Bone

Question 1

What are three basic qualities of bone that can help explain its histology?

Answer 1

Its alive
Its light
It has high tensile strength

Question 2

What are the two shape classifications of bone?

Answer 2

Flat

Long

Question 3

What are the two mechanisms of bone formation?

Answer 3

Intramembranous

Endochondral

Question 4

What does intramembranous formation mean?

Answer 4

Mesenchymal CT CHANGES INTO bone

Question 5

What does endochondral formation mean?

Answer 5

Cartilage is REPLACED by bone

Question 6

How can inferences about the bone’s age be made?

Answer 6

By examining its microscopic structure

Question 7

What features of bone would suggest youth/immaturity?

Answer 7

Woven or immature bone

Question 8

What features suggest a mature/older bone?

Answer 8

Lamellar

Spongy/Compact

Question 9

What are some qualities of woven bone?

Answer 9

Very cellular
Irregular matrix
Low mineral content

Question 10

What are some qualities of lamellar bone?

Answer 10

Matrix is arranged in layers

Bone can be spongy or compact

Question 11

What is the only way bone Grows?

Answer 11

Appositional

Question 12

What are the three regional divisions of a long bone?

Answer 12

Diaphysis/Shaft
Epiphysis/Rounded End
Epiphyseal Plate

Question 13

What is the structural makeup of the long bone diaphysis?

Answer 13

Compact bone on outside, marrow cavity inside

Question 14

What is the term for blood cell formation?

Answer 14

Hematopoiesis

Question 15

Where in the bone does hematopoiesis take place?

Answer 15

In the red marrow

Question 16

What is yellow marrow filled with?

Answer 16

Adipose CT

Question 17

What is the structural makeup of the epiphysis?

Answer 17

Compact bone on outside, spongy bone on inside

Question 18

What two regions does the epiphyseal plate separate?

Answer 18

It separates the diaphysis from the epiphysis

Question 19

Where is the periosteum found?

Answer 19

It covers the entire exterior of the bone except for articular surfaces

Question 20

What are the two primary layers of periosteum?

Answer 20

Outer layer of Dense Fibrous CT

Inner Osteogenic layer

Question 21

Where is the endosteum found?

Answer 21

It lines the marrow cavity,

aka all internal surfaces of the long bone

Question 22

What makes up the endosteum?

Answer 22

A single layer of osteoblasts or osteogenic cells

Question 23

What type of cartilage makes up the articular cartilage?

Answer 23

Hyaline

Question 24

How do blood vessels get into the mature bone layers?

Answer 24

Periosteal vessels are “trapped” as the periosteum lays down new bone

Question 25

What do Nutrient vessels supply?

Answer 25

Long bone marrow

Question 26

Where do the nutrient vessels enter?

Answer 26

The diaphysis compact bone

Question 27

What are the function of epiphyseal vessels?

Answer 27

To supply the epiphysis

Question 28

Where do epiphyseal vessels enter?

Answer 28

Near the epiphyseal plate

Question 29

Where is there an abundance of nerve cells

Answer 29

In the periosteum, not in the "bone" cells

Question 30

How do the vasomotor nerves get inside the bone?

Answer 30

They run alongside the blood vessels

Question 31

What are the components of flat bone?

Answer 31

Inner and Outer Tables of thick compact bone Diploe layer Periosteum

Question 32

What is the diploe of flat bone?

Answer 32

Spongy bone between the tables

Question 33

Where is the periosteum found in the cranial flat bones?

Answer 33

On the outer surface | Inner surface is dura mater

Question 34

What are the 3 primary histological components of bone?

Answer 34

Osteoblasts Osteoclasts Osteocytes

Question 35

Where do you find osteoblasts

Answer 35

They (or their precursors) form a row of cuboidal cells of the surfaces of bone on both the periosteal and endosteal surfaces

Question 36

What is the nucleus of the osteoblast like?

Answer 36

Its usually on the side of the cell away from the bone | It has a prominent nucleolus

Question 37

Why is the osteoblast cytoplasm so basophilic?

Answer 37

Because of the large amount of RER

Question 38

Besides the basophilic RER, what else is notable about the osteoblast cytoplasm?

Answer 38

Negative image golgi | Lots of mitochondria

Question 39

When depositing new bone, what is the first thing synthesized by an osteoblast?

Answer 39

Osteoid

Question 40

What are the two components of the Osteoid?

Answer 40

Type I collagen | Ground Surface: Condroitin sulfate

Question 41

What do the osteoblasts secrete to ossify the osteoid?

Answer 41

Alkaline phosphatase

Question 42

What does the alkaline phosphatase do?

Answer 42

Causes the calcification of the osteoid along the collagen fibers

Question 43

What do osteocytes look like?

Answer 43

Flattened ovoid with long processes extending from it through caniculi in the bone towards other osteocytes. They are joined by gap junctions

Question 44

What is the function of the osteocyte?

Answer 44

They transport materials between blood and bone to maintain the surrounding matrix

Question 45

How many nuclei can osteoclasts have?

Answer 45

Up to 15-20!

Question 46

Where are osteoclasts located?

Answer 46

Surface of bone, frequently in depressions called Howship's lacunae

Question 47

What are the precursors for Osteoclasts?

Answer 47

Monocytes in the bone marrow

Question 48

How do they resorb bone?

Answer 48

Primarily with proteolytic enzymes (acid phosphatase)

Question 49

How can the cytoplasm of osteoclasts be described?

Answer 49

frothy of vacuolated contain granules of acid phosphatase surface facing bone is ruffled

Question 50

What percent of the dry weight is the organic portion of bone?

Answer 50

35%

Question 51

What organic component makes up 90% of the bone matrix?

Answer 51

Type I collagen

Question 52

What feature identifies Type I collagen

Answer 52

banding

Question 53

What is the other major portion of the organic bone matrix?

Answer 53

Glycosaminoglycans

Question 54

What do the GAGs do?

Answer 54

Cement collagen fibers together

Question 55

Why is the matrix more acidophilic than cartilage?

Answer 55

There are less chondoitin sulfates

Question 56

What is the function of the organic matrix

Answer 56

Gives bone great toughness and resiliency

Question 57

What makes up the inorganic portion of bone?

Answer 57

Crystals like Hydroxyapaptite Calcium ions Phosphate ions Citrate & Carbonate

Question 58

What do the deposition needles look like physically?

Answer 58

Slender needles along collagen fibers

Question 59

What is the function of the inorganic portion

Answer 59

Hardness

Question 60

What are the three types of Lamella?

Answer 60

Haversian System Inner and Outer circumferential lamellae Interstitial Lamellae