2

Question 1

whats epiphyseal growth plate

Answer 1

cartilage plate

Question 2

when do epiphyseal growth plate close

Answer 2

16 17

clavicle up to 23 yo

Question 3

how do bones develop

Answer 3

intramembranous and endochondral ossification but end product is the same

Question 4

how do bones grow in width

Answer 4

apposition

Question 5

what is the major type of bone in mature skeleton

Answer 5

lamellar bone.
made of two layers

cortical bone: outer part of bone gives structure. dense. 80% of adult skeleton in mass

cancellous/trabeular bone is the layer inside that’s made of a mesh gives bone bendability. 20% of adult skeleton mass

woven bone
its in diff directions. a lot in children skeleton. makes bone softer. can be remodelled.
its immature healing and pathological

Question 6

does collagen run in same direction

Answer 6

yes per layer.

diff layers diff directions.

Question 7

what are osteons

Answer 7

cylinders that make up cortical bone

Question 8

what type of collagen is found in bones

Answer 8

type 1

Question 9

whats matrix made up of

Answer 9

40% organic (mostly collagen but also proteogluycans)
60% inorganic (calcium hydroxiapetite)
a bit of water

Question 10

how does hydroxyapatite allow for some movement

Answer 10

form blocks around collagen fibre

Question 11

whats the cycle of development of bone cell

Answer 11

from osteoprogenitor cell to osteoblast and Ince that forms matrix it becomes osteocyte and then that becomes osteoclast

Question 12

osteoblast found where

Answer 12

line bone trabedculae

Question 13

whats makes new bone matrix organic component

Answer 13

osteoblast

Question 14

what sense how well bone is doing (bone maintainer)

Answer 14

osteocyt

Question 15

where do osteoprogenitor cells found

Answer 15

perioctyoum or endostium

Question 16

where do osteoclast come from

Answer 16

cousin of macrophage. it destroys bone.
remove woven bone so osteoblast can remodel it so you have cortical and spongy bone.
osteoclast remove bone from medullary cavity and fills with red bone marrow

Question 17

special feature of osteoclast

Answer 17

multi nucleated

Question 18

when does ossification happens

Answer 18

week 6 7 of intrauterine life

Question 19

how does ossification happens

Answer 19

2 mechanisms:

• intramembranous for skull where bone forms directly
• endochondral: from cartilage precursor to endpoint.

Question 20

explain the process of intramembranous ossification

Answer 20

you start w mesenchymal cells in skull which become osteoblasts directement.
so mesenchymal cells are quite multipotent. osteoblasts becomes osteocytes. and so that becomes bone when calcified with caliusm hydropaetite.

Question 21

whats the periocytium

Answer 21

its mesenchymal cells that’s on outside and condenses to host all osteoprogenitor cells your gonna need and remodel bone from woven bone to lamellar bone

Question 22

why do you need blood supply

Answer 22

mesenchymal stem cells make osteoblasts and osteocytes. but osteoclasts come from hematopoeitic stem cells so the only way it can get in is if it comes via blood.

Question 23

explain the process of endochondra ossification

Answer 23

mesenchymal cells get signals that make them differentiate as chondroblast (cartilage cell lineage) forming hyaline cartilage.
then perichondrium forms around cartilage.
perichondrium holds stem cell mesenchymal cells. and can change ECM so that they can become chondroctyes. then chondrocyte divide to form isogenic groups. each chondrocyte lays down matrix and forms its own lacunae and spread apart.
increase in matrix means appositional growth and interstitial growth.

Question 24

what happens to chondrocytes in centre of cartilage model

Answer 24

hypertrophy so release alkali which triggers calcification
condroctye death within calcifying matrix forms small cavities for new osteoblasts to move into the bone collar from the periochrondrium (so becomes periosteum)
nutrient artery penetrates periochondreium via nutrient foramen. on outside periochndrium changes to periosteum

Question 25

what triggers ossification

Answer 25

alkaline pH

Question 26

whats the secondary ossification

Answer 26

femoral head separated by epiphyseal growth plate
its woven bone
around it is hyaline cartilage which remains at end of bone.

Question 27

what does epiphyseal growth plate separate

Answer 27

primary ossification centre (dyaphisis=
and
secondary ossification centre (epiphysis=

Question 28

whats dyaphysis

Answer 28

central part of a long bone

Question 29

whats epiphysis

Answer 29

end part of a bone

Question 30

epiphyseal growth plate can be divided into 4 xzones

Answer 30

resting cartilage
under
zone of proliferating chornocytes
chornodryte hypertrophy
zone of cell death where osteoblast will move into to turn to bone.

Question 31

how many epiphyseal growth plate per bone

Answer 31

2 or more

Question 32

clavicle only bone outside skull that forms by

Answer 32

intramembraouns ossification and endochondrial ossification.

cleidocranial diplasa… missing clavicle.

Question 33

how does width increase

Answer 33

Osteoprogenitors in periosteum differentiate as osteoblasts – secrete new bone matrix​
they Form bone ridges on either side of periosteal blood vessel​

Ridges fuse together enclosing blood vessel in a tunnel​
​Inside tunnel:​
Former periosteum becomes endosteum​
Osteoblasts make new bone lamellae filling tunnel​
As new bone added to outside of bone - Bone must be removed from the inner medullary cavity ​
Maintains the thickness of the cortical bone
As new bone added on to outside, ​
Bone must be removed from the inner medullary cavity ​
This maintains the thickness of the cortical bone​