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Anatomy & Physiology > CHAPTER 6- BONES AND SKELETAL TISSUE PT 2 > Flashcards

CHAPTER 6- BONES AND SKELETAL TISSUE PT 2 Flashcards

1
Q

2 types of ossification (bone formation)

A
  1. Intramembranous ossification (within fibrous membrane)
  2. Endochondral ossification (“bone chases cartilage”)
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2
Q

Intramembranous ossification

A
  • growth within fibrous membrane, bone will start growing
  • bone develops from fibrous membrane
  • forms most flat bones (cranial bones, for example)
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3
Q

Endochondral ossification

A

*within cartilage, bone chases cartilage
- cartilage (endochondral) bone forms by replacing hyaline cartilage model
- forms most of the rest of the skeleton
- requires breakdown of hyaline cartilage PRIOR to ossification

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4
Q

Endochondral ossification steps

A
  1. Bone collar starts to form around diaphysis
  2. Medullary cavity starts to form inside bone collar
  3. Blood vessels move into medullary cavity
  4. Diaphysis elongates then the secondary ossification centers form in epiphyses (both ends of bones)
  5. The epiphyses ossify (turn into bone)
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5
Q

postnatal bone growth

A
  1. interstitial growth
    - length of long bones (growth between cartilage lacuna)
  2. appositional growth
    - thickness and remodeling of all bones by osteoblasts and osteoclasts on bone surfaces
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6
Q

Bone resorption

A

*Taking away bone
osteoclasts secrete:
1. lysosomal enzymes (digest organic (osteoids and proteins) matrix)
2. acids (convert calcium salt into soluble forms)
- dissolved matrix is transcytoses across osteoclast, enters interstitial fluid and then blood

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7
Q

Bone remodelling

A
  1. resorption (removal) and deposit occur together
  2. occurs at the surface of periosteum and endosteum
    • performed by osteoclasts (resorption) and osteoblasts (deposit)
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8
Q

Bone remodeling

A
  • resorption (removal) and deposit occurring together
  • occurs at bone surface of periosteum and endosteum
    *performed by osteoclasts (resorption) and osteoblasts (deposit)
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9
Q

Bone remodeling doesn’t…

A

happen equally throughout the skeleton
- areas of high stress (like neck of femur) remodel more to prevent becoming too brittle

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10
Q

osteocytes are like the…

A

bosses of osteoclasts and osteoblasts, telling them to remodel

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11
Q

Control of remodeling

A
  1. hormonal mechanisms that maintain calcium homeostasis in the blood (for ions)
  2. Mechanical and gravitational forces sensed by osteocytes:
    • communicate over large distances to stimulate remodeling
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12
Q

removal of osteocytes causes…

A

loss of remodeling activities

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13
Q

hormonal control of blood Ca2+

A

since most of the calcium in the body is stored in bone, calcium is necessary for:
- transmission of nerve impulses
- muscle contraction (in heart!)
- primarily controlled by parathyroid hormone (PTH)

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14
Q

PTH process

A
  1. Blood calcium levels drop (due to lots of exercise, for example)
  2. Parathyroid glands increase release of PTH
  3. PTH stimulates osteoclasts to resorb bone matrix and release calcium
  4. Blood calcium levels increase
  5. Parathyroid gland turns of influx of PTH
    ***NEGATIVE FEEDBACK LOOP (GOING BACK TO HOMEOSTASIS)
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15
Q

Response to mechanical stress:

A
  • Wolff’s Law: a bone grows/remodels in response to forces or demands placed upon it
  • observations supporting Wolff’s Law:
    • handedness results in that hand’s bone being stronger and thicker
    • curved bones are thickest where they are most likely to buckle
    • trabeculae form along lines of stress
    • large, bone (tubercles and trochanters) projections occur where heavy, active muscles attach
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16
Q

statistics

A
  1. fractures of extremities are most common
  2. more common in men up to 45 years of age
  3. more common in women over 45 years of age
  4. up to 75 years, wrist fractures most common
  5. after 75 years, hip fractures most common
17
Q

Classification of bone fractures:

A
  1. position of bone ends after fracture
    • nondisplaced: ends retain normal position
    • displaced: ends out of normal position
  2. completion of the break (self explanatory)
  3. orientation of the break to the long axis of the bone
    • linear: parallel to long axis of the bone
    • transverse: perpendicular to long axis of the bone
    • spiral or oblique: on an oblique angle (paper towel roll)
  4. whether or not the bone ends penetrate the skin
    • compound (open): bone penetrates skin
    • simple (closed): bone ends don’t penetrate skin
18
Q

Common types of fractures:

A
  1. Comminuted fracture
  2. Compression fractures
  3. Spiral or oblique
  4. Epiphyseal fracture
  5. Depression fracture
  6. Greenstick
  7. Transverse
19
Q

Comminuted fracture

A

3 or more bone pieces broken
High energy trauma

20
Q

Compression fracture

A

AKA Crush fracture (mostly vertabrae)
Fracture in spongy bone (result of compression- osteoporosis)

21
Q

Spiral or oblique

A

Caused by violence transmitted through limb from a distance (twisting movements)

Like twisting arm from wrist

22
Q

Epiphyseal fracture

A

Breakage at the growth plate

23
Q

Depression fracture

A

Broken bone portion is pressed inward (most common on the skull)

24
Q

Greenstick fracture

A

*mostly younger kids
Bone is broken incompletely (bone is bent without being completely broken)

25
Q

Transverse fracture

A

perpendicular to the fracture

26
Q

Functions of the x-ray

A
  1. localizes fracture and possible fragments
  2. indicates degree of displacement
  3. evidence of pre-existing bone disease
  4. foreign bodies or air in tissues, show other fractures
    * need MRI, CT or ultrasound to reveal soft tissue damage
27
Q

How to handle a fracture

A
  1. Reduction: putting bone ends in right position
    • closed reduction: manipulation (cracking bone back into place w/o surgery)
      - open reduction (surgery): allows accurate reduction, risk of infection
  2. manipulation: usually with anesthesia
  3. traction fractures or dislocation requiring slow pulling resistance
28
Q

Steps in bone repair: Step 1

A

Hematoma (blood clot) forms:
- torn blood vessels hemorrhage (because breaking bone tears blood vessels)
- clot forms
- inflammation site lasts 6-8 hours after surgery

29
Q

Steps in bone repair: Step 2

A

Fibrocartilaginous (soft) callus forms:
*bone has to be fixed first
- phagocytic cells clear debris
- osteoblasts begin forming spongy bone within 1 week
- fibroblasts secrete collagen fibers to connect bone ends
- most of repair tissue now called soft callus (because it’s not strong, just spongy bone)
- lasts about 3 weeks

30
Q

Steps in bone repair: Step 3

A

Bony (hard) callus formation:
- new trabecular form a bone (hard) callus
- bony callus formation continues until firm union is formed in about 2 months
*important to start using the bone

31
Q

Steps in bone repair: Step 4

A

Bone remodeling:
- replacing trabeculae with osteons, compact bone

32
Q

Osteoporosis

A
  • in vertebrae and neck of femur
  • loss of bone mass- bone resorption outpaces deposit
  • due to lack of estrogen, calcium or vitamin D

Anatomy & Physiology (20 decks)

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