CH 6 - Skeletal System Flashcards
1
Q
What are the components of the skeletal system?
A
Bones, cartilages, joints, connective tissues
2
Q
Osteology
A
The study of bone structure and treatment of bone disorders
3
Q
What are the functions of the skeletal system?
A
Support
Store minerals and lipids
Blood cell production
Protection
Leverage
4
Q
Hematopoiesis (hemopoiesis)
A
Process of producing blood cells
5
Q
What are examples of long bones?
A
Phalanges Metacarpals Metatarsals Femur Tibia Fibula
6
Q
What are examples of irregular bones?
A
Vertebrae Pelvic bones Sacrum Sphenoid Ethmoid
7
Q
What are examples of flat bones?
A
Ribs
Scapula
Cranial bones
Sternum
8
Q
What are examples of short bones?
A
Talus
Carpals
Tarsals
9
Q
Diaphysis
A
The shaft of a long bone, made of compact bone
10
Q
Medullary cavity
A
Central space within a long bone that contains yellow bone marrow
11
Q
Epiphysis
A
The wide ends of a long bone that articulates with other bones, made of spongy bone
*May contain red or yellow bone marrow
12
Q
Cortical bone (cortex)
A
A layer of compact bone that surrounds spongy bone
13
Q
Epiphseal growth plate
A
Residual hyaline cartilage allowing the bones to grow longer
14
Q
Epiphyseal line
A
The ossified bone tissue product once the epiphyseal growth plate is done growing
*Adult height is reached
15
Q
Describe the structure of a flat bone.
A
Spongy bone between two layers of cortical bone
16
Q
Diploë
A
Spongy bone layer within the cranium
17
Q
Osseous tissue
A
A type of supporting connective tissue that contains specialized cells, ground substance, and extracellular protein fibers that form the matrix of bone tissue
18
Q
What is the organic matrix of bone comprised of?
A
Collagen fibers and bone cells
19
Q
What does the organic matrix of bone do?
A
Provide strength & flexibility
20
Q
What is the inorganic matrix of bone comprised of?
A
Calcium salts
- calcium phosphate
- calcium hydroxide
- calcium carbonate
Minerals
- sodium
- magnesium
- fluoride
- phosphorus
21
Q
What does the inorganic matrix of bone do?
A
Provide rigidity & compression strength
22
Q
What are osteocytes?
A
Amitotic, mature bone cells within a lacuna
23
Q
What are the functions of osteocytes?
A
Maintain protein/mineral content of bone matrix
Participate in repairs of damaged bone
24
Q
Canaliculus
A
Gap junctions that provide osteocytes with nutrients and oxygen
25
What do osteoblasts do?
Produce & release proteins/organic components of the organic bone matrix
Promote calcification to produce new bone
26
What is osteogenesis (bone deposition) and what are the 2 steps involved?
Process of forming bone
1. Ossification
2. Mineralization
27
Ossification
Replacing tissue with bone
28
Calcification
Accumulation of calcium salts in the organic matrix
29
Mineralization
The addition of calcium and other minerals to osteoid
30
What are osteoprogenitor (osteogenic) cells?
Connective tissue stem cells that arise from mesenchymal cells
31
What do osteoprogenitor (osteogenic) cells do?
| Where are they found?
Produce & maintain population of osteoblasts
Cell (osteogenic) layer of periosteum, endosteum
32
What are osteoclasts?
Giant cells with 50+ nuclei, derived from stem cells that produce leukocytes
33
What do osteoclasts do?
Osteolysis/bone resorption
Secretes acids to dissolve calcium salts, and collagenase to dissolve collagen fibers, in order to destroy/erode bone
*Releases stores minerals into blood
34
Why do osteoclasts have ruffled borders?
To increase their surface area
35
Osteon (haversian system)
The basic unit of bone
36
Central canal (Haversian canal)
Hollow tube in the middle of the osteon that contains an artery, a vein, and a nerve
37
Perforating canals (volkmann’s canals)
Hollow tubes running perpendicular to the central canal that carry blood vessels and nerves into bone
38
Concentric lamallae
Thin layers of bone matrix produced by osteoblasts around the central canals of compact bone
*Osteocytes are arranged in concentric lamellae which forms the osteon
39
Circumferential lamellae
Layers of bone matrix found at the external and internal bone surfaces that enclose the osteons and is covered by the periosteum or endosteum
40
Interstitial lamellae
Remnants of recycled osteons that fills in the spaces between existing osteons
41
Trabeculae
A meshwork of supporting thin columns (bony struts) that are covered by the endosteum
*Grows and adapts throughout life
42
Describe the structure of spongy bone.
Trabeculae allows for stress in many directions.
Spaces between trabeculae are filled with red or yellow bone marrow.
43
Periosteum
An external membrane that covers all external bone surfaces except parts enclosed in joint capsules or articular cartilage
44
What are the 2 layers of the periosteum?
Outer, fibrous layer
Inner, cellular layer (osteogenic layer)
*No osteocytes, but all others
45
Perforating fibers
Thick bundles of collagen fibers of the periosteum that secure it to underlying bone
46
What are the functions of the periosteum?
Isolate bone from urrounding tissue
Provide entrance for blood vessels & nerves
Participates in bone growth/repair/remodeling
Attachment point for tendons/ligaments
47
Endosteum
An internal membrane composed of a single layer of endosteal cells
48
Endosteal cells
Osteoblasts, osteoprogenitors, and osteoclasts
*No osteocytes
49
Where is the edosteum?
Lining of medullary cavity
Lining of inner surface of central canals/perforating canals
Covers trabeculae of spongy bone
50
What is the function of the endosteum?
Participates in bone growth, repair, and remodeling
51
What are the 4 types of bone formation?
Initial bone formation of a fetus
Pre-adult bone growth
Bone remodeling
Repair of fractures
52
When does bone begin to develop in a fetus? When is it complete?
Bony skeleton begins forming 6 weeks after fertilization
Fetal skeleton is complete after 3 months but is made primarily of cartilage
53
What are the 2 forms of ossification?
Intramembranous ossification &
| Endochondral ossification
54
Intramembranous ossification
Bones form directly within mesenchyme
* Occurs in flat bones of the cranium
* Starting tissue: dense fibrous connective tissue
55
Endochondral ossification
Bone forms within hyaline cartilage
* Occurs in all bones
* Starting tissue: hyaline cartilage
56
Describe the steps of intramembranous ossification.
1. Ossification center develops, osteoblasts secrete organic ECM
2. Calcification of ECM with added calcium salts/minerals
3. ECM > trabeculae > spongy bone
4. Periosteum develops from mesenchyme
57
Describe the steps of endochondral ossification. 🙃
1. Insterstitial (length) & appositional (width) growth of cartilage
2. Chondroblasts produce a cartilage model surrounded partially by perichondrium
3. Perichondrium of diaphysis becomes periosteum, bone collar produced, cartilage calcifies
4. Ossification center forms, blood vessels/osteoblasts invade cartilage, osteoblasts lay down bone matrix, spongy bone forms
5. Step 4 continues, epiphyses/medullary cavity form
6. Secondary ossification centers form in epiphyses
7. Unossified cartilage becomes epiphyseal plate and articular cartilage
8. Epiphyseal plate becomes epiphyseal line, bone fully formed
58
Interstitial growth
Increase in the length of bones (longitudinal or vertical) at the epiphyseal growth plate
59
What are the 5 zones of interstitial growth?
1. Zone of resting cartilage
- non dividing chondrocytes
2. Zone of proliferating cartilage
- chondrocytes actively divide
3. Zone of hypertrophic cartilage
- chondrocytes hypertrophy
4. Zone of calcified cartilage
- calcified cartilage forms
- chondrocytes die & leave open space
5. Zone of ossification
- osteoblasts fill open spaces
- osteogenesis begins
*Zone 5 will be closest to medullary cavity and zone 1 will be closest to articular cartilage of each epiphysis
60
Appositional growth
An increase in the diameter and thickness of bone
61
What are the steps of appositional growth?
1. Osteoblasts beneath periosteum lay down bone in ridges to form grooves for blood vessels
2. Groove is transformed to a tunnel when bone of adjacent ridges meet, periosteum of groove becomes endosteum of tunnel
3. Appositional growth by osteoblasts from endosteum forms new concentric lamellae
4. Additional concentric lamellae fills tunnel and forms osteon
62
Osteolysis (bone resorption)
Removal of minerals and collagen fibers by osteoclasts
63
Bone remodeling
Bone resorption & bone deposition
* Must balance or will end up with over/undergrowth
* Life-long process
* No osteoprogenitor cells, but all others
* Appositional growth
64
Calcitriol
The active form of vitamin D3
*Helps absorb calcium and phosphorus from the digestive tract
65
What does vitamin C do for bones?
Collagen synthesis
Stimulation of osteoblasts differentiation
66
What do calcium and phosphorus do for bones?
Harden bone ECM
67
What do growth hormone, thyroxine, estrogens and androgens do for bones?
Stimulate osteoblasts
68
What do calcitonin and parathyroid hormone do for bones?
Regulate calcium and phosphate levels
69
What is the normal range of blood calcium?
8mg/dL - 11mg/dL
70
Hypercalcemia
A blood calcium content above 11mg/dL
71
Hypocalcemia
A blood calcium content below 8mg/dL
72
What are the functions of calcium?
Bone development/maintenance
Nerve impulse transmission
Muscle contraction
Blood clotting
73
What is calcium homeostasis maintained by?
Calcitonin and parathyroid hormone control the storage, absorption, and excretion of calcium
74
How does parathyroid hormone increase blood calcium ion levels? Where does this happen?
1. Stimulate osteoclasts
2. Increase intestinal absorption of calcium
3. Decrease calcium excretion from kidneys
4. Increase calcitriol secretion by kidneys
Parathyroid glands
75
How does calcitonin decrease blood calcium ion levels? Where does this happen?
1. Inhibit osteoclasts activity
2. Decrease intestinal absorption of calcium
3. Increase calcium excretion by kidneys
4. Decrease calcitriol secretions by kidneys
Thyroid gland
76
What is a fracture?
A crack or break in bone
77
What are the 4 steps of the bone repair process?
1. Fracture hematoma
2. Fibrocartilaginous callus
3. Bony callus
4. Remodeling
78
Describe a fracture hematoma.
A mass of clotted blood (from broken blood vessels within the bone) that forms within 6-8 hours
79
Describe a fibrocartilaginous callus.
A fibrocartilage callus fills the space between the ends of broken bone for 3 weeks and tissue repair begins
*Cartilage is present due to avasularity from broken blood vessels
80
Describe a bony callus.
Osteoblasts produce trabeculae of spongy bone, and fibrocartilage callus is converted to a bony callus joining the broken bones
*3-4 months
81
Describe bone remodeling.
Osteoblasts build compact bone to form the bone collar, then osteoclasts absorb the spongy bone to create a medullary cavity
82
What is an avulsion fracture?
Complete severing of a body part
83
What is a colles fracture?
Fracture at the distal end of the radius
84
What is a comminuted fracture?
Bone is splintered into several small pieces between the main parts
85
What is a complete fracture?
Bone is broken into two or more pieces
86
What is a compound (open) fracture?
Broken ends of the bone protrude through the skin
87
What is a compression fracture?
Bone is squashed
88
What is a depressed fracture?
Broken part of the bone forms a concavity
89
What is a displaced fracture?
Fractured bone parts are out of anatomic alignment
90
What is an epiphyseal fracture?
Epiphysis is separated from the diaphysis at the epiphyseal plate
91
What is a greenstick fracture?
Partial fracture where one side of the bone breaks while the other is bent
92
What is a hairline fracture?
Fine crack in which sections of bone remain aligned
93
What is an impacted fracture?
One fragment of bone is firmly driven into the other
94
What is an incomplete fracture?
Partial fracture extends only partway across the bone
95
What is a linear fracture?
Fracture is parallel to the long axis of the bone
96
What is a nondisplaced fracture?
Bone fragments retain their anatomic position
97
What is an oblique fracture?
Diagonal fracture at an angle
98
What is a pathologic fracture?
Weakening of a bone caused by disease or infection
99
What is a pott fracture?
Fracture is at distal ends of the tibia and fibula
100
What is a simple (closed) fracture?
Bone does not break through the skin
101
What is a spiral fracture?
Fracture spirals around axis of long bone due to twisting stress
102
What is a stress fracture?
Thin fractures due to repeated/stressful impact
103
What is a transverse fracture?
Fracture is at right angles to long axis of bone
104
Osteopenia
A condition that occurs when the body undergoes more more resorption that deposition
* Bones become thinner/weaker with age, beginning at 30-40 years
* Women lose 8% of bone mass per decade, men 3%
105
Osteoporosis
Significant reduction of bone mass that compromises normal function
106
Bone mineral density (BMD)
The total amount of bone mass in a defined area
* For a specific bone, total amount of mineral content (calcified bone tissue) measured in grams per centimeter squared
* High BMD means strong bone
107
Dual energy x-ray absorptiometry (DEXA)
A DEXA scanner passes 2 x-ray beams through the body to determine BMD
* Can measure 1% changes in BMD
* Focuses on hip joint and vertebrae
108
Fibrodysplasia ossificans progressiva (FOP)
A rare genetic disease that replaces muscle tissue with bone
109
Gigantism
A condition caused by overproduction of growth hormones BEFORE the closure of the epiphyseal plate
110
Acromegaly
A condition caused by the overproduction of growth hormones AFTER the closure of the epiphyseal plate in which bones become abnormally thick
111
Osteitis deformans (paget disease)
A chronic disorder that results in enlarged/weak/deformed bones due to excessive bone resorption & regrowth
112
Achondroplasia
A genetic disorder of bone growth causing cartilage to be abnormally converted to bone
*Epiphyseal growth plate prematurely ossifies preventing the bones from lengthening
113
Osteogenesis imperfecta (brittle bone disease)
Genetic disorder of bone characterized by extreme fragility of bones due to a defect in collagen deposition
*Babies can be born with bone fractures
114
Osteosarcoma (osteogenic sarcoma)
A type of cancer that starts in bone
115
Rickets
A disease that affects the bones of children/adolescents caused by the failure of the osteoid to calcify, resulting in soft/weak bones from extreme vitamin D deficiency
116
Osteomalacia
Adult version of rickets
117
Osteomyelitis
A bone infection usually caused by Staph. bacteria
*Can begin from an open fracture, infection after surgery, or infection of another body part that has spread to bone
