Bone Histology

Question 1

functions of bone

Answer 1

support

protection of soft organs

levers for muscle action

reservoir for calcium/phosphorus ions

blood cell production

Question 2

what is the inner part of the bone called? function?

Answer 2

spongy, cancellous, or trabecular

makes it hollow - provides strength and reduces weight, hold bone marrow

Question 3

what is the outer part of the bone called?

Answer 3

compact bone

Question 4

what lines the endosteal surface of bones? function?

Answer 4

osteoclasts, osteoblasts, osteoprogenitor cells - for remodeling

Question 5

Bone composition

Answer 5

hydroxyapatite (calcium and phosphate that precipitate onto organic matrix)

organic matrix (type I collagen)

cellular maintenance (osteoblasts, osteocytes, osteoclasts)

Question 6

osteoid

Answer 6

non-mineralized organic matrix

Question 7

osteoblasts

Answer 7

bone-forming cells that secrete osteoid

found along endosteal surfaces

Question 8

osteocytes

Answer 8

living cell embedded in matrix that maintain bone by connecting to other osteocytes to exchange nutrients/waste,

Also detect mechanical stress

Question 9

osteoclasts

Answer 9

bone destroying/reabsorption cells

large, mutlinucleated, can move around bone

seal onto bone and digest bone surface with acidic environment (via proton pumps, lysosomes)

Question 10

Howship’s Lacuna

Answer 10

space that is chewed away by an osteoclast

Question 11

How does PTH increase blood calcium levels via acting on bone?

Answer 11

activates receptors on osteoblasts -> osteoblasts release substance that tells osteoclasts to start eating up the bone to release calcium into the blood

Question 12

woven bone

Answer 12

very immature bone without sheets/lamella that is later eaten up by osteoclasts and remade as mature bone by osteoblasts

seen during fetal development and healing of fractures

Question 13

Lamellar bone

Answer 13

mature, post-remodeling bone

have lamella that make up osteons

Question 14

haversion canals

Answer 14

where blood vessels and nerve innervate bone (in center of osteons

Question 15

where is lamellar bone?

Answer 15

in both compact and trabecular bone

Question 16

intramembranous bone formation (ossification)

Answer 16

occurs in fetus in skull, jawbones, ribs

no cartilage involved - instead generic connective tissue is replaced by bone

Question 17

Endochondral ossification

Answer 17

fetal cartilage scaffold is replaced by bone

occurs in long, irregular, or short bones

allows for growth plates and growth of bones until the individual reaches puberty

Question 18

Epiphyseal plate

Answer 18

collar of cartilage formed by ossification of diaphysis and epiphysis first

allows bone to grow

completely replaced by bone during puberty

Question 19

how does growth plate allow bone to grow?

Answer 19

chondrocyte proliferation occurs in the center and gets replaced by osteocytes and osteoblasts from the metaphysis/diaphysis

Question 20

which type of osteogenesis is responsible for closure of skull sutures?

Answer 20

intramembranous