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Flashcards in Bone Deck (59)
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1

Is bone a type of connective tissue?

Yes, bone consists of cells, fibers and ground substance like other connective tissues

2

What is the osteoid?

The unmineralized organic matrix made of fibers and ground substance

3

What causes bone to become rigid?

The mineralization of the organic matrix by deposition of hydroxyapatite crystals

4

What are osteoblasts?

Osteoblasts are basophilic and cuboidal (if active, flattened if inactive) and produce the organic extracellular matrix

5

Where are osteoblasts found?

Surface of bone tissue

6

What are osteocytes?

Cells that are within bone lacunae to maintain bone matrix

7

Are osteocytes connected?

Yes. Osteocytes are connected by gap junctions on cell processes

8

What are osteoclasts?

Multinucleated macrophages that remove bone.

Osteoclasts are acidophilic with a ruffled border, located next to Howship's lacunae

9

Name an example of a syncytium

Osteoclast

10

What % collagen fibers make up the osteoid?

90% collagen fibers, 10% ground substance

11

How much mineral does bone consist of?

65% mineral (hydroxyapatite)

Hydroxyapatite gradually deposits on and within the collagen lattice of osteoid

12

What is the endosteum

Loosely organized connective tissue that has 3 continuous regions and is located within the bone

Diaphyseal endosteum lines the walls of the marrow cavity

Trabecular endosteum covers the trabeculae of spongy bone

Osteonal endosteum goes in to blood vessel canals that are within the bone

13

What cells produce osteablasts?

Osteprogenitor cells

14

Where do osteopregenitor cells originate?

Endosteum and inner layer of periosteum

15

What is the periosteum?

Thick outer connective tissue layer on bone that consists of a fibrous outer layer and an inner cellular layer

16

What are Sharpey's fibers?

Collagen fibers that anchor the periosteum to the bone

17

What is the Haversian system?

The osteon, the basic unit of mature compact bone

18

What are osteons composed of?

Concentric lamellae or layers of mineralized bone matrix around a central canal that holds blood vessels and connective tissue

19

How are osteons arranged?

Along the long axis of the bone

20

Where are osteocytes found in the osteon?

Positioned between the lamellae of the osteons

21

What are canaliculi?

Tiny channels that connect lacunae

22

What are Volkmann's (perforating) canals?

Channels in bone that transmit blood vessels from the periosteum or endosteum in to the bone.

This provides a functional connection between the endosteum and the periosteum so there is connective tissue covering all surfaces

23

How are perforating canals arranged?

Perpendicular to the Haversian canals (osteons)

24

Describe spongy bone

Spongy bone is found in the heads of long bones and fills most irregular bones

25

Describe compact bone

Compact bone forms the outer shell of all bone and shafts in long bones

26

What is intramembranous ossification?

Formation of bone within the mesenchymal tissue without a cartilage model

Most flat bones of the skull develop this way

27

How does intramembranous ossification work?

Mesenchymal cells differentiate to osteoblasts, osteablasts secrete the osteoid and become trapped.

Bone spicules form and fuse in to solid bone

28

What is bone formation from the periosteum called?

Intraembranous ossification

29

What is a bone spicule?

A small structure such as a calcium carbonate process that supports the soft tissue of certain invertebrates

30

What is a trabecula?

A small bar or septal membrane in the framework of an organ

Any intersecting osseous bars that occur in cancellous bone