Histology > Connective Tissue > Flashcards

Connective Tissue Flashcards

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1
Q

CT vs. Epithelium

A

CT: widely spread, no polarity, vascularized (usually.. not cartilage)

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2
Q

general CT composition

A

cells + ECM

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3
Q

CT cells

A

long-term resident or transient resident

principal cell produces ECM components, all other cells do something else NOT produce ECM

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4
Q

Principal long-term resident cell

A

produces ECM components (ground substance + fibers)

usually fibroblasts

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5
Q

ECM components

A
  • gelatinous ground substance + fibers/fibrils

- both parts produced by principal CT cell

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6
Q

Ground Substance

A

rich in GAGs and proteoglycans (interact to form proteoglycan aggregates)
secrete multiadhesive glycoproteins (stabilize matrix and aid in cell-connective tissue interactions)

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7
Q

GAG

A

Glycosaminoglycan

-long chain, linear polysaccharides

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8
Q

GAGs in CT

A

in ground substance: keratan sulfate, heparan sulfate, condroitin sulfate, and hyaluronic acid (hyaluronan)

  • sulfate = negative (basophilic).. attracts sodium ions which attract water to the matrix
  • interact with proteins to form proteoglycans
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9
Q

hyaluronic acid in ground substance

A
  • longer and more rigid than other GAGs

- increases the viscosity of ground substance (makes it thicker)

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10
Q

proteoglycans

A
  • linear proteins with glycosaminoglycan (GAG) side chains

- look like a bottle brush

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11
Q

proteglycan aggregate

A

proteglycan + GAG (hyaluronic acid)

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12
Q

mutiadhesive glycoproteins

A
  • secreted by principal CT
  • stabilize ECM and link EXM to the surface of cells
  • ex: fibronectin and laminin (attach epithelial cells to basal lamina)
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13
Q

FIbrous component of CT

A
  • proteins secreted from principal CT cells

- proteins assemble into fibrils (TEM), which usually assemble inter fibers (LM)

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14
Q

3 major types of fibers in connective tissue

A
  1. collagen
  2. elastic
  3. reticular (type III collagen)
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15
Q

constituency of CT

A

can be solid (bone) , watery (blood), or viscous (cartilage)

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16
Q

role of ground substance vs. fibers

A

fibers: tensile strength + resiliance

ground substance: diffusion of molecules + access of blood borne cells

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17
Q

fibroblasts (derived from? role in loose CT, function, in LM, in TEM)

A

derived from mesenchymal cells
PCT in loose CT
produce TYPE I COLLAGEN + ELASTIC FIBERS
in LM: elongated nucleaus, thin cytoplasm, and hard to tell (unless cell is making a lot of collagen)
in TEM: lots of rER (making proteins!), scalloped cell body, and thin processes extending from cell into collagen bundles

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18
Q

Macrophages (derived from? role in loose CT, function, in LM, in TEM)

A

derived from monocytes
-monocytes in blood, enter loose CT via diapedesis = macrophages
-function: resident phagocytic cells; phagocytosize bacteria or dying cells
in LM: larger nuclei than FB, and indented nuclear envelope, vesicles are apparent (foamy looking) when active
in TEM: lots of lysosomes, extending pseudo pods if active

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19
Q

mast cells

A

promote inflammation

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20
Q

granules in mast cells and their respective function

A 
heparin (anticoagulant); 
histamine (promotes inflammation);
eosinophil chemotactic factor
tryptase (mast cell marker)
NO leukotrienes (produced from PM after the release of granules)
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21
Q

uriticaria

A

hives;

produces from skin mast cell activation

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22
Q

explain inflammation response via mast cell (starting from antibody production) (DEGRANULATION OF MAST CELLS)

A
  1. antibody produced by plasma cell and released
  2. IgE specific receptor on extracellular mast cell bind the antibody to the mast cell
  3. antibodies bind to antigen (when present)
  4. ca 2+ channels open (calcium influx)
  5. granules pour out supstances: heparin (anticoagulant), histamine (promotes inflammation), eosinophilic chemotactic factor
  6. production of leukotrienes from PM (promotes inflammation)
    “promote inflammation” = calls for leukocytes from blood vessel
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23
Q

leukocytes

A

promote immune response to antigens, parasites, or bacteria (that pass through epithelium)
-include granulocytes and agrangulocytes

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24
Q

cells in CT

A
  1. fibroblasts (produce collagen type I + elastic fibers)
  2. Macrophage (phagocytsize bacteria + old cells)
  3. Plasma cells (make antibodies)
  4. Mast cells (promote inflammation)
  5. adipose (energy storage, convert hormones to estrogen, weight control)
  6. leukocytes (promote immune response..WBC)
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25
Loose CT ECM
produced from fibroblasts (PCT) | contain type I collagen, elastic fibers + viscous ground substance (sulfated and non-sulfated glycoasminoglycans
26
type I collagen
- most abundant type of collagen in humans - most of loose and dense CT - high tensile strength, but very flexible (links on a chain) - best visualized with trichrome stain
27
how is type I collagen produced?
- from fibroblasts 1. FB secrete procollagen via constitutive exocytosis into ECM; 2. peptidase cleaves terminal end of procollagen = tropocollagen 3. tropocollagen proteins self assemble into collagen fibrils 4. fibrils assemble into eosinophilic fibers that are held together with proteoglycans
28
type IV collagen
- component of basal (external) lamina - secreted by epithelial cells, adipocytes, schwann cells, muscle cells - (also the anchoring protein in hemidesmosome)
29
Elastic fibers content/compostion
-made of elastic fiber, elastin (desmosine + isodesmosine), fibrillin, other glycoproteins LITTLE HYDROXYPROLINE; NO HYDROXYLYSINE
30
function of elastin
stretchiness
31
function of fibrillin
organizing and structural protein
32
desmosine and isodesmosine
bind adjacent elastin molecule together to allow them to stretch and recoil
33
elastic fiber stain
orecein, resorcin fuchsin, aldehyde fuchsin, verhoeffs stain
34
Dense CT (Regular): location, structure
- in tendons/ligaments, type I collagen fibers are oriented linearly in direction to best resist stress - poorly vascularized - FB nucleus widely spread (compared to smooth muscle and peripheral nerve)
35
Dense CT (Irregular): location/structure
- in dermis of skin and capsule of other organs - type I collagen is arranged into sheets and stacked. within each sheet the fibers are all lineraly aligned in one direction, but since the layers are stacked, it appears like they are going in all different directions (FB randomly w/in the collagen)
36
vit C and collagen?
vitamin C is a cofactor in the synthesis of type I collagen; deprivation of vit c greatly reduces collagen synthesis resulting in SCURVY (especially seen in the periodontal ligament anchoring teeth in their bone sockets.. loose teeth)
37
Loose CT vs. Dense CT
Loose: more cells less collagen Dense: more collagen less cells
38
reticular fiber formation
via reticular cells: same as collagen I production (via FB): -reticular cell secretes procollagen, cleaved to tropocollagen, assemble to collagen III fibrils, fibrils arrange into a mesh-bag network
39
reticular fiber stain
PAS (carbohydrates), silver
40
Ehlers Danlos Type IV Syndrome
insufficient synthesis of type III collagen... aorta and intestines have large amounts of type III.. thus they are very prone to rupture
41
Marfan's syndrome
- caused by mutations in the gene for microfibrilar component of elastic Ct - affects large vessels - elastic wall of aorta is deficient and leads to rupture
42
fibers affiliated with adipocytes
reticular (collagen III) network
43
Mesenchyme
- loose, primitive CT found in embryo | - allows passage of cells and fluid within the organ
44
whartons jelly
found in umbilical cord ground substance has lots of hyaluronic acid and sulfated GAGs that draws in water... makes the ground substance a good compression protection.. which prevents the umbilical cord from kinking TYPE I +III collagen
45
Brown Fat
has multiocular fat cells (lots of lipid inclusions and lots of mitochondria... make it look brown). this fat is good for converting lipid into thermal energy type III collagen
46
cartilage (general)
- flexible CT that resists compression and provides an organizing framework for other cells - avascular - aneaural
47
3 types of cartilage
1. hyaline 2. elastic 3. fibrocartilage
48
what type of cartilage is surrounded by perichondrium? what is perichondrium
- hyaline + elastic cartilage - dense irregular CT (fibroblast) = outer layer - chondrogenic layer of chondrocytes (produces chondrocytes) = inner layer
49
aggrecan
a proteoglycan that contains high concentrations of sulfated GAGs (keratan sulfate + chondroitin sulfate)
50
whats the advantage of sulfated gags?
bring in water (negative sulfate attracts sodium, which brings water with it). this results in a ground substance that can resist compression and in cartilage: allows free diffusion of material to/from blood vessels outside the cartilage
51
why is the matrix of hyaline cartilage basophilic?
lots of sulfated GAGs
52
Lacuna
space that contains a chondrocyte inside (visible in H/E after the cell shrinks) -territorial matrix/interterritorial matrix
53
territorial matrix
borders the lacuna; appears darker because the GAGs (matrix material) is concentrated there... very basophilic
54
interterritorial matrix
between the groups of matrix; stains lighter (ie: if there are two chondrocytes/lacunae next to each other, then two dark circle around the chondrocyte = territorial matrix, and the little space between them is the interterritorial matrix)
55
Cartilage growth
2 ways: 1. appositional 2. interstitial
56
appositional cartilage growth
- growth at the edges - chondroblasts in inner chondrogenic layer of perichondrium divide and add to cartilage along the outside - "chondrogenic" cells of the perichondrium (i.e., the cells in the overlying CT that have the potential to become chondrocytes) gear up, begin active synthesis, and start creating new cartilage at the boundaries of the structure. Eventually these new chondrocytes will become trapped in lacunae and become integrated as part of the main mass of cartilage. At that point, if they're still active in synthesis, they'll be participating in interstitial growth.
57
interstitial cartilage growth
- growth from the inside - mitosis of chondrocytes in lacunae produce isogenous groups of cells (clones) within the cartilage matrix - result of chondrocytes in their lacunae actively synthesizing matrix material. This causes the total volume of the cartilaginous structure to increase
58
Fibrocartilage
combo of dense regular CT + chondrocytes (no perichondrium) - function as a strong anchor for dense CT - in public symphosis, intervertebral discs, meniscus of knee etc.
59
cartilage repair
damaged cartilage is largely incapable of repair.. avascular! few chondrocytes are added following damage (most repair is done by producing more dense CT)
60
hyaline cartilage can ossify as a part of normal aging
ie: in tracheal cartilage
61
osteoarthritis
- erosion of the hyaline cartilage lining the articular surfaces of bones - loss of aneural cartilage allows grinding of bony surfaces (highly innervated .. produce intense pain
62
chondroma vs. chondrosarcoma
``` chondroma = benign tumor formed by chondrocytes chondrosarcoma = malignant ```
63
PCT in Loose CT
fibroblast
64
fibers in Loose CT
type I collagen + elastic fibers
65
ground substance in Loose CT
sulfated and nonsulfated GAGs
66
PCT in dense CT
fibroblasts
67
fibers in dense CT
type I collagen mainly (some elastic) in regular: all run in the same direction in irregular: run obliquely
68
ground substance in dense CT
minimal - GAGs
69
PCT in reticular CT
reticular cells (lymphatics), schwann cells, adipocytes, muscle cells
70
fibers in reticular CT
type III collagen
71
ground substance in reticular CT
minimal- GAGs
72
PCT in elastic CT
fibroblasts, chondrocytes, smooth muscle
73
fibers in elastic CT
elastic fibers mainly - elastin = fiber component - fibrilin = microfibril component
74
ground substance in elastic CT
minimal- GAGs
75
PCT in adipose
adipocytes
76
fibers in adipose
reticular fibers (type III collagen)
77
ground substance in adipose
minimal - GAGs
78
PCT in mesenchyme CT
mesenchymal cells
79
fibers in mesenchyme
type III collagen
80
ground substance in mesenchyme
abundant: thin, gelatinous
81
PCT in Wharton's Jelly
mesenchymal cells
82
fibers in Wharton's Jelly
type III collagen fibers (reticular) + type I collagen
83
ground substance in Wharton's Jelly
Jelly- like | lots of hyaluronic acid + sulfated GAGs cause an influx of water.. its good for compression
84
PCT of brown adipose tissue
multilocular adipocytes rich in mitochondria
85
fibers of brown adipose tissue
type III collagen fibers (reticular fibers)
86
ground substance of brown adipose tissue
minimal - GAGs
87
hyaline cartilage PCT
chondrocyte
88
fibers in hyaline cartilage
type II collage FIBRILS
89
ground substance in hyaline cartilage
aggrecan (high concentration of sulfated GAGs (keratan sulfate + chondroitin sulfate))
90
PCT in elastic cartilage
chondrocyte
91
fibers in elastic cartilage
type II collage FIBRILS | elastic FIBERS
92
ground substance in elastic cartilage
aggrecan
93
PCT in fibrocartilage
chondrocyte + fibroblast
94
fibers in fibrocartilage
type II collagen FIBRILS | type I collagen FIBERS
Histology
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