Bone

Question 1

Function of bone (5)

Answer 1

• support
• movement
• protection
• calcium homeostasis
• storage

Question 2

haematopoiesis

Answer 2

formation of blood cellular components

Question 3

haematopoiesis location

Answer 3

takes place in bone marrow. specifically red

Question 4

Types of bone

Answer 4

• sutural
• pneumatised
• flat
• short
• long
• irregular
• sesamoid

Question 5

sutural bones

Answer 5

• Small, flat, oddly shaped
• Found between flat bones of skull in the suture line
• Develop from separate centres of ossification
• Type of flat bone

Question 6

Flat bones

Answer 6

• Contain thin, roughly parallel surfaces of compact bone
• Resembles spongy bone sandwich
• Strong but light
• Roof of the skull, sternum, ribs and scapulae
• Provide protection for soft tissues and extensive surface area for attachment of skeletal muscles
• Thick layers of compact bone = internal and external tables
  Layer of spongy bone between = diploë

Question 7

Pneumatised bones

Answer 7

• hollow
• contain numerous air pockets
• ethmoid (nose)

Question 8

short bones

Answer 8

• Boxlike
• External surfaces covered by compact bone
• Interior contains spongy bone
• Carpal bones (wrists)
• Tarsal bones (ankles)

Question 9

long bones

Answer 9

• Long and slender - Contain a diaphysis, 2 metaphysis, 2 epiphyses and a medullary cavity
• Found in upper and lower limbs
  e.g. humerus, radius, ulna, femur, tibia, fibula

Question 10

irregular bones

Answer 10

• Complex shapes with short, flat, notched or ridged surfaces
• Varied internal structure
• Vertebrae, bones in the skull

Question 11

sesamoid bones

Answer 11

• Small, round and flat
• Develop inside tendons
• Mostly located in joints at the knee/hands/feet
• kneecaps

Question 12

order of sections of bone from top to centre

Answer 12

epiphysis -> metaphysis -> diaphysis

Question 13

articular surface

Answer 13

located on epiphysis, provides smooth lubricated surface for articulation

Question 14

order of sections of bone from outside in

Answer 14

articular cartilage -> periosteum -> compact bone -> endosteum -> trabecular bone -> medullary cavity

Question 15

periosteum

Answer 15

• Is a tough, vascularised fibrous sheath
• Superficially covers parts of the bone where there is no cartilage
• Nourishes and protects the bone
• Forms an attachment site for ligaments and tendons
• Superficial layer high on fibres
• Deep layers have osteogenic (bone forming) cells for bone repair

Question 16

Endosteum

Answer 16

• A thin membrane that lines medullary cavity
• Single layer of bone forming (osteoprogenitor) cells
• Sparse matrix of collagen fibres

Question 17

medullary cavity

Answer 17

• a hollow cavity containing bone marrow
• minimises the weight of the bone where it is least needed

Question 18

organic matrix of bone

Answer 18

• 35%
• type 1 collagen
• Proteoglycans and glycosaminoglycan
• Glycoproteins: osteonectin and osteocalcin

Question 19

inorganic matrix of bone

Answer 19

• 65%
• calcium phosphate -> hydroxypatite
• hardness, compressive strength

Question 20

osteocyte

Answer 20

mature bone cell that maintains and monitors the protein and mineral content of the matrix, signals stress

Question 21

osteoprogenitor cell

Answer 21

a stem cell that differentiates from mesenchyme and divisions of which produces osteoblasts

Question 22

osteoblast

Answer 22

immature bone cell that secretes organic components of matrix in the process of osteogenesis

Question 23

osteoclast

Answer 23

a large, multinucleate cell derived from monocytes which secretes acids and enzymes to dissolve bone matrix in the process of osteolysis

Question 24

woven bone

Answer 24

• Immature bone
• Random arrangement of collagen fibres
• First formed during foetal development or repair of fracture
• Remodelled into lamellar bone

Question 25

lamellar bone

Answer 25

• Mature bone - virtually all bone in healthy adults
• Either compact or spongy
• Concentric bands of collagen
• Fibres are oriented in one direction in each layer, but each layer is in different directions -> increase in strength

Question 26

Osteon

Answer 26

• functional unit consisting of concentric lamellae
  contains:
• lacunae
• canaliculi
• haversian canals
• Volkmann canals

Question 27

lacunae

Answer 27

spaces between concentric lamellae

Question 27

canaliculi

Answer 27

small extracellular fluid filled channels radiating from lacunae, link lacunae

Question 28

haversian canals

Answer 28

• central canals
• neurovascular

Question 29

Volkmann canals

Answer 29

• perforating canals
• provide channels for neurovascular structures between adjacent osteons, periosteum and marrow`

Question 30

spongy bone

Answer 30

• Also known as cancellous or trabecular bone
• Composed of a latticework of thin plates of bone called trabeculae, oriented along lines of stress
• Spaces in between the struts are filled with red marrow
• It is found in the ends of long bones with inside flat bones such as hip bones, sternum and ribs
• Although the concentric lamellae within resembles that of an osteon, there are no true osteons in spongy bone

Question 31

concentric lamellae

Answer 31

tubes of different size fitting inside each other to make an osteon

Question 32

2 methods of bone formation

Answer 32

1. intramembranous ossification
2. endochondral ossification

Question 33

intramembranous ossification

Answer 33

• Ossification within a membrane
• Special cells secrete a protein matrix that later mineralises
• Primarily flat and irregular bones (facial bones, skull, clavicle)

Question 34

endochondral ossification

Answer 34

• The replacement of hyaline cartilage by bone
• Mesenchyme turns into cartilage that is later replaced by bone
• Majority of bones in skeletal system
• Normally associated with growth in length