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Muscoloskeletal Pathophysiology - Bones and Trauma
Pathology of the Muscoskeletal system
61
Physiology
Undergraduate 3
12/13/2013

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Cards

Term
Name the 3 sections of a long bone, and where each is located
Definition
1. Epiphysis - head of bone
2. Metaphysis - between two other zones where growth occurs
3. Diaphysis - the shaft
Term
What is the periosteum?
Definition
The CT sheath that covers bones
Term
(T/F) The periosteum provides blood supply to bones
Definition
True
Term
What is the endosteum?
Definition
The lining of the medullary cavity
Term
What is contained within the endosteum?
Definition
Bone marrow
Term
(T/F) This is the site of hematopoiesis
Definition
True
Term
Which 4 bones does this process occur in in adults?
Definition
1. Sternum
2. Cranium
3. Ribs
4. All long bones
Term
What are the two bone types?
Definition
1. Spongy (cancellous/trabecular)
2. Compact (cortical)
Term
Name 4 components of compact bone structure
Definition
1. Haversian system
2. Lamellae (matrix rings)
3. Haversian canals
4. Osteocytes in lacunae
Term
What are the two components of a bone's composition, and what contribution does each component contribute?
Definition
1. Collagen matrix - the "scaffolding"
2. Hydroxyapatite (Ca10(PO4)6(OH)2) - the "bricks"
Term
What determines the composition of a bone?
Definition
Balance between osteoblast and osteoclast activity
Term
What is the function of osteoblasts?
Definition
- Ca2+ deposition
- Increases alkaline phosphotase
Term
What is the function of osteoclasts?
Definition
- Bone resorption (breaking down bone) to release calcium
Term
How is osteoclast/osteoblast activity regulated?
Definition
By hormonal activity
Term
What type of receptors do osteoclast precursors have?
Definition
RANK receptors
Term
What two substances do osteoblasts make?
Definition
1. RANK ligand
2. Osteoprotegrin (OPG)
Term
What does RANK-L do?
Definition
- Stimulates osteoclast activity when it binds with RANK-R on osteoclasts
Term
What does OPG do? How does it do this?
Definition
- Inhibits osteoclast activity
- Joins with RANK-L therefore no binding at RANK-R
Term
(T/F) Estrogen presence decreases OPG synthesis
Definition
False, it increases it
Term
(T/F) In men, testosterone is converted to estrogen in bone by aromatase
Definition
True
Term
Which two substances (hormonal or otherwise) increase osteoclast activity?
Definition
1. PTH
2. Vitamin D3
Term
(T/F) Vitamin D3 needs to be activated before it induces osteoclast activity
Definition
True
Term
Which organ activates it, and what is active vitamin d3 (1,25-D3) called?
Definition
- Kidney (renal activation)
- Calcitriol
Term
What does calcitriol cause, other than bone resportion?
Definition
Increased GI absorption of Ca2+ and PO4
Term
What does increased Ca2+ and PO4 on the blood trigger?
Definition
Bone mineralization by osteoblasts
Term
What is the effect of growth hormone on bone remodeling?
Definition
GH increases osteoblast activity therefore increased bone formation
Term
What is the effect of cortisol on bone remodeling?
Definition
Cortisol causes removal of the bone matrix by stimulating osteoclasts
Term
What is responsible for cartilage production?
Definition
Chondrocytes
Term
Describe how bones are lengthened
Definition
1. Chondrocytes produce cartilage
2. Osteoblasts invade the newly synthesized cartilage
3. Cartilage phosphate becomes calcified by osteoblasts, making it more rigid
Term
Where does bone growth occur?
Definition
At the epiphyseal plate
Term
(T/F) Androgens stimulate the close of the epiphyseal plate
Definition
True
Term
What is complete bone trauma? Incomplete?
Definition
A complete fracture; a partial fracture
Term
Describe what occurs with a greenstick break, and what type of trauma is this?
Definition
- Bone splits similar to a young tree (doesn't brake cleanly)
- Incomplete
Term
Why is a greenstick fracture more likely to occur with children?
Definition
Because their bones are still developing, therefore do not have a full mineralization and are more flexible
Term
What is an open break? A close break?
Definition
Open = bone penetrates skin; closed = break remains within tissue
Term
What is a segmented fracture? A comminuted fracture?
Definition
Segmented: only two pieces created - 1 fracture line
Comminuted: bone has broken into several pieces - multiple fracture lines
Term
List the 3 common fracture types, and describe each
Definition
1. Transverse - 90 degree angle to the bone
2. Spiral - One part of bone is twisted
3. Oblique - at a diagonal to bone axis
Term
List 4 other types of bone fractures?
Definition
1. Impacted
2. Pathological
3. Stress
4. Depressed
Term
Describe impacted fractures
Definition
Fracture caused by bone segments being driven into each other
Term
Describe pathological fractures
Definition
The bone is made weak by a pathology
Term
Describe stress fractures
Definition
Fracture is not through the entire bone, but multiple fracture lines that weaken the bone overall
Term
Describe depressed fractures, and where they usually occur
Definition
Bones are displaced inwards - usually happens in the skull (blunt force trauma)
Term
List the two special types of fractures
Definition
1. Colles'
2. Pott's
Term
What occurs in a Colles' fracture?
Definition
Occurs at the distal radius, where the tips of the radius are broken off
Term
What occurs in a Pott's fracture?
Definition
Occurs at the ank;e, can break the tips of the fibula/tibia off
Term
List common symptoms of fractures?
Definition
 swelling
 loss of function/deformity
 crepitus (sound of bone breaking)
 pain
 early numbness
Term
List the pathophysiological steps to a fracture, and what occurs in each
Definition
1. Bleeding/hematoma - under the periosteum
2. Granulation tissue is formed
3. Procallus formation
4. Bony callus created
5. Remodelling
Term
What is responsible for forming the procallus?
Definition
Chondrocytes
Term
What is osteogenesis, and what step does it occur at?
Definition
"Throwing bone in wherever you can" - creation of the bony callus
Term
What cells are the most important for bone remodeling, how long does the remodeling occur for, and what is the purpose of it?
Definition
- Osteoclasts
- 3-4 months
- Removes parts of the bony callus that are not needed
Term
List the 5 factors that affect bone healing
Definition
1. Degree of damage
2. Inflammation/blood supply
3. Approximation
4. Foreign material
5. Systemic factors
Term
What is approximation? What two things does it consist of?
Definition
How well the bones are realigned to their original position. Reduction and immobilization
Term
What is the purpose of reduction?
Definition
Getting the bones into their original alignment
Term
What is the purpose of immobilization?
Definition
Preventing motion so that calcium and phosphate is laid down right away
Term
What is depridement, and why is it important for bone healing?
Definition
- Removal of foreign material from the site of break
- Important because foreign materials increase recovery time
Term
List 3 systemic factors that affect bone repair
Definition
1. Diabetes
2. Glucocorticoids
3. Nutrition
Term
List 6 complications that can arise with healing?
Definition
 Muscle spasm  Infection  Ischemia  Compartment syndrome  Fat emboli  Non-union
Term
How do muscle contractions complicate healing, and how is this combated?
Definition
- Change approximation (unalign bone)
- Traction - counteracts muscle spasms and ensures proper approximation
Term
What is compartment syndrome?
Definition
Initial swelling after trauma can squeeze nerves and vessels, leading to reduced healing
Term
How can it arise?
Definition
Cast is too tight
Term
How is compartment syndrome avoided?
Definition
By utilizing multiple casts over the healing process to ensure proper fit
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