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Cellular Week 3 > CT/Adipose in Class Lec > Flashcards

CT/Adipose in Class Lec Flashcards

1
Q

Connective tissues range from liquid (blood) to soft tissue (fascia and adipose tissue) to harder substances (cartilage and bone).

A

….

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2
Q

Common Features of CT?

A
  • Rich ECM, lesser in number of cells per unit area
  • Common embryological origin (most from embryonic mesenchyme and some from neural crest like the CT in the head)

never exposed to outside world

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3
Q

ecto/endo form what?

A

epi cells

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4
Q

mesoderm forms what?

A

mesenchyme - loose collectio not cells with lots of ECM

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5
Q

what can an undifferentiated mesenchymal cell form?

A 
fibroblast
osteocyte
osteoblasts
chondrocytes
chondroblast
adipocyte
endothelial cell/smooth muscle cells
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6
Q

elements of CT? (3)

A

fibers
cells
matrix

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7
Q

CT functions?

A
  • structural support (bone/cartilage)
  • energy depot and cushioning
  • defense: immune responses and inflammation
  • repair and wound-healing
  • cues for differentiation
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8
Q

Exs of CT functioning as structural support

A

bone and cartilage
capsules of spleen and lymph nodes
basal laminae

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9
Q

three types of fibers in CT?

A

collagen
reticular
elastic

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10
Q

things in the matrix of CT?

A

proteoglycans
glycoproteins
tissue fluid

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11
Q

cells in the CT?

A 
derived from differentiation of mesenchyme:
fibroblasts
mesenchymal
adipocytes
chondrocytes
osteocytes
arise elsewhere and migrate into CT:
macrophages
lymphocytes
mast cells
granulocytes
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12
Q

collagen fibers:
what type of subunits
what diameter
color on H&E?

A
  • collagen subunits
  • .5-20 micrometer diameter
  • pink/orange on H&E
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13
Q

reticular fibers:
subunits?
diameter?
color on H&E?

A
  • collagen subunits
  • .5-2 micrometers in diameter
  • not stained by H&E! (silver or PAS)
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14
Q

elastic fibers:
subunits?
diameter?
color on H&E?

A
  • elastin + microfiber glycoproteins (fibrillin +)
  • .5-1 micrometer diameter
  • poorly stained by H&E (orcein or resorcinol) - sometimes show up as pale pink on H&E
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15
Q

collagen and reticular fibers are very similar. Collagen are thicker, reticular are thinner and not as strong.

A

…

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16
Q

There are about 20 collagen genes… how many collagen types?

A

28 but we only care about first 4

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17
Q

collagen: glycine repeated every 3 aa.

A

….

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18
Q

collagen type I
forms?
distribution?

A

COLLAGEN FIBERS
thick fibers
skin, bone, cornea, tendons

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19
Q

collagen type II
forms?
distribution?

A

fine fibrils

cartilage

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20
Q

collagen type III
forms?
distribution?

A

RETICULAR FIBERS
thin fibers
loose connective tissue, arteries, smooth muscle, stroma of many glands

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21
Q

collagen type IV
forms?
distribution?

A

sheets

basal laminae

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22
Q

Different types of collagen result from different combinations of collagen polypeptides. The different types differ somewhat in physical properties and have different tissue distributions - you should know these!

A

..

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23
Q

Type I thick collagen fibers are composed of many fibrils. The fibrils have a striated appearance and form a staggered array.

(thick fibers in skin, bone, cornea, and tendons)

A

..

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24
Q

What do collagen fibers show up as in H&E? (type I)

A

pink threads!

wispy looking for type I!

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25
Q

what do collagen fibers look like in a EM? (cross section and longitudinally)

A

cross section - spots/stippled
longitudinally - individual fibrils with characteristic striations that result from staggered but regular polymerization

can tell its NOT skeletal muscle because there are no organelles!

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26
Q

Type I - denser CT

Type III - looser CT

A

…

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27
Q

which fibers cannot be visualized at all on H&E?

A

reticular! (use silver/ PAS instead)

elastic fibers are also poorly visualized but do show up as pale pink

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28
Q

special stain type I collagen?

A

trichrome

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29
Q

special stain reticular?

A

silver

PAS

30
Q

special stain elastic?

A

roscorcinol

orcein

31
Q

what is special about collagen?

A

It has a high tensile strength - meaning it has resistance to be lengthened/stretched. (NOT THE RESISTANCE TO SHEAR - meaning the ability to resist bending or breaking).

makes sense bc you want your skin to go back after you pull on it (don’t want droopy skin)

32
Q

how to collagen get its high tensile strength? (3)

A
  • compact triple helix
  • ordered polymerization
  • cross-linking between lysine residues
33
Q

which fibers have high tensile strength?

A

collagen and reticular

ability to resist stretching (put fibers at different angles to prevent stretching from all diff angles)

34
Q

elastic fiber structure?

A

elastin core and microfibrils made of fibrillin, MFAP, and emilin

35
Q

Marfan syndrome caused by what?

A

mutations in fibrillin

36
Q

TEM of elastic fiber?

A

amorphous shape

core doesn’t stain but the microfibrils do!

37
Q

elastic fibers property?

A

resiliency or elasticity - the ability to elongate and recoil

this comes from the fact that elastin is made of segments of rigid alpha-helix separated by random coils; the random coils allow the protein to extend, but when released, it recoils to a more globular structure.

cross-links between lysines check the extension so that the fiber is not pulled spar

when stretched, hydrophobic residues get exposed!

38
Q

what do elastic fibers look like in H&E?

A

look like doubled wavy lines

39
Q

resorcin for elastic fibers shows up what color?

A

black/ purple

40
Q

the ratio of the different fibers in a tissue (collagen, reticular, elastic) determine the tissues properties!

A

….

41
Q

properties of the ECM?

A

fibers (3)
proteoglycans
glycoproteins

fibers are embedded within the ECM - a gell composed of proteoglycans and glycoproteins that hold the tissue fluid

42
Q

what are proteoglycans composed of?

A

a protein component and a glycan.

the glycan is a glycoaminoglycan (GAG) built up from repeating disaccharides (alternating glucose and amino glucose residues)

different GAGs are composed of different pairs of sugars

ex. GAG = dermantan sulfate or heparin

43
Q

the carboxyl groups of GAGs are negatively charged and most are sulfated - overall negative!!

Thus, GAGs are highly-charged, long, unbranched chains of repeating disaccharides

A

….

44
Q

what is the key feature of GAGs?

A

the negative charge!

The long, charged chains repel each other - thus tissues rich in GAGs resist compression.

45
Q

GAGs on proteins assume what appearance?

A

proteoglycans look like bottle brushes because they stick out at right angles to maximize distance from each other!

46
Q

Because the GAG chains repel each other, they occupy large volumes and cannot readily be compressed. The “empty space” between GAG chains allows for diffusion of tissue fluid.

A

….

47
Q

Two properties of proteoglycans?

A

rigidity and porosity

48
Q

proteoglycans are classic in synovial fluid, cartilage, and important to the immune system.

A

…

49
Q

elastic fibers show up as thin purply lines when close up on resorcinol or orcein

A

…

50
Q

type I collagen is found where in skin?

A

dermis

51
Q

CT is like an intelligent building because it can sense its environment, reach decisions about the state of that environment, and communicate those decisions.

A

…

52
Q

Embryonic mesenchyme gives rise to ________ (the main cells of CT proper) and to cells of various specialized tissues..

A

fibroblasts

53
Q

fibroblast characterisitcs (4)

A
  • elongated or fusiform cells
  • ovoid nuclei
  • prominent nucleoli
  • eosinophilic cytoplasm

if they are actively synthesizing, they will have lots of RER! but that usually goes away and most fibroblasts are resting. if you are injured, it will go back to synthesizing.

54
Q

vast majority of bone marrow derived cells are found in CT

A

…

55
Q

CT provides surveillance and security services for the body… (2)

A

1) immune response: specific - nonself antigens recognized by lymphocytes
2) inflammation: nonspecific - foreign substances engulfed by phagocytes

56
Q

CT is just under epi… so if you get cut, the CT has stuff (immune cells) to combat damage/infection

A

…

57
Q

macrophages derived from?

A

monocytes
found in many tissues through the body
named big eater

58
Q

macrophage characterisitcs?

A
  • active in phagocytosis (frothy cytoplasm and irregular membrane)
  • involved in in inflamm responses
  • ag presentation during immune responses

lots of euchromatin!! very active with big nucleus
lots of lysosomes that appear dark on EM

59
Q

what causes metachromasia?

A

proteoglycans/GAGs (heparin sulfate)
granules in mast cells

dye originally blue turns purple/red

60
Q

what are in granules of mast cells?

A 
Granules contain bioactive substances:
Histamine
Leukotrienes
Proteoglycans e.g. heparin sulfate (metachromasia)
ECF-A
proteases
61
Q

slow release of granules in mast cells cause….

A

slow release of granule contents and cytokines regulates innate immune response

62
Q

rapid release of granule contents in mast cells?

A

anaphylactic shock!/allergic reactions

63
Q

mast cells are found..?

basophils…?

A

mast - tissues

basophil - blood

64
Q

mast cells are concentrated near blood vessels in tissues where they will likely encounter foreign pathogens.

A

…

65
Q

Histamine causes what two things?

A
  • bronchoconstriction by inducing contraction of smooth muscle - can cause death rapidly
  • vasodilation - lowers BP rapidly and causes loss of consciousness

both affect smooth muscle but cause opposite effects in diff places (reap =contract; vasc = dilation)

66
Q

epinephrine binds to what type of receptor?

causes what action?

A

adrenergic

its actions vary by tissue type depending on the expression of adrenergic receptors

causes smooth muscle relaxation in the airways and contraction of muscle in the arterioles

reverses effect of histamine

67
Q

epinephrine (Adrenaline) is the choice of tx of patients with…?

A

anaphylaxis

68
Q

what happens in the first exposure to an allergen?

A

slow immune response - 10-14 days
then the IgE bind to receptors on mast cell surfaces

induces a weak immune response - that is some lymphocytes are stimulated to proliferate and differentiate into plasma cells which secrete ab (IgE) - takes several days after exposure

69
Q

what happens during a second exposure to allergen? (2)

A
  • the allergen again triggers an immune response, which is more powerful and slightly quicker (may now occur within 3 days rather than 7-10)
  • In susceptible individuals, the allergen also binds directly to IgE on the “primed” mast cells, causing anaphylaxis, which is rapid (within minutes) and life-threatening.
70
Q

Binding of allergen to IgE on mast cells causes….

A

immediate release of cytoplasmic granules

constriction of airways

71
Q

diverse diseases with CT!

A

joint hyper mobility
rheumatoid arthritis
autoimmune diseases
anaphylactic shock

Cellular Week 3 (21 decks)

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