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Yr 2 - IBMS > Bone > Flashcards

Bone Flashcards

1
Q

What is the Ratio Composition of Bone?

A

1:2:7
water:collagen:hydroxyapatite

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2
Q

Describe the Outer Layer of the Bone

A

= cortical
made up of osteons of compact bone

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3
Q

Describe an Osteon

A
  • a central haversion canal
  • surrounded by concentric rings of matrix = lamellae
  • between rings = osteocytes in spaces called lacunae
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4
Q

Describe the Inner Layer of Bone

A

= cancellous
- trabeculae of spongy bone

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5
Q

What Happens to Bone Under Stress, leading for reasons to Remodel

A
  • bone take stress and strain
  • leads to microfractures
  • lead to macrofracture
    = breakage of the bone
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6
Q

How Does Bone Remodel? Which 2 Hormones are used?

A

maintaining homeostasis between osteoclast and osteoblast

Osteoclast = dissolve bone
Osteoblast = produce bone

Hormones
- Parathyroid Hormone - increase osteoblasts
- Oestrogen - increase osteoblasts

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7
Q

How do Osteoclasts Activate the Production of Osteoblasts?

A
  • Osteoclast have RANK receptor
  • Osteoblasts produce RANK-L and OPG
  • RANK-L and OPG activate RANK
  • influences differentiation of osteoprotegenitor cells (form of stem cell)
  • stimulate and proliferate
  • mature into osteoblast

OPG = Osteoprotegerin

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8
Q

What can Negatively Affect Bone Remodeling

A

tumour factors - dissolve bone

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9
Q

What would Happen if Osteoblasts produced only RANK-L and not OPG?

A
  • would only stimulate osteoclast activation
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10
Q

What is Osteoporosis?

A

porous weaker bones
- more cancellous bone
- stress is not evenly distributed and so more likely to break

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11
Q

What are the 3 Typical Osteoporotic Fractures?

A

spinal
- back can become humped - Dowager’s Hump
- posture is stooped and lose height

hip/femur fracture

wrist - collect fracture, when fall on open hand

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12
Q

Which 5 Groups does Osteoporosis Affect?

A
  1. post-menopausal women
  2. elderly
  3. those with inflam conditions
  4. those with auto-immunity
  5. those on long-term corticosteroids
    - for rheumatoid arthritis, connective tissue diseases, severe asthma

e.g. prednisolone and hydrocortisone

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13
Q

What must you Incorporate in life to Manage Osteoporosis (5), alongside *drugs (2)?

A

active
healthy diet
sunlight
no smoking
hormone replacement therapy - oestrogen

*anti-resorptives
*bisphosphonates
- related to pyrophosphate
- used in toothpaste - strengthen enamel
- has a high affinity for bone

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14
Q

What is Hypercalcaemia? Give 2 Effects.

A

excess calcium entering the blood when bone and hydroxyapatite dissolves

affects the heart, abnormal rhythm and high blood pressure

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15
Q

What are the Symptoms of Hypercalcaemia in Dif Parts of the Body?

brain, gut, kidney

A

brain - drowsiness, fatigue, cognitive dysfunction, memory loss, coma
gut - nauseous, loss of appetite, constipation, loss of weight
kidney - crystallised stoned, kidney failure, nephrogenic diabetes insipidus

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16
Q

What Is Paget’s Disease of Bone?

A

an inherited disorder causing an imbalance in the homeostatic mechanisms controlling bone production

Two Phases:
- bone dissolution
- bone laid down - not in correct pattern, weaker

= more prone to fracture, can trap nerves and cause pain

17
Q

What is the Appearance of Paget’s Disease of Bone on X-ray and Microscope

A

bone on x-ray is wispy

under microscope - fewer lacunae and fewer osteocytes

18
Q

What Problems do Paget’s Disease of Bone Cause?

A

pain and deformities - bone sticks out

19
Q

What is Osteogenesis Imperfecta?

A

an inherited disorder where bones aren’t formed properly, easily bend and fracture

related to dentinogenesis imperfecta

20
Q

What is a Bisphosphonate?

A

a drug that helps to prevent/slow down bone thinning

21
Q

Describe the Structure of a Bisphosphonate.

A

2 pyrophosphates welded together by a carbon
- R1 and R2 molecule from the molecule
= determines the activity and how well it prevents osteoporosis
- R1 is usually hydroxyl group = high affinity for hydroxyapatite
- R2 determines efficacy

*if R2 was nitrogen - can interfere with protein production, mess with cell function, cant prevent apoptosis = die

22
Q

Give 6 Types of Bisphosphonates, in Descending Order of Efficacy.

Zon’t Ruin A Perfectly Clear Egg

A

Zoledronate - 10,000
Risedronate - 2,000
Alendronate - 500
Pamidronate - 100
Clodronate - 10
Etidronate - 1

  • higher = more protection and inteference with bone resorption
23
Q

How are Bisphosphonates Administered?

A

orally or intravenously

24
Q

What are the Problems with Bisphosphonates? is it Likely?

A

1)
- due to affinity to bone - stays for a long time
- can interfere with regular cellular process or protein production - apoptosis?

2)
- osteoblast can dissolve bone full of bisphosphonate
- BPP releases around osteoclast
- BPP soak into osteoclast
- = kill
- soak into medium around osteoblast
- = kill

3)
- affect other cells - keratinocytes and fibroblasts

LOL ITS NOT EVEN LIKELY, CAN TAKE A LONG TIME FOR THAT TO HAPPEN

in other words
= reduced activity of clast and blast
= reduced healing ability
= affects other cells
= exposed bone

25
Q

What is Osteonecrosis of the Jaw? The 3 Types.

A

when osteoclasts and osteoblasts have died in the jaw.

BRONG - Bisphosphonate Related Osteonecrosis of the Jaw
ARONJ - Anti-Resorptive RONJ
MRONJ = Medically RONJ

26
Q

What Bisphosphonates can Lead to MRONJ?

A

Alendronate = low risk
Zolendronate = high risk

27
Q

What Drugs Can Lead to MRONJ and its clinical appearance?

A

Avastin, Sutent, Zaltrap
= exposed bone, pain, infection, pus, radiographic discharge

28
Q

Why Would a Patient be Taking Avastin, Sutent, Zaltrap, and the Risks for MRONJ.

A
  • osteoporosis - risk is <15%
  • cancer - risk is 3%
  • myeloma - risk is 7%
29
Q

How Long Does it Take for Medication to be High Risk for MRONJ?

A

5 years

30
Q

What are other Risk Factors for MRONJ?

A

recent dental extractions
untreated gum disease and decay
poor fitting dentures
smoking
alcohol
steroids

31
Q

What 6 Patients Typically Take Bisphosphonates?

A

osteoporotic
elderly
post-menopause
steroids
cancer
myeloma

32
Q

What are your Responsibilities when a Patient is about to Start a Course of Bisphosphonates?

A
  • OHI
  • explain risks
  • optimise dental health - restore teeth, extract unrestorable teeth, regular check ups
33
Q

What are your Responsibilities when a Patient is ON Bisphosphonates or Anti-Resorptive Treatment?

A
  • OHI
  • optimise dental health - keep all restorable teeth, avoid extractions if possible, warn patients of risk of extractions and careful follow up

Yr 2 - IBMS (21 decks)

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