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Flashcards in Bone Deck (38):
1

Functions of bone

Support, lever for effective movement, protection of internal organs, calcium store and haemopoiesis

2

How much calcium is found within bone

About 95% of total body calcium

3

Composition of bone

65% biopatite, 23% collagen, 10% water, and 2% non-collagen proteins

4

Fibrous connective tissue surrounding bone is known as

Periosteum

5

What are the two types of bone

Cortical bone and cancellous bone

6

What type of bone makes up the shaft

Cortical bone

7

What type of bone makes up the ends of bone

Cancellous bone

8

What is the main difference between the morphology of cortical and cancellous bone

The presence of spaces, known as marrow cavities, adjacent to cancellous bone

9

Bone that is made up from layers is known as

Lamellar bone

10

What is within the small canals in bone

Blood vessels and nerves

11

What are the cells living within bone called

Osteocytes

12

Characteristics of trabecular bone

- Has osteocytes
- Lamellar in nature
- Haversian canals are uncommon

13

The outer layers of bone are organised in lamellae that run around the bone and are called

Outer circumferential lamellae

14

What are the cells found within bone

Osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts

15

Osteoprogenitor cells

- Located on bone surfaces under the periosteum
- Reserve pool of osteoblasts

16

Osteoblasts

- Bone forming cells
- Found in the surface of developing bone
- Plentiful RER and prominent mitochondria

17

Osteocytes

A bone cell trapped within the matrix

18

Osteoclasts

- Large multinucleate cells
- Found on the surface of bone
- Responsible for bone resorption

19

How do osteoblasts produce new bone

They actively secrete a matrix onto the top of pre-existing bone

20

What is the main make up of the mineral of bone

Calcium phosphate crystals

21

What do osteoblasts secrete

Collagen, GAGs, proteoglycans, and other organic compounds

22

What is osteoblast secretion known as

Osteoid

23

Other than osteoid, what else do osteoblasts secrete

Matrix vesicles

24

What do matrix vesicles contain

Enzymes which produce phosphates and accumulate calcium phosphate salts

25

What type of bone is laid down after a break

Woven bone

26

How does woven bone differ to lamellar bone

In lamellar bone the collagen fibres are orientated in one diffraction but in woven bone they are laid down in a haphazard fashion

27

Characteristics of woven bone

- Not as strong as lamellar
- Eventually remodelled into lamellar bone by being broken down by osteoclasts and reformed by osteoblasts

28

Osteoclasts

- Derived from macrophage lineage
- Several will fuse and form a single giant multinucleated cell

29

What is the collection of osteoclasts and osteoblast that particiapate in bone remodelling at a particular site called

The basic multicellular unit (BMU)

30

How is bone remodelled

- A number of osteoclasts congregate and begin to drill into bone forming a tunnel
- A blood vessel grows into the tunnel and brings osteoblasts with it
- Osteoblasts line the tunnel and begin laying down new bone
- Process continues until only the Haversian canal is left

31

Lines around an osteon

Cement lines

32

What are interstitial lamellae

Lamellae between old osteons that are the remnants of old osteons

33

Periosteum

- Dense connective sheath around bone
- Has two layers

34

Types of ossification

Intramembranous and endochondral

35

Intramembranous ossification

- Mesenchymal cells differentiate into osteoblast and begin to synthesis and secrete osteoid
- This process begins at the centres of ossification

36

How does endochondral ossification begin

With a hyaline cartilage model of the bone to be formed

37

Examples of bones produced from endochondral ossification

Most long bones, base of skull, and the medial and lateral ends of the clavicle

38

Characteristics of bone

- Rigid
- Non-permeable
- Appositional growth
- Cells within bone nourished by blood vessels that pervade the matrix