what is the function of bone

Question 1

what are the 3 main functions of bone

Answer 1

store of calcium

production of red blood cells/platelets

maturation with blood cells

Question 2

what is the predominant gelatinous fluid in bone

Answer 2

ground substance (amorphous gelatinous material. It is transparent, colourless, and fills the spaces between fibres and cells)

Question 3

what other substance holds a high proportion of bone formation

Answer 3

collagen (collagen fibres)

Question 4

what is difference about collagen fibres in bone

Answer 4

they are calcified under physiological conditions

Question 5

define osteoid

Answer 5

pre mineralisation cartilaginous tissue

Question 6

what makes the extracellular matrix in bone strong

Answer 6

formation of hydroxyapatite crystals from calcium and phosphate

Question 7

what prevents the formation of hydroxyapatite crystals in other tissues (despite them having normal levels of phosphate and calcium)

Answer 7

they have an inhibitor called pyrophosphate

Question 8

what can happen if a tissue fails to produce pyrophosphate

Answer 8

degenerating tissues that fail to make this can become calcified

Question 9

what might cause tissue calcification

Answer 9

under physiological conditions alkaline phosphates remove pryophosphate allowing bone mineralisation

Question 10

what is extracellular matrix (similar to cartilage) formed by

Answer 10

osteoblasts

Question 11

how do osteoblasts create the extracellular matrix

Answer 11

by secreting collagen and ground substance

Question 12

what do osteoblasts create when they reach a quiescent state (dormant)

Answer 12

osteocytes

Question 13

how are osteoblasts simulated

Answer 13

by compressive forces

Question 14

why might astronauts experience osteoperosis

Answer 14

due to lack of compressive forces on bones

Question 15

what component can break down bone

Answer 15

osteoclasts

Question 16

what property do osteoclasts have in common with monosytes

Answer 16

contain lysosomes that can degrade tissue

Question 17

what 2 functions do osteoblasts hold besides formation of matrix?

Answer 17

• hold precursors with PTH receptors that secret RANK ligand. RANKL stimulates differentiation of immature osteoclasts into active cells
• produce osteoprotegrin which can block the RANKL receptor and promote bone growth

Question 18

what are osteoclasts indirectly stimulated by

Answer 18

RANK ligand

Question 19

what drug increases bone density and how

Answer 19

bisphosphonates,

they can incorporate well into calcium rich tissue and when taken up by osteoclasts, they can severely reduce osteoclast function.

Question 20

what are some disadvantages to taking biphosphates to promote bone growth

Answer 20

can irritate the stomach and oesophageal lining and increase peptic ulcer risk

Question 21

what does synergistic mean

Answer 21

cooperation of 2 substances creates a greater effect than sum of separate effects

Question 22

why is it important to be wary of the medications being taken with biphosphates

Answer 22

risk is synergistic

(patients who need biphosphates may have indication for non steroidal anti-inflammatory drugs and or cortisteroid medication - both can affect lining of GI tract

Question 23

what is ostenecrosis

Answer 23

a degenerative bone condition characterized by the death of cellular components of the bone secondary to an interruption of the subchondral blood supply

Question 24

why is biphosphate prescribed to patients with poor dentition something to be wary of

Answer 24

can cause osteonecrosis of jaw

Question 25

what are the 2 main sources of vitamin d and what type of vitamin d do each provide

Answer 25

sun = vitamin d3 fish = vitamin d2

Question 26

what is the process of producing activated vitamin D

Answer 26

vitamin d2 and d3 get hydroxylated by the liver and then it gets hydroxylated by the kidney to make activated vitamin D3

Question 27

what happens when the parathyroid gland detects low serum calcium in blood

Answer 27

- parathyroid hormone is secreted (PTH) - stimulates bone breakdown released calcium and phosphate into blood - PTH release favours calcium reabsorption (from urine) and stimulates phosphate loss/excretion of phosphate - PTH also stimulates kidney to activate vitamin D - activated vitamin D causes increase absorption of calcium from diet

Question 28

what are Haversian canals in bone

Answer 28

tubes which form a network in bone and contain blood vessels.

Question 29

what do the Haversian canals allow in bone

Answer 29

vascular and neural connections in bone

Question 30

what can be found around the Haversian canals

Answer 30

cone osteocytes and bone tissue forming concentric rings called lamellae

Question 31

what is an osteon

Answer 31

unit of tissue forming rings around a canal

Question 32

what is cortical bone

Answer 32

harder 'compact' bone found towards outer edge

Question 33

describe the structure of inner bone

Answer 33

less densely packed, forms a spongy matrix type structure known as spongy/ CANCELLOUS bone

Question 34

what component does the spongy tissue in diaphysis of bone house

Answer 34

yellow bone marrow which predominantly produces cells of immune system

Question 35

what component does the spongy tissue in epiphysis house

Answer 35

red bone marrow which produces red blood cells (erythrocytes) and platelets

Question 36

what is cancellous bone formed of

Answer 36

trabeculae

Question 37

describe process of bone formation

Answer 37

form ossification of cartilage - initially bone is totally cartilaginous structure that ossifies in stages

Question 38

describe ossification in long bones

Answer 38

ossification happens at epiphyses before diaphysis

Question 39

explain how bone growth stops when you become an adult

Answer 39

- cartilage at metaphysics keeps producing new cartilage until end of puberty - if cartilage production exceeds rate of ossification the bone will continue to grow - as growth of cartilage slows the diaphysis and metaphysics fuse and bone growth stops/adult heigh is reached

Question 40

what is the salter-harris classification system

Answer 40

a method used to grade fractures that occur in children and involve the growth plate

Question 41

whats the difference between primary and secondary bone healing

Answer 41

primary = involves low strain conditions secondary = higher strain conditions

Question 42

how is a fractured bone healed

Answer 42

1. initially hepatoma is formed 2. haematoma can organise to form a callus 3. callus is replaced by spongy 'cancellous' bone 4. bone is reorganised

Question 43

what can failure to heal bone lead to

Answer 43

pseudoarthrosis, occurs when bones do not fuse correctly after an injury or surgery

Question 44

how might you be able to diagnose osteoporosis

Answer 44

- DEXA scans measure bone mineral density - this can be used with other things to measure a FRAX score which gives the risk of fragility fracture

Question 45

what is osteosarcoma and where in the bone is this typically ound

Answer 45

- tumour arising from osteoblastic precursor - found close to metaphysis

Question 46

what is the difference between primary and secondary osteosarcoma

Answer 46

primary= in children with no history of bone disease secondary = in adults with previous history of bone disease (symptoms being pain worsening with excersise)

Question 47

what are 2 types of treatment for osteossarcoma

Answer 47

1. surgery 2. chemotherapy

Question 48

where can ewings sarcoma typically be found

Answer 48

diaphysis of long bones