Bone

Question 1

Cortical Bone

Answer 1

Hard outer layer
Covered by periosteum
Forms osteons with central canals for NV bundles

Question 2

Trabecular Bone

Answer 2

Spongy inner layer

Holds marrow

Question 3

Extracellular Bone

Answer 3

Collagen matrix and inorganic compounds (hydroxyapatite and minerals)

Question 4

Osteoblasts

Answer 4

Make osteoid from collagen
Make hormones, ALP and matrix proteins
Become osteocytes when trapped in matrix

Question 5

ALP

Answer 5

Released in growth, Paget’s, fractures and HPPT

Makes PINP

Question 6

Osteoclasts

Answer 6

Break down bone in reabsorption bays
Large and multinucleated
Make enzymes to bread down matrix
Regulated by PTH, calcitonin and IL-6

Question 7

NTX+ CTX

Answer 7

Collagen cross links
Released if bone degraded (HPPT, teens, menopause)
Diurnal variation

Question 8

Osteoporosis

Answer 8

Thoracic vertebrae biconcave
Lose height and get pain
Causes= less oestrogen, DM, Cushing’s, coeliac, RA, steroids, HPTH, myeloma
Treatment= bisphosphonate

Question 9

Bisphosphonates

Answer 9

Ingested by osteoclasts and stop them resorbing bone
Poorly absorbed
Get fluey and jaw osteonecrosis

Question 10

Metastates

Answer 10

Lytic/Destructive= breast, lung, kidney, thyroid
Sclerotic/Despositing= prostate, lymphoma, breast, lung

Question 11

Paget’s of Bone

Answer 11

Rapid bone turnover and formation but abnormal arrangement

High ALP

Question 12

Osteomalacia

Answer 12

Lack of mineralisation
Causes= lack of vit d, calcium or phosphate
Widened osteoid seams and epiphyses
High ALP+ PTH

Question 13

Osteomyelitis

Answer 13

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