Osseous Tissue (Ch. 6) Flashcards
1
Q
What are the other two parts of the skeletal system besides bones?
A
- Cartilage
2. Ligaments
2
Q
Where are blood cells produced in osseous tissue?
A
In the red marrow
3
Q
Where are triglycerides stored in osseous tissue?
A
In the yellow marrow
4
Q
Which of the four types of tissue (muscle, connective, neural, epithelial) is bones?
A
Connective tissue
5
Q
What are the 4 kinds of cells in osseous tissue?
A
- Osteoprogenitor cells
- Osteoblasts
- Osteocytes
- Osteoclasts
6
Q
What do osteoprogenitor cells do?
A
They are the stem cells of bones
7
Q
What type of embryonic tissue do osteoprogenitor cells (bone stem cells) come from?
A
Mesenchyme
8
Q
What are bone stem cells called?
A
Osteoprogenitor cells
9
Q
What do osteoblasts do?
A
Form new bone by secreting matrix around themselves
10
Q
What do osteocytes look like? What do they do?
A
They maintain daily metabolic processes of bone.
They are mature bone cells within lacunae.
11
Q
What are osteoclasts?
A
Huge cells - fusion of up to 50 phagocytes
12
Q
Where do osteoclasts hang out?
A
In the endosteum
13
Q
Is cartilage tissue vascularized or innervated?
A
No, neither
14
Q
What is the name for the layer of dense irregular connective tissue that surrounds the cartilage?
A
Perichondrium (“around the cartilage”)
15
Q
What does the pericardium do for the cartilage when the cartilage is compressed?
A
It acts like a girdle, keeping the cartilage in (resisting outward expansion)
16
Q
What kind of cartilage makes up articular cartilages, costal cartilages, respiratory cartilages, and nasal cartilages?
A
Hyaline cartilages
17
Q
Which type of cartilage makes up the external ear and the epiglottis?
A
Elastic cartilages
18
Q
Which type of cartilage makes up intervertebral discs and menisci of the knees?
A
Fibrocartilages
19
Q
Which type of osseous tissue is made up of osteons, compact or spongy bone?
A
Compact
20
Q
What are the 4 main components of an osteon?
A
- Central canal
- Concentric lamellae
- Lacunae
- Canaliculi
21
Q
What is the central canal in an osteon?
A
Runs longitudinally
Contains blood vessels and nerves
22
Q
What are the concentric lamellae made of in an osteon?
A
Rings of calcified matrix around the central canal
23
Q
What is in the lacunae of osteons?
A
Osteocytes
24
Q
What are canaliculi?
A
Tunnels running outward from the osteocytes
Contain processes of osteocytes surrounded by extracellular fluid
Pathways for diffusion to blood vessels in the central canal
25
Long bones: What are perforating canals? Which direction do they run through osteons (longitudinally or transversely)?
Connect with the central canals
Contain vessels and nerves
Run transversely through osteons
26
What do circumferential lamellae do on long bones?
Resist twisting of the long bone
27
Where are circumferential lamellae located?
Between the periosteum and the central rings of osteons.
They encircle the inner and outer surfaces of bone, deep to the periosteum and superficial to the endosteum that lines the medullary cavity
28
What are interstitial lamellae?
Fragments of old osteons lying around between the whole osteons
29
How do osteons align themselves?
Along lines of stress, to resist bending and torsion
30
Does spongy bone contain osteons?
No
31
What is the network of little beams in spongy bone called?
Trabeculae
[Alex Trebek from Jeopardy
"Trebek, you lay down,"]
32
How are trabeculae connected to each other?
Canaliculi
33
What are the spaces between trabeculae filled with?
Red marrow
34
Where are 4 common kinds of bones where spongy bone can be found?
Mainly in:
1. Flat bones
2. Short bones
3. Irregular bones
4. Ends of long bones
35
Where is red marrow is produced, and what are some examples of locations in the body?
```
Red marrow produced in trabeculae of spongy bone
Ex: Hip bones
Breastbone
Vertebrae
Ends of long bones
```
36
What are the 3 main parts of a long bone?
1. Diaphysis (shaft)
2. Epiphyses (ends)
3. Metaphyses (transitional zones btw diaphysis and epiphyses - where the growth/epiphyseal plate is)
37
What is the epiphyseal plate?
The growth plate in immature long bones. I
38
What specific material is the epiphyseal plate made out of?
Hyaline cartilage
39
What is articular cartilage? What kind of cartilage is it?
Hyaline cartilage
Covers joint surfaces of epiphyses
Shock absorber and friction reducer
40
What is the periosteum?
The membrane that covers bone (except at joint surfaces - that would be articular cartilage)
41
What is the periosteum made of? (3 layers)
1. Outer fibrous layer made of dense irregular connective tissue
2. Inner layer with osteoblasts and osteoclasts
3. Perforating fibers (collagen fibers that anchor the periosteum to the bone)
42
What part of the long bone is the medullary cavity? What does it hold?
```
The marrow (yellow fatty) cavity
Space in central diaphysis
```
43
What is the endosteum?
The thin cellular lining of the medullary cavity
44
What is the endosteum made of?
Osteoprogenitor cells and some osteoclasts
45
What is hematopoesis?
Blood cell formation
46
What is the difference between intramembranous ossification and endochondral ossification?
Intramembranous ossification is when a bone forms from a membrane (membrane bone).
Endochondral ossification is when a bone forms from cartilage (cartilage bone or endochondral bone)
47
What are the two ways that bones can be formed in the human body (developmentally)?
From cartilage (endochondral) or from a loose fibrous connective tissue membrane (intramembranous)
48
What bones are formed with intramembranous ossification?
Flat bones of the skull and clavicle
49
What happens during intramembranous ossification?
1. Ossification center develops
2. Trabeculae form
3. Periosteum and endosteum develop
50
When an intramembranous bone is developing, what is the role of the ossification center?
Holds mesenchymal cell cluster where bone will develop
Mesenchymal cells differentiate into osteoblasts and secrete organic matrix around themselves
Osteocytes that are trapped in lacunae deposit mineral salts and calcification occurs
51
When an intramembranous bone is developing, how are trabeculae formed?
Matrix fuses to form trabecular network (of spongy bone)
Blood vessels grow between trabeculae
Associated connective tissue turns into red marrow
52
When an intramembranous bone is developing, how do the periosteum and endosteum develop?
Osteoprogenitor cells and connective tissue around the spongy bone condense to form the periosteum and endosteum
A thin layer of compact bone forms under the periosteum
53
Are most bones formed by endochondral or intramembranous ossification?
Endochondral
| Most bones below the skull (except clavicles) are made from endochondral ossification
54
What are the 5 steps in endochondral ossification?
1. Cartilage model develops
2. Primary ossification center (medullary cavity) develops
3. Osteoclasts form medullary cavity
4. Secondary ossification centers (in epiphases) develop
5. Epiphysis fills with spongy bone
55
Endochondrial ossification starts with building a cartilage model. What kind of cells are clustered in the shape of the future bone?
Mesenchymal cells
(They differentiate into chondroblasts which secrete a matrix of hyaline cartilage
Together the mesenchyme and connective tissue at the surface condense to form the perichondrium)
56
How is the perichondrium built?
Mesenchymal cells differentiate into chondroblasts
Chondroblasts secrete a matrix of hyaline cartilage
Together the mesenchyme and connective tissue at the surface condense to form the perichondrium
57
What are the 2 methods of cartilage-model growth?
1. Appositional growth
| 2. Interstitial growth
58
What is appositional cartilage growth? Where does it take place?
In endochondrial ossification, the perichondrium produces new chondroblasts which deposit matrix
Makes the cartilage model grow in thickness
59
During endochondral ossification, what is interstitial growth? Where does it take place?
The chondrocytes of the cartilage model divide and secrete matrix between themselves
Cartilage model grows in length
60
During endochondral ossification, how does the primary ossification center develop?
Stimulated by blood vessels
Periosteal arteries form
Perichondrium cells differentiate into osteblasts and turn the perichondrium into the periosteum
Nutrient artery grows in the center of the cartilage model
Ossification center grows towards ends of bone
Fibroblasts become osteoblasts
61
What type of cells work to form the medullary cavity?
Osteoclasts
| Remodeling replaces spongy bone with compact bone
62
Where are the secondary ossification centers?
Epiphyses of long bones
63
Bones can grow in length or thickness. Which causes which; interstitial or appositional growth?
```
Length = Interstitial
Width = Appositional
```
64
Where does interstitial growth take place (what part of the bone)?
Epiphyseal (growth) plates
65
What is the epiphyseal line?
The bony line in mature bone where the growth plate was
66
When does the epiphyseal plate close?
Age 18-25
| Injury to the plate can cause early closure
67
What external factors does bone growth depend on?
Nutrient availability
Minerals (esp. calcium and phosphorus)
Vitamins (esp. C and A)
68
What is the first step in appositional bone growth?
Osteoprogenitor cells in the periosteum differentiate into osteoblasts, which secrete matrix around themselves, becoming osteocytes
69
What are the 5 steps of appositional bone growth?
1. Osteocytes form from osteoprogenitor cells
2. Lamellae (layers) of matrix and osteocytes form
3. Osteons form - concentric lamellae surround the periosteal blood vessels
4. Circumferential lamellae are formed by osteoblasts in the periosteum
5. Osteoclasts in the endosteum enlarge the medullary cavity
70
What organ of the body produces human growth hormone (hGH)?
PItuitary gland
71
How does hGH (human growth hormone) act on the body?
Encourages bone growth
72
What conditions arise from having too much or too little hGH?
Gigantism/dwarfism
73
What role do sex steroids play in bone growth?
Increase of sex steroids at puberty (androgen and estrogen) stimulates growth spurt
High levels of sex steroids eventually close growth plate
74
During bone remodeling, what processes are occuring? How often does remodeling take place?
Remodeling is continuous.
Homeostasis happens when osteolysis = ossification.
Osteoclasts remove bone tissue, and osteoblasts replace it.
Function: renew aging bone tissue, repair damages
75
True or false: Remodeling redistributes bone along lines of mechanical stress.
True.
76
What is bone osteolysis?
Breaking down of bone matrix (by osteoclast secretions)
77
What do osteoclasts secrete to cause osteolysis?
Enzymes (to digest collagen)
| Acid (to dissolve mineral salts)
78
How does weight-bearing exercise affect your bones?
Makes them grow and strengthen to protect themselves against damage
Stress stimulates ossification
79
What is the condition that occurs when osteolysis is happening more than ossification in a body?
Osteoporosis
80
Which mineral in bones aids in nerve and muscle function, blood clotting, and enzyme function?
Calcium
81
What hormone is responsible for the negative feedback loop that regulates blood calcium when it gets too low?
Parathyroid Hormone (PTH)
82
Which organ secretes parathyroid hormone?
The parathyroid gland
83
What are the 3 missing steps of the parathyroid hormone negative feedback loop?
1. Low calcium is detected by receptors
5. Blood calcium increases
1. Low calcium detected by receptors
2. Parathyroid gland secretes PTH
3. Osteoclasts are stimulated, break down bone, and calcium from cell matrices enters bloodstream
4. Kidneys excrete less calcium and produce more calcitriol, which is needed to absorb dietary calcium
5. Blood calcium increases
84
Why does the body need calcitriol?
To absorb dietary calcium
85
What are the 5 types of fractures?
1. Closed (simple)
2. Open (compound)
3. Comminuted
4. Greenstick
5. Stress
86
What are the 4 steps of bone repair?
1. Fracture hematoma
2. Cartilage callus forms
3. Bony callus replaces cartilage callus
4. Bone remodeling
87
When a bone is broken, what happens during the formation of the fracture hematoma? Why does the fracture hematoma form?
Torn blood vessels bleed into the area of the break and form a clot
Phagocytic cells and osteoclasts removed damaged tissue from the area
It forms to take away the debris
88
When a bone is broken, how does the cartilage callus form?
Fibroblasts enter the fracture hematoma and become chondroblasts (start making hyaline cartilage)
Osteoprogenitor (stem) cells in the periosteum an endosteum produce spongy bone at the margins of the callus (formerly the hematoma)
89
When a bone is broken, what is the bony callus, and how does the bony callus form?
Replaces cartilage callus in healing process
Begins near the healthy bone and works inwards
Osteoblasts replace cartilage with spongy bone
Spongy bone links the fracture site together and stabilizes it
90
When a bone is healing, after the bony callus is in place, what is the process called of replacing the callus with "normal" bone?
Bone remodeling
91
When a bone is broken, what is reduction?
Aligning the ends of a fractured bone (you have to pull on the muscles to get it back into place)
92
When a bone is broken, what is fixation?
Holding the fracture still so that a bony callus can form
| Done with casts, pins, plates, etc.
93
What does the body do if it senses that the blood calcium is too high?
Calcitonin negative feedback loop
94
What are the steps of the calcitonin negative feedback loop?
1. High blood calcium is detected by receptors
2. Thyroid gland increases production and secretion of calcitonin
3. Calcitonin inhibits osteoclast activity, which increases calcification of bones
4. This makes blood calcium decrease
95
Where are the periosteal arteries?
Run along the outer periosteum of diaphysis of long bones
| Branches pass through periosteum and perforating canals
96
What do the periosteal arteries supply?
Supply periosteum and outer compact bone with blood
97
What is the nutrient artery? Where is it located?
Supplies inner bone with nutrients.
| Enters at mid-diaphysis through the nutrient foramen (hole) into the medullary cavity
98
What do metaphyseal arteries do? What do its branches form?
Supply metaphyses with blood
| Branches form epiphyseal arteries
99
Does the periosteum have sensory nerves?
Yes, lots
