bones

Question 1

functions

Answer 1

leverage for movement + muscle action
blood cell production
protection of organs
support against gravity
strorage- calcium, phosphorus and fat

Question 2

long bones

Answer 2

eg humerus, femur
longer than they are wide

Question 3

flat bones

Answer 3

eg ribs, cranium
formed of internal and external table separated by diploe

Question 4

short bones

Answer 4

eg carpals
same width as length, transfer forces well

Question 5

irregular bones

Answer 5

eg vertebrae
complex shapes

Question 6

sutural bones

Answer 6

eg between skull bones

Question 7

sesmoid bones

Answer 7

develop between tendons
eg patella

Question 8

long bone structure

Answer 8

formed of diaphysis- shaft- compact bone which surround medulla cavity
epiphyses (ends)- spongy bone (trabecular)
articular cartilage

Question 9

bone tissue

Answer 9

type of connective tissue
ground substance- makes up 2/3 mass of bone, minerals (hydroxyapatite, calcium and ions) which makes it hard but brittle

protein- reinforced with protein fibres incl collagen which is very dense and tough , 1/3 mass of bone

bone cells- 2% of bone mass
incl mesenchymal stem cells which form osteoblasts (form new bone) which form into osteocytes (mature bone cell) and osteoclasts which dissolve away old bone

Question 10

osteoblasts

Answer 10

immature bone cells
secrete matrix protein
form new bone
located in periosteum

Question 11

osteocytes

Answer 11

mature bone cells in lacunae
maintain bone matrix
connected via canniculi

Question 12

osteoclasts

Answer 12

multinucleated cell
secrete acid and enzymes to dissolve bone matrix

Question 13

structure of compact bone

Answer 13

osteon- basic functional unit, columnar and strong in long axis
central canal- tunnel for blood vessels, allowing blood flow
lamallae- concentric layers of matrix around central canal
lacunae-little lakes- osteocytes sit in, between lamallae

Question 14

structure of spongy bone

Answer 14

no osteons
trabecullae- arches, rods and plates branching off
red marrow- between trabeculae, form red blood cells + provide nutrients to osteocytes
yellow marrow- stores fat, in medullary cavity

Question 15

loading patterns

Answer 15

osteon structure provides strength in long axis
trabecular bone provides strength in a range of directions
trabeculae align according to habitual loading patterns

Question 16

periosteum

Answer 16

membrane around outside of bone
outer layer= fibrous layer containing collagen fibres (continuous with bone), tendons and joint capsule
inner layer= cellular with metabolic function, lymph vessels and nerves
contains specialised cells

Question 17

endosteum

Answer 17

membrane lining bone (inner surface)
line whole bone incl medullary cavity, central canal and trabeculae

Question 18

bone formation

Answer 18

ossification- formation of/conversion into bone
intramembrane ossification- flat bone formation (inside bone)
endochondrial ossification- formation from cartilage
appositional bone growth- growth in width

Question 19

intramembrane ossification

Answer 19

mesenchymal stem cells differentiate into osteoblasts (produce bone)
forms spicules of bone with cavities for blood vessels
trabecular bone formed
as forces are applied to surfaces, compact bone formed at top and bottom

Question 20

endochondrial ossification

Answer 20

starts in cartilage model
chondrocytes in matrix enlarge then die
osteoblasts cover shaft (outer) in thin layer of bone
blood vessels and osteoblasts penetrate inside to form primary ossification centre
POC enlarges and marrow cavity is formed
secondary OC extends to epiphyses

Question 21

growth in bone length

Answer 21

growth continues at epiphyseal cartilages during childhood
hormonal changes during childhood trigger fusion of epiphyseal cartilages
growth in length stops

Question 22

appositional bone growth

Answer 22

increase in diameter of bone
outer layer- bone deposited by osteoblasts
inner layer- bone reabsorbed by osteoclasts

Question 23

bone remodelling

Answer 23

continuous breakdown and reforming of bone tissue
reabsorption of by osteoclasts and formation by osteoblasts

Question 24

bone remodelling

Answer 24

adaption to loading- ostoecytes detect forces and control growth, becoming stronger where there is more loading
calcium homestasis- 99% is calcium stored in bone
calcium needed for muscle contraction
hormones (PTH) control storage and release

Question 25

bone mineral density

Answer 25

changes with age and peaks during 30s
rapid loss for women after menopause due to low levels of oestrogen
low bone mineral density may results in osteoporosis- low bone mass, increased fracture risk

Question 26

fracture repair

Answer 26

bleeding + formation of fracture haematoma (clot)
replaced by internal (spongy bone) and external calluses (cartilage)
internal callus unites broken ends + external callus replaced by bone
gradually replaced by bone, initial swelling eventually remodelled
external callus may remain