MCBM Exam 3 (connective tissue, cartilage/osteogenesis PP) Flashcards
1
Q
What are the 2 classifications of connective tissue?
A
connective tissue proper (soft tissue)
supportive connective tissue (hard tissue)
2
Q
What is the classification of connective tissue based on?
A
relative density of components
characteristics of extracellular matrix (ground substance + fibers)
3
Q
What is soft connective tissue?
A
components in a fluid or gelatinous ground substance (adipose tissue, blood)
4
Q
What is hard connective tissue?
A
components embedded in a solid ground substance (cartilage and bone)
5
Q
What are the components of connective tissue that is found in all types of connective tissue?
A
fibers
ground substance
cells
6
Q
What does the subtypes of connective tissue depend on?
A
depends on the arrangement of fibers
7
Q
What types of fibers are there (complex proteins)?
A
collagen
elastic
reticular
8
Q
What is 30-40% of the bodies protein?
A
collagen
9
Q
Does collagen stretch or contract?
A
no
10
Q
Is collagen high or low molecular weight?
A
high molecular weight
11
Q
What is collagen primarily composed of?
A
primarily composed of glycine (33%)
12
Q
What else is collagen composed of?
A
proline (12%) and hydroxyproline (10%)
13
Q
What are 2 features of collagen?
A
basic molecule (monomer): tropocollagen heat labile: becomes gelatinous and glue-like
14
Q
What would be the diagnosis for something that has a bunch of collagen?
A
fibroma (overproduction of collagen)
15
Q
Is collagen produced intracellularly extracellularly or both?
A
both
16
Q
What is the precursor for collagen intracellularly?
A
procollagen
17
Q
Procollagen is held together by what type of bonds?
A
hydrogen
18
Q
Where does synthesis of collagen intracellularly occur?
A
in the rough ER
19
Q
What is procollagen composed of?
A
helical tripeptide: 2 (alpha-1) and one (alpha-2)
20
Q
What is a fibroblast?
A
a type of cell that synthesizes collagen
21
Q
What amino acids are present in collagen and what enzyme hydroxylizes them?
A
proline and lysine which are hydroxylated by peptidyl hydroxylase
22
Q
What is a cofactor (coenzyme) for collagen production?
A
ascorbic acid (vitamin C)
23
Q
What is the precursor for collagen extracellularly?
A
tropocollagen
24
Q
Procollagen is cleaved by what enzyme to form tropocollagen?
A
procollagen peptidase
25
Crosslinks between tropocollagen molecules are polymerized to form microfibrils by what enzyme?
lysyl oxidase
26
What are microfibrils turned into?
fibrils
27
What are fibrils turned into?
fibers (collagen)
28
What are a lot fibers?
bundles of fibers (form collagen)
29
What are the features of fibers (collagen)?
fibers are straight or wavy and can be loosely or densely packed depending on the location and functional need
30
What type of collagen is most common?
type 1
31
What is type 2 collagen?
cartilage
32
Where is type 3 collagen found?
smooth muscle, uterus, spleen, lungs, aorta
33
Where is type 4 collagen found?
basal lamina
34
Where is type 5 collagen found?
in placental membranes
35
What are the features of elastic fibers?
stretch and return to normal size
| resistant to heat
36
What are elastic fibers composed of?
elastin (amorpous protein) surrounded by microfibrils (fibrillin, a glycoprotein)
37
Elastin protein are rich in which amino acids?
glycine and proline
38
What other amino acids are found in elastin protein?
valine, alanine, desmosine, and isdesmosine
39
Where are reticular fibers usually located?
usually located where collagen is found (not necessarily vise versa)
40
Where are reticular fibers abundant?
at boundaries between connective tissue and other tissues
41
Where are reticular fibers found?
stroma in bone marrow, lymphoid tissues, and liver
42
How can you differentiate collagen from elastin or reticular fibers?
with H&E staining
43
What stains darker with PAS collagen or reticular fibers?
reticular fibers stain darker
44
Reticular fibers are argyophilic what does that mean?
blackens with silver stains
45
What is ultrastructurally very similar to collagen?
reticular fibers
46
What is the composition of reticular fibers?
type III collagen fibrils (never forms bundles therefore it is only at the fibril stage)
47
What is ground substance?
a mixture of proteins, lipids, carbohydrates, and water which varies in consistency from a viscous solution to a hard material
48
What are the components of ground substance?
glycoproteins and glycosaminoglycans (GAGS)
49
What is the majority of the molecule in a glycoprotein?
mostly protein with a little bit of sugar
50
What is the majority of the molecule in a glycosaminoglycan or GAG?
mostly sugar with a little bit more sugar with an amino acid attached to it
51
Do GAGs have many hydrophilic groups?
yes - likes to absorb water
52
What is the function of a GAG?
serves as a selective barrier to diffusion of inorganic ions and charged molecules
53
GAGs are long branching polymers that form 3D networks for ________ and ________
strength, support
54
What are some examples of GAGs?
hyaluronic acid, chondroitin sulfate, and dermatan sulfate
55
What is a feature of ground substance?
viscosity of ground substance is related to types of GAGs present
56
What is hyaluronic acid?
a non-sulfated GAG capable of binding large amounts of water
57
Where is hyaluronic acid found and what does it contain?
present in large amounts in the skin and contains glucosamine
58
What is chondroitin sulfate and where is it found?
a sulfated GAG present in the hard connective tissues (cartilage)
59
What are the components of loose connective tissues?
several cell types
| all three types of fibers (collagen, elastin, reticular)
60
What is the structure of areolar connective tissue and what is its function?
```
loosely arranged collagen predominates
function is to bind organs together
```
61
What is the function of adipose connective tissue and what is its function?
structure: adipocytes predominate function is to store fat
62
What is the structure and function of reticular connective tissue?
structure: reticular fibers predominate
function: forms stroma of lymph nodes, liver, spleen and bone marrow
63
What types of cells are found in all three types of loose connective tisuses?
fibroblasts
64
What are the 4 types of loose connective tissue?
areolar
adipose
reticular
hemopoietic
65
What is the most common cell in loose connective tissue?
fibroblasts
66
Where do fibroblasts come from?
they arise from another fibroblast or mesenchymal cell
67
What are some characteristics of fibroblasts?
fusiform or stellate shaped
nucleus: fine chromatin
1-2 nucleoli
68
What is the function of fibroblasts?
to produce fibers and ground substance which is very important in wound healing
69
What is the function of mesenchymal cells and what is different from fibroblasts?
function: undifferentiated stem cells capable of giving rise to other cells of mesenchymal origin
similar to fibroblasts except that chromatin is more coarse
70
What is the function of adipocytes?
specialized for the synthesis and or intake of lipids
71
What are some features of adipocytes?
unilocular (yellow) fat
| adipocytes from several small lipid droplets fuse into a singelalr ge droplet
72
What is different about the cytoplasm and nucleus in an adipocyte?
the cytoplasm and nucleus are displaced peripherally
73
In multilocular (brown) fat do the adipocytes fuse into a large single droplet?
no they retain multiple lipid droplets
74
Where do macrophages originate?
from blood monocytes
75
What is the function of macrophages?
phagocytosis of cell debris, altered intercellular material, microorganisms and foreign material
76
What do macrophages contribute to?
the initiation of the immunological reactions of the body by processing antigens
77
What are some features of macrophages?
irregular outline, ovoid nucleus, usually distinguished from fibroblasts by the presence of phagocytosed matter
78
What can macrophages fuse to form?
may fuse to form giant cells
79
What is the function of mast cells?
contain heparin (anticoagulant) and histamine (dilates blood vessels)
80
What are some features of mast cells?
granulocyte, cytoplasm full of secretory granules (vesicles)
| usually associated with capillaries and are relatively small with a dark-staining nucleus
81
Where do hematopoetic tissue arise?
from a stem cell
82
What are hematopoetic tissues?
specialized type of loose connective tissue
83
Hematopoetic cells can become which 2 types of cells?
myeloid or lymphoid cells
84
What can myloid responsible for?
making rbcs, platelets and granulocytes
85
What can lymphoid cells turn into?
B or T cells
86
If a B cell is exposed to an antigen what will happen?
it will produce antibody and become a plasma cell
87
What are lymphoid cells?
leukocytes, cells of lymphoid origin that are mature in lymphoid tissue which utilize vascular channels for transport to the connective tissues
88
What are T and B cells?
lymphocytes and plasma cells
89
What is the smallest cell in the connective tissue?
lymphocytes
90
What will a lymphocyte look like if stained?
large dark staining nucleus thin rim of basophilic cytoplasm
91
Where are lymphocytes found?
numerous in connective tissue supporting the epithelium of the respiratory and GI tracts
92
What is the function of a T cell?
cell-mediated immunity; direct and regulate immune responses, directly attack infected or cancerous cells
93
What is the function of a B cell?
recognize antigen, each B cell is programmed to make one specific antibody
94
What is a plasma cell?
a B cell that produces antibody
95
What are some features of plasma cells?
oval-shaped; cytoplasm stains basophilic as a result of its large content of rough endoplasmic reticulum
96
What is seen on the nucleus of plasma cells when stained?
a perinuclear halo
97
Heterochromatin disposed around the periphery of the nucleus of a plasma cell is said to have what type of appearance?
a cartwheel appearance
98
What is a plasma cell responsible for?
for humoral immunity, synthesizing and secreting antibodies that will travel in the blood to gain access to the connective tissue spaces
99
A lot of plasma cells would be considered what?
multiple myeloma
100
What are myeloid cells?
leukocytes; cells of myeloid origin; developed in hemopoietic tissue, mature and move into connective tissue from blood vessels; function in connective tissues
101
What are some examples of myeloid cells?
neutrophil, monocyte, eosinophil
102
What is one feature of monocytes?
they are large cells
103
What are the functions of monocytes?
precursor to macrophages, phagocytes that circulate in the blood
104
what happens when monocytes migrate into tissues?
they develop into macrophages and function in phagocytosis
105
What is the function of neutrophils?
acute inflammation, phagocytose bacteria
106
What are some features of neutrophils?
granulocytes, contain lysosomes, lobulated nucleus: usually 2-5 lobes
107
What is the function of eosinophils?
allergy, parasites, phagocytosis of antigen-antibody complexes
108
What doe some granules contain and what does it prevent?
some contain profibrinolysin which prevents intravascular clotting
109
What are some features of eosinophils?
granulocyte, usually beloved, contain cytoplasmic granules (stain red in a blood smear using Wrights stain)
110
What is the function of basophils?
granules contain heparin (an anticoagulant) and histamine (a vasodilator) precise function is unknown
111
What are some features of basophils?
granulocyte, rare in connective tissue usually found in bone marrow, wrights stain on blood smear shows cytoplasmic granules are blue - purple
112
What are the 2 types of regularly arranged connective tissue?
ligament or tendons
113
What are general features of dense connective tissue subtypes?
differs from loose connective tissue mainly in preponderance of fibers (collagen) over cells and ground substance
114
How much force can dense connective tissue withstand?
1000-18000 lbs/In2
115
What are dense irregular connective tissues?
fiber bundles form interwoven sheets, collagen fibers predominate, some elastic and reticular fibers may be present
116
What is the function of dense irregular connective tissue?
comprises dermis of the skin, fibrous sheaths of cartilage and bones, capsules of some organs (ex: testes, liver, lymph nodes)
117
Where is dense irregular connective tissue found?
in areas where tensions are exerted in several directions
118
What is dense regular connective tissue?
mostly collagen fibers, occasional elastic fibers, orderly, parallel arrangement
119
What is the function of dense regular connective tissue?
comprises tendons, ligaments, aponeuroses and occurs in structures subject to tension in one direction
120
What are the major roles of connective tissue?
fluid dynamics and inflammatory response
121
Connective tissue forms what type of fluid?
interstitial fluid
122
How does fluid exit the blood vascular system?
through capillaries
123
What is the function of interstitial fluid?
delivers nutrients to cells carries waste material from the cells
124
What is hydrostatic pressure?
(think fluid as the driving force)
| causes fluid to leak out of the capillaries into the interstitial space
125
Are large molecular weight materials able to leave the vessels under hydrostatic pressure?
no because of the close approximation of endothelial cells
126
What is osmotic pressure?
(think particles as driving force) fluid reenters venules hydrostatic pressure is reduced in the v enules and osmotic pressure in venules is higher than in arterioles as a result of fluid loss from capillaries
127
Does all fluid return to the blood vascular system?
no
128
What is edema?
excess tissue is present in the connective tissues paces or imbalance of fluid dynamics
129
What causes increased formation of tissue fluid?
increased hydrostatic pressure in the capillaries
increased permeability of capillary endothelium results in a leaking of blood colloids (large molecular weight substances) into tissue spaces
130
What are some examples of increased formation tissue fluid?
venous obstruction, venous thrombosis, cardiac failure
131
What is decreased resorption of tissue fluid?
lowered blood colloids which lowers osmotic pressure
| lowering of resorption gradient, lymphatic obstruction
132
What are some examples of decreased resorption of tissue fluid?
kidney diseases, lymphatic obstruction, tumors
133
What is important in host defenses?
connective tissue
134
What plays a critical role in inflammation?
connective tissue
135
How is inflammation classified?
acute inflammation or chronic inflammation
136
What is acute inflammation?
```
initial response
short duration (few hours to 4 days)
```
137
What is chronic inflammation?
follows acute inflammation if the casual agent is not removed, long duration: may last for months to years
138
What is the Lewis triple response?
acute inflammatory response invoked by skin with a ruler or something similar, first described by Sir Thomas Lewis in 1927
139
What are the three responses in Lewis triple response?
flush: due to a dilation of capillaries and venules
flare: due to dilation or arterioles
wheal: swelling due to ocalizled edema
140
What happens during flush?
histamine release (mast cells) located in close association with the capillaries
141
What happens during flare?
this is due initially to an axonal reflex but is perpetuated by histamine (mast cells) and prostaglandins (endothelial cells)
142
What happens during wheal?
a result of fluid and large molecular weight substances leaking out of the capillaries and venules
143
What are the cardinal signs of inflammation?
```
heat (calor)
redness (rubor)
pain (dolor)
swelling (tumor)
loss of function (function laesa) in later stages
```
144
What is the purpose of inflammation?
serves to dilute toxins and allow leukocytes and antibodies to access extravascular spaces
145
What is the process of inflammation?
changes in the caliber of the vessels, changes in vascular permeability, changes in vascular flow, stasis (leukocyte exudation)
146
What is the first stage in inflammation?
transient vasoconstriction: initial response of arterioles, varies with degree of injury: seconds to minutes (ex burns)
like neurogenic
147
What is the second stage in inflammation?
vasodilation: first involved capillary beds and venules, later arterioles
148
What is the result of vasodilation of arterioles?
results in further opening of micro vascular beds in the area
149
What is responsible for the redness and heat seen in inflammation?
increase in blood flow
150
What causes an increased local hydrostatic pressure and what does it cause?
increased volume in capillaries and venules results in increased local hydrostatic pressure which causes a transudation of protein poor fluid into the extravascular spaces
151
What is increased permeability of inflammation?
capillaries and venules due to chemical mediators which causes an outpouring of protein rich fluid into the extravascular spaces
152
What does increased permeability result in?
results in loss of fluid in vessels which causes increased concentration of red blood cells which is concomitant in slowing blood flow (increased viscosity)
153
What is stasis in inflammation?
slowing of blood flow which increases margination of white blood cells and thus increased diapedesis (movement of WBCs out of the blood vessels)
154
What are chemical mediators and where do they originate?
injury precipitates the inflammatory response but released chemicals mediate it
originate from plasma, cells, damaged tissue
155
What are the two classes of inflammation?
vasoactive amines (histamine and serotonin), vasoactive polypeptides formed by specific enzyme action (breakdown products of proteins and tissues (kallikerin ndabr adykinin)
156
What are other agents influencing inflammation?
toxins from bacteria, prostaglandins (from endothelial cells), lysosomal enzymes (from neutrophils), products of DNA and RNA breakdown, antigen-antibody complexes
157
In acute inflammation the presence of monocytes increase after how many hours?
24-48hrs
158
If acute inflammation is due to an allergic reaction than large numbers of what will be present?
eosinophils
159
What is formed if pyogenic bacteria is involved in acute inflammation?
pus is formed
160
What is predominate in the first 6-24 hours of acute inflammation?
emigration of neutrophils (in this period there is some emigration of monocytes (which transform to macrophages)
161
What does chronic inflammation include?
reductions in numbers of neutrophils, appearance of lymphocytes and plasma cells
162
What plays an important role in chronic inflammation?
macrophages (in some cases there is the formation of foreign body giant cells0
163
What forms new capillaries in chronic inflammation?
proliferation of vascular endothelium
164
In chronic inflammation there is proliferation of what?
fibroblasts and collagen production and subsequent fibrosis
165
What is another name for spongy bone?
cancellous
166
What is perosteum?
surrounds outside of compact bone; continuous with tendon
167
What is endosteum?
lines inner surface of bone facing marrow cavity and haversian canals
168
What is dense connective tissue?
fibroblasts and collagen bundles
169
What do progenitor cells become and what do they do?
they become osteoblasts that heal and grow bone
170
What are osteoblasts?
secrete bone matrix (uncalcified)
171
Where are osteoblasts found?
found only at the boundary between bone and periosteum/endosteum
172
Why do osteoblasts have extensive rough ER and Golgi?
because they are actively secreting matrix
173
What are osteocytes?
osteoblasts that have become trapped within calcified matrix
174
How are osteocytes connected to one another?
by gap junctions via processes that extend through canaliculi for the transport of nutrients and wastes
175
What are osteoclasts?
multinucleated cells, large blood derived (similar to macrophages)
176
What do osteoclasts do?
degrade the bone matrix (secretes H+ and lysosomal enzymes for reabsorption)
177
What is collagen type I?
glycosaminoglycans, glycoproteins, organic components (bone matrix is arranged in layers called lamellae)
178
What is calcium phosphate crystals?
inorganic salts that makes bone hard
179
How much of the weight of bone is from inorganic salts?
over 50% of the weight of bone
180
How is mature bone laid down?
in layers
181
What are the components of bone matrix?
collagen (type I) and calcium phosphate crystals (inorganic salts)
182
What is an osteon?
concentric rings of lamellae
183
How is immature bone laid down?
randomly interwoven collagen fiber-hydroxyapatite matrix
184
What type of bone is laid down in osteons that run parallel?
mature bone
185
What are osteocytes really close to ?
osteocytes are very close to one another and very close to vessels
186
What is involved in the remodeling of bone by breaking down the matrix?
osteoblasts
187
each concentric lameallae has fibers in what direction?
opposite orientation
188
What are interstitial lameallae remnants of?
remnants of older osteons
189
What lays down new matrix in concentric lamellae?
osteoblasts
190
What is something very important to know about cartilage?
it is avascular
191
What are chondroblasts derived from?
progenitor cells in perichondrium
192
What is perichondrium?
dense connective tissue containing fibroblasts and collagen (type I)
193
What do blood vessels in the perichondrium do?
support cartilage cells via diffusion of nutrients/wastes through the matrix
194
Does perichondrium have the ability to repair cartilage?
only limited ability
195
Where is perichondrium not present?
not present at articular surfaces and epiphyseal plates
196
Can cartilage regenerate?
not very well - normally is replaced with fibrous tissue
197
What do chondroblasts secrete?
matrix=appositional growth
198
Once the chondroblasts become totally surrounded by the matrix they become what kind of cell?
become chondrocytes
199
What increases with appositional growth?
increases circumference of cell
200
Do chondrocytes actively divide?
yes
201
What do chondrocytes secrete?
matrix=interstitial growth
202
Where are chondrocytes found?
inside the lacunae
203
How much water is in cartilage matrix?
about 75% by mass
204
What is hyaline cartilage?
type II collagen
205
What is elastic cartilage?
type II collagen and elastic fibers
206
What is fibrocartilage?
type I and II collagen
207
What does type II collagen form and can it be seen with light microscope?
fibrils but NOT fibers therefore they cannot be seen by light microscope
208
What is hyaluronic acid?
a very large molecule with a lot of proteins and a lot of negative charge
209
What re the proteoglycans and GAGs in the cartilage matrix?
aggrecan, chondroitin, sulfate and keratin sulfate
210
What does hyluronate bind?
cations and water forming hydrated gel that is resistant to compression
211
What is hyaline cartilage?
"typical" cartilage that is homogenous and has an amorpheous matrix
212
Where is hyaline cartilage found?
in articular surfaces and epiphyseal plates
213
Where is endochondral bone?
fetal skeleton
214
What does a darker stain indicate?
higher proteoglycans
215
Where is elastic cartilage found?
in pinna of ear, ear canal and epiglottis
216
Where is fibrocartilage found?
at symphysis joints (pubic symphysis and intervertebral disks), articular disks, and menisci
217
What type of cartilage resists compression because it has hyaluronic acid?
fibrocartilage
218
What is NOT found in fibrocartilage?
no periochondrium; instead fibroblasts are incorporated within tissue
219
Which cartilage is more columnar shaped?
fibrocartilage
220
What type of cartilage is more round in shape?
hyaline cartilage
221
What will you see in elastic cartilage?
fibers
222
What is endochondral ossification?
bone is formed through the ossification of a cartilaginous model
223
What is intermembraneous ossification?
mesenchyme within connective tissue differentiated directly to osteoblasts which create bone de novo
224
How is most bone formed?
through endrochondral ossification
225
What is different about intermembraneous ossification?
it skips the cartilage step
226
What are the 5 zones of endochondrial ossification that are all happening at the same time?
zone of reserve cartilage (resting zone), zone of proliferation, zone of hypertrophy, zone of calcification, zone ossification
227
What happens when there is hypertrophy?
we end up with empty lacunae, chondrocytes increase in size and accumulate glycogen
228
What is happening in the zone of ossification?
osteoblasts are invading and building new bone over the layer of calcified cartilage
229
What is happening in the zone of proliferation?
chondrocytes are actively dividing producing columns of isogenous cells
230
What happens in the zone of calcification?
chondrocytes degenerate, hydroxyapatite crystals form within cartilage, blood vessels are invading
231
What happens during a bone fracture?
blood clots inside bone, connective tissue is formed, cartilage forms which will calcify and give a callus which remodels and creates mature bone
