Week 6 - Ageing Flashcards Preview

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Flashcards in Week 6 - Ageing Deck (77):
1

What is calcification?

calcium deposition

2

What is ossification?

bone formation

3

What is an osteoid/callus and what are the 2 types?

-protein mould of future bone --> embryo/fracture

1. soft callus --> no calcium (early)
2. hard callus --> with calcium (late)

*soft = not seen on xray, hard callus is

4

Which cells produce, lyse and mantain the bone?

production --> osteoblast
lysis --> osteoclast
maintain --> osteocyte

5

Which artery supplies bones?

nutrient artery in nutrient foramen (diaphysis/metaphysis) --> epiphysis has a different blood supply

6

How are lamellae orientated?

along lines of stress

7

What is at the centre of lamellae?

haversian canals

8

What is the name of the crystal found in bone?

calcium hydroxyapatite in collgen protein framework (matrix)

9

What % of bone is recycled per year?

5-10%

10

At what age do we begin to lose bone each year and what % is it?

>30yrs, 0.5% bone loss per year (physiological ageing)

11

What is osteoporosis?

-excess lysis of bone or less production --> loss of bone density --> osteoporosis

12

What is new bone formation AKA and what is mature bone AKA?

woven bone - irregular, immature, fetus/growth plate/fracture (no lamellae)

lamellar bone - mature, regular bone (compact, solid + spongy with marrow)

13

What hormones/vitamins/minerals are involved in the control of bone recycling?

-GH
-insulin
-Vit D
-Vit C
-calcium
-PTH
-calcitonin

14

Outline the pathology of fracture healing

Fracture
-1 week --> haematoma, inflammation
-1-3wks --> soft callus (osteoid - not seen on xray)
-3-6wks --> hard callus (seen on xray)
-8wks --> remodelling (*stress - normal bone again)

15

True or False?
Remodelling only occurs with stress

True
-i.e. required to remove support after a fracture (~8wks)

16

What is the microscopy of woven bone - osteoid?

1. irregular osteoid trabeculae
2. lack of lamellae
3. prominent lining by osteoblasts
4. irregularly arranged osteoclasts
5. granulation tissue

17

What is microscopy of lamellae/mature bone?

-marrow
-lamellae
-osteocytes

18

What are the systemic factors affecting bone healing?

-age*
-nutrition, vitamin/minerals
-immune status
-systemic diseases --> chronic disease; diabetes*
-drugs --> steroids
-genetic disorders --> hemophilia, etc

19

What are the local factors affecting bone healing?

-immobilisation*
-alignment --> improper reduction
-infection - debris, dead tissue in wound
-joint involvement
-damage to nerves/BVs
-bone pathology --> tumours, osteoprosis, etc

20

What are the short term complications of bone healing?

-haemorrhage, vascular injury*
-nerve/visceral injury*
-crush syndrome*
-fat embolism
-renal failure
-shock, DIC
-thromboembolism
-infection --> septicemia
-tetanus, gas gangrene

21

What are the long term complications of bone healing?

-delayed union
-non-union
-mal-union --> deformity
-growth disturbances
-contractures
-avascular necrosis
-osteomyelitis (infection)
-pseudoarthrosis (false joint formation)
-osteoarthritis

22

What terms are used for dead bone and new bone formation in bone necrosis following a fracture?

dead bone --> sequestrum
new bone --> involucrum

23

True or False?
CT neoplasms (sarcomas) are characterised by cells in a matrix/stroma with no tight junctions

True

24

What is the commonest malignant CT tumour?

osteosarcoma

#2 = Ewing's sarcoma

25

What is the commonest benign bone tumour?

osteochondroma

26

What is the commonest benign and malignant soft tissue tumour?

benign --> lipoma
malignant --> liposarcoma

27

What are the typical gross and microscopic features of sarcomas?

Gross:
-soft
-fleshy
-grey
-infiltrative

Micro:
-pleomorphic spindle cells

28

What does a single vs multiple osteochondromas on a patient suggest?

single --> acquired
multiple --> familial

29

What do osteochondromas typically present like?

-outpocket of hard nodules (bone) with a cartilage cap
-marrow can sometimes enter the nodule

30

What is the microscopy of giant cell tumour?

-aggressive
-cystic lesions with plenty of osteoclasts/giant cells ("osteoclastoma")

31

How does a patient with osteosarcoma typically initially present?

-pain + fever

32

Which body part is most commonly affected by osteosarcoma and where specifically in the bone is affected commonly?

-knee (60% cases) --> #2= shoulder
-affects METAPHYSIS of long bones

33

What gene mutation is commonly associated with osteosarcoma cases?

Rb gene mutations in >60% of cases

34

What are the microscopic and characteristic radiographic features of osteosarcoma?

Micro:
-irregular fine lacy osteoid
-pleomorphic cells

X-Ray:
-microcalcification (pulmonary spread)
-particularly on metaphysis (epiphysis = spared)

35

What is Codman's triangle?

-in osteosarcoma, there is swelling of tissue around bone causing lifting of periosteum
-lifting of periosteum --> reactive bone formation in a triangular-shaped fashion (Codman's triangle)

36

Which cells are affected in Ewing's sarcoma?

-primitive blast cells (like neuroblastoma) --> embryonic bone tumour
-small blue cells in sheets, no osteoid

37

Which mutation is commonly seen in pts. with Ewing's sarcoma?

95% pts. have a translocation --> t(11;22)

38

What is normal degeneration from ageing known as?

-senile atrophy (physiologic)

39

What are some examples of pathologic causes of degeneration?

-decreased workload --> disuse atrophy of muscles
-loss of nerve --> denervation atrophy
-decr. blood supply --> brain atrophy
-malnutrition --> marasmus
-loss of endocrine support --> Addison's

40

Which chromosome are the biological clock genes located on?

1

41

What % of our ageing is genetically determined vs. acquired causes?

genetic (biological clock genes) --> 60%
acquired --> 40%

42

What happens to telomeres with each cell division?

-progressively lost with each division until they disappear

43

What is progeria?

-disorder of ageing
-Hutchinson-Gilford synd, Werner synd, etc
-rare, genertics
-normal at birth but develop accelerated ageing
-develop AS, scleroderma, CVS disorders, dementia, etc. in childhood --> live till late teen

*Down's synd = another example of ageing disorder

44

What are the senile changes?

-balding
-cataracts
-senile dementia
-deafness
-loss of teeth
-dermal elastosis
-HTN/IHD
-osteoporosis
-prostatic hyperplasia (M)
-diverticular disease
-degenerative joint disease
-osteoarthritis
-ankle oedema (heart failure)
*decreased height, weight, muscle
*altered posture
*increased fat, wrinkles

45

What is solar elastosis?

-loss of elastin and collagen in the superficial dermis --> replaced by amorphous protein (hard) --> loss of skin turgor (elasticity)

46

What is osteoporosis?

-reduced bone mass --> normal composition
-osteoblast/clast function imbalance
-loss of strength --> deformity --> fractures

47

What are the 2 types of primary osteoporosis?

Type 1 --> post-menopausal
Type 2 --> senile

48

What are the secondary causes of osteoporosis?

-immobilisation (i.e. post-fracture)
-endocrine
-myeloma
-nutrition
-drugs (steroids; chemo)
-alcohol

49

What happens to bone in osteoporosis?

-thinning of vertical trabeculae
-loss of horizontal trabeculae

50

Where is osteoporosis more common in postmenopausal women?

-vertebrae
-neck of femur

51

What is the pathophysiology of osteoporosis?

-genetics + physical activity + endocrine/nutrition/drugs --> PEAK BONE MASS
-Menopause (1) + Ageing (2) contribute to loss of peak bone mass --> osteoporosis
-menoupause --> decreased serum estrogen, increased inflammatory cytokines, increased RANK/RANKL expression
-increased osteoclast activity
-ageing --> decreased replicative activity of osteoprogenitor cells/synthetic activity of osteoblasts/biologic activity of matrix-bound growth factors/physical activity

52

What is compartment syndrome?

inflammation --> increased osteofascial compartment pressure --> muscle ischaemia + necrosis (due to i.e. trauma, bleeds, insect bites, etc)

53

What is crush syndrome?

-muscle crush common in limbs
-road traffic accidents
-pressure --> necrosis --> inflammation
**c.f. compartment syndrome where inflammation causes an increased compartment pressure, crush syndrome is initiated by direct pressure leading to inflammation

54

What are the clinical features of compartment + crush syndrome?

-pain, swelling, inflammation, mottling (necrosis), blisters
-toxins enter circulation

55

What are the complications of compartment/crush syndrome?

-rhabdomyolysis
-DIC (due to toxins)
-acute renal failure (myoglobin has nephrotoxic metabolites)
-uremia
-acidosis

56

What is the Tx for compartment/crush syndrome?

fasciotomy
-to releave osteofascial pressure

57

What are the 2 types of skeletal muscle fibres?

Type 1
-slow fibres
-fat
-red
"One Slow Fat Red Ox"

Type 2
-pale
-fast-acting fibres

58

What is myositis and muscular dystrophy?

myositis = inflammation of muscle
dystrophy = embryonic disorganisation (congenital)

59

What is myopathy?

-non-inflammatory abnormality
-toxic/congenital (alcohol, drugs)

60

What gene mutation is present in muscular dystrophy?

-mutation of dystrophin on X chromosome p21

61

Why is muscular dystrophy known as pseudohypertrophy?

-initially there is hypertrophy due to fat + fibrosis --> then atrophy

62

What are the 2 types of muscular dystrophy?

Duchenne MD (DMD)
-common
-early 5yrs
-severe --> death by 20yrs

Becker MD (BMD)
-rare
-late
-less severe

63

How does muscular dystrophy typically present?

-normal at birth
-starts with pelvic + limb weakness (even though muscles appear large) --> characteristic ladder sign (pt. has to climb on themselves to stand up from the ground)
-death typically by heart failure

64

What are the 3 types of myositis and which is most common?

1. polymyositis (rheumatica)***
2. dermatomyositis
3. inclusion body myositis

65

What is polymyositis?

-polymyositis rheumatica
-autoimmune (usually seen with other autoimmune disorders)
-CD8 cytotoxic T cell mediated myofibre necrosis
-Tx. with steroids

66

What is dermatomyositis?

-common in children
-paraneoplastic (esp. lung) in adults
-periseptal (outer) fibre inflammation + SKIN inflammation

67

What is inclusion body myositis?

-old age (>60)
-amyloid + tau protein deposition in muscle fibres
-age-associated degeneration --> like alzheimer's*

68

What can cause toxic myopathy?

-thyrotoxicosis
-alcohol --> binge drinking
-drugs --> statins

69

What is myasthenia gravis?

-autoimmune disorder (Ab to acetylcholine receptors at NMJ) --> block receptors resulting in muscle paralysis
-muscle weakness --> esp. extra occular muscles (ptosis/diplopia) --> then becomes generalised
-Tx. = acetylcholine esterase, immunosuppression
-assoc. with thymic hyperplasia (65%)/thymoma (15%)

70

What is osteogenesis imperfecta?

-congenital bone disorder
-brittle bone, type 1 collagen
-severe deformity

71

What is osteopetrosis?

-congenital bone disorder
-stone bone
-osteoclast deficiency

72

What is the commonest cause of dwarfism?

-achondroplasia
-congenital bone disorder
-chondrocyte abnormality --> cartilage deficiency
-central body normal, limbs affected --> disproportionate growth

73

What is paget's disease?

-pain, sclerosis, deformity, fracture, nerve compression/deafness (if skull affected)
-can led to secondary osteosarcoma (late stage)

1. excess osteoclastic activity (osteolytic stage)
2. excess osteoblastic activity (osteoblastic stage)
3. finally, exhaustion of cellular activity (osteosclerotic stage)

74

What are the gross + microscopic features of paget's disease?

Gross:
-thick
-deformed
-mosaic

Micro:
-mosaic lamellae
-sclerosis
-increased osteoclasts + blasts

75

What is vitamin D deficiency referred to as in children vs. adults?

children (before closure of epiphyseal plates) --> rickets

adults --> osteomalacia

76

What is vitamin d deficiency and what are the features of it?

-defective mineralisation
-more osteoid (protein)/less calcium --> bones are soft

*bowing of legs, lumbar lordosis, rachitic rosary, harrison groove, pigeon breast, frontal bossing

77

What is lipomatosis?

-multiple lipomas
-genetic/congenital cause