1
Q
2 types of bone:
A
cancellous and compact
2
Q
3 types of cartilage:
A
hyaline, fibro, elastic
3
Q
Tendons
A
connect skeletal m. to bone
4
Q
ligaments
A
connect bone to bone
5
Q
5 functions of the skeletal system:
A
support movement protection blood cell production storage
6
Q
Skeletal System Functions: Support
A
- supports the body and cradles soft organs
- bone is the major supporting tissue of the body
- cartilage provides firm yet flexible support
7
Q
Skeletal System Functions: Protection
A
protective case for: organs, brain, spinal cord
8
Q
Skeletal System Functions: Movement
A
bones are levers for skeletal m.
9
Q
Skeletal System Functions: Storage
A
calcium, phosphorus, and fats stored within bones
10
Q
Skeletal System Functions: Blood Cell Production
A
Hematopoiesis
11
Q
most of the bones in the body develop from…
A
hyaline-cartilage model
12
Q
Cartilage: Hyaline: Chondroblasts
A
produce cartilage matrix
13
Q
Cartilage: Hyaline: Chondrocytes
A
- cartilage cells
- sit with lacunae (holes) in the matrix
14
Q
Cartilage: Hyaline: Cartilage Matrix
A
- Collagen fibers: provide strength
- Proteoglycans: trap water (water bed)
15
Q
Articular cartilage DOES NOT contain…
A
perichondrium, blood vessels, or nerves
16
Q
Hyaline Cartilage: Perichondrium
A
-double-layered CT sheath that surrounds most cartilage
17
Q
Hyaline Cartilage: Perichondrium: Outer Layer
A
dense irregular CT
18
Q
Hyaline Cartilage: Perichondrium: Inner Layer
A
more delicate CT that contain chondroblasts
19
Q
The outer layer of perichondrium contains…
A
- blood vessels, but they do not enter the cartilage matrix
- nutrients diffuse through the matrix to reach chondrocytes
20
Q
2 types of cartilage growth:
A
appositional and interstitial
21
Q
Cartilage Growth: Appositional Growth
A
- addition of new cartilage matrix on the surface of the cartilage
- chondroblasts form the inner layer of perichondrium lay down new matrix on the surface of the cartilage
- once chondroblasts are surrounded by matrix, they develop into chondrocytes in the new layer of cartilage
22
Q
Bones CANNOT grow…
A
interstitially
23
Q
Interstitial Growth
A
- addition of new cartilage matrix from within cartilage
- chondrocytes within the tissue divide and add more matrix between cells increasing the thickness of the cartilage
24
Q
Bone matrix is made up of…
A
~35% organic and 65% inorganic material by weight
25
Bone: Organic Material
- collagen provides flexible strength to the matrix
| - proteoglycans provide resiliency
26
Bone: Inorganic (mineral) Material
-Hydroxyapatite provides compression (weight-bearing) strength to the matrix
27
Hydroxyapatite
- calcium phosphate crystal
| - hardest substance in the body
28
Osteoblasts
- produce new matrix
| - have an extensive ER, numerous ribosomes, and golgi apparatuses
29
Osteoblasts produce collagen and...
proteoglycans that're packaged into vesicles by the Golgi apparatus and released from the cell by exocytosis
-also produce matrix vesicles
30
Ossification
- osteoblasts rest on a preexisting surface, such as cartilage or bone
- the cell processes of different osteoblasts join together
31
osteoblasts surround themselves with...
bone matrix
32
once engulfed, the osteoblasts become...
osteocytes
33
Osteocytes come from...
osteoblasts
34
Osteocytes
- mature bone cells that maintain the bone matrix
| - located in lacunae
35
Osteocyte cell processes are connected to one another through...
canaliculi (tunnel like)
36
Nutrients and gases pass through...
canaliculi and lacunae or pass from cell to cell via gap junctions connecting the cell processes
37
Osteoclasts
- reabsorb (breakdown) bone
- large multi-nucleated cells
- Release H+ to produce an acidic environment that decalcifies the bone matrix
38
Osteoclasts release...
enzymes that digest the protein components of the matrix
39
Osteoclasts use endocytosis to...
take some of the products of resorption into the osteoclast
40
What are the source of osteoblasts and chondroblasts?
OPCs
41
____ gives rise to more specialized cell types
mesenchymal cells
42
Osteochondral Progenitor Cells (OPCs)
- stem cells that become osteoblasts or chondroblasts
| - located in the inner layer of the perichondrium, the inner layer of the periosteum and the endosteum
43
Osteocytes are derived from...
osteoblasts
44
Osteoclasts are dervied from...
redbone marrow and monocytes
45
Woven Bone
fetal form of bone that consists of collagen fibers randomly oriented in many different directions
46
When is woven bone formed?
initially during fetal development and subsequently during the repair of a fracture
47
Woven bone is remodeled to form...
- lamellar bone
| - osteoclasts break down woven bone and osteoblasts build new matrix
48
Lamellar bone
-mature form of bone consisting of collagen fibers oriented parallel to one another, but at an angle to collagen fibers in other lamellae
49
Lamellar bone is arranged in...
thin sheets or layers called lamellae
50
Cancellous (spongy) bones
- less bone matrix and more space than compact bone
| - internal layer is a honeycomb of trabeculae filled with yellow bone marrow
51
Compact Bone
- more bone matrix and less space than cancellous bone
| - external layer of bone
52
Cancellous bone is covered with...
- a layer of bone membrane called endosteum
| - porous in appearance
53
Trabeculae
- Framework of cancellous bone
| - thin rods or plates of interconnecting bone
54
Trabeculae are oriented along...
lines of stress to provide structural strength
55
What fills the space between trabeculae?
bone marrow and blood vessels
56
Trabecular Structure
- consist of several lamellae
| - osteocytes located within lacunae between the lamellae
57
Each osteocyte is associated with...
other osteocytes through canaliculi
58
How do osteocytes obtain nutrients?
through their canaliculi
59
T/F: Osteoclasts are multinucleated
True
60
Circumferential Lamellae
form the outer surface of the compact bones
61
Concentric Lamellae
surround central canals, forming osteons (Haversian system)
62
Interstitial Lamellae
remnants of lamellae left behind after the remodeling process
63
Osteon
modular unit of compact bone
64
Central Canal
canal in the center of the osteon that contains blood vessels
65
Lacuna
space within osteon where osteocytes are located
66
Concentric Lamellae
surround central canals
67
Canaliculi connect..
central canals to osteocytes
68
Canals within compact bone provide a means for...
the exchange of gases, nutrients, and waste products
69
Perforating (Volkman's) Canals
- carry blood vessels to central canals
| - run perpendicular to the long axis of the bone
70
Compact Bone: Circulation: Canaliculi
-nutrients are transferred to the osteocytes through the canal system
71
Bone Shapes: Long Bones
- longer than they are wide
| - most bones of the upper and lower limbs
72
Example of long bones:
femur, ulna, radius, tibia, fibula
73
Bone Shapes: Short Bones
-about as wide as they are long
74
Example of short bones:
carpals, tarsals
75
Bone Shapes: Flat Bones
-relatively thin, flattened shape and are usually curved`
76
Example of flat bones:
parietal bone, sternum, scapula, ribs
77
Bone Shapes: Irregular Bones
-don't fit into the other 3 categories
78
Examples of irregular bones:
vertebrae, pelvic girdle and facial bones (sphenoid bone)
79
Bone: Structure of a Long Bone: Diaphysis
- tubular shaft that forms the axis of long bones
| - composed of compact bone that surrounds the medullary cavity
80
Medullary Cavity
- contains yellow bone marrow
| - certain bones also contain red bone marrow
81
Bone: Structure of a Long Bone: Bone Marrow
-site of blood cell formation (hematopoiesis)
82
In mature bone, yellow marrow....
replaces red marrow in the limbs except for some red marrow in the proximal arm and thigh
83
T/F: Adult bones are primarily made up of red marrow?
False, infant/child bones are mostly made up of red marrow and adult bones are made up of yellow marrow
84
Bone: Structure of a Long Bone: Epiphyses
- expanded ends of long bones
| - exterior is compact bone and the interior is cancellous bone
85
Bone: Structure of a Long Bone: Joint Surfaces are covered with...
articular (hyaline) cartilage
86
Bone: Structure of a Long Bone: Epiphyseal plate
- site of bone growth in length
| - becomes the epiphyseal line when all cartilage is replaced with bone
87
Bone: Structure of a Long Bone: Epiphyseal Line
Separates the diaphysis from the epiphyses
88
Periosteum
-double layer of protective membrane covering the outer surface of bone
89
Periosteum: Outer Fibrous Layer:
-dense regular CT, which contains blood vessels and nerves
90
Periosteum: Inner osteogenic layer:
osteoblasts, osteoclasts, and osteochondral progenitor cells
91
Endosteum
delicate membrane covering internal surfaces of bone, including cancellous bone
92
Flat bones contain the...
inferior framework of cancellous bone sandwiched between 2 layers of compact bone
93
Short and irregular bones have composition...
similar to the ends of long bones
94
T/F: compact bone will always be on the outer surface
True
95
what surrounds outer layer of the bone?
periosteum
96
how does the skeleton form prior to birth?
Intra-membranous ossification
97
Intra-membranous ossification
- Formation of bone within a CT membrane
| - some skull bones, part of the mandible, and the diaphyses of the clavicles (only forms small # of bones)
98
Endochondral ossification
- formation of bone within cartilage
- from a hyaline cartilage model
- 95% of bones are produced this way
- bones of the base of the skull part of the mandible, the epiphyses of the clavicles, and most of the remaining skeletal system
99
Intra-membranous ossification: Centers of ossification
- areas in the membrane where ossification begins
| - gradually expands to form bone by ossifying membrane
100
Intra-membranous Ossification: Fontanels
- Area of membrane between developing skull bones that haven't been ossified at birth (soft spots)
- closed by ~2 years of age
101
what is the more common way for the skeleton to develop?
endochondral ossification
102
Bone increase in size by...
- appositional growth only (unlike cartilage)
| - addition of new bone on the surface of older bone or cartilage
103
Increases in bone length occur at the...
epiphyseal plate
104
increase in length results in an increase in...
the length of the diaphysis and bony processes
105
growth in length ceases when...
the epiphyseal plate becomes ossified and forms the epiphyseal line
106
5 zones of the epiphyseal plate:
1. ) Zone of resting cartilage
2. ) zone of proliferation
3. ) zone of hypertrophy
4. ) zone of calcification
5. ) ossified bone
107
1. Zone of resting cartilage
contains chondrocytes that do not divide rapidly
108
2. zone of proliferation
- new cartilage is produced through interstitial cartilage growth
- chondrocytes divide and form columns of cells
109
3. zone of hypertrophy
the chondrocytes mature and enlarge
110
4. zone of calcification
matrix is calcified and hypertrophied chondrocytes die
111
5.) ossified bone
calcified cartilage on the diaphyseal side of the plate replaced by bone
112
where does bone growth take place?
at the epiphyseal plate
113
Growth: Articular Cartilage
- interstitial cartilage followed by appositional bone growth
- results in larger epiphyses and an increase in the size of bones that don't have epiphyseal plates (short)
114
Growth of Articular Cartilage ceases when...
bones reach mature size
115
Articular cartilage lasts...
throughout life and does not become ossified
116
Growth: Width: 1.) Appositional bone growth beneath the periosteum increases the...
diameter of long bones and the size of other bones
117
Growth: Width: 2.) Osteoblasts from the periosteum...
form ridges with grooves between them
118
Growth: Width: 3.) The ridges grow together, converting...
the grooves into tunnels filled with concentric lammelae to form osteons
119
Growth: Width: 4.) Osteoblasts from the periosteum lay down...
concentric lamellae, which can be remodeled
120
Size and shape of a bone are determined by...
genetics, but can be modified and influenced by other factors
121
Growth: Factors: Nutrition
-inadequate intake of materials necessary to support chondroblast and osteoblast activities results in decreased cartilage and bone growth
122
Growth: Factors: Hormones
- can increase bone growth and cause closure of the epiphyseal plates
- testosterone
- estrogen/progesterone
- growth hormone
- parathyroid hormone
- calcitonin
- thyroid hormones
123
Lack of calcium, protein and other nutrients during growth and development...
can cause bones to be small
124
Growth: Factors: Nutrition: Vitamin D
- Necessary for the normal absorption of calcium from the intestines
- The body inability to absorb fats in which Vitamin D is soluble can also result in deficiency
125
Insufficient Vitamin D in children:
Rickets: a disease resulting from reduced mineralization of the bone matrix; can result in bowed bones and inflammation of joints
126
Osteomalacia
adult form of rickets disease
127
Growth hormone increases bone growth by ...
stimulating interstitial cartilage growth and appositional bone growth
128
Giantism
- abnormally increased height
| - results from abnormal cartilage and bone formation at the epiphyseal plates of long bones
129
Thyroid Hormone
required in adequate amounts for growth of all tissues
130
Estrogen and Testosterone
- initially stimulate bone growth (burst in growth at puberty when production increases)
- stimulates closure (ossification) of the epiphyseal plates
131
Females usually stop growing before males because...
estrogen causes a quicker closure of the epiphyseal plate than testosterone
132
Bone: Remodeling
- converts woven bone to lamellar bone
| - allows bones to change shape, adjust to stress, repair themselves, and regulate blood calcium levels
133
Basic Multicellular Units (BMUs)
-assemblies of osteoclasts and osteoblasts that travel through or across the surface of bone removing old matrix and replacing it with new matrix
134
BMUs: 1. Osteoclasts break down...
bone matrix, making tunnels in the bone
135
BMUs: 2. Osteoblasts move in and lay down...
a layer of bone on the tunnel wall, forming concentric lamellae
136
BMUs: 3. Interstitial lamellae...
are remnants of bone not removed by BMUs
137
BMUs: 4. BMU activity renews...
the entire skeleton every 10 years
138
When mechanical stress is applied to a bone...
- osteoblast activity is increased in bone tissues
| - increases bone density
139
when mechanical stress is reduced under certain conditions such as bed rest...
- osteoclast activity remains normal, while osteoblast activity is reduced
- bone density may be decreased at an accelerated rate
140
4 classification of bone fractures:
open/closed
incomplete/complete
comminuted/impacted
linear/transverse
141
Bones: Fractures: Open or closed
whether or not the bone ends penetrate the skin
142
Bones: Fractures: Incomplete of Complete
the completeness of the break
143
Bones: Fractures: Comminuted or Impacted
the position of the bone ends after the fracture
144
Bones: Fractures: Linear or Transverse
the orientation of the bone to the long axis
145
Bones: Fractures: Complete
bone broken into at least 2 fragments
146
Bones: Fractures: Incomplete
fracture does not extend completely across the bone
147
Bones: Fractures: Comminuted
bone breaks in more than 2 pieces
148
Bones: Fractures: Impacted
one fragment is driven into the cancellous
149
Bones: Fractures: Transverse
occurs at a right angle to the long axis
150
Bones: Fractures: Spiral
helical course around the bone
151
Bones: Fractures: Oblique
run obliquely to the direction of the long axis
152
4 phases of bone repair
1. hematoma formation
2. callus formation
3. callus ossification
4. bone remodeling
153
Bone Repair: Step 1
- hematoma formation
| - blood released from damaged blood vessels forms a hematoma
154
Bone Repair: Step 2
- callus formation
| - the internal callus forms between the ends of the bones, and the external callus forms a collar around the break
155
Bone Repair: Step 3
- callus ossification
| - woven, cancellous bone replaces the internal and external calluses
156
Bone Repair: Step 4
- bone remodeling
| - compact bone replaces woven bone and part of the internal callus is removed, restoring the medullary cavity
157
Bone is the major storage site for...
Calcium (Ca2+)
158
Blood Ca2+ levels depend on...
movement of calcium into and out of bone
159
Skeletal System: Calcium Homeostasis: Osteoblast Activity
- increases bone density
| - increases Ca2+ in bone
160
Skeletal System: Calcium Homeostasis: Osteoclast Activity
- decreases bone density
| - decreases Ca2+ in bone
161
What two hormones regulate Ca2+ levels in the blood?
- parathyroid hormone (PTH)
| - calcitonin
162
parathyroid hormone (PTH)
- major regulator of blood Ca2+
- crucial for normal muscle and nervous tissue formation
- falling blood Ca2+ levels signal the parathyroid gland to release PTH
163
PTH stimulates...
- osteoclasts to degrade bone matrix and release Ca2+ into the blood
- Ca2+ absorption from the small intestines
- reabsorption of Ca2+ from the urine
164
Calcitonin inhibits...
osteoclast activity and decreases Ca2+ within the blood stream
-rising blood Ca2+ levels trigger the thyroid to release calcitonin
165
Calcitonin stimualtes...
Calcium salt deposition in bone by decreasing osteoclast activity
166
Osteoblasts remove Ca2+ from...
the blood to make bone
167
in the kidneys, PTH increases...
Ca2+ reabsorption from urine
168
In the kidneys, PTH promotes formation of...
active Vitamin D which increases Ca2+ reabsorption from the small intestine
169
Skeletal system: Aging: Matrix
more brittle due to lack of collagen and less hydroxyapatite
170
Skeletal system: Aging: Bone Mass
- overall decrease starts around age 30
- slower in males
- may be slowed by adequate nutrition and weight bearing activity
171
Skeletal system: Aging: Cancellous bone loss
thinning and loss of trabeculae
172
Skeletal system: Aging: Compact Bone Loss
less osteon formation
173
Skeletal system: Aging: Loss of Bone
- increase the risk for fractures
- causes deformity
- loss of height
- pain
- stiffness
- loss of teeth
A&P Lecture Exam 2
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