Connective Tissue Flashcards Preview

Histology > Connective Tissue > Flashcards

Flashcards in Connective Tissue Deck (94):
1

CT vs. Epithelium

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

2

general CT composition

cells + ECM

3

CT cells

long-term resident or transient resident
principal cell produces ECM components, all other cells do something else NOT produce ECM

4

Principal long-term resident cell

produces ECM components (ground substance + fibers)
usually fibroblasts

5

ECM components

-gelatinous ground substance + fibers/fibrils
-both parts produced by principal CT cell

6

Ground Substance

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

7

GAG

Glycosaminoglycan
-long chain, linear polysaccharides

8

GAGs in CT

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

9

hyaluronic acid in ground substance

-longer and more rigid than other GAGs
-increases the viscosity of ground substance (makes it thicker)

10

proteoglycans

-linear proteins with glycosaminoglycan (GAG) side chains
-look like a bottle brush

11

proteglycan aggregate

proteglycan + GAG (hyaluronic acid)

12

mutiadhesive glycoproteins

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

13

FIbrous component of CT

-proteins secreted from principal CT cells
-proteins assemble into fibrils (TEM), which usually assemble inter fibers (LM)

14

3 major types of fibers in connective tissue

1. collagen
2. elastic
3. reticular (type III collagen)

15

constituency of CT

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

16

role of ground substance vs. fibers

fibers: tensile strength + resiliance
ground substance: diffusion of molecules + access of blood borne cells

17

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

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

18

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

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

19

mast cells

promote inflammation

20

granules in mast cells and their respective function

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

21

uriticaria

hives;
produces from skin mast cell activation

22

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

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

23

leukocytes

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

24

cells in CT

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)

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