Bone 2

Question 1

Epiphyseal GP zones

Answer 1

Reserve/resting zone
Proliferation zone
Maturation zone
Hypertrophy zone
Degenerative zone
Osteogenic zone

Question 2

Reserve zone

Answer 2

Layer of normal hyaline containin Chondrocytes

Question 3

Proliferation zone

Answer 3

Layer of actively dividing Chondrocytes undergoing successive militia divisions and forming columns of cells surrounded by basophilic matrix of proteoglycans

Question 4

Maturation zone

Answer 4

Chondrocytes have ceased dividing

Question 5

Hypertrophy zone

Answer 5

Chondrocytes swell and become vacuolated

The matrix becomes calcified

Question 6

Degen zone

Answer 6

Chondrocytes start to die and leave spaces around spicules of calcified cart for osteoprogenitor cells to invade

Question 7

Osteogenic zone (metaphysis)

Answer 7

Osteoprogenitor cells diff into osteoblasts which congregate in surface of calcified cart spicules and bone formation commences
Calcified cart spicules strong basophilic woven bone eosinophilic

Question 8

Cause of short or deformed bones

Answer 8

Premature GP closure due to trauma
Drugstore some antibiotics
Disease

Question 9

Periosteum growth

Answer 9

To accomodate incr bone length width incr is req
Done via deposition of bone beneath periosteum by osteoprogenitor cells present in deepest periosteum layer diff into osteoblasts
Maintain cortical bone thickness by osteoclast activation in endosteum causing cortical bone remodelling

Question 10

Growth of bone types

Answer 10

Length epiphyseal growth

Width growth originate at periosteum

Question 11

Fracture repair stages

Answer 11

Inflammatory
Repair
Remodelling

Question 12

Inflammatory stage duration

Answer 12

First few days

Question 13

Repair stage duration

Answer 13

Weeks to months after

Question 14

Remodelling stage duration

Answer 14

Months to years after

Question 15

Inflammatory stage key events

Answer 15

Haematoma formed
Acute inflam response brings in phagocytic cells
Osteoclasts begin to clear clot and necrotic tissue
Neovascularisation establish new tissue blood supply
Granulation tissue formed at fracture site

Question 16

Repair stage key events

Answer 16

Migration of mesenchymal cells to fracture site and periosteal and endosteum reaction brings in Chondrocytes and osteoblasts
Provisional callus formed bridging gap composed of varying amounts of hyaline cart and woven bone
Endochondral ossification occurs to produce a bony callus at which point a bony Union is achieved

Question 17

Remodelling stage key events

Answer 17

Remodelling of callus commences in response to normal use
Replacement of woven bone with lamellae bone
Periosteal reaction remains for a log time after fracture repair

Question 18

Specialised varieties of bones

Answer 18

Sesamoid
Splanchnic
Pneumatic

Question 19

Splanchnic bones

Answer 19

Bones that develop in soft organs remote from the rest of the skeleton eg os penis ossa cordis os clitordis

Question 20

Sesamoid bones

Answer 20

Bony structures found with in tendons eg patella navicular bone
If extirpated only reform if movement of the area is allowed

Question 21

Sesamoid bone fx

Answer 21

Prevent tendon wear and injury as it passes over a joint and displaced tendon away from joint axis causing incr leverage of muscle acting via tendon
Reduce friction and change direction of pull of tendon. Form synovial joints with the major bones with which they are in contact

Question 22

Pneumatic bones

Answer 22

In mammals confined to the skull and contain the paranasal sinuses which comms with the nasal cavity. Dev principally after birth when basal mucosa outgrowths invade certain flat bones and replace the diploe. Post natal remodelling of the skull can result in extensive changes in some species skull shape eg pigs cattle

Question 23

Pneumatic bones in birds

Answer 23

Skeleton dev an extensive system of air filled cavities in comms with the respiratory organs. This is an important adaptation to lighten the skeleton for flight and is found to be more extensive in the best fliers

Question 24

Compressive strain concentrated where

Answer 24

Conc on outer parts of any structure, so no need for a solid interior

Question 25

Tubes v rods

Answer 25

Tubes are stiffer and harder to break by bending

Lighter so leg, etc is lighter

Question 26

Bone stress natures

Answer 26

Compressive on caudal sides and tensile on cranial sides

Question 27

Limb bones optimised for

Answer 27

Impact strength

So side under tensile stress gives first

Question 28

Muscle pull affect on bone growth

Answer 28

• infraspinatous m red Infraspinous fossa, - trapezius m red scapula spine, - lower incisors shorten mandible
  Most of mandible and cranium sig red if fed in soft food as mastication m not used much. Weightlessness &a lack of use cause bone loss, once gravitation cause heavier bones

Question 29

Age and physiological affects on bone

Answer 29

Pregnancy lactation can have bone loss

Affect of neck m dev and rootin behaviour on shape of pig skull

Question 30

What occurs post foetal dev bone formation and fracture repair

Answer 30

Woven bone replaced with lamellar bone in response to stress applied. B active in growth but occurs throughout life at slow rate and re activate when incr use, change in physiological state or in fracture repair. In adv age it decr sig

Question 31

Result of bone remodelling

Answer 31

Several gen of haversion systems

Increased strength in areas of stress application

Question 32

Osteoclast role in bone remodelling

Answer 32

They cut through bone producing a cutting come through the bone. Followed immediately by neovascularisation into resorptive cavity which is lined with osteoprogenitor cells which diff into osteoblasts which lay down osteoid producing a closing cone

Question 33

What occurs as new lamellae are produced in bone remodelling

Answer 33

Osteoblasts become embedded and mature into osteocytes within lacunae of new haversion system