Oral Tissues Flashcards
1
Q
what is the most abundant protein in the body?
A
collagens
2
Q
how many types of collagen is there?
A
28
3
Q
what is the most common type of collagen?
A
Type I (makes up 80-90%)
4
Q
what is the starting material for mature collagen?
A
pro-a collagen chains
5
Q
what is the base unit structure for all collagen?
A
chains of tightly wound RIGHT turned triple helices
6
Q
what can be mix and matched to make the different types of collagens?
A
different combinations of 3 pro-a collagen chains
7
Q
what is a defining feature of collagen?
A
33? glycine
13% proline
9% hydroproline
in its repeating tripeptide form
8
Q
what is special about glycine in the triple helix?
A
its a small R group and flexible so can form tightly packed, allows helix turns
9
Q
what is special about proline/hydroproline in the triple helix?
A
ridged, provides strength
10
Q
what bonds strengthen and stabilize collagen?
A
hydrogen and covalent bonds
(hydroxylation)
11
Q
what is the difference between tropocollagen and procollagen?
A
pro still has carboxyl terminal extension peptides
tropo has these removed, it is just the triple pro-a helix
12
Q
what occurs within the post translational modification of prolines and lysine’s
A
redox reactions that require Vit C as reducing agent
13
Q
what are proline and lysine reduced to?
A
4-hydroxyproline residue or 5-hydroxylysine residue
succinate
CO2
14
Q
what is the only irreversible aspect of scurvy?
A
bone growth in children
15
Q
Collagen is a _______
A
glycoprotein
16
Q
Most glycoproteins are ______ or _____ linked in collagen, this also includes hydroxylysine
A
N-linked (Asparagine) or O-linked (Serine or Threonine)
(he said not a test Q)
17
Q
Covalent attachment of disacharides to hydroxylysine on collagen occurs in these two steps:
A
first galactose and then glucose
18
Q
what does glycosylation not effect?
A
biochemical properties or
immunogenicity
19
Q
crosslinks in collagen form both within _____ and _______
A
1 triple helix and between adjacent triple helices
20
Q
The _____ route predominates in skin, cornea and sclera
A
allysine
21
Q
- The ______ route predominates in bone, cartilage,
ligaments and tendons
A
hydroxyallysine
22
Q
what is the first step of Biosynthesis of collagens
A
Pre-pro-α chains are synthesized in rough ER, where signal peptide is cleaved
23
Q
what is the second step of Biosynthesis of collagens
A
Prolines and lysines in pro-α chains are hydroxylated
THIS IS VIT C DEPTENDANT STEP
24
Q
what is the third step of Biosynthesis of collagens
A
Glycosylation of pro-α chains occurs in the smooth ER
25
what is the fourth step of Biosynthesis of collagens
4. Triple helix-containing procollagen forms inside the Golgi
26
what is the fifth step of Biosynthesis of collagens
5. Cleavage of extension peptides occurs outside the cell, as does assembly of tropocollagen units into collagen fibers
27
how are fibrillar collagens assembled?
10% extension area, 90% overlap,
this makes strong and lengthens
28
what is the arrangement of fibrillar collagens in tendons?
Parallel Bundles
29
what is the arrangement of fibrillar collagens in cartilage?
No regular arrangement; associated with glycosaminoglycans
30
what is the arrangement of fibrillar collagens in skin?
Planar sheets of microfibrils layered wat many angles
31
what is the arrangement of fibrillar collagens in cornea?
Planar sheets stacked crossways for strength
32
what does collagen IX do?
Connects collagens to cells and other matrix components
33
where is collagen X made
Produced by chondrocytes, required for normal bone growth
34
where is collagen IV found?
Unique to basement membranes
35
what collagen pays a roe in muscular dystrophy?
Collagen VI
36
what does collagen VII do?
epiderma BM to dermal CT
37
where is transmembrane collagens found?
connective tissue expressing cells
38
what do multipexins do?
proteoglycans expressed in endothelial and epithelial cell
39
what are some symptoms of Ehlers Danlos syndrome?
skin hyperelasticisty
fragile tissue
joint hypermobility
40
what causes osteogenesis imperfecta?
altered collagen type I
(type 1 causes had normal collagen, type II causes fully disrupted collagen)
41
what is a similarity shared by elastin and collagen?
high in glycine and proline
Covalent bonds provide
strength
42
what are some differences in Elastin than collagen
* Unlike collagen, no
repeating patterns
* Alternating coiled-coil
domains and hydrophobic
domains create elasticity
43
in elastin fibrils _______ is identical to covalent links found in collagen
Lysinorleucine
44
_______ results from
identical chemical reactions,
but is unique to elastin
Desmosine
45
what is Fibrillin
--provides a scaffold for elastin deposition
--forms more rigid microfibrils in tissues where
elastin is not present
46
what do fibrillin/Elastin microfibrils do?
facilitate flexibility of skin,
ligaments, and blood
vessels.
47
Fibrillin microfibrils provide:
limited elasticity; the majority comes from elastin INSTEAD
provide support for bones, and
tissues that support nerves, muscles and lenses of the eye
48
what is marfan syndrome?
defect in Fibrillin
longer than normal limbs, fingers, cardiac risk with too stretchy arteries
49
what makes bone and teeth so hard?
Collagen Microfibrils Hydroxyapatite Crystals
50
what does collagen do for bones
shape and strength
51
what does hydroxyapatite do for bones?
bone hardness
52
what does acid do to bones?
decalcifies them which is why they get soft (or get cavities)
53
collagen has sites for ____ of hydroxyapatite crystals
nucleation
54
________ Removes Inhibitor of Hydroxyapatite formation
Pyrophosphatase
55
Pyrophosphatase limits formation of what?
crystal formation
56
what is the structural organization of bone?
amino acids, tropocollagen, mineralized collagen fibrils, fibril arrays, fiver patterns, osteons/haversian canals, bone
57
acidity shifts equibrium of bone toward what?
toward dissociation of hypocyapitite crystals
58
_____ and _____ are critical for osteoclast differentiation, but process also required Ca2+-dependent NFAT activity
RANKL and m-CSF
59
Osteoblasts differentiate
from stroma and regulate
________ differentiation
osteoclast differentiation
60
what are the physiological roIes of osteocIasts?
* Osteoclasts are essential for sustaining serum Ca2+ levels
* Works in concert with osteoblasts for maintenance of healthy bone
61
pathological roles of osteoclasts
Mediates bone erosion in osteoporosis, arthritis, multiple myeloma,
tuberculosis, anorexia.
62
Why does bone erosion happen in so many different
inflammatory conditions?
because rank aIso triggers NFkB causing pro inflammatory activation
63
Crosstalk between _______ and _______ cause bone erosion during arthritis
RANK and inflammatory cytokines
64
bone erosion during arthritis happens from
introduction of foreign collagen
65
why does bone loss occur with menopause?
lack of regulation of interleukin 6 by estrogen makes
66
how does anorexia effect bones?
causes too many clasts resuting in bone loss
67
how does menopause effect teeth?
causes loss of surrounding bone structure resulting in loss of teeth
68
how are osteoclasts and blasts meditate bone remodeling?
mechanical force stimulates them to remodel (this is why astronauts without gravity get bone loss)
69
what is the technique used for bone remodeling in orthodontics?
compression and tension forces in the root trigger the movement of the tooth
70
what is the composition of enamel?
hypoxyapatite crystal: 90% Collagen: 0%
71
what is the composition of dentin?
hypoxyapatite crystal: 70% Collagen: 18%
72
what is the composition of cementum?
hypoxyapatite crystal: 65% Collagen: 19%
73
what is the composition of bone?
hypoxyapatite crystal: 65% Collagen: 19%
74
enamel has more what wereas bone has more
enamel: Ca
bone carbonate
75
what is dental calculus made from?
calcium phosphate gets altered by bacteria
76
what is the most abundant mineral in the human body?
calcium (and it is very tightly regulated)
77
about how much Ca do we need each day?
1 g
78
what effect does Ca have on cells?
potent signaling molecule, activates them
79
what is the difference between a resting platelet and a Ca activated one?
regular look like disc, activated like pointy blob
80
what are the roles of Ca in activating cells
* Contraction of skeletal, cardiac and smooth muscle
* Neurotransmitter release
* T cell activation
bone structure
81
how does Ca impact thrombin?
esentay retracts blood clot
review the chart on side 439, draw it out
82
how is Ca homeostasis maintained?
want to keep it at around 1g a day, take in much more through diet but only absorb to keep at 1g
(900mg to feces, 100mg to urine, excess stored in bones)
83
what promotes osteoclasts?
PTH, Vit D
INHIBITED by Calcitonin
84
what is necessary for ca absorption?
vit D and PTH
85
PTH promotes
Ca resorption and phosphate excretion
86
what triggers PTH release?
low blood ca
87
what inhibits pth?
high blood ca
88
what other thing stimulates PTH release other than Ca?
cAMP
89
Extracellular calcium
sensing receptor (CaR)
is a ______
GPCR
90
CaR activates Gai which inhibits ______
adenylate cyclase (AC)
91
CaR activates Gaq which stimulates _____
PLC
92
Ca2+ binding to Ca receptor has this effect:
* Gai _____
* cAMP _____
* PTH _____
activated
decreased
decreased
93
Ca2+ binding to Ca Receptor has this effect:
* Gaq ______
* cytosolic Ca2+ ______
* PTH ______-
activated
increases
decreases
94
how does PTH act on bone and kidney?
increases Ca uptake by kidney and increases osteoclasts/ activates vit D to get Ca from bones to increase blood Ca
95
How PTH acts on the intestine:
PTH increases VitD, increases Ca absorption from food increases blood Ca
(no PTH receptor in intestine do does this through raising vit D)
96
how do osteoclasts work?
secrete acid and proteases
97
how do osteoblasts work?
Type 1 collagen, alkaline phosphatase, Ca2+ rich vesicles
98
what happens with cronic ow Ca?
increased PTH mRNA
99
Osteoclasts express receptors
for ______ and _______
M-CSF and RANKL
100
Osteoblasts secrete the
ligands _____ and _____
M-CSF and RANKL
101
Osteoblasts secrete _____
which neutralizes RANKL
OPG
102
Effects of PTH on Bone:
1. PTH stimulates osteoblasts to release M-CSF and RANKL
2. M-CSF and RANKL stimulate
-Differentiation of osteoclasts
-Secrete acid and endopeptidases
3. Growth factors released from bone activate osteoblasts
4. Osteoblasts secrete
-Collagen, Ca2+ vesicles
-Alkaline phosphatase
(cleaves PPi)
103
M-CSF and RANKL stimulate:
-Differentiation of osteoclasts
-Secrete acid and endopeptidases
104
how do Osteoclasts Erode Bone Matrix at the Ruffled Border
1. Osteoclasts attach to bone
surface through integrins
* Integrins keep H+ high by
“sealing” ruffled border to bone
2. Carbonic anhydrase
II generates H+
3. H+ pumped out at ruffled border
* H+ “dissolves” hydroxyapatite.
4. Ca2+ and Pi are
released by transcytosis.
105
how does hyperparathyroidism or high PTH effect body?
increases risk of Kidney Stones
Bone fragility, Cardiac hypertrophy
HIGH URINE PHOS
106
what occurs with hypothyroidism?
Multiple neurological effects
Heart failure, muscle cramps
Can be caused by injury,
hypomagnesemia, hypokalemia
and alkalosis
ow urine phos, high urine Ca
107
what does calcitonin do?
counter balances PTH, inhibits bone resorption, stim Ca excretion
108
where is calcitonin made?
thyroid gland
parafollicular cells
109
what is calcitons actions for osteoclasts?
-decreases activity of ruffed boarder
-dedifferentiation of osteoclasts
110
what protective feature does calcitonin provide?
protects against excessive bone resorption
111
what does vitamin D do?
needed for Ca absorption, w/o it low Ca
112
what happens with low Ca?
Vit D activated, PTH, 1,25 VIT D triggers Ca absorption from gut and bone while inhibiting excretion
113
what happens with high Ca?
PTH inhibited, non active vit D calcitonin inhibits clasts, bones take Ca and kidneys excrete
114
what happens with low vit D?
some resorpt from PTH
Rickets
* Low serum Ca2+
* Dental deformities
* Impaired growth
* Increased bone fractures
* Muscle cramps
* Short stature
* Skeletal deformities
115
what happens with excess vit D?
rare but possibe, vit D becomes inactive, mre Ca absorbed, but more osteocasts so bones softened
