Microscopic Anatomy of Bone

Question 1

What are the four different types of Bone Cells?

Answer 1

1. Osteoprogenitor Cells
2. Osteoblasts
3. Osteocytes
4. Osteoclasts

Question 2

Osteoprogenitor Cells

Answer 2

Will differentiate and become bone cells, when it matures it becomes osteoblasts

Question 3

Osteoblasts

Answer 3

Secrete osteoid, forming bone matrix

Question 4

Osteocytes

Answer 4

Mature bone cells that sense stress/strain on the bone

Question 5

Osteoclasts

Answer 5

Break down bone, activate when there’s low calcium

Question 6

Compact Bone

Answer 6

Strong, Heavy

Question 7

Spongy Bone

Answer 7

Porous, not as strong as compact, has trabeculae (pieces/bridges of bone that make up spongy bone)

Question 8

Osteon

Answer 8

• The basic unit of compact bone
• AKA Haversian system
• Cylindrical structures
• Run parallel to the diaphysis

Question 9

Central Canal

Answer 9

Spaces at the core of each osteon

Question 10

Concentric Lamellae

Answer 10

Make up osteon

Question 11

What are the three structures in Compact Bone?

Answer 11

1. Osteocytes (embedded in)
2. Canaliculi
3. Perforating canals

Question 12

Canaliculi

Answer 12

Little canal where osteocytes can communicate with each other

Question 13

Perforating Canals

Answer 13

Run perpendicular to central canals

Question 14

Spongy Bone Characteristics

Answer 14

• Lack osteons
• Trabeculae contains parallel lamellae
• Distributes stress from mechanical forces across framework

Question 15

Ossification

Answer 15

The formation of bone connective tissue

Question 16

Intramembranous Ossification
(No cartilage stage)

Answer 16

How flat bones are formed (Ex. Skull)

Question 17

Endochondral Ossification

Answer 17

How long bones are formed

Question 18

Intramembranous Ossification Process

Answer 18

• Produces flat bones of the skull, some facial bones, mandible, and central portion of clavicle
• Bones develop from mesenchyme membrane
• Calcification entraps osteoblasts within lacunae in bone matrix
• Osteoblasts become osteocytes
• Woven bone and surrounding periosteum form
• Lamellar bone replaces woven bone, as compact and spongy bone form

Question 19

Endochondral Ossification Process

Answer 19

• Formation of most bones of skeleton: upper/lower limbs, pelvis, vertebrae, ends of clavicles
• Bones develop from hyaline cartilage model

Question 20

How do bones develop from the hyaline cartilage model?

Answer 20

1. The fetal hyaline cartilage model develops
2. Cartilage calcifies, and a periosteal bone collar forms
3. The primary ossification center forms in the diaphysis
4. Secondary ossification centers form in the epiphyses
5. Bone replaces cartilage, except the articular cartilage and epiphyseal plates
6. Epiphyseal plates ossify and form epiphyseal lines

Question 21

A long bone’s growth in length

Answer 21

Growth within

Question 22

Growth in a bone’s diameter

Answer 22

Growth on outside, covers inside

Question 23

Epiphyseal Plate

Answer 23

• Site of interstitial growth
• Consists of five distinct microscopic zones

Question 24

Effects of exercise

Answer 24

When physically active it causes the bone to be more mineralized because the bone senses strain/stress