bone physiology

Question 1

name the functions of the skeleton

Answer 1

protection
framework
levers
mineral storage
fat storage
blood cell production

Question 2

what make up bone

Answer 2

collagen fibres
glycosaminoglycans
mineral salts

Question 3

what is the main crystal salt

Answer 3

calcium phosphate
CaPO4 (hydroxyapatite)

Question 4

why is collagen in bone

Answer 4

makes bone flexible

Question 5

what is the purpose of hydroxyapatite in bone (CaPO4)

Answer 5

fills spaces between collagen fibres
gives strength and rigidity

Question 6

which bone type has the most cancellous bone found

Answer 6

irregular

Question 7

what is the connnective tissue lining bone

Answer 7

periosteum

Question 8

what cells develop into osteoblasts

Answer 8

osteogenic cell

Question 9

what is the function of osteocytes

Answer 9

sense and respond to changes in the extracellular matrix

Question 10

where are osteocytes found

Answer 10

lacunae (depressions in bone)

Question 11

how do osteocytes signal

Answer 11

through canaliculi canals

Question 12

what is the bone cell layer

Answer 12

periosteum
endosteum
haversian canals

Question 13

what is the function of the bone fluid

Answer 13

transport calcium phosphate into and out of the blood

Question 14

what do osteoblasts secrete

Answer 14

osteoid (becomes mineralised bone by mixing with CaPO4 crystals)

Question 15

what enzyme aids in the production of calcium phosphate

Answer 15

alkaline phosphate

Question 16

how do osetoclasts dissolve the bone

Answer 16

acidify the sub cellular space
enzymatically digest collagen + matrix proteins

Question 17

describe how osteoblasts are triggered to resorb bone

Answer 17

osteoclasts leave mitogens (growth factors) which cause osteoblasts to mature and lay down new bone

Question 18

why are osteoclasts needed

Answer 18

removed damaged matrix to avoid incorrect healing of an injury

Question 19

what is osteopetrosis

Answer 19

too much osteoblast activity

Question 20

what is osetoporosis

Answer 20

too much osteoclast activity

Question 21

describe how the bone is vascularised

Answer 21

nurtient artery supplies centre 2/3
periosteal vessels supple outer 1/3

Question 22

where does ossification start on long bones

Answer 22

middle (diaphysis)

Question 23

what are young animal bones made of

Answer 23

hyaline cartilage

Question 24

describe the stages of ossification of long bones

Answer 24

blood vessels grow from the diaphysis into the periosteum
this vascularises and stimulates osteoprogenitor cells to differentiate into osteoblasts.
osteoblasts produce osteoid which leads to the development of the bone collar.
this becomes ossified (CaPO4 crystals form) as alkaline phosphatase is released
matrix is vascularised, osteoblasts and osteoclasts move along the blood vessels for bone remodelling

Question 25

what are secondary ossification centres in long bones

Answer 25

epiphyseal growth plates

Question 26

what is appositional growth

Answer 26

allows bone to get thicker

Question 27

what is endochonreal ossification

Answer 27

how long bones are formed

Question 28

what is intramembranous ossification

Answer 28

how flat bones form

Question 29

describe the process of intramembranous ossification

Answer 29

osteogenitors differentiate to osteoblasts in the centre, they secrete osteoid which is mineralised.
periosteum forms and is vascularised.
bone collar forms outwards along the periosteum

Question 30

what is the difference between intramembrous and endochondral ossification

Answer 30

intramembrous has no cartilage precursor
bone forms between periosteal membranes