Osseous Physiology Flashcards
1
Q
Medullary cavity
A
“Marrow” cavity
Hollow cavity in diaphysis. Contains yellow bone marrow for adipose storage
2
Q
Greenstick fracture
A
Usually seen in kids.
Partial fracture.
Once side broken, other side bent.
3
Q
Osteoclasts
A
Cells that destroy bone as a natural part of growth and repair.
4
Q
Haverian System
A
aka Osteon
Repeating units of all the components of compact bone around one central canal.
Includes canal, blood and lymph vessels, lacunas, canaliculi, oseocytes and concentric lamellae
5
Q
Osteoblasts
A
Bone builders
Synthesize collagen fibres and initiate calcification.
Take Ca+ from blood for use in cells
6
Q
Under what circumstances does ossification a occur?
A
- As an embryo (beginning in 6th week)
- Childhood and adolescence
- Normal remodelling of bone through adulthood
- Fracture repair.
7
Q
Metaphyseal arteries/veins
A
Enter at the metaphysis to supply blood to the metaphysis and red bone marrow
8
Q
Six key functions of the skeletal system:
A
- Support
- Protection
- Movement
- Control of mineral content (Ca+, P, Fe+)
- Hemopoesis
Storage of triglycerides.
9
Q
Articular cartilage
A
Covers epiphysis. Reduces friction and allows movement at joints.
Most commonly composed of hyaline cartilage.
10
Q
Pott’s fracture
A
Occurs only in legs. Closed fracture with damage to ankle articulation.
11
Q
Stress fracture
A
Microscopic tears in the fissures of the bone.
Usually caused by repetitive and strenuous activities.
12
Q
Diaphysis
A
Main portion of the bone (the shaft)
13
Q
Development of Marrow Cavity
A
Part of endochondral ossification.
Occurs through osteoclast activity.
14
Q
Osteocytes
A
Mature bone cells
Maintain daily metabolic activities of the bone
15
Q
Perforating canals
A
aka Volkmann’s canals
Perpendicular canals that run superficial to deep.
Carry blood, lymphatic vessels, nerves, from periosteum.
16
Q
Spongy bone
A
No osteons
Appears spongy due to lattice and irregular pattern of bone tissue distribution.
Greater blood supply than compact bone
17
Q
Periosteum
A
The “skin” surrounding bones.
Made of irregular sense connective tissue.
Merges with tendons
Contains nerve endings which detect irregularities/pathologies
18
Q
Osteogenic cells
A
AKA osteoprogenitors
Unspecified stem cells serviced from mesenchyme cells
19
Q
Hypertrophic cartilage zone
A
In metaphysis, in between proliferating and calcified cartilage zone.
Large mature chondrocytes situated in columns.
20
Q
X Rays
A
aka radiography
developed by William C. Roentgen
Electron beam shot through object and reflect off of hard objects. Use ionizing radiation.
Digital X-rays 50% more efficient and less harmful than traditional cathode tubes
21
Q
What are the two types of canals found in compact bone?
A
Perforating (Volkmann’s) and Central (Haversian)
22
Q
What are the two type of bone formation?
A
Intramembranous and endochondrial
23
Q
Crystallized mineral salts in the ECM of the bone
A
Calcium phosphate Ca3(PO4)2 most abundant
Calcium hydroxide second most abundant.
24
Q
What are the stages of Endochondral Ossification?
A
- Development of cartilage model
- Growth of cartilage model
- Development of primary ossification centre
- Development of the marrow cavity
- Development of secondary ossification centres
- Formation of articular cartilage and epiphyseal plate
25
Calcitriol
A form of Vitamin D which increases absorption of Ca+ from the GI tract.
26
Reparative Phase 2.0
Osteogenic cells become osteoblasts, which convert fibrocartilage into spongy bone. (bony callus formation)
Lasts 3-4 months
27
Epiphysis
Proximal and distal ends of bones.
| Tend to have projections and fossa that articulate with other bones
28
What are some of the key roles of Ca+?
1. act as a cofactor in numerous chemical reactions in the body
2. deeply involved in blood clotting
3. involved in muscle contractions
29
What are the stages of Intramembranous Ossification?
1. Development of ossification centre
- - chemical messages cause mesenchymal cells to develop into osteoblasts, which secrete bone ECM
2. Calcification
- - osteoblasts --> osteocytes
3. Formation of trabelculae
- - matrix continues to harden and trabeculae form.
- - development of spongy tissue, red bone marrow
4. Development of periosteum
- - periosteum forms. Compact bone replaces spongy bone where appropriate.
30
Deposition
The process by which osteoblasts will lay down minerals and collagen fibres to create ECM
31
Two main portions of bone tissue
Spongy and compact
32
Concentric lamellae
Concentric rings surrounding each central canal.
AKA osteon
33
Factors that affect bone growth
```
Minerals (Ca+, P, F, Mg, Mn)
Vitamins
Vit A -- promotes osteoblasts
Vit C -- collagen formation
Vit D -- absorption of Ca+
Vit K & B12 -- build bone proteins
Hormones (T3 & T4 from thyroid and IGF in response to hGH -- promote bone growth)
```
34
Proliferating cartilage zone
In the metaphysis, next to resting cartilage zone.
Contain large chondrocytes that replicate and divide to replace old/dying chondrocytes.
Appear like a stack of coins.
35
Epiphyseal arteries/veins
Enter at epiphyseal portion to supply blood to the epiphysis and red bone marrow
36
Development of secondary ossification centres.
Part of endochondral ossification
-- epiphyseal place formed from penetration of epiphyseal arteries
Growth occurs outwards from epiphysis.
Cartilage continues to be converted into bone.
37
Parathyroid Hormone
Secreted by parathyroid cells. Increases Ca+ levels in the blood
Effects:
1. increases activity of osteoclasts; reduces activity of osteoblasts. (increases resorption)
2. increases formation of calcitriol
3. stimulates kidney cells to retain Ca+ from urine
38
Canaliculi
Small channels that radiate in all directions from each lacunae.
Filled with ECF.
Arms of metaphoric snow angels
39
What cells are produced in spongy bone?
White blood cells
Red blood cells
Platelets
40
What are the four layers of hyaline cartilage in the metaphysis?
Resting cartilage zone
Proliferating cartilage zone
Hypertrophic cartilage zone
Calcified cartilage zone
41
Growth of cartilage model
Part of endochondral ossification.
| -- Chondroblasts --> chondrocytes. Model grows longer. Interstitial growth and appositional growth occurs
42
Avulsion
Forceful tearing of muscles and tendons that pull portions of bone with it.
43
What is the composition of the bone extracellular matrix?
25% water
25% collagen fibre
50% crystallized mineral salts
44
Periosteal arteries/veins
Enter through Volmann's/perforating canals
| Carry blood to and from outer portion of compact bone and periosteum
45
Endosteum
Layer of dense irregular connective tissue that lines medullary cavity.
46
Reactive phase of fracture repair
Clots form around broken vessels, creating a fracture hematoma.
Blood flow stops, local bone cells dies.
Inflammation occurs in response; phagocytes and osteoclasts move in to clean up.
Lasts several weeks.
47
Lacunae
Areas/spaces within lamellae where osteocytes can be found.
Snow angel bodies.
48
Impacted fracture
One bone if forced into another bone
49
Interstitial growth
replication of chondrocytes accompanying new matrix --> lengthening
Part of Growth of cartilage model
50
Circumferential lamellae
Surround the medullary cavity or lie underneath the periosteum, along circumference of the bone. Tends to circle around interstitial and concentric lamellae.
51
What are the stages of apposition cell growth?
1. Periosteal cells differentiate into Osteoblasts, which turn into osteocytes, which create ridges on either side of blood vessel.
2. Ridges fuse and become tunnel.
3. Osteoblasts in (new) endosteum create new concentric lamellae
4. As osteon forms, osteoblasts under periosteum create new circumferential lamellae.
5. All the while, osteoclasts are destroying bone lining medullary cavity to enlarge it as well.
52
Metaphysis
Portion in between diaphysis and epiphysis.
Weakest portion.
Contains epiphysial plate --> epiphysial line
53
Trabeculae
Lamellae of spongy bone
| Coral-like appearance
54
Bone Remodelling
Final stage of fracture repair.
Osteoclasts move in to resorp any remaining fragments. Compact bone eventually replaces spongy bone around the periphery.
55
Nutrient arteries/veins
Enter through nutrient foramen in the diaphysis
| Supplies blood to the inner portion of the compact bone and also proximal parts of the spongy bone
56
What is the normal levels of Ca+ in the blood?
9-11 mg/100ml
More that than, heart stops.
Less than that, respiration stops.
57
Cole's fracture
Occurs in hands and wrist, often as a result of a FOOSH.
| Fall drives carpals posteriorly.
58
Wolf's Law
Bone tissue will lay down along lines of stress
| ex. trauma, infection, cancer, aging
59
Development of cartilage model
Part of endochondral ossification.
-- mesenchyme --> chondroblasts, which secrete ECM, producing a cartilage model consisting of hyaline cartilage, surrounded by perichondrium
60
Closed fracture
aka simple fracture
| doesn't break skin
61
Bone scan
Radioactive tracer in injected and taken up by bone. Hot spots show increased metabolism (i.e. cancer) and cold sports suggest healed fractures.
62
Ca+ concentration is controlled by:
1. Parathyroid hormone (PTH)
| 2. Calcitonin
63
Development of Primary Ossification Centre
Part of endochondral ossification.
-- nutrient artery penetrates into the middle of the cartilage, initiating activity of osteoblasts. Perichondrium --> periosteum. Local cartilage --> bone
64
Resorption
The process by which osteoclasts breakdown and destroy portions of bone ECM.
Part of normal bone growth and of healing after fractures.
65
Calcification
Calcium phosphate + calcium hydroxide --> hydroxyapatite
Which will combine with Fl-, K+, (So4)2- and Mg2+.
Adhere to collagen fibres and harden.
66
Reparative Phase 1.0
Fibroblasts invade site and lay down collagen fibres.
Chondroblasts invade from periosteum and produce fibrocartilage.
Fibrocartilaginous Callus is formed.
67
Calcified cartilage zone
In metaphysis.
Mostly dead chondrocytes. Calcified.
Osteoblasts invade to lay down new extracellular bone matrix to convert it from calcified cartilage to new diaphysis and new blood vessels are formed.
68
Osteomalacia
Called rickets in kids
Failure of bones to calcify.
Organic matrix is present but calcium salts not deposited.
Often due to Vitamin D deficiency
69
Intramembranous Ossification
Simpler method. Flat bones of skull, facial bones, mandible, medial clavicle.
70
Four main types of bone cells
1 osteogenic
2 osteoblasts
3 osteocytes
4 osteoclasts
71
Three types of lamellae
Concentric
Interstitial
Circumferential
72
Interstitial lamellae
Located between osteons
73
When does ossification occur?
Begins in 6th week of embryonic development and continues into maturity,
74
Osteoporosis
Loss of bone mass associated with deterioration of the micro-architecture of bone tissue
75
Ossification/Osteogenesis
bone formation
76
Central canals
aka Haversian canals
| Parallel canals that run deep and longitudinally. Carry blood, lymphatic vessels, nerves.
77
Comminuted fracture
Bone splinters and pieces are trapped between main fragments
78
Resting cartilage zone
The zone of the metaphysis nearest to the epiphysis.
Consists of small chondrocytes that anchor epiphyseal plate to the bone.
"Resting" because cells not involved in bone growth
79
Lamellae
The matrix of bone, arranged in thin, platelike structures.
80
Sharpey's fibres
Perforating fibres that mesh with bone matrix and help keep periosteum in place.
81
Appositional growth
Deposition of ECM on cartilage surface and periphery.
| Part of Growth of Cartilage Model
82
Endochondral Ossification
A method of bone formation where cartilage is developed fires, then replaced by bone. Most bones of the body formed this way.
83
Where is spongy bone found?
In long bone, mostly concentrated in ends.
| Flat bones, some irregular and all cuboidal bones are predominantly spongy.
84
Calcitonin
A hormone, produced by thyroid parafollicular cells. Released in response to elevated Ca+ levels.
Decreases activity of osteoclasts; increases activity of osteoblasts (bone formation increases)
85
How do hormones regulate blood Ca+ levels?
```
Controlled condition (decreased Ca+ levels) -->
Receptor (parathyroid gland) --> Releases PTH --> bone resorption increases/ kidneys retain Ca+/ increased absorption of Ca+ in GI tracts --> increase in blood Ca+ level --> homeostasis achieved. High five!
```
86
Open fracture
aka compound
| broken ends of bone protrude through skin.
87
Why is compact bone compact?
Because there is little space between cells. Composed mostly of calcium, phosphate, collagen and other minerals.
88
What are the steps of fracture repair in bones?
1. formation of fracture hematoma (reactive phase)
2. fibrocartilaginous callus formation (reparative phase 1.0)
3. bony callus formation (reparative phase 2.0)
4. bone remodelling
89
Resorption
The breaking down of bones by osteoclasts. Ca+ is taken from the bone and put in the blood.
90
Where is extra Ca+ stored?
Muscle and liver cells, in smooth endoplasmic reticulum
91
Formation of articular cartilage and epiphyseal plate
Last stage of endochondral ossification
| hyaline cartilage becomes articular cartilage
