Histology of MSDR Disorders Flashcards
1
Q
Common features of bones and cartilage
A
- Designed for support and movement
- Common origin of mesenchymal cells
- Contains extracellular matrix and cells
2
Q
Functions of bone
A
- Mineral storage – provides “sink” for calcium, phosphates, and “poisons”
- Hematopoietic – medullary canal is site of hematopoiesis
- Mechanical support – framework for muscle attachment
3
Q
Wolff’s Law
A
Wolff’s Law – bone remodeling by osteoclasts and osteoblasts occur due to electrical current changes produced by pressure changes on bone
4
Q
Extracellular matrix
A
type I collagen fibers laid down in ground substance called osteoid
5
Q
Specific components of bones
A
- Extracellular matrix
- Mineral component – inorganic mineral salts (osteoblasts deposit calcium)
- Cells
- Osteoblasts
- Osteocytes
- Osteoclasts
6
Q
A
Osteoblasts – mononuclear cells that sit on surface of bone and build bone
7
Q
A
Osteocytes – osteoblasts with dendritic ends that get incorporated into bone matrix that maintain bone and participate in ion exchange
8
Q
A
Osteoclasts – multinucleated giant cells that degrade bone
9
Q
Woven bone
A
- Randomly oriented collagen fibers (think: particle board)
- Only found in fetus and abnormal states in adults (i.e. tumor, fractures)
10
Q
Lamellar bone
A
- Highly organized, strong, parallel collagen fibers (think: sheets of wood)
- Mature bone
11
Q
Cortical bone
A
- Outer lamellar shell of bone
- Shows up as brightest white on X-ray
- Contains osteons, Haversian canal (vertical supplying blood to individual osteon), and Volkmann’s canal (horizontal connecting osteons)
12
Q
Trabecular bone
A
Spongy bone in medullary canal
13
Q
Periosteum
A
- Fibrovascular sheath surrounding cortex (read: cortical) bone
- Contains progenitor cells (osteoblasts and fibroblasts) that are involved in fracture healing
14
Q
Enchondral ossification
A
- Cartilage undergoes degeneration and calcification and gradually gets replaced by osteoid by coupled reaction of osteoblasts and osteoclasts except for the skull and clavicle bones
- Most bones are formed this way
- Physis growth pathway (lengthening of bone)
- Physis is made up of cartilage
15
Q
Steps in Enchondral ossification
A
Necrosis → calcification → ingrowth of new vessels → resorption → transformation into osteoid matrix
16
Q
Membranous bone formation
A
- Osteoid forms directly from primitive fibrous tissue without cartilage
- Skull and part of clavicle are formed this way
17
Q
Function of cartilage
Tow main discriminating factors?
A
- Function of cartilage: structural model for development of bone (endochondral ossification) → allows for articulation of joints
- Type II collagen
- Avascular
18
Q
Diarthrodial (or synovial) joint
A
- Diarthrodial (or synovial): allows for complete movement with hyaline cartilage
- Enclosed by synovial membrane
19
Q
Types of cells in the synovial membrane
A
- Type A cells have phagocytic properties
- Take metabolites made by articular cartilage and transfers to blood stream
- Type B cells have secretory properties
20
Q
Fibrocartilagenous joints
Found where?
A
- Fibrocartilagenous: limited movement usually with fibrocartilage
- Vertebral joints
21
Q
Fibrous (synarthrosis) joint
Found where?
A
- Fibrous (synarthrosis): allows for no movement usually with fibrocartilage or just fibrous tissue
- Cranial sutures
22
Q
Fibrocartilage
A
Description: Layers of collagen
Location: Intervertebral discs, joint capsules, pubic symphysis
23
Q
A
Fibrocartilage
24
Q
A
Fibrocartilage
25
Elastic
26
Hyaline
27
Hyaline
28
Elastic
Description: Bundles of branching elastic fibers
Location: Ears, epiglottis
29
Hyaline
Description: Glossy white lining of bone articulations
Location: Joints, nasal septum
30
What is shown?
What is the related disorder?
* Osteoarthritis
* Eburnation (1) – cartilage is worn away and underlying bone is polished
* Subchondral cyst (2) – a fluid sac under the cartilage near the epiphysis
* Normal cartilage (3)
* Osteophytes – bone growths
31
What is shown?
What is the related disorder?
* Rheumatoid arthritis
* Pannus – synovial lesion in RA
32
What is shown?
What is the related disorder?
* Gout
* Tophi – chalky paste-like deposits made up of sodium urate crystals
* Needle-like crystals
33
What is shown?
What is the related disorder?
* Pseudogout (Calcium pyrophosphate dehydrate)
* Rhomboid shaped-like crystals
34
What is shown?
What is the related disease?
* Avascular necrosis of bone
* Loss of blood supply resulting in wedged shaped infarct (aka necrosis)
* Can be seen on radiographs as a “crescent sign”
35
Achondroplasia
Inheritance pattern? Clinical presentation?
* Defect in formation of cartilage – mutation in fibroblast growth factor-3 receptor
* Mainly affects physeal plates – decrease in chondrocyte proliferation
* Autosomal dominant
* Most common inherited form of dwarfism
* Large heads and clavicle bones because there is no cartilage present
* Bridge of nose is compressed
36
Osteogenesis Imperfecta Congenita
* Affects formation – both quantity and quality – of type I collagen (COL1A1 and COL1A2)
* Bone fragility causes repeated fractures with ineffectual healing causing short stature
* Bones look bendy, but they actually only heal this way after fractures
37
Fibrous Dysplasia
Clinical presentation? Common site of dsease?
* Benign disorder where woven bone is unable to form organized lamellar bone
* Bones affected – femur, tibia, ribs, maxilla
* Clinical
* Usually affects only one bone (monostotic)
38
Fibrous Dysplasia
Pathology? (Gross and Micro)
* Gross – involves medullary canal which causes bone expansion
* Ground glass appearance with widened bone under XR
* Micro – islands of osteoid without osteoblasts
39
Fibrous Dysplasia
40
Paget's Disease
Patho? Epidemology? Symptoms? Sites of Disease?
* Osteoclasts “go crazy” autonomously without external signals
* Remove bone where it doesn’t need to be broken down
* Clinical – after age 40 in white northern Europeans
* Symptoms
* Pain = bone turnover
* Microfractures = immature bone laid down
* Large forehead
* Bowed legs
* Enlarged bones
* Compression of the brain = herniation
* Bones affected – skull, pelvis, and femur
* Affects more than one bone at a time, and affects them with different waves of activity
41
Paget's Disease
Three Phases
* Osteolytic phase – crazy osteoclasts resorb bone
* Mixed phase – bone formation in attempt to repair (osteoclast activity \> osteoblast)
* Burnt out phase – quiescent with mosaic pattern of cement lines
42
Paget's Disease
Treatment?
Treatment with bisphosphonates (inhibits osteoclast activity)
43
Osteosarcoma
* Osteosarcoma – neoplasm of bone
* Anaplastic cells making osteoid
44
Chondrosarcoma
* Chondrosarcoma – neoplasm of cartilage
* Lots of chondrocytes that grow in clones
* Invasion of marrow space
45
Primary neoplasms of bone metastaize to?
**flat bones,** which Arsh for some reason thinks is spelled "falt bones". So I had to look up what a "falt bone" was. And there is no such thing. Thanks Arsh.
46
Secondary neoplasms of the bone come from
blt w/kp, m – breast, lung, thyroid, kidney, prostate, melanoma
47
Pseudo-tumors
* Arise from primitive mesenchymal cells (pluripotent stem cell)
* When one cell type grows where another cell type exists
48
Nodular Fasciitis
Nodular Fasciitis – after injury, reparative cells become fibroblasts rather than fibrous tissue
49
Myositis Ossificans
Myositis Ossificans – bone forms inside of muscle
50
Signicifance of seeing this type of radiograpgh?
All three stages of Paget's disease are seen
51
Paget's disease: Mixed stage
52
Paget's disease: Burnt out phase
53
Osteosarcoma
## Footnote
Anaplastic cells making osteoid
54
Chondrosarcoma
55
Nodular Fasciitis
56
Myositis Ossificans
57
What is Osteoporosis?
Patho? Areas affected? symptoms?
Osteoporosis – low bone mineral density causing increased risk of fracture
* Pathophysiology
* Osteoclast activity overtakes osteoblast activity due to physical activity, genetic factors, and nutrition
* Common affected areas
* Wrist, hip, and spine
* Sequelae
* Fragility fractures – any fracture that occurs from a fall at ground level
* Deformities of bone (secondary to fractures)
* High incidence rate and high mortality
58
Osteoporosis
Risk factors? Sceening options?
* Risk Factors
* Age
* Females more than males
* Post-menopause (2%/year bone loss)
* Every comorbidity under the sun
* Screening
* DEXA Scan – measures bone density
* Considered gold standard of diagnosis
59
Osteopenia treatment?
* Treatment
* Medications
* Calcium and vitamin D
* Weightbearing exercise
60
Osteopenia versus osteoporosis
* Patients with osteopenia have higher bone density than osteoporosis
* Patients with osteopenia have higher incidence of fractures because oftentimes more active lifestyles
61
What is Rickets/Osteomalacia?
Who does each effect?
Rickets/Osteomalacia – decrease in the mineralization of the otherwise normally formed matrix secondary to vitamin D deficiency
* Rickets – growing child
* Osteomalacia – skeletally mature person
62
Normal vitamin D metabolism
* Normal vitamin D metabolism
* Maintains normal levels of plasma levels of Ca++ and phosphate
* Absorption through skin and GI tract
* Metabolism in liver and kidney
63
Hyperparathyroidism Types?
* Types
* Primary – tumor on parathyroid
* Secondary – abnormal Ca++ or phosphate levels influencing parathyroid activity
64
Hyperparathyroidism
Patho? Symptoms?
* Increased secretion of PTH by parathyroid → stimulation of osteoclasts (via osteoblasts)
* Ca++ resorption
* Results
* Osteopenia – loss of bone
* Brown tumor of bone – hemorrhagic cysts
* Osteitis fibrosa cystica – cystic spaces in bone replaced with fibrous tissue instead of bone
65
Renal Osteodystrophy
* Blanket term for when chronic renal disease causes disorders of bone, including secondary hyperparathyroidism
* Chronic renal failure (CRF) → increase in serum phosphate → stimulation of parathyroid gland → secondary hyperparathyroidism → bone disease
