The Immune/Lymphoid System Flashcards by Imgonnatickle yourpickle

What are the functions of the protective surface inmmune system mechanism?

first line of defense in skin and mucous membranes
protected by a variety of antibacterial substances including defensins and lysozymes (in tears and saliva)

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What are the three main lines of defense for humans?

protective surface mechanisms
innate immune system
adaptive immune system

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What are the functions of the innate immune system?

rapid reaction to a pathogen
same magnitude of reaction with each encounter (no learning)
cells, proteins, peptides that circulate in the blood
many of the same cells and signaling molecules used in innate are vital in the adaptive as well

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What are the characteristics of acute inflammation?

vascular changes including dilation, enhanced permeability of capillaries, and increased blood flow
production of fibrin-rich inflammatory exudate

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What are the functions of the adaptive immune system?

ability to learn so that the subsequent response elicits a greater, more specific, faster response
uses T and B lymphocytes
requires antigen-representing cells

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What are the actions of the neutrophil, eosinophil, and macrophage?

Phagocytosis and killing of pathogenic organisms
Secretion of cytokines and extracellular antimicrobial
molecules, including neutrophil extracellular traps
(NETs) and pattern recognition molecules (PRMs)

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What are the actions of the complement and chemokines?

Opsonises organisms to facilitate phagocytosis
Chemoattractant for various cells
Membrane attack complex (MAC) kills cells by
puncturing plasma membrane

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What are the actions of the natural killer (NK) cells?

Recognize and kill virus-infected and cancerous cells

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What are the dense lymphoid tissues?

organized into discreet structures or organs (lymph nodes, spleen, thymus, tonsil)

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What are the diffuse lymphoid tissues?

—located throughout body, associated with mucous membranes

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What is primary lymphoid tissue?

— lymphoid tissue where b- & t-cells acquire surface receptors
— bone marrow for b cells and thymus for t cells

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What is the secondary lymphoid tissue?

Mature b- & t-cells secondarily migrate to all other lymphoid tissue

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What are malignant tumors of the immune system called when they involve a solid organ?

lymphomas

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What are malignant tumors of the immune system called when they involve blood?

leukemias

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What do lymphatic vessels allow for?

route which allows cells and large molecules in ECM to re-enter the bloodstream
assist circulation of lymphocytes
concentrate antigens for elimination within lymph nodes

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What activates a lymphocyte?

antigen binds to their surface receptor

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What cell constantly patrols the body, circulates in blood,
lymph and extracellular fluid, and pauses in organized
lymphoid tissue?

lymphocytes

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What does the binding of B cell receptors depend on?

shape and electrical charge

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What does binding to T cell receptors require?

shape, electrical charge, and must bind to the major histocompatibility complex (MHC)

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What are the roles of T-lymphocytes?

T helper cells (TH cells) - ‘help’ other cells to perform their effector functions by secreting a variety of mediators
Cytotoxic T cells (TC cells) - kill virus-infected and some cancer cells. They require interaction with TH cells to become activated and proliferate to form clones
Regulatory T cells (TREG) - suppress immune responsiveness to self-antigens (autoimmunity) and switch off the response when antigen is removed
Memory T cells - develop from activated T cells to provide a ‘rapid reaction force’ for a subsequent encounter with the same antigen

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Which T cell s ‘help’ other cells to perform their effector functions by secreting a variety of mediators? TH cells thus provide ‘help’ to B cells, cytotoxic T cells and macrophages.

T helper cell

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What T cells s are able to kill virus-infected and
some cancer cells and require interaction with TH cells to become activated and
proliferate to form clones?

Cytotoxic T cell

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What T cell suppresses immune responsiveness to self-antigens (autoimmunity) and switch off the response when antigen is removed?

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Regulatory T cell (TREG)

What T cell is developed from activated T cells to provide a ‘rapid reaction force’ for a subsequent encounter with the same antigen and is the basis of persisting immunity?

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Memory T cell

Where do plasma cells develop and what do they do?

- mature from B cells in the bone marrow - synthesize large amounts of antibodies (IgG, IgA, IgD, IgE, IgM)

What are lymph nodes and how are they arranged?

- encapsulated aggregates of lymphocytes & lymphoid tissue, distributed throughout the body - Arranged in chains or clusters along vessels of lymphatic origin (submandibular, cervical, axillary, femoral, popliteal)

What are the four functions of lymph nodes?

* Non-specific filtering of particulate matter & microbes from lymph * Interaction of circulating lymphocytes with Ag in lymph * Aggregation, activation, & proliferation of B-cells with subsequent Ab production * Aggregation & proliferation of T-cells & induction of cytotoxic immunity

What are immune accessory cells?

antigen presenting cells (macrophages, b and t cells; originate in bone marrow)

What are two types of immune accessory cells/macrophages?

– follicular dendritic cells - macrophages at periphery of germinal centers; Ag-presenting cells – Tingible body macrophages - 1’ found in germinal centers; possess numerous phagocytic vesicles

What are stromal cells in the lymph nodes?

fibroblasts and reticular cells

What are the three cell types in the lymph nodes?

lymphoid cell immune accessory cell stromal cell

What is the morphology of the lymph node?

* Outer, fibrous capsule of dense, irregular connective tissue * dense, outer, cellular cortex (B and T-cells, & plasma cells) & less cellular inner medulla * Extensions of cortical tissue into medulla called medullary cords * Separated by medullary sinuses * Interspersed throughout cortex & medulla are very thin, collagenous trabeculae * Blood vessels enter & leave lymph nodes at hilus

What type of follicle are densely packed, highly cellular, and located within the cortex of the lymph node?

primary follicle

What type of follile is paler and contains less dense germinal centers?

secondary follicle

Which type of follicle is responding to anitgens?

secondary follicle

What does proliferation of lymphocytes via clonal expansion and other means do to lymph nodes?

enlargement and "swollen glands"

What is the darker staining rim surrounding a germal center called?

mantleor marginal zone

What is the space beneath the capsule where numerous afferent lymph vessels drain into?

cortical or subcapsular sinus

What is the nature of the endothelium in the lymph node for lymphatic drainage?

endothelium on side adjacent to capsule - continous (prevents leakage) endothelium on side adjacent to parenchyma - discontinous

Are lymphatic sinuses open spaces like blood sinuses?

NO - filled with reticular fibers and macrophage processes

What is the process where B and T cells leave the bloodstream and enter the node faciliated by complementary adhesion molecules?

diapedesis

Where do B and T cells leave the bloodstream?

specialized post-capillary venules (high endothelial venules) - lined by cuboidal to columnar endothelium (at the paracortical zone)

What are the sinuses in the outer cortex of the lymph node?

cortical sinuses, trabecular sinuses, or peritrabecular sinuses

What is the path of lymphatic drainage?

- outer cortex sinus - medullary sinus - lymph drains from hilus of node via a single efferent lymph vessel - returns to blood stream via thoracic duct or right lymphatic duct

What is the clinical relevace of lymphatic drainage to regional lymph nodes?

important in metastasis of tumor cells

What are the functions of the thymus?

* Production of mature, immunocompetent Th & Tc cells * Clonal proliferation of Tc cells * Clonal deletion of self-Ab’s * Secretion of hormones regulating t-cell development & maturation

As t-cells mature in the thymus they express?

* Ag specific t-cell receptors * CD (cluster of differentiation) surface markers * Class I & II HLA (human leukocyte Ag) surface markers

What does the thymus have that is unique?

hassall's corpuscles - eosinophilic lamellated structures within both the medulla and cortex of the thymus - either degenerated reticular or epithelium nurse cells

What do nurse cells in the thymus secrete?

various hormones (thymotaxin, thymosin, & thymopoietin) to attract, regulate & promote t-cell proliferation & differentiation into Tc, Ts & Th cell

What is the difference between lymph nodes and the thymus?

- thymus is less cellular - thymus central medulla contains mostly b-cells, plasma cells, and macrophages - thymus lacks secondary follicles

What is the structure of the thymus?

-highly cellular coretex (t-cells and macrophages) - secondary follicles absent - thin capsule of dense, irregular ct - slender interlobular septa or trabeculae

What is in the outer cortex of the thymus?

– Immature T-Lymphocytes – Epithelial Cells (Nurse Cells); secrete thymic hormones – Some Macrophages

What is in the inner medulla of the thymus?

– Epithelia Cells – Mature T-Lymphocytes – Thymic Corpuscles (Hassall Corpuscles); Circular aggregations of aged, degenerated Nurse Cells

Which organ degnerates at puberty and is vestigial in adults?

thymus

What process allows for the thymus to degenerate?

- fatty infiltraiton and lymphatic depletion (thymic involution) - no afferent lymph vessels to thymus because continous epithelium isolates it - blood-thymus barrier forms an antigenic barrer that isolates thymus from immune system

The Immune/Lymphoid System Flashcards

(55 cards)