chapter 6 part 2

Question 1

woven bone

Answer 1

Collagen fibers randomly oriented.
* First type of bone formed by osteoblasts during ossification.
* During fetal development, growth, and fracture repair.

Question 2

Remodeling

Answer 2

• Osteoclasts remove old bone and osteoblasts add new.
• Woven bone is remodeled into lamellar bone.

Question 3

Lamellar bone

Answer 3

• Mature bone in sheets called lamellae. Fibers are oriented in one direction in each layer, but in different directions in different layers for strength.

Question 4

Trabeculae

Answer 4

sponge bone
interconnecting rods or plates of bone.
* Spaces filled with marrow.
* Covered with endosteum.
* Oriented along stress lines

Question 5

compact bone

Answer 5

• Solid, outer layer surrounding each bone; has more matrix and is denser than spongy bone.
• Blood vessels enter the bone and the lamellae are oriented around the blood vessels.
• Functional unit of compact bone is an osteon or haversian system.
• Composed of concentric rings of matrix around a central canal, giving the appearance of a bulls-eye.
• Osteocytes are sandwiched between the rings of the matrix and connected by canaliculi.
• Central or Haversian canals: parallel to long axis.
• Lamellae: concentric, circumferential, interstitial

Question 6

Central or Haversian canals:

Answer 6

parallel to long axis of compact bone

Question 7

Lamellae

Answer 7

think layers of bone matrix in compact bone

Question 8

Perforating or Volkmann’s canal

Answer 8

part of compact bone
perpendicular to long axis. Both perforating and central canals contain blood vessels that run from the periosteum or medullary cavity to the osteocytes in their lacunae.
* Direct flow of nutrients from vessels through cell

processes of osteocytes within the canaliculi and from one cell to the next.
* Nutrients and wastes travel to and from osteocytes via.
* Interstitial fluid of lacunae and canaliculi.
* From osteocyte to osteocyte by gap junctions.

Question 9

Diaphysis

Answer 9

Shaft; primarily compact bone surrounding the medullary cavity.

Question 10

Medullary cavity

Answer 10

• In children medullary cavity is red marrow for blood cell formation.
• In adult, red marrow is replaced by yellow in limb bones (except for proximal epiphyses of arm and thigh bones). Elsewhere, varying proportions of yellow/red marrow are found.

Question 11

Epiphysis

Answer 11

• End of the bone; primarily spongy bone covered with compact bone.
• Within joints, covered with hyaline cartilage called articular cartilage.

Question 12

Epiphyseal plate

Answer 12

growth plate.
* Hyaline cartilage; present until growth stops.

Question 13

Epiphyseal line

Answer 13

epiphyseal plate is ossified as bone stops growing in
length.

Question 14

Periosteum

Answer 14

structure of a long bone
Connective tissue membrane covering the outer surface of a bone.
* Outer portion is dense irregular collagenous C T containing blood vessels and nerves.
* Inner is single layer of bone cells including osteoblasts,
osteoclasts and osteochondral progenitor cells.
* Fibers of tendons and ligaments become continuous with fibers of periosteum.

Question 15

Perforating fibers (Sharpey’s fibers):

Answer 15

structure of a long bone
some periosteal fibers penetrate through the periosteum and into the bone. Strengthen attachment of tendon to bone.