Brain and Fracture Repair

Question 1

Components of bone

Answer 1

Cells
Fibers
Ground substance
Mineral
Very little water

Question 2

What is another name for extracellular matrix?

Answer 2

Osteoid

Question 3

In osteoblasts, nucleus is on ____ _____ from matrix

Answer 3

side awary

Question 4

What shape are osteoblasts?

Answer 4

Cuboidal

Question 5

Describe osteocytes

Answer 5

Incapable of mitosis
Maintain bone matrix, not actively synthesizing matrix
Less rER and golgi than osteoblasts

Question 6

Filopodial processes

Answer 6

Extension of the cells

Question 7

Osteoclasts

Answer 7

Derived from blood monocytes-mononuclear phagocyte system

Contain many nuclei (multinucleate) (2-50)

Question 8

Howship’s lacunae

Answer 8

In osteoclasts- osteoclasts lie in enzymatically etched depression

Question 9

Function of periosteum

Answer 9

Connective tissue capsule surroundng bone
Provides blood supply for nutrition of cells
Provides continuous supply of new osteoblasts

Question 10

Fibrous layer of periosteum

Answer 10

Outermost layer
Contains collagen and fibroblasts
Dense regular CT

Question 11

Osteogenic layer of periosteum

Answer 11

Inner layer
very cellular
contains osteoprogenitor cells-have ability to dividde and differentiate into osteoblasts
Contains Sharpey’s fibers-collagen fibers that penetrate bone matrix and bind periosteum to bone

Question 12

Function of endosteum

Answer 12

Contains osteoprogenitor cells

Question 13

Location and compositio nof endosteum

Answer 13

Lines marrow cavity and extends into Haversian canals
Composed of reticular tissue
thinner than periosteum

Question 14

What provides resistance to tension to a bone?

Answer 14

osteoid (organic material)- removal of organic material results in structure with same shape, but very fragile and breaks easily

Question 15

What provides hardness and rigidity to the bone?

Answer 15

Mineral portion (inorganic)- removal of the mineral portion results in structure with same shape, but becomes very flexible

Hydroxyapatite cystals

Question 16

Parathyroid hormone

Answer 16

stimulates bone breakdown

Indirect activation of osteoclasts
Acts on osteoblasts (have receptors)
Osteoblasts secrete cytokines which stimulate osteoclasts
Increased bone resorption

Question 17

Calcitonin

Answer 17

Stimulates bone synthesis
Acts directly on osteoclasts (on calcitonin receptors)
Inhibits resorption activities of OC
Stimulates bone deposition by osteoblasts

Question 18

What is another name for trabecular bone?

Answer 18

Spongy bone

Question 19

Location of trabecular bone

Answer 19

Epiphyses
Interior of bones
Flat bones of skull (between plates of compact bone)-called dipole

Question 20

Characteristics of cancellous bone

Answer 20

Foms trabeculae (bone spicules)
Interconnecting cavities
3D lattice with many open spaces

Question 21

Which bone type contains Haversian systems (osteon)?

Answer 21

Compact bone. No open spaces or trabeculae
Organized into lamellae

Locatoin: covers spongy bone in epiphyses
Diaphysis
Flat bones of skull

*Always secondary bone

Question 22

Haversian canals

Answer 22

Parallel to long axis of diaphysis
Lined with endosteum
Contains blood vessels, nerves, lymphatic vessels
Lamella farthest from blood vessels form first

Question 23

What is lamellae?

Answer 23

Lamellae are layers of bone tissue. The collagen fibers are arranged in parallel fashion in each lamella, but are perpendicular to the fibers in adjacent lamellae

Question 24

Outer circumferential lamellae

Answer 24

“Rings” of bone tissue lining the outer portion of the bone, immediately beneath the periosteum

Question 25

Inner circumferential lamellae

Answer 25

“Rings” of bone tissues surrrounding the marrow cavity lined by endosteum

Question 26

Interstitial lamellae

Answer 26

Partial lamellae between osteonss-parts of old osteons

Question 27

Intramembranous ossification

Answer 27

No cartilage model formed

Mesenchyme differentiates directly into osteoblasts to form bone

Question 28

Endochondral ossification

Answer 28

• Mesenchyme condensation formed
• Mesenchyme cells differentiate to form chondroblasts
• Cartilage model of each skeletal structure formed
• Cartilage model has the same shape as future bone
• Chondrocytes become more specialized
• “Zones” of chondrocytes form

*Epiphyseal plate is responible for the growth in length of the bones

Question 29

What forms the epiphyseal plate?

Answer 29

Zones of chondrocytes

Question 30

Endochondral bone formation- layers

Answer 30

Resting zone
Zone of proliferatoin
Zone of hyperrophy
Zone of calification
Zone of Ossification