Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Oral Biology > QUIZ 2 Enamel I > Flashcards

QUIZ 2 Enamel I Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

mature enamel is ___ in orgin, and is a product of the ___

A
  • ectodermal
  • enamel organ
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

enamel is brittle, so underlying ___ support is critical for function

A

dentin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

can enamel be both demineralized and remineralized?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

is mature enamel cellular or acellular?

A

acellular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

is enamel vital or nonvital?

A

nonvital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

is there vasculature associated with mature enamel?

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

enamel is the hardest tissue in the body. in other words, it is the most ___

A

mineralized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe the color of mature enamel

A

it is translucent, with a range of colors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

mature enamel covers the ___ of the tooth

A

crown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

mature enamel is thicker at the ___, around 2.5mm, and relatively thin at ___

A
  • crown
  • cervical line
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

mature enamel is composed primarily of what?

A

hydroxyapatite crystals

small but essential protein component: organization of crystals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe the components of mature enamel by weight

A
  • 96% inorganic material (hydroxyapatite)
  • 1% organic material
  • 3% water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe the components of mature enamel by volume

A
  • 85% inorganic (hydroxyapatite)
  • 3% organic
  • 12% water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe the organic component of enamel

A
  • 1-2% distributed between hydroxyapatite crystals
  • no collagen
  • enamel proteins, some present only in developing enamel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the major enamel proteins in the organic component of enamel?

A

amelogenins, ameloblastins, enamelin, tuftelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe enamel crystals

A
  • form the organization of enamel
  • closely packed, long, ribbon-like
  • many crystals packed together form both the enamel rods and the interrod enamel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

the mineral component of enamel is hydroxyapatite, but lots of enamel crystals are actually composed of ___

A

carbonatoapatite (carbonated apatite)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the formula for hydroxyapatite?

A

Ca5(PO4)3(OH) x2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how can carbonatoapatite be formed from hydroxyapatite?

A

CO32- can substitute for both PO43- (usually) and OH- (sometimes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

hydroxyapatite can incorporate what 3 things into its structure?

A

carbonate, magnesium (more vulnerable to acid attack), and fluoride (less vulnerable to acid attack)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

___ and ___ are incorporated into the more inner enamel, and ___ in the outer enamel

A
  • carbonate and magnesium
  • fluoride
  • thus, outer enamel is said to be more resilient in the face of an acid attack
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

each enamel crystal is ___ in shape, reflective of the individual ___ unit cell

A
  • hexagonal
  • hydroxyapatite
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are the dimensions of mature enamel crystals?

A

60-70nm wide, 25-30nm thick, and can be very long - may run the entire length of the enamel layer (in the mm range)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

___ symmetry increases as crystals mature

A

hexagonal

but fully mature enamel crystals lose their shape somewhat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is an enamel rod?

A

cylindrical accumulation of enamel crystals, lined up along the long axis of the rod

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

rods generally run perpendicular to the ___

A

DEJ (pulp)

they radiate outwards from the center

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

are enamel rods straight?

A

not completely; they curve somewhat as they progress towards the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

rods are often called prisms. why is this technically incorrect?

A

rods are not that regular in terms of geometry

29
Q

1 rod = 1 ___

A

ameloblast

it is important to realize that 1 ameloblast will actually contribute to the surrounding rods as well

30
Q

rods are organized into rows, which run in ___ directions

A

alternating

forms a dense meshwork of cylinders

31
Q

why is the orientation of rods impossible to tell from light microscopy?

A

rods throw off light in all directions

32
Q

what is the relatively protein-rich area of enamel that surrounds the rods?

A

rod sheath

33
Q

the rod sheath runs about 3/4 of the way around each rod, for the most part separating ___ and ___

A

rod and interrod enamel

34
Q

in the gaps of the rod sheath, ___ are continuous with the interrod enamel, linking the two together

A

enamel crystals

35
Q

crystal orientation is mainly parallel to the long axis of the rods, except where?

A

at the gaps in the sheath area - they bend outwards and become continuous with the interrod enamel

36
Q

what are the two main rod sheath proteins?

A

ameloblastins and amelogenins

37
Q

interrod enamel has the same basic composition as ___, but just in different enamel crystal orientation

A

rods

38
Q

essentially, ___ fills the gaps between rods

A

interrod enamel

more accurately, columns embed in interrod enamel

39
Q

caries are thought to penetrate through the ___ areas, thus between rod and interrod enamel

A

higher protein rod sheath areas

40
Q

the enamel rod head is ___ to the surface of enamel

A

perpendicular (they point outwards)

41
Q

in histological sections, they are often demineralized in order to cut sections, so the enamel is not there. what is this called?

A

the enamel space

42
Q

what are the 3 main phases of the ameloblast lifecycle?

A
  1. pre-secretory - mature from pre-ameloblasts to ameloblasts
  2. secretory - deposition of enamel
  3. maturation - reduction of organic matrix, increase mineralization via ion transport

4th phase…protective phase

43
Q

what cells form the first pre-dentin?

A

odontoblasts

44
Q

describe ameloblast activation and deposition of enamel

A

intial deposition is only around 30% mineralized, with a much larger organic component

45
Q

as enamel matures, ___ component is reduced, and ___ increases

A
  • organic component
  • mineralization
46
Q

describe the deposition of enamel

A
  • ameloblasts deposit organic matrix via secretory vesicles, which exit the cell apically
  • the basal lamina separating the pre-dentin and ameloblasts is penetrated by cell projections and broken down
  • enamel is laid down directly in apposition to pre-dentin/mantle dentin
  • tomes’ process (not tomes’ fiber) forms, projects into the developing enamel, and is the site of secretory activity (gives a picket fence morphology)
47
Q

ameloblasts are bound together by ___, forming a front of enamel deposition and keeping the efront moving together in sync

A

junctional complexes (terminal bars)

48
Q

initial enamel in apposition to dentin does not have a ___ arrangement; it is uniform

A

rod

49
Q

___ effectively forms the enamel rod structure

A

tomes’ process

50
Q

describe the orientation of tomes’ process

A
  • distal - towards the forming enamel
  • proximal - towards the stratum intermedium
51
Q

describe how tomes’ process forms the enamel rod structure

A
  1. secretion fro different parts of the process forms interrods first, forms a groove, into which rods are formed
  2. small gap around 3/4 of the process fills with organic material and forms the rod sheath
  3. eventually, tomes’ process retracts
52
Q

after enamel rods have been made and tomes’ process retracts, the outer rods are ___ and the final (outermost) enamel is formed without ___

A
  • straighter
  • rods
  • thus, tomes’ processes = rods
53
Q

after enamel has been laid down, what do the ameloblasts do?

A

they return to being a squat cell, much like a pre-ameloblast

54
Q

what results in a single layer of reduced enamel epithelium?

A
  • loss of the stellate reticulum and fusion of the OEE and the IEE
  • apoptosis reduces cell number
55
Q

prior to eruption, what happens to enamel?

A

it hardens and becomes highly mineralized through the removal of water, organic material, and increased hydroxyapatite crystal diameter

56
Q

what is the rate of the maturation of enamel?

A

relatively slow - up to 5 years for some permanent teeth

57
Q

roughly 2/3 of ___ is maturation

A

amelogenesis

it is a relatively slow process

58
Q

the maturation of enamel involves the production of a unique basal lamina at the ___ (generally not collagen IV)

A

external enamel surface

59
Q

disruption of proteins in the unique basal lamina produced during enamel maturation can result in ___

A

enamel hypoplasia

the basal lamina probably helps regulate movement of fluid/material

60
Q

what is modulation?

A
  • occurs during enamel maturation
  • the process by which water and proteins are removed
61
Q

fusion of the enamel organ forms ___

A

reduced enamel epithelium

62
Q

after maturation of the enamel, the remains of the enamel organ attaches to the tooth until ___. enamel organ remnants fuse with the ___, forming a covering over the tooth

A
  • eruption
  • oral epithelium
63
Q

a canal (through which the tooth erupts) forms in the covering over the tooth formed by the fusion of the enamel organ with the oral epithelium, and this layer goes on to form the ___

A

dentogingival junction

64
Q

what is nasmyth’s membrane?

A
  • the membrane formed by cells, basal lamina, and debris that remains on the crown initially after eruption
  • it is actually composed of the primary enamel cuticle and secondary enamel cuticle
65
Q

what is the primary enamel cuticle?

A

the mineralized coating, which is the last secretory product of the ameloblasts (possibly the basal lamina)

66
Q

what is the secondary enamel cuticle?

A

aka dental cutlcle; formed from the remains of the reduced enamel epithelium merged with the oral epithelium and is removed due to mechanical forces

67
Q

what are ruffled cells?

A
  • during the maturation of enamel, infiltration and incorporation of calcium ions into crystals occurs during “ruffling”
  • lowered pH favors mineralization
  • secretion of proteolytic enzymes
  • cell spends 80% of its lifetime in the ruffled form
68
Q

what are smooth cells?

A
  • smooth cells allow diffusion out of protein fragments out of enamel, which leak in between cells and laterally defuse through the cell layer
  • cell spends 20% of its lifetime in this form
69
Q

during the maturation of enamel, fluctuations in the distal membrane of ameloblast layers causes the transition between ___ and ___ cells

A

ruffled and smooth

this transition can go back and forth, from ruffled to smooth and back to ruffled

Oral Biology (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions