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HDM Midterm 2018 > Lympoid Tissue > Flashcards

Lympoid Tissue Flashcards

(49 cards)

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1
Q

Lymphocytes

A

activated in response to presented antigens

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2
Q

Non-encapsulated Lympoid Tissue

A

-diffuse
-nodular (single, secondary)
aggregate (tonsils, peyer’s patches, vermiform appendix)

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3
Q

Functional Classification

PRIMARY

A

thymus and red bone marrow

produces lymphocytes needed to recognize antigens

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4
Q

Functional Classification

Secondary

A

diffuse lymphoid tissue where lymphocytes are activated in response to antigens

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5
Q

Diffuse Lymphoid Tissue

A

non-encapsulated accumulation of lympoid tissue

  • located in lamina propria of GI tract, genitourinary tract, resp passages
  • intercept antigens and initiate an immune response
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6
Q

Lymphatic nodules

A

discrete concentrations of lymphocytes

sharply defined but non-encapsulated

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7
Q

Primary nodule

A

consist of only small lymphocytes
inactive or naive
cells uniformly distributed
lack a germinal center

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8
Q

Secondary nodule

A
  • activated primary nodules exposed to antigen
  • has germinal center (develops when lymphocyte returns and undergoes proliferation, light stained)
  • has mantle zone(outer ring of small lymphocyte that encircles the germinal center)
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9
Q

Aggregated Lymphoid Tissue

A 
nodules are typically dispersed singly in a random manner
tonsils
peyers patch
veriform appendix
mucosa associated lymphatic tissue
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10
Q

Tonsils

A

large, irregular masses of lymphoid tissue

  • mucosa of post oral cavity, oropharynx, nasopharynx
  • helps protect against inhaled or ingested substances
  • can be PARTIALLY encapsulated
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11
Q

Palatine Tonsil

A

lined with non-keratinized stratified squamous epithelium
possess 10-20 deep invaginations (tonsillar cyrpts)
-dense connective tissue acts as a partial capsule

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12
Q

Pharyngeal Tonsil

A 
single structure
post wall of nasopharynx
covered w/ pseudostratified columnar ciliated epithelium
thin underlying capsule
invaginated mucosa w/ shallow infoldings
NO CRYPTS
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13
Q

Lingual Tonsil

A

positioned along base of tongue

  • covered w/ stratified squamous epithelium
  • germinal center
  • crypts
  • NO CAPSULE
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14
Q

Peyer’s Patch

A

numerous aggregation of lymphatic nodules in the small intestines, particularly ileum

  • associated w/ intestinal villi
  • covered by simple columnar epithelium w/ goblet cells
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15
Q

Veriform Appendix

A

aggregated nodular tissue

  • small diameter projection off the cecum
  • lamina propria almost completely infiltrated w/ lymphocytes
  • simple columnar epithelium w/ goblet cells
  • characterized by crypts, but no villi
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16
Q

Mucosa associated Lymphoid Tissue

A

single/clusters of lympoid nodules named for region organ when present
lumen open to external environment, enlarge when exposed to antigens

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17
Q

Lymph

A

clear, yellowish fluid comporised of interstitial fluid, solutes, foreign materials

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18
Q

Lymphatic capillaries

A

closed-ended tubes that are found among capillary beds

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19
Q

Lymph Nodes

A

small encapsulated structures positioned along lymphatic vessels

  • comprised of reticular tissue
  • increased in axilla, around neck vasculature, thorax, inguinal regions
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20
Q

What do lymph nodes do?

Study These Flashcards
A

filter lymph
remove debris
facilitate Ab production
produce lymphocytes

21
Q

Parenchyma

Study These Flashcards
A

cortex and medulla

22
Q

stroma

Study These Flashcards
A

supportive CT of an organ (capsule, trabeculae)

23
Q

superficial cortex:

Study These Flashcards
A

receive lymph from afferent lymphatic vessels

location of lymphatic nodules (primary, secondary)

immune cells are suspended on reticular fibers
GC have been presented w/ antigen
mantle zone contains active B cells

24
Q

deep cortex

Study These Flashcards
A

region between cortex and medulla

-free of nodules and high in T-cell counts

25
medulla
sinuses converge at the efferent lymphatic vessel
26
Hilum
exit for efferent lymphatic and exit/entry for neurovasculature
27
Reticular Meshwork
reticular cells (fibroblasts): secrete fibers and ground substance dendritic cells (APCs), macrophages, follicular dendritic cells
28
High Endothelial Venules
lined by cuboidal or columnar endothelial cells - --> facilitate movement of lymphocytes from circulation into lymph node - B and T cells leave blood stream through HEV (diapedesis)
29
Lymph Node Medulla
consists of cords and separated by medullary sinuses -network of reticular cells (framework of parenchyma) Cords: have B-lmph, mac., dendritic cells, plasma cells medullary sinuses: converge near hilum, drain into efferent lymph vessels
30
medullary cords
masses of lymphoid tissue extending from paracortex T and B cells and plasma cells
31
Medullary Sinuses
dilated spaces that separate medullary cords | clusters of macrophages and neutrophils
32
Thymus
bilobed structure in mediastinum - lymphoblasts invade tissue and proliferate - lymphocytes mature in T-cells
33
involution
decreased activity of thymus, becomes filled w/ adipose tissue
34
Characteristics of thymus
thin CT capsule w/ trabeculae extending into parenchyma trabeculae establish domains (thymic lobules) -cortical caps covering inner medullary core lack lymphoid nodules and germinal centers
35
Thymic Cortex
site of t-lymphocyte maturation basophilic, packed w/ thymocytes epithelioreticular cells provide framework for T-cell development
36
Type I: cortical epithelioreticular cells
boundary of the cortex and capsule, between cortical parenchyma and trabeculae - separate thymic parenchyma from CT of organ - occluding junctions create barrier that isolates developing T cells from stroma
37
Type 2: cortical epithelioreticular cells
located w/i cortex desmosomes join adj cells cells are stellate, and have large nucleus, stain lightly -compartmentalize cortex into isolate areas for developing T cells -express MHC I and MHC II molecules
38
Type 3: cortical epithelioreticular cells
located at the boundary of cortex/medulla - occluding junctions between processes of adj cells - create functional barrier between cortex and medulla - express MHC1/ MHC2 molecules
39
Thymic Medulla
inner portion of parenchyma, large # of epithelioreticular cells/loosely packed T cells - stain less intensely than cortex bc contains larger lymphocytes - thymic corpuscles are a distinguishing feature of medulla - houses T cells from cortex
40
Type 4: medullary epithelioreticular cells
located near type III cells sheet like processes w/ occluding junctions btwn adjacent cells and type 3 cells -make barrier at corticomedullary junction
41
Type 5: medullary epithelioreticular cells
located throughout medulla desmosomes join adj cells compartmentalize groups of lymphocytes
42
Type 6: medullary epithelioreticular cells
form thymic corpuscles exhibit flattened nuclei keratohyalin granules, int filaments, lipid droplets thought to produce interleukins (IL4, IL7)
43
Blood Thymus Barrier
barrier btwn T cells and lumen of cortical blood vessels from lumen outwards 1) endothelium lining the capillary wall 2) macrophages 3) type 1 epithelioreticular cells surround capillary wall
44
Spleen
unilateral organ in left superior quadrant - filtering functions - initates immune response to blood Ag - reservoir for platelets - recycling center for erythrocytes - hematopoiesis
45
Characteristics of spleen
dense CT capsule w/ trabeculae..contain myofibroblasts (help to expel RBCs and produce EC fibers) no cortex or medulla
46
White pulp
reticular fibers T, B cells and macrophages -lymphoid nodules -central arteriole -periarteriolar lymphoid sheaths: t cells surrounding arteriole -corona/mantle zone -marginal zone: blend of lymphoytes that span white red pulp
47
Red Pulp
venous supply, RBCs, platelets, macrophages, plasma cells - involved in blood filtration and erythrocyte turnover - composed of splenic sinusoids/cords - penicillar arteries - macrophage-sheathed capillaries
48
Stave Cells
Line the sinusoids of the red pulp!!! | they are specialized endothelial cells that separate healthy vs unhealthy RBCs
49
Splenic Vasculature
Splenic a. branches off from celiac trunk -divides into trabecular a. that enter into the parenchyma splenic a---> trabecular a. --> central arteriole/PALS---> white pulp ---> penicillar a ---> splenic sinuses ---> splenic cords - macrophages remove old/dead erythrocytes from circulation - viable erythrocytes reenter circulaion through sinuses

HDM Midterm 2018 (2 decks)

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