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Body logistics > L15- Bone formation and repair > Flashcards

L15- Bone formation and repair Flashcards

1
Q

5 Types – What are they called?

A 
long
short
flat
irregular
sesamoid
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2
Q

Long

A

Support Weight and Facilitate Movement

FEMUR

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3
Q

short

A

Cube shaped- stability and some movement.

The carpals in the wrist and the tarsals in the ankles

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4
Q

irrregular

A

protective role

  • vertebre protect the spinal cord
  • pelvis protects vital organs
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5
Q

flat

A

Protect Internal Organs

  • ribs
  • sternum
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6
Q

sesamoid

A

function to protect tendons from stress and wear.

These small, round bones are commonly found in the tendons of the hands, knees, and feet.

  • patella
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7
Q

Which method: endochondral or intra-membranous ossification is used to make
them?

A

flat bones- intramembranous ossification

all other bones- endochondral ossification

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8
Q

Can you distinguish between these two methods of bone formation?

A

In endochondral ossification, a cartilage is formed as a precursor on which new bone is laid down.

Intramembranous ossification is the direct laying down of bone into the primitive connective tissue (mesenchyme) and there is no intermediate cartilage involved.

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9
Q

What are the differences between compact and cancellous bone?

A

Compact

  • highly organised into osteons
  • not porous
  • much more dense

Cancellous

  • randomly organised into trabeculae
  • filled with bone marrow
  • very light
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10
Q

When are bones made?

A

Ossification begins about the third month of fetal life in humans and is completed by late adolescence.

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11
Q

osteoblast

A

are the cells that form new bone.

ONE NUCLEUS

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12
Q

osteocytes

A

a bone cell, formed when an osteoblast becomes embedded in the material it has secreted.

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13
Q

osteoclasts

A

large multinucleate bone cell which absorbs bone tissue during growth and healing

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14
Q

What happens when a bone repairs itself? What are the different stages of bone repair called and can you describe what happens at each stage?

A

1) Haematoma formation
- A blood clot (haematoma) is formed in which granulation tissue arises

2) Fibrocartilaginous callus formation
- The procallus of granulation tissue is replaced by a fibrocartilaginous callus in which bony trabeculae are developing

3) Bony callus formation
- Endochondral and intramembranous ossification give rise to a bony callus of spongy/ cancellous bone

4) Bone remodelling
- Cancellous bone is replaced by compact cortical bone until remodelling is complete

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15
Q

1) Haematoma formation

A

Blood vessels in bone and periosteum break

A mass of clotted blood (haematoma) forms

Bone cells at the fracture edge die (no blood supply)

Swelling and inflammation occurs (granulocytes enter the site)

A procallus of granulation tissue (i.e. tissue rich in capillaries and fibroblasts) starts to develop

Phagocytic cells and osteoclasts begin to remove dead and damaged tissue

Macrophages eventually remove the blood clot

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16
Q

2) Fibrocartilaginous callus formation

A

New blood vessels infiltrate the fracture haematoma
Some fibroblasts produce collagen fibres
that span the break. Others differentiate into chondroblasts that give rise to a sleeve of hyaline cartilage

Simultaneously:
osteoblasts from the nearby periosteum and endosteum, (and multipotent cells from the bone marrow) invade the fracture site and begin bone reconstruction by forming spongy/ trabecular bone

17
Q

3) Bony callus formation

A

Within a week, new bone trabeculae begin to appear in the fibrocartilaginous (soft) callus.

The trabeculae develop as the former fibrocartilaginous callus is converted to a hard (bony) callus of cancellous bone

Endochondral ossification replaces all cartilage with cancellous bone

Intramembranous ossification produces new cancellous bone in any gaps

Bony callus formation continues for about two months until a very firm union across the fracture site is formed

18
Q

4) Bone remodelling

A

Cancellous bone begins to be re-modelled into compact bone, especially in the prior cortical region (i.e. in the region of the former bone shaft walls)
This process continues for several months (or even years)

The material bulging from the outside of the bone, and inwards, into the medullary cavity, is removed by osteoclasts

The final shape of the re-modelled area is the same as that of the original unbroken bone because it responds to the same set of mechanical stressors

19
Q

How long does bone remodelling take for a child?

A

many months but usually <1 year

20
Q

How long does bone remodelling take for an adolescent?

A

between 1 -5 years

21
Q

How long does bone remodelling take for a young adult?

A

2-10 year

22
Q

How long does bone remodelling take for an elderly person?

A

continuously

23
Q

How long does bone remodelling take for a baby?

A

does not occur because nones not fully formed

24
Q

How long does bone remodelling take for an infant?

A

usually <6 months (if walking)

25
Q

bone remodelling rates is related to age how

A

inversely

26
Q

all bones are formed through

A

ossification

27
Q

ossification can take

A

1 of 2 forms, depending on the type of bone it is forming

28
Q

flat bones (ribs, scapula, pelvis and skull) undergo

A

intramembranous ossficiation

29
Q

intramembranous ossficiation

A
  1. mesenchymal cells within the fibrous connective tissue differentiate into osteoblasts
  2. These osteoblasts form ossification centres
  3. ostoeblasts begin to lay down osteoid (organic part of bone- collagen fibres)
  4. Some osteoblasts become trapped within the osteoid- then said to be osteocytes]
    5) osteoid then calcifies and forms spicules, which aggregate into a honey form formation called trabeculae- as this thickens it forms spongy cancellous bone
    6) periosteum forms
30
Q

most bones in the body are formed via

A

endochondral ossification

31
Q

endo

A

within

32
Q

chondro

A

cartilage

33
Q

ossification

A

bone formation

34
Q

long bone development by endochondral ossification

A

embryo 5-6 weeks
- intitial cartilage model forms

embryo 6-8 weeks
- collar of periostesal bone appears in the shaft

fetus 8-12 weeks

  • central cartilage calcifies
  • nutrient artery penetrates (supplying osteogenic cells)
  • primary ossificantion centre nformed in the middle of the diaphysis

Post natal

  • medulla becomes cancellous bone
  • cartilage forms epiphyseal growth plate
  • epiphyses develop secondary centres of ossification

Prepubertal
- epiphyses ossify and growth plates continue to move apart lengthening the bone

mature adult
- epiphyseal growth plates replaced by bone

35
Q

endochondral ossification involves

A

hyaline cartilage models

36
Q

when does endochondral ossification begin

A

within the developing foetus (starts at 8 weeks

37
Q

what is found at the articular edges of long bones

A

hyaline articular cartilage

- protects bone

Body logistics (39 decks)

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