Lymphoid Organs 1 Flashcards

1
Q

Non encapsulated tissues and encapsulated tissues

A

Non encapsulated - diffuse lymphoid tissue, nodules, tonsils, payer’s patches, appendix

Encapsulated- lymph nodes, spleen, thymus

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2
Q

All lymphoid tissues composed off

A

lymphocytes
Reticular cells and fibers make up the stroma (cortex of thymus is exception)
Lymphocytes make up the parenchyma

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3
Q

Size categories of lymphocytes

A

90% small
10% large

Large have more cytoplasm but nucleus is same size

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4
Q

2 functional types of small lymphocytes

A
B cells (20-30%)...give rise to plasma cells which produces ABs
T cells (70%) - CMI
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5
Q

Lamina propria

A

Loose CT under epithelial membrane in rest, digestive, urinary and reproductive pathways where tissue fluid sampled for antigens

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6
Q

Diffuse lymphoid tissues

A

Transient…contain macrophages, reticular cells, dendritic cells, B and T cells

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7
Q

Lymphoid nodules

A

Structural and functional unit of the rest of diffuse lymphoid tissues…(all but lamina propria)

Do not have a CT capsule

Filter tissue fluid for antigens

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8
Q

Primary nodule

A

Transient and round

Mostly B memory cells…reticular cells, some macros, dendritic and T cells present as well

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9
Q

Secondary nodule

A

Where B cells have been exposed to antigens and produce more progeny

Germinal center of active B cells

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10
Q

What is in each part of secondary nodule

A

Germinal center - APCs, macros, proliferating B lymph’s
Corona - mostly B memory
Between corona and germinal center - T helpers

Germinal center cells will have ore cytoplasm than corona cells

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11
Q

Peyer’s patches

A

Found in submucosa and lamina propria of the lieum (being in lamina propria and move down into submucosa)
Bulge out from intestinal wall
No villi on top of them

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12
Q

M cells

A

Specialized epithelial cells of mucosa associated lymphoid tissues that transport antigens from lumen to cells of immune system

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13
Q

Tonsils

A

Aggregates of no-encapsulated lymphoid nodules
Partial CT capsule posteriorly but anteriorly lined by oral epithelium

3 types - lingual, palatine and pharyngeal

Epithelial lined crypts on all but pharyngeal

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14
Q

Appendix

A

Large masses of lymphoid nodules present n lamina propria and submucosa of appendix

Form complete ring of lymphoid tissue

Materials can get trapped in here and they penetrate int the lamina propria

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15
Q

Lymph node basic cellular structures

A

Cortex - contains B cell nodules (some activated and some not)
Paracortical area/deep cortex/paracortex/T cell zone - contains T cells
Medullary cords in the medulla - more B than T cells, also macrophages that scan lymph for antigens

Also will have multiple afferent vessels and one efferent vessel

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16
Q

Lymphatic circulation

A

Afferent lymphatic vessels bring it in to the sub capsular sinus…then flows through narrow cortical/trabecular sinuses until it reaches medullary sinus and leaves via efferent lymphatic vessels

17
Q

Sinuses of lymph node

A

Filled with lymph and lined by reticular cells and macrophages…this slows down the flow of lymph

18
Q

Reticular meshwork of lymph nodes

A

Reticular cells secrete extensive reticular fiber meshwork

Dendritic reticular cells similar to macrophages that are APCs with long processes and a pale nucleus

19
Q

3 regions of lymph node in detail

A

Cortex - primary nodules (B-memory), secondary nodules (B-cell proliferation), Internodular region (T-helper)

Deep cortex - T-helper mostly with some naive and some CD8s

Medulla - medullary cords, sinuses, and hilus

20
Q

Blood flow of lymph nodes

A

Afferent artery in the hills to the cortex
Cortical capillaries to lymphatic nodules
Post capillary venues
Efferent veins to hilus

21
Q

Post capillary venues

A

Found in the deep cortical region
Lined with cuboidal cells
HEVs - T cells stick to them and migrate into the deep cortical region