Lecture 8: Bone

Question 1

The structure of individual bones is designed to provide maximum resistance to ____ ____ while maintaining the least _____ _____.

Answer 1

Mechanical stress

Body mass

Question 2

Applied histology definition of bone

Answer 2

Specialized connective tissue consisting of cells embedded within a gel-like substance that becomes mineralized

Question 3

Bone has the property of marked ____ and _____ while retaining some degree of _____

Answer 3

rigidity
strength
elasticity

Question 4

Bone is considered both a ____ and an ____ because

Answer 4

tissue
organ
an organ is a group of tissues which perform a specific function or group of functions

Question 5

4 functions of bones

Answer 5

• Support/protect
• Shape/movement
• Source of calcium reserve (99%) and storage of other inorganic ions
• Active participation in the maintenance of calcium homeostasis in the body

Question 6

To acommodate changes related to mechanical stresses and demands on calcium homeostasis, bones are in a dynamic state of

Answer 6

growth and resorption throughout life

Question 7

Bone is composed of

Answer 7

Cells and an organic extracellular matrix containing primarily glycoproteins and collagen fibers called the osteoid

Question 8

Osteoid rapidly undergoes mineralization by

Answer 8

deposition of inorganic salts, mainly calcium hydroxyapatite crystals, to form bone

Question 9

The bone matrix growth factors play an important role in

Answer 9

bone development
modeling
remodeling

Question 10

Bone composition percentages

Answer 10

• 9% water
• 22% organic matrix
• 69% inorganic matrix

Question 11

Organic matric is ___% collagen which is responsible for

Answer 11

95

tensile strength

Question 12

Collagen in organic matrix is mainly type

Answer 12

I

Question 13

Bone organic matric contains

Answer 13

• Sulfated GAGs like chondroitin and karatan sulfate

- Glycoproteins such as alkaline phosphatase, osteonectin, and ostepontin

Question 14

Inorganic matrix is mainly composed of

Answer 14

Hydroxyapatite crystals deposited within collagen fibrils to enhance tensile strength

Question 15

How are the microcrystals of hydroxyapatite formed?

Answer 15

Calcium phosphate reacts with calcium hydroxide

Question 16

The main minerals of the bones

Answer 16

• Calcium phosphate (85%)
• Calcium carbonate (10%)
• Amounts of Na, Mg, and Fe are substantial but constitute less than 5% of bone total

Question 17

What provide the framework and necessary tensile strength?

Answer 17

Collagen fibers produced by osteoblasts

Question 18

What serve as carriers for minerals?

Answer 18

Proteoglycans of the bone (osteoid) embedded in the collagen fibers

Question 19

How does the bone matrix harden?

Answer 19

By deposition mainly of hydroxyapatite

Question 20

Two bone envelopes

Answer 20

Periosteum

Endosteum

Question 21

Periosteum

Answer 21

• A fibrous connective tissue layer that covers outer/external surface of bones
• Site of insertion of muscles, tendons, and ligaments

Question 22

Endosteum

Answer 22

-Inner delicate connective tissue surface of the bone - lines the trabeculae of the spongy bone

Question 23

Immature bone cells originating from osteoprogenitor cells

Answer 23

osteoblasts

Question 24

Osteoblasts are responsible for

Answer 24

synthesis and secretion of collagen and organic compounds of the extrallcellular matrix of bone (osteoid)

Question 25

Osteoid quickly mineralizes and osteoblasts are trapped as

Answer 25

osteocytes