Lecture 9- Bone Flashcards Preview

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1

What type of tissue is bone?

Connective

2

What are the components of bone?

Cells and Extracellular Matrix (Bone Matrix)

3

What cells make up bone?

1. Osteoblasts
2. Osteoclasts
3. Osteocytes
4. Bone lining Cells
5. Osteoprogenitor Cells

4

What makes up Bone Matrix?

1. Fibers
2. Ground Substance

5

What is general fibrous structure of bone and why is it like that?

Fibers are aligned parallel but are oriented in different directions.
Adds strength.

6

What gives bone its strength?

A calcified bone matrix

7

What cells help "maintain" the bone matrix?

Osteocytes

8

How does the osteocyte gets its nutrients and get rid of waste?

Canaliculi

9

What happens in the canaliculi?

Exchange of nutrients and waste products that travel down cell to cell of dendritic processes of osteocytes

10

What structure aids w/ transfer of nutrients from one osteocyte to another?

Gap Junctions

11

2 General Types of Bone Structure

1. Compact Bone
2. Cancellous Bone (AKA spongy or trabecular bone)

12

Is compact bone and cancellous bone made of the same material?

Yes. Both Lamellar bone. Organized differently.

13

Where do osteoblasts come from?

Bone lining cells or osteoprogenitor cells.

14

Steps of the bone remodeling cycle (3).

1. Osteoclast (apoptosis)
2. Osteoblast Secretes bone matrix (osteoid - unmineralized bone)
3. Mineralization

15

Where does bone remodeling occur?

1. On the surface of bone
2. In the middle of bone

16

How does bone modeling occur in the middle of bone?

1. Clasts come through blood vessel, start working to make a connecting canal
2. Blasts stay on surface (bone lining cells) and fill in canal with bone (surround blood vessels)
3. Cytes sit in lacuna and maintain matrix and stim remodeling cycle from stress

17

What is osteoporosis?

1. Decreased bone mass per unit volume of anatomical bone.
2. After 35, clast > blast

18

Biphosphonates can help limit osteoporosis, but osteonecrosis may be a side effect, why?

Biphosphonates disrupt bone remodeling. When there is continual stress on the bones, they have a limited capacity for healing

19

Different kinds of osteogenesis (2)

1. Intramembranous Ossification
2. Endochondral Ossification

20

Most flat bones develop via _______ ossification.

Intramembranous

21

Steps of intramembranous ossification (4)

1. Mesenchymal cells in CT membrane or sheet form clusters
2. Cluster differentiates into osteoblasts = ossification center
3. Osteoblasts secrete osteoid
4. Becomes mineralized

22

What is condensed mesenchyme?

Mesenchyme that is more cellular

23

What kind of bone is intramembranous bone?

Primary bone or Woven Bone = SPONGY
*NOT LAMELLAR BONE or secondary bone

24

What are trabeculae made of and how is it oriented?

Collagen Fibers
Oriented Randomly

25

What happens during the remodeling of woven bone?
Where can you find this kind of bone?

It become lamellar bone, with collagen fibers oriented in parallel.
Flat bones like in the skull.

26

What does endochondral ossification mean?

Cartilage that turns to bone.

27

Steps of endochondral ossification.

1. Mesenchymal Cells Condense during fetal development
2. Develop into chondrocytes
3. Cartilage is developed into the shape of the bone that it will form (surrounded by perichondrium)
4. Cartilage deteriorates and becomes primary ossification center (woven bone), has blood vessel of periosteal bud
5. Secondary Ossification Centers develop at the ends of the bone

28

Why is epiphyseal cartilage important?

It allows you to get taller

29

Zones of epiphyseal growth plate (5)

Zone 1 - Hyaline Cartilage (resting zone)
Zone 2 - Proliferation - making more chondrocytes
Zone 3 - Hypertrophy
Zone 4 - Calcification - osteoblasts come in and lay down bone
Zone 5 - Ossification

30

What happens to chondrocytes at the epiphyseal growth plate? (7)

1. Hypertrophy of chondrocytes
2. Compress surrounding cartilaganous matrix
3. Chondrocytes die (apoptosis)
4. Carilage matrix become more calcified (basophilic)
5. Blood vessels and osteoblasts invade the tissue
6. Lay down Osteoid
7. Mineralized to bone