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BRS Bioregulatory Systems > Innury And Healing > Flashcards

Innury And Healing Flashcards

1
Q

Why does bone break

A

Trauma-low energy or high energy
Stress-repetitive abnormal force on bone so weakening occurs leading to fractures
Pathological-normal stress on abnormal bone

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2
Q

What conditions lead to pathological insufficiency fractures

A

Osteopenia and osteoporosis - Soft bone

Malignancy

Vitamin-D deficiency - leads to osteomalacia (adults) or rickets (children)

Osteomyelitis (bone infection)

Osteogenesis Imperfecta - Collagen deficiency

Paget’s disease

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3
Q

Osteopenia/osteoporosis

A

Loss of bone density
Osteoclasts activity is greater than osteoblasts activity

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4
Q

Primary vs secondary osteoporosis

A

Primary related to old age
Secondary occurs at any age due to hypogonadism,glucocorticoids in excess as it inhibits insulin growth factor reducing osteoblasts activity
Alcoholism increases pth which leaches calcium from bones

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5
Q

What does osteoporosis do to bone

A
  • Fewer trabeculae
  • Thinning of the cortical bone
  • Widening of Haversian canals
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6
Q

Vitamin D deficiency

A

Leads to defects in osteoid mineralization
Causes rickets in children and osteomalacia in adults

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7
Q

Congenital osteoimperfecta

A
  • Decreased type 1 collagen due to decreased secretion and production of abnormal collagen
  • Leads to insufficient osteoid production
    Affects bones hearing heart and sight
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8
Q

Pagers disease

A

Excessive bone breakdown and disorganized remodeling
Due to too much or too little osteoblasts and osteoclasts activity

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9
Q

Bone cancers CEOL

A
  • Osteosarcoma- cancers in osteoblasts
  • Chondrosarcoma- cancer in chondrocytes
  • Ewing Sarcoma
  • Lymphoma
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10
Q

Secondary bone cancer

A

Metastatic bone tumours from other tissue

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11
Q

How do we describe fractures

A

Open - Fracture in which at least one end of the bone penetrates the skin; presenting potential risk of infection

Closed - A fracture in which the skin remain intact

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12
Q

How do bone tissues heal

A

Bleeding- blood products involved

2) Inflammation- neutrophils, macrophages involved

3) New tissue formation- blasts involved (fibro-, osteo-, chondro-)

4) Remodelling- macrophages, osteoclasts and osteoblasts involved

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13
Q

What fractures heal more specifically

A

1) Haematoma forms- bleeding between bone ends

2) Inflammation- cytokines released & there’s granulation (connective/fibrotic) tissue deposited + blood vessel formation

3) Repair- chondroblasts make soft callus (type 2 cartilage collagen) which is converted to hard callus (type 1 collagen which is more like bone), facilitated by increased osteoblast activity

4) Remodelling- callus responds to activity, external forces, functional demands and growth- osteoblasts heavily involved. Excess bone is also removed

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14
Q

Wolffs law

A

Bone grows and remodels in response to the forces that are placed on it

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15
Q

Primary bone healing

A
  • Intramembranous healing
  • Mesenchymal stem cell goes straight to osteoblast and there’s direct formation of woven bone
  • Happens when you have a stable fracture (absolute stability) and ends of bone are really close together
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16
Q

Secondary bone healing

A
  • Endochondral healing
  • Results in more callus forming
  • Involves responses in the periosteum and external soft tissues
  • Occurs when you have a relatively stable fracture
  • Mesenchymal stem cell goes to chondral precursor which produces bone cells
  • takes longer than primary bone healing
17
Q

Fracture management

A
  • Reduction- bring fracture ends together, (can either be closed or open)
  • Hold- the ends in the right position with metal or no metal
  • Rehabilitate- once bone has healed, limb will still be weak- needs rehabilitation
18
Q

What two ways do bones develop in utero? (and which bone class does each development method form)

A

Intramembranous Ossification - First occurs after conception → flat bones

Endochondral Ossification - Begins 2 months into utero → long bones

19
Q

Intramembranous ossification

A
  1. Clustering/condensation of mesenchymal stem cells which differentiate into osteoblasts
  2. The ossification centre forms
  3. Osteoblasts begin to secrete osteoid inwards towards ossification centre
  4. Osteoblasts become trapped in osteoid (unmineralised organic tissue) causing differentiation into osteocytes
  5. Osteoid calcifies and hardens after several days
  6. Trabecular matrix (cancellous bone) and periosteum (outside connective tissue layer) form (Mesenchyme differentiate into periosteum)
  7. Compact bone/cortical bone develops superficial to cancellous bone and crowded blood vessels (in trabecular spaces) condense into red bone marrow

!https://s3-us-west-2.amazonaws.com/secure.notion-static.com/e4f765dd-c50a-4d2a-b1ed-ca2ac69febd9/Untitled.png

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20
Q

Endochondral ossification

A
  1. Start with a hyaline cartilage precursor- then forms a ring of tissue around it called perichondrium (perichondrium vascularised and blood vessels supply new nutrients to mesenchymal, causing differentiation)
  2. Mesenchymal stem cells in cartilage differentiate into osteoblasts
  3. Osteoblasts gather at diaphysis wall of the bone to form the bone collar
  4. Chondrocytes within central cavity enlarge, form a calcified matrix, making it impermeable to nutrients, causing cell death
  5. Primary ossification centre (diaphysis) forms at the centre of the bone
  6. Periosteal bud (consisting of artery, vein, lymphatics and nerves) invades cavity causing formation of spongy bone, by delivering osteoclasts that break down cartilage and osteoblasts that deposit new spongy bone
  7. Healthy chondrocytes at ends depositing new cartilage causing bone elongation
  8. At primary oss. centre, diaphysis continues to enlarge and osteoclasts break down centre of spongy bone to form medullary cavity where yellow bone marrow (fat) will be.
  9. Secondary ossification centre appears in epiphyses (the ends of long bones)
  10. Junction between primary and secondary ossification is epiphyseal plate and cartilage at ends of bone only stays at surface to lubricate ends for joints
21
Q

What is the structure of long bones?

A

Epiphysis- at joint

Physis- growing area

Diaphysis- long bone

22
Q

Osteogenic cells

A

Bone stem cells
Found in periosteum

23
Q

Osteoblasts

A

Bone forming cells that secrete osteoid and catalyse osteoid mineralization

24
Q

Osteoclasts

A

Bone breaking cells that dissolve and resorb bone by phagocytosis
Entrapped in matrix

25
Q

Osteocyte

A

mature bone cells that are formed when osteoblasts become embedded in their owns secretions- sense mechanical strain to direct osteoclast and blast activity
Found at bone surfaces at old injured bone

26
Q

Immature bone

A
  • The first bone produced by the body
  • Laid down in a ‘woven’ manner and is relatively weak
  • Mineralised and replaced by mature bone
27
Q

Mature bone

A
  • Lamellar (layer) structure- relatively strong
  • Mineralised woven bone
  • Replaces immature bone
28
Q

2 types of mature bone

A
  • Cortical bone- compact and dense, suitable for weight bearing
  • Cancellous bone- spongy and honeycomb structure, not suitable for weight bearing
29
Q

Osteon

A

Concentric ‘lamellae’ around a central ‘Haversian Canal’

The ‘Haversian Canal’ contains blood vessels, nerves and lymphatics

  • A structural unit of cortical bone
  • Concentric lamellae of bone laid down by osteoblasts that get trapped within their mineralisation to become osteocytes
30
Q

Lacunae

A

Small spaces containing osteocytes

Tiny Canaliculi radiate from lacunae filled with extracellular fluid

31
Q

What are transverse perforating canals in the bone called (2 word VSAQ), and what do they do (4 word VSAQ)?

A

Volkmans canals join Haversian canals

32
Q

Interstitial growth

A

Long bones

Zone of elongation in long bone

Contains hyaline cartilage

Epiphyseal side - Hyaline cartilage active and dividing to form hyaline cartilage matrix

Diaphyseal side - Cartilage calcified and dies and then replaced by bone

33
Q

Appositional growth

A

Deposition of bone beneath periosteum to increase thickness

1) Ridges in periosteum create groove for periosteal blood vessel

2) Periosteal ridge fuses, forming an endosteum-lined tunnel

3) Osteoblasts in endosteum build new concentric lamellae inward toward centre of tunnel, forming a new osteon

4) Bone grows outwards as osteoblasts in periosteum build new lamella- osteon formation repeats as new periosteal ridges form over blood vessel

  • Can happen in growing bones in children but also healing bones after fracture!https://s3-us-west-2.amazonaws.com/secure.notion-static.com/d7a44530-8e00-4294-8b40-a6158b70580a/Untitled.png

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34
Q

Where do to find osteogenuc osteoblasts and osteoclasts and osteocytes

A

Osteogenuc cells-found in narrow and deep layers of periosteum
Osteoblasts-found in growing portions of bone including periosteum and endosteum
Osteoclasts-bone surfaces at sites of injured or unneeded bone
Osteocytes are trapped in matrix

BRS Bioregulatory Systems (54 decks)

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