence what are the two major events involved in growth in length?
1. Interstitial growth of cartilage on the epiphyseal side of the epiphyseal plate
2. Replacement of cartilage on the diaphyseal side of the epiphyseal plate; with bone by endochondral ossification.
82
Epiphyseal line (plate)
layer of hyaline cartilage in the metaphysis of a growing bone that consists of four zones:
83
What are the four zones in epiphysealine growth
Zone of resting cartilage; zone of proliferating cartilage; zone of hypertrophic cartilage; and zone of calcified cartilage
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Zone of resting cartilage
[Nearest epiphyses; small; scattered chondrocytes; cells do not function in bone growth. They are “resting.”
Function of cells: anchor the epiphyseal plate to the epiphysis of the bone]
85
Zone of proliferating cartilage
[Slightly larger chondrocytes; arranged like a stack of coins. Chondrocytes undergo interstitial growth as they divide and secrete ECM.]
Function of the chondrocytes: replace those that die at the diaphyseal side of the epiphyseal plate.
86
Zone of hypertrophic cartilage
[Large; maturing chondrocytes arranged in columns]
87
Zone of calcified cartilage
[Only a few cells thick; mostly chondrocytes that are dead because the ECM around them has calcified.
Osteoclasts dissolve the calcified cartilage and osteoblasts and capillaries from the diaphysis invade the area.
Osteoblasts lay down bone ECM replacing calcified cartilage by the process of endochondral ossification.
This becomes the “new diaphysis” firmly cemented to the rest of the diaphysis.]
88
Fracture of the epiphyseal plate
fractured bone may end up shorter than normal once the individual reaches adult stature.
Damage to cartilage; which is AVASCULAR; accelerates the closure of the epiphyseal plate; caused by cessation of cartilage cell division.
89
Closure of epiphyseal plate:
1. End of adolescence [women;18 and men; 21] due to estrogen and testosterone
2. Fracture/injury where there is a cessation in cell division
3. Anabolic steroid use as adolescent.
90
How can the diaphysis increase in length?
In general; the ACTIVITY OF THE EPIPHYSEAL PLATE is the only way the diaphysis can increase in length.
1. As bone grows; chondrocytes proliferate on the epiphyseal side of the plate
2. New chondrocytes proliferate on the epiphyseal side of the plate
3. New chondrocytes replace older ones; which are destroyed by calcification.
4. Thus; cartilage is replaced by bone on the diaphyseal side of the plate.
Benefit: Thickness remains constant; while bone lengthens.
91
Hormones/Chemicals involved with Epiphyseal Growth Plate:
1. Growth hormone (GH) stimulates chondrocytes to synthesize and respond to insulin growth factor-I (IGF-1) 2. IGF-I produced locally (along with IGF-I produced by the liver) stimulates cell division 3. Estrogen and testosterone stimulate closure of epiphyseal plates.
92
Epiphyseal line
the bony structure left after epiphyseal plates fade.
93
Growth in thickness (appositional growth)
1. At bone surface; periosteal cells ? osteoblasts; which secrete the collagen fibers and other organic molecules that form bone ECM
Osteoblasts become surrounded by ECM and develop into osteocytes?forms bone ridges on either side of periosteal blood vessel. These ridges slowly enlarge and create a groove for the periosteal blood vessel. 2. Ridges eventually fold together and fuse. Groove becomes a tunnel that encloses the blood vessel. Former periosteum ? endosteum lining the tunnel 3. Osteoblasts in endosteum deposit bone ECM forming new concentric lamellae. Formation of additional concentric lamellae proceed inward; toward the periosteal blood vessel. Tunnel fills creating a new osteon. 4. As osteon forms; osteoblasts under the periosteum deposit new circumferential lamellae; further increasing the thickness of the bone. Additional periosteal BV become enclosed as in step 1; continues.
94
Bone remodeling
the ongoing replacement of old bone tissue by new bone tissue
95
Bone resportion
removal of minerals and collagen fibers from bone osteoclasts [destruction of bone ECM]
96
Bone deposition
addition of minerals and collagen fibers to bone by osteoblasts [formation of bone ECM]
97
Functions of remodeling
1. Replaces old bone 2. Removes injured bone; replaces it with new bone
98
Triggers for bone remodeling
1. Exercise 2. sedentary lifestyle 3. changes in diet
99
Benefits of bone remodeling:
1. removes injured bone 2. bone that is subject to heavier loads can grow stronger and thicker 3. bone shape can be altered for proper support; based on the stress patterns experienced 4. new bone is more resistant to fracture than old bone
100
What are the factors affecting bone remodeling and growth?
Minerals; vitamins; and hormones
101
Minerals
[larger amounts of calcium and phosphorus are needed while bones are growing]
[smaller amounts magnesium; fluoride; manganese]
102
Vitamins
[Vitamin A=stimulation of osteoblast activity; Vitamin C for synthesis of collagen; Vitamin=increases absorption of calcium from foods in the GI tract; into the blood; Vitamin K ad B12=synthesis of bone proteins]
103
Hormones
[Childhood: insulin-like growth factors; produced by liver and bone tissue for 1. stimulation of osteoblasts; promotion of cell division at epiphyseal plates and in periosteum. 2. Enhance synthesis of the proteins needed to build new bone; IGF’s are produced in response to the secretion of human growth hormone from the anterior lobe of the pituitary gland. Thyroid hormones (T3 & T4) promote growth by stimulating osteoblasts. Insulin promotes bone growth by increasing synthesis of bone proteins.
Sex Hormones: estrogen and androgen (testosterone)? increased osteoblast activity; synthesis of bone ECM; responsible for “growth spurts.” Estrogen also promotes changes in the female skeleton; such as widening of the pelvis; shutting of growth at epiphyseal plates; causing elongation of the bones to cease
Older age: estrogens slow resorption by promoting apoptosis of osteoclasts
Parathyroid hormone; calcitriol (active form of vitamin D) and calcitonin also affect bone remodeling
104
What are the phases in repair of bone fracture
Reactive phase; reparative phase; reparative phase; and bone remodeling phase
105
Reactive Phase
[early inflammatory phase] [may last several weeks] 1. Blood vessels crossing the fracture line are broken; blood leaks out of these vessels and forms a fracture hematoma (blood clot) about 6-8 hours after the injury 2. Circulation is stopped near the site of the fracture hematoma; therefore nearby bone cells will die 3. Death of these bone cells triggers swelling and inflammation. This produces cellular debris 4. Phagocytes (neutrophils and macrophages) and osteoclasts remove the dead/damaged tissue around the fracture hematoma.
106
Reparative Phase
Fibrocartilagenous callus formation [Bridges the gap between both sites of the fracture] 5. Blood vessels grow into the fracture hematoma and phagocytes begin to clean up dead bone cells 6. Fibroblasts from periosteum invade the fracture site and produce collagen fibers 7. Fibroblasts also develop into chondroblasts and begin to produce fibrocartilage 8. This forms a Fibrocartilagenous callus [a mass of repair tissue consisting of collagen fibers and cartilage that bridges the broken ends of the bone.]
107
Preparative Phase II
Bony Callus Formation [3-4 months] 9. The areas closer to healthy bone tissue; osteoprogenitor cells develop into osteoblasts and produce spongy bone trabeculae 10. Trabeculae join dead and living portions of the original bone fragments 11. After some time fibrocartilage will be converted to spongy bone [callus=bony or hard callus]
108
Bone remodeling phase
[months] 12. Dead portions of the original fragments of broken bone are gradually resorbed by osteoblasts. 13. Compact bone replaces spongy bone around periphery of fracture [can be so thorough; fracture line is undetectable; even with x-ray] 14. Thickened area on the surface of the bone remains-evidence of a healed fracture.
109
Why do bones heal faster than cartilage?
rich blood supply is the reason bone heals much quicker than cartilage
110
Explain treatment for fractures
will vary depending on the age; type of fracture and bone involved.
Ultimate goal of fracture repair:
1. Realignment of bone fragments
2. Immobilization to maintain realignment
3. Restoration of function
111
Reduction
The process of bringing bones into alignment [setting a fracture]
112
Closed reduction
bones are brought into alignment by manual manipulation; where the skin remains intact.
113
Open reduction
bones are brought back into alignment by a surgical procedure using internal fixation devices such as screws; plates; rods; and wires.
114
What are the types of fractures?
Open (compound fracture); comminuted fracture (crumbled); greenstick fracture; impacted; Pott's fracture; Colles fracture
115
Open (compound fracture)
Compound Fracture Description: Broken ends of the bone protrude from the skin [closed fracture; does not break the skin]
116
Comminuted Fracture [crumbled]
Description: Bone is splintered; crushed or broken into pieces at the site of impact. Smaller bone fragments can be found between the two main fragments.
117
Greenstick Fracture
Description: Partial Fracture; one side of the bone is broken and the other side of the bone bends; similar to how a green twig breaks on one side and the other side stays whole. Occurs only in children whose bones are not fully ossified and contain more organic material than inorganic.
118
Impacted
Description: The ends of the fracture bone are driven into the interior of the other
119
Pott's fracture
Description: Fracture of the distal end of the lateral leg bone (fibula) with serious injury of the distal tibial articulation
120
Colles Fracture
Description: Fracture of the distal end of the lateral forearm bone (radius) in which the distal fragment is posteriorly displaced.
121
Benefits of exercise for the bone
Bone has the ability to alter its strength in response to mechanical stress. With mechanical stress; bone becomes stronger due to increased deposition of mineral salts and production of collagen fibers by osteoblasts.
Without stress; bone does not remodel normally. Bone resorption occurs more quickly than bone formation.
The higher the impact (running; jumping); the more this occurs.
122
Demineralization
loss of calcium and other minerals from the extracellular matrix.
123
Female aging and bone tissue
Loss begins in females around age 30 yrs and greatly accelerates around 45; due to the decrease in estrogen levels.
There is an expected 30% loss of bone density around 70 years of age. Bone loss occurs at a rate of 8% every 10 years.
124
Male agining and bone tissue
Begins after the age of 60 years. Bone is lost at a rate of 3% every 10 years.
125
Osteoporosis
loss of calcium from bone; This is literally “porous” bone. Breakdown of bone occurs faster than bone can be formed.
Osteopenia: low bone mass
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Drug treatment for osteporosis
1. anti-resorptive drugs: slow down progression of bone loss 2. bone-building drugs: promote increase in bone mass
127
Rickets & Osteomalacia
The same disease that result from inadequate calcification of extracellular bone matrix and usually caused by vitamin D deficiency.
128
Rickets
a disease of children in which the bones become rubbery or soft and are easily deformed. New bone fails to form at the growth plates; resulting in a bowing of the legs and deformities of the skull; rib cage and pelvis
129
Osteomalacia
adult rickets. New bone formed during remodeling fails to ossify.
130
How to treat rickets and osteomalacia?
Vitamin D supplementation and exposure to moderate sunlight.
131
Osteoarthritis
degeneration of articular cartilage; such that the bony ends touch; resulting in friction of bone against bone. This worsens the condition. This is usually associated with the elderly.
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Osteomyelitis
Infection of the bone; characterized by high fever; sweating; nausea; chills; pain; pus formation; edema; warmth over affected bone and rigid overlying muscles. Most often caused by Staphylococcus aureus.
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How does bacteria reach the bone?
From the outside of the body through open fractures; penetrating wounds; orthopedic surgical procedures Blood from ther sites of infection in the body (abscessed teeth; burn infections; UTI’s or upper respiratory infections)
Adjacent soft tissue infections (wounds in diabetes mellitus
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Osteopenia
reduced bone mass due to a decrease in the rate of bone synthesis to a level that is too low to compensate for normal bone resorption. Any decrease in bone mass below normal. Osteoporosis is an example of this.
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Osteosarcoma
Bone cancer that primarily affects osteoblasts and occurs most often in teenagers during a growth spurt. Most common sites: Metaphyses of femur (thigh) Shin (tibia) Humerus (upper arm) Most common sites for metastases: lung Treatment: multiple drug regimens of chemotherapy and removal of malignant growth (amputation of the limb).
