Lymphatic System I Flashcards by Nadia Jacob

…… cells migrate from bone marrow to the thymus gland to mature and become immunocompetent

T-Cells

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T-Cells destroy the antigen by using ……. or activating ……… cells

Cytotoxic action (CD8+) 
B cells

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➢ Produce interleukin 2 (IL2), interferon (gamma) and tumor necrosis factor (alpha) ➢ interact with CD8+ cells to destroy intracellular antigens (viruses & microorganisms).

CD4+ Helper Cells (TH1 cells)

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➢ Produce IL 4, IL5 , IL10 and IL13

➢ interact with B lymphocytes to destroy extracellular antigens

CD4+ helper cells (TH2 cells)

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Immunocompetent B cells activated by

CD4+ T lymphocyte

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Natural killer cells attack ….

Virus infected cells and cancer cells

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Types of Immune Responses

Innate Response (Non-specific Immunity)
Adaptive Response (Specific Immunity)

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Which immune response occurs through fast action of neutrophils, macrophages, mast cells & NK cells?

Innate Response (Non- Specific Immunity)

-Do not produce memory cells

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Which immune response depends on initial recognition of antigens by B and T cells?

Adaptive Response (Specific Immunity)

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Two Types of Adaptive Immune Response

Antibody Mediated Immunity

Cell Mediated Immunity

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…… Immunity uses Specific T cells that specialize in cytotoxicity • Granzymes and perforins as an immune response

Cell Mediated Immunity

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…….. Immunity uses helper T-cells, B-cells and Plasma cells that cause a release of antibodies that act on invading antigen as an immune response

Antibody Mediated Immunity

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Types of Lymphoid Tissue:

Diffuse Lymphoid Tissue

Nodular Lymphoid Tissue

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3 Primary Lymphoid Organs

➢ Bone Marrow ➢ Thymus ➢ GALT

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3 Secondary Lymphoid Organs

➢ Lymph nodes ➢ Spleen ➢ Tonsils

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The following characteristics are associated with which lymphoid tissue: 
o Initial immune response 
o Found in lamina propria 
o Intercepts antigen 
o No capsule

Diffuse Lymphoid Tissue

Example: MALT (mucosa associated lymphoid tissue)

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The following characteristics are associated with which lymphoid tissue:

➢Characterized by nodules / follicles
➢Primary nodule 
– mainly consists of small lymphocytes 
➢Secondary nodule 
– consist of germinal center(GC)- area where lymphocytes undergo proliferation.

Nodular Lymphoid Tissue

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The paler region in Germinal Center (GC) of Nodular lymphoid tissue

Immature lymphocytes (lymphoblasts)

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The ………….. region has FDCs-follicular dendritic cells and indicates lymphatic tissue response to antigen.

Germinal Center

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The ……….. region consists of small lymphocytes around the GC

Mantle zone or corona

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Within in the lymphatic nodule, reticular cells produce…

Reticular Fibers (stroma)

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Within in the lymphatic nodule, B-lymphocytes are activated, proliferate, and turn into ……. and …….. cells

Plasma Cells and Memory Cells

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Within in the lymphatic nodule, the two Antigen Presenting Cells (APCs) are…..

Macrophages and Dendritic Follicular Cells

Dendritic Follicular Cells and Macrophages within in the lymphatic nodule present which antigens?

MHC I and II molecules

Follicular Dendritic Cells within in the lymphatic nodule contain which molecules?

Harbors Ag-Ab complexes | Lack MHC II

......... interact with helper CD4+ T lymphocytes to facilitate immune responses.

Antigen Presenting Cells (APC's)

Functions of Macrophages:

1. APC 2. endocytosis and partial digestion of protein and polysaccharide antigen before they present them on MHC II molecules to help CD4+T cells 3. digest pathogenic microorganisms by lysosomal action 4. produces multiple cytokines- lymphokines, complement, interleukins, acid hydrolases and lipases

Macrophages, Kuppfer cells, dust cells, Langerhan cells and dendrtic cells (spleen & lymph nodes) are APC of the ......... system

Mononuclear Phagocytic System (MPS)

......... is primary lymphoid organ located in the superior mediastinum.

Thymus

Epithelial Component of the thymus

Epithelial Reticular Cells (ERCs)

........ run within the thymus to divide tissue as lobules. Each lobule has a cortical cap over portions of highly convoluted but continuous inner medullary tissue.

Trabeculae

Parenchyma of the Thymus:

In Cortex: - mainly immature T lymphocytes (thymocytes) & ERCs (epithelial reticular cells) In Medulla: - mature T lymphocytes & ERCs

...... primary support cells in the cortex.

Epithelial Reticular Cells (ERCs)

Epithelial Reticular Cells (ERCs) form a ....... which is held together by desmosomes

Cytoreticulum

...... ensheath blood vessels in cortex and sequester the developing T cells from blood born antigens.

Epithelial Reticular Cells (ERCs)

ERCs are Characterized by .......

Characterized by continuous capillaries

The thymus cortex are made of:

Cortex of tightly packed lymphocytes and support cells (epithelial reticular cells)

........ has lower concentration of lymphocytes

Inner Medulla

The Blood Thymus Barrier is only found in the.....

Cortex

Within the Medulla, lymphocytes.....

Differentiate and enlarge | Mature T cells migrate into medullary blood vessels and efferent lymphatics

ERC’s contract into spherical, degenerative masses

Hassall’s Corpuscle

Hassall’s Corpuscles are found only in the ......... and consist of rings of degenerating epithelial reticular cells

Thymic medulla

Disease: Absent Thymus Gland caused by defect in the development of the 3rd & 4th branchial pouches & arches.

DiGeorge Syndrome (22q11.2 Deletion Syndrome)

DiGeorge Syndrome is also called CATCH 22 which stands for.....

``` Cardiac Anomaly Abnormal Faces Thymic Aplasia Cleft Palate Hypocalcemia ```

Kidney Shaped Organs that filters lymphatic fluid

Lymph Nodes

.......... mounts immune response by recirculation of lymphocytes (route of metastases)

Lymph Nodes

Where arteries and nerves enter and veins and lymphatic vessels leave the node.

Hilum

Afferent lymphatic vessel – drains lymph through .......

Convex margin

........ in the deep cortex and medulla allow for the transition of lymphocytes from the blood stream to lymph tissue

High Endothelial Venules (HEVs)

The outer cortex of the thymus is mainly composed of ........

Lymphatic nodules of B-cells | Few T lymphocytes, macrophages, reticular cells, and APCs

Paracortex is the ..............

Area between cortex and medulla) that is primarily composed of T-cells where excess lymph is reabsorbed

....... allow for the transition of lymphocytes from the blood stream to lymph tissue

Paracortex (deep cortex)

Branched cordlike extension of dense lymphoid tissue  | Contain primarily B lymphocytes, plasma cells, reticular cells and macrophages

Medullary Cords

Dilated spaces separating medullary cords Contain lymph, few wandering macrophages  Granulocytes maybe present when lymph node is draining an infected region

Medullary Sinuses

The stroma of lymph node consists of....

1. Reticular cells (modified fibroblasts) cytoplasmic extensions cover reticular fibers 2. Framework for myeloid (bone marrow) and lymphoid (lymph nodes, spleen) organs

Lymph node stained with ........

Silver Stain