Immunity to Microbes/Mucosal Defenses Flashcards

1
Q

mucosae

A

tissues continually bathed in a thick layer of mucus that they secrete

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2
Q

Gut associated lymphoid tissue

A
  • lamina propria
  • mesentric lymph nodes
  • peyer’s patches
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3
Q

Functions of mucosal tissue

A
  • gas exchange
  • food absorption
  • sensory activities
  • reproduction

Mucosal surfaces are thin, permeable barriers to the interior of the body. These tissues are by nature vulnerable to subversioin and breach by pathogens.

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4
Q

Urogenital tract

A
  • uterus
  • bladder
  • vagina
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5
Q

gastrointestinal tract

A
  • oral cavity
  • esophagus
  • stomach
  • pancreas
  • intestine
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6
Q

respiratory tract

A
  • sinus
  • trachea
  • lungs
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7
Q

intestines (# of lymphocytes)

A

50x10^9

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8
Q

lungs (# of lymphocytes)

A

30x10^9

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9
Q

75% of the body’s lymphocytes are in

A

secondary lymphoid organs serving mucosal surfaces

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10
Q

majority of all anitbodies made by the body

A

are dimeric or secretory IgA which localize to mucosal surfaces

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11
Q

GI tract of humans

A

continious contact with large numbers of commensal microbes

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12
Q

challenge to the mucosal immune system

A

eliminate pathogens while limiting growth of commensals and not attack our food

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13
Q

surface area of small intestine

A

200x that of the skin

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14
Q

Intestinal epithelial cells are covered by

A

two layers of mucus

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15
Q

inner mucosal layer

A

firmly adherent and works to seperate microbes from epithelial cell

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16
Q

outer mucosal layer

A

microbes are mostly associated with the outer layer. The outer layer is loosely adherent.

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17
Q

Overall thickness of mucosal layer

A

differs in the various sections of the gastrointestinal tract

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18
Q

mucosal layer in stomach

A

corpus
- protects the gastric mucosa from the pH of the stomach

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19
Q

Duodenum/Jejenum (small intestine)

A

very very thin layer of inner layer and outer layer, covering the villi

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20
Q

colon

A

large intestine,

thickest outer layer

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21
Q

which layer has the most microbes?

A

outer layer

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22
Q

secondary lymphoid tissues of the small intestine

A
  • Peyer’s patches
  • lamina propria
  • isolated follicles

These all drain to the mesentric lymphnodes

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23
Q

villus

A

peak/projection of tissue, into the lumen, coated with epithelial cell layer.

very important for absorption of food.
Villus also contains epithelial cells, that contain cillia that enable cells to be absorptive of food when it’s being digested and degrated.

24
Q

intraepithelial lymphocytes

25
Paneth cells
produce anti-microbial peptides
26
goblet cells
produce mucus. becomes more unfolded eventually
27
peyer's patch
underneath the epithelial layer - contains both B and T cell zones - very small - located right below epithelial lining of the gut
28
M cells
specialized for transport of things from the lumen to the peyer's patch
29
mesenteric lymph node
majority of anitgens and cell that migrate and be presented to B or T cells, go to the draining lymph nodes named **mesentric lymph node**.
30
major draining lymph node of the gut
mesenteric lymph node
31
lamina propria
it is a lymphoid tissue, but lacks the level of organization such as the peyer's patch and mesenteric lymph nodes.
32
cells that live within lamina propria
- plasma cells (IgA) - macrophages - Mast cells - T cells - B cells - Dendritic cells
33
classification of cells in the lamina propria
**Effector cells, not many naive cells** intraepithelial lymphoid cells -> when these cells ^ go into the mucosal layer.
34
NLR and TLR
face the basolateral surface of the epithelial layer (NOT facing the lumen)
35
Intestinal epithelial cells
- polarized - apical surface that faces the lumen 1. absorption - basolateral surface that faces the underlying tissue 1. adherent to ECM
36
NLR location
cytoplasm
37
TLR location
basolateral surface
38
TLR and NLR are able to
detect if a bacteria has entered the cell
39
M cells directly within the
Epithelial layer Specialized in transport across the epithelial barrier
40
dendritic cells can also live right on the epithelial layer
DC pushes a projection through the epithelial layer, so they may sample luminal contents to present those to T cells.
41
Surveying of mucosal immune system
DC and M cells
42
Microfold (M) cells
have very little degradtive activity Function primarily to transport of particles, pathogens, and antigens across the epithelium
43
M cells mechanism
- M cells take up antigen by endocytosis and phagocytosis - Antigen is transported across the M cells in vesicles and released at the basal surface - Antigen is bound by dendritic cells, which activates T cells
44
2 mechanisms of DC takeup of luminal content
1. projection reached through epithelial layer and reach the antigen in the lumen and then perform endocytosis 2. antigens may cross the epithalial layer through a "breach" = **Presentation of antigen to T cells** in mucosa-associated lymphoid tissues or mesenteric lymph nodes
45
primary anitbody isotype found in the gut
dimeric IgA
46
IgA
neutralizing, because of its association with the J-chain, it can be moved acorss the epithelial layer by polyIG receptor.
47
intraepithelial lymphocytes
"specialzed cell type" that resides directly **between** the epithelial cells and the barrier - effector lymphocytes - integrated into the epithelial layer of the small intestine - **IEL's are generally CD8+Tcells, either alphabeta or gammadelta and have limited range of antigen specificities**
48
1 IEL
for every 7-10 epithelial cells
49
IELs are generally
CD8 + T cells
50
Naive lymphocytes activated in a Peyer's patch, gives rise to
effector cells that travel in the lymph and blood to gain access to the lamina propria of the mucosal tissue
51
chemokines instruct
T cells on when to leave the certain vessel they are found in. + adhesion molecules = tells the T cell where to stop and perform diapedesis.
52
**Lamina Propria**
(loosely) connective tissue underlying the intestinal epithelia and where many immune components are located (plasma cells, T cells, DCs, macrophages, mast cells and eosinophils)
53
**Peyer's Patch**
lymphoid tissue integrated in the intestinal wall and contains numerous B cell follicles with germinal centers
54
**Mesenteric lymph node**
lymph nodes located in the intestinal mesentery and are dedicated to defending the gut
55
Intraepithelial lymphocytes
T (typically, CD8+) cells, integrated into the epithelial layer
56
**M (microfold) cell**
cells that uptake and transport antigen and cells from the intestinal lumen to Peyer's patches located beneath them
57
mechanisms of surveillance
- uptake and transport into Peyer's Patches by M cells - DCs extending through epithelial layer - paracellular (in between epithelial cells)