Chapter 6: The skeleton bone-Bone tissue Flashcards
(117 cards)
1
Q
What 7 tissues make up the bone?
A
1) bone
2) cartilage
3) dense connective tissue
4) epithelium
5) various blood-forming tissues,
6) adipose tissues
7) nervous tissue
2
Q
What 2 things make up the skeleton system?
A
1) Bone
2) Cartilage
3
Q
Is a bone an organ? Does it stop changing?
A
Yes; No
4
Q
What are the 5 functions of the bone?
A
1) supporting & protecting soft tissues
2) Attachment site for muscles making movement possible
3) Storage of the minerals, calcium & phosphate – mineral homeostasis
4) Blood cell production occurs in red bone marrow (hemopoiesis or hematopoiesis)
5) Energy storage in yellow bone marrow
5
Q
What is diaphysis?
A
Shaft
6
Q
What is epiphysis?
A
One end of a long bone
7
Q
What is metaphyses? What does it include.
A
metaphyses are the areas between the epiphysis and diaphysis and include the epiphyseal plate in growing bones.
8
Q
What is articular cartilage over? What is its functions?
A
Articular cartilage over joint surfaces acts as friction reducer & shock absorber
9
Q
What is the medullary cavity?
A
marrow cavity
10
Q
What is endosteum?
A
The lining of the marrow cavity
11
Q
What is periosteum?
A
the tough membrane covering bone but not the cartilage
12
Q
What are the 2 layers of the periosteum? What are they made up of?
A
1) fibrous layer = dense irregular CT
2) osteogenic layer = bone cells & blood vessels that nourish or help with repairs
13
Q
What is the % makeup of bone tissue?
A
Matrix of 25% water, 25% collagen fibers & 50% crystalized mineral salts
14
Q
What is osseous?
A
Bone
15
Q
What is bone tissue consists of?
A
Widely separated cells surrounded by large amounts of matrix.
16
Q
What does the matrix of bone contain?
A
Inorganic salts, primarily hydroxyapatite and some calcium carbonate, and collagen fibers.
17
Q
What is the process of calcification or mineralization?
A
salts are deposited in a framework of collagen fibers
18
Q
Where does the process of calcification occur?
A
Only in the presence of collagen fibers.
19
Q
What do mineral salt and college fibers do?
A
Mineral salts confer hardness on bone while collagen fibers give bone its great tensile strength.
20
Q
What are the 4 cells in the bone tissue? What do they do?
A
1) Osteogenic (Osteoprogenitor) cells undergo cell division and develop into osteoblasts.
2) Osteoblasts are bone-building cells.
3) Osteocytes are mature bone cells and the principal cells of bone tissue.
4) Osteoclasts are derived from monocytes and serve to break down bone tissue.
21
Q
What fills up the spaces in bones? Describe the spaces in spongy and compact bones
A
Bone is not completely solid since it has small spaces for vessels and red bone marrow; spongy bone has many such spaces and compact bone has very few such spaces
22
Q
compact bone is arranged in what units?
A
osteons or Haversian systems
23
Q
What did osteons contain?
A
Osteons contain blood vessels, lymphatic vessels, nerves, and osteocytes along with the calcified matrix.
24
Q
How are osteons aligned?
A
Osteons are aligned in the same direction along lines of stress. These lines can slowly change as the stresses on the bone changes.
25
Where does compact or dense bone make up of?
Makes up the shaft of long bones and the external layer of all bones
26
What is an osteon?
Osteon is concentric rings (lamellae) of calcified matrix surrounding a vertically oriented blood vessel
27
Where are osteocytes found?
Osteocytes are found in spaces called lacunae
28
How do osteocytes communicate?
Osteocytes communicate through canaliculi filled with extracellular fluid that connect one cell to the next cell
29
What is Interstitial lamellae?
Interstitial lamellae represent older osteons that have been partially removed during tissue remodeling
30
What is the structure of spongy bone?
Spongy (cancellous) bone does not contain osteons. It consists of trabeculae surrounding many red marrow filled spaces .
31
Where does spongy bone forms?
It forms most of the structure of short, flat (hipbones, sternum, sides of skull, and ribs) , and irregular bones, and the epiphyses of long bones.
32
What is the function of spongy bone?
protects the red bone marrow.
33
What is trabeculae? Where is it?
Latticework of thin plates of bone called trabeculae oriented along lines of stress
34
What is in spaces between the structs of spongy bone?
Spaces in between these struts are filled with red marrow where blood cells develop
35
What do periosteal arteries do?
supply periosteum
36
How do nutrient arteries enter? What does it do?
enter through nutrient foramen and supplies compact bone of diaphysis & red marrow
37
What is fetal skeleton constructed of before week 8?
Prior to week 8, fetal skeleton is constructed of fibrous membranes and hyaline cartilage
38
What did embryonic connective tissue begin as?
mesenchyme
39
What is bone formation? When does it begin?
Bone formation is termed osteogenesis or ossification and begins when mesenchymal cells provide the template for subsequent ossification.
40
What are the 2 types of ossification that occurs? What are they from?
Intramembranous ossification- the formation of bone directly from or within fibrous connective tissue membranes.
Endochondrial ossification- the formation of bone from hyaline cartilage models.
41
What bones does intramembranous ossification form?
Intramembranous ossification forms the flat bones of the skull, the mandible, and the clavicles .
42
what did mesenchyme differentiate into?
osteogenic progenitor cells & then osteblasts
43
What did osteoblasts secret?
osteoblasts secrete osteoid: unmineralized matrix
44
woven bone is remodeled into what?
Woven bone is remodeled into spongy/ diploe & compact bone
45
what are fontanels?
fontanels (soft spots) that ossify later in development
46
What are the 4 parts of intramembranous ossification?
1. Ossification centers appear in the fibrous connective tissue membranes
2. Osteoid is secreted within the fibrous membrane that calcifies
3. Woven bones and periosteum form
4. Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears.
47
What forms periosteum?
Mesenchyme
48
what does endochondrial ossification involve? What does it form?
Endochondrial ossification involves replacement of cartilage by bone and forms most of the bones of the body .
49
What is the first step in endochondrial ossification?
The first step in endochondrial ossification is the development of the cartilage model.
50
What bone does endochondral ossification form?
Long bone development
51
What is the 4 parts of endochondral ossification?
1. Formation of a Cartilage Model
2. Formation of the Periosteal Bony Collar
3. Formation of the 1o Ossification Center
4. Formation of 2o Ossification Centers
52
What 3 things happen during the formation of a cartilage model?
1. Mesenchyme occupies areas of future bone & forms
chondroblasts
2. A hyaline cartilage model forms
3. Cartilage enlarges via mitosis
53
What 2 things happen during the formation of the periosteal bony collar?
1. Perichondrial OPCs form Osteoblasts
| 2. Bone forms on the outer mid-diaphysis
54
What 7 things happen during the formation of the 1 ossification center?
1. Chrondrocytes / lacunae hypertrophy
2. Matrix calcifies & cells begin to die, matrix deteriorates
3. Nutrient arteries penetrate the diaphysis
4. Osteoblasts invade (from periosteal OPCs)
5. Woven bone forms & the 1o ossification center enlarges towards the epiphyses
6. Woven /bone is converted to compact bone
7. The medullary cavity is formed by Osteoclasts
55
What forms during the formation of the 2 ossification centers? Where does it occur?
1. Occurs at the epiphyses
2. Events similar to the 1o ossification center
3. Form inner spongy & outer compact bone
56
What is epiphyseal/ growth plate? What does it allow?
The layer of cartilage that remains in the epiphyses. Allows ↑ in bone length
57
5 parts of endochondral ossification?
1. Bone collar forms around the diaphysis of the hyaline cartilage model
2. Cartilage in the center of the diaphysis calcifies and then develops cavities
3. The periosteal bud invades the internal cavities and spongy bone forms
4. The diaphysis elongates and the medullary cavity forms. Secondary ossification centers appear in the epiphysis
5. The epiphysis ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages
58
What are the 4 zones of the epiphyseal plate?
1. zone of resting cartilage,
2. zone of proliferation cartilage,
3. zone of hypertrophic cartilage, and
4. zone of calcified cartilage
59
What happens when the epiphyseal plate closes?
When the epiphyseal plate closes, is replaced by bone, the epiphyseal line appears and indicates the bone has completed its growth in length.
60
How are cartilage cells produced?
cartilage cells are produced by mitosis on epiphyseal side of plate
61
When do epiphyseal plates close?
Between ages 18 to 25. Growth in length stops at age 25
62
Bone grows in thickness or diameter by what?
appositional growth
63
The medullary cavity is formed/ enlarged by what?
Osteclasts
64
What two factors affect bone growth?
Nutrition and sufficient levels of specific hormones
65
What are the minerals and vitamins needed for bone growth?
1. calcium and phosphorus for bone growth
2. vitamin C for collagen formation
3. vitamins K and B12 for protein synthesis
66
What insulin-growth factors do we need? What do they promote?
need hGH (growth), thyroid (T3 &T4) and insulin; promotes cell division at epiphyseal plate
67
What are the two sex hormones? What do they do at puberty?
At puberty the sex hormones, estrogen and testosterone, stimulate sudden growth and modifications of the skeleton to create the male and female forms.
68
What do estrogen and testosterone promote?
bone growth and ossification of epiphyseal disk
69
What gender reaches height first?
females reach max height earlier than males
70
What causes giantism and short stature?
Oversecretion of hGH during childhood produces giantism
| Undersecretion of hGH or thyroid hormone during childhood produces short stature
71
What is estrogen responsible for? What does a lack estrogen receptors cells cause?
estrogen is responsible for closure of growth plate; Both men or women that lack estrogen receptors on cells grow taller than normal
72
What is achondroplastic dwarfism?
Improperly proportioned body
73
What is Giantism?
GH overproduction in children
74
What is acromegaly? What is the symptoms?
GH increase in adults;
| Enlarged hands, feet & jaw, Normal height
75
What is remodeling?
Remodeling is the ongoing replacement of old bone tissue by new bone tissue.
76
What does osteclasts and osteblasts do in remodeling? How do they do it?
Old bone is constantly destroyed by osteoclasts, whereas new bone is constructed by osteoblasts; Ongoing since osteoclasts carve out small tunnels and osteoblasts rebuild osteons.
77
What controls bone growth and bone remodeling?
Several hormones and calcitriol
78
what are the 4 steps of bone remodeling?
1. osteoclasts form leak-proof seal around cell edges
2. secrete enzymes and acids beneath themselves
3. release calcium and phosphorus into interstitial fluid
4. osteoblasts take over bone rebuilding
79
How often is distal femur fully remodeled?
Every 4 months
80
Where is continual redistribution of bone matrix?
along lines of mechanical stress
81
How is a bone scanned? What is the amount of uptake related to.
Radioactive tracer is given intravenously
| Amount of uptake is related to amount of blood flow to the bone
82
What are "hot spots"?
“Hot spots” are areas of increased metabolic activity that may indicate cancer, abnormal healing or growth
83
What are "cold spots"?
“Cold spots” indicate decreased metabolism of decalcified bone, fracture or bone infection
84
What is a fracture?
A fracture is any break in a bone.
85
What are the steps to frature repair?
Fracture repair involves formation of a clot called a fracture hematoma, organization of the fracture hematoma into granulation tissue called a procallus (subsequently transformed into a fibrocartilaginous [soft] callus), conversion of the fibrocartilaginous callus into the spongy bone of a bony (hard) callus, and, finally, remodeling of the callus to nearly original form.
86
Why is healing faster in bone than cartilage?
Healing is faster in bone than in cartilage due to lack of blood vessels in cartilage
87
What causes slow healing of bone?
Healing of bone is still slow process due to vessel damage
88
What are the two clinical treatment to fracture repair?
closed reduction = restore pieces to normal position by manipulation
open reduction = realignment during surgery
89
What are the two common types of fracture?
1. greenstick -- partial fracture
2. impacted -- one side of fracture driven into the interior of other side
3. closed -- no break in skin
4. open fracture --skin broken
5. comminuted -- broken ends of bones are fragmented
6. Pott’s -- distal fibular fracture
7. Colles’s -- distal radial fracture
8. stress fracture -- microscopic fissures from repeated strenuous activities
90
What 3 things happens during formation of fracture hematoma?
1. damaged blood vessels produce clot in 6-8 hours, bone cells die
2. inflammation brings in phagocytic cells for clean-up duty
3. new capillaries grow into damaged area
91
What 2 things happens during formation of fibrocartilagenous callus formation?
1. fibroblasts invade the procallus & lay down collagen fibers
2. chondroblasts produce fibrocartilage to span the broken ends of the bone
92
What happens during formation of bony callus? How long does it last?
osteoblasts secrete spongy bone that joins 2 broken ends of bone; lasts 3-4 months
93
What 2 things happen during the bone remodeling step?
1. compact bone replaces the spongy in the bony callus
| 2. surface is remodeled back to normal shape
94
What is a skeleton a reservoir of?
Skeleton is a reservoir of Calcium & Phosphate
95
What 3 things is calcium ions involved in body systems?
1. nerve & muscle cell function
2. blood clotting
3. enzyme function in many biochemical reactions
96
Where is plasama level maintained?
9-11mg/100mL
97
What changes happen if Ca+2 is too high or low?
cardiac arrest if too high
| respiratory arrest if too low
98
What is secreted if ca+2 levels falls?
Parathyroid hormone (PTH) is secreted if Ca+2 levels falls
99
What is secreted if ca+2 blood levels gets too high?
Calcitonin hormone is secreted from parafollicular cells in thyroid if Ca+2 blood levels get too high
100
What does calcitonin hormone do?
inhibits osteoclast activity
| and increases bone formation by osteoblasts
101
What does parathyroid hormone (PTH) cause?
osteoclast activity increase, kidney retains Ca+2 and produces calcitriol
102
How does the bone alter its strength in response to mechanical stress?
Within limits, bone has the ability to alter its strength in response to mechanical stress by increasing deposition of mineral salts and production of collagen fibers.
103
What does the removal of mechanical stress lead to?
Removal of mechanical stress leads to weakening of bone through demineralization (loss of bone minerals) and collagen reduction.
104
What can help build and retain bone mass?
Weight-bearing activities, such as walking or moderate weightlifting, help build and retain bone mass.
105
What is Wolff's law?
bone growth is promoted by stress on bone
106
What does mechanical stress create?
Mechanical stress creates an anionic charge on hydroxyapatite (a naturally occurring form of the mineral calcium apatite)
107
What is the result of the stimulation of osteblasts?
hypertrophy & strengthening of bone
108
What is the two principle effects of aging on bone?
1. Loss of calcium and other minerals from bone matrix
| 2. Decrease of protein synthesis
109
When is osteoporosis rapid in men and women?
very rapid in women 40-45 as estrogens levels decrease
| in males, begins after age 60
110
3 effects of decreased protein synthesis?
1. decrease in collagen production which gives bone its tensile strength
2. decrease in growth hormone
3. bone becomes brittle & susceptible to fracture
111
What is osteoporosis?
Decreased bone mass resulting in porous bones and abnormally high loss of mineral content
112
3 types of people at risk of osteoporosis?
1. white, thin menopausal, smoking, drinking female with family history
2. athletes who are not menstruating due to decreased body fat & decreased estrogen levels
3. people allergic to milk or with eating disorders whose intake of calcium is too low
113
How to prevent or decrease osteoporosis severity?
1. adequate diet, weight-bearing exercise, & estrogen replacement therapy (for menopausal women)
2. behavior when young may be most important factor
114
What is osteopenia?
Slight decrease in bone density
115
Where does osteroporosis commonly affect?
vertebral column, hip & wrist
116
What is the cause of rickets? What is the result of it?
calcium salts are not deposited properly;
bones of growing children are soft and
bowed legs, skull, rib cage, and pelvic deformities result
117
What is the result of osteomalacia? Where is it common?
new adult bone produced during remodeling fails to ossify;
| hip fractures are common
