Immunology Quiz on Defense Mechanisms

Lymphatic System Structures

• Palatine tonsil, submandibular node, cervical node, right internal jugular vein, right lymphatic duct, right subclavian vein, thymus, lymphatic vessel, thoracic duct, cisterna chyli, intestinal node, large intestine, appendix, left internal jugular vein, thoracic duct, left subclavian vein, axillary node, spleen, small intestine, aggregated lymphatic follicle (Peyer's patch), iliac node, and inguinal node are components of the lymphatic system.

Lymph Capillaries in the Tissue Spaces

• Lymph capillaries are located in the tissue spaces.
• Lymph capillaries absorb tissue fluid.
• Arterioles provide tissue fluid to the tissues.
• Venules receive lymph from the lymphatic vessels.
• Lymphatic vessels and lymph capillaries work together to collect and transport lymph.
• Lymph capillaries are like mini valves that prevent lymph from flowing backwards.

Lymph Node Anatomy and Physiology:

• Lymph flows into the lymph node via afferent lymphatic vessels.
• Lymph flows out of the lymph node via efferent lymphatic vessels.
• The lymph node filters lymph for pathogens.
• Lymph nodes contain B-cells and T-cells.
• B-cells reside in the cortex, and T-cells mainly reside in the deep cortex.
• Lymph nodes contain blood capillaries that surround lymphatic nodules.
• The capsule, trabeculae, cortex, and medulla are parts of the lymph node.

Immune System

• The immune system has three lines of defense against invading pathogens.
• The first line of defense consists of non-specific natural barriers.
• The second line of defense consists of innate non-specific immune defenses.
• The third line of defense consists of antigen-specific immune responses.

5 Cardinal Signs of Inflammation

• Pain, heat, redness, swelling, and loss of function are the five cardinal signs of inflammation.

Helper T-Cell Activation and Action

• The process of helper T-cell activation and action involves antigen recognition, clonal selection, and interleukin secretion.

Th1 and Th2 Cells

• Th1 cells are involved in cellular immunity, activating T-cells for cell cytotoxicity, activating monocytes, and increasing proinflammatory cytokines production.
• Th2 cells are involved in humoral immunity, activating B-cells, activating eosinophils, deactivating monocytes, and decreasing proinflammatory cytokines.

Specific Immunity - T-Cells

• T-cells, which are lymphocytes, are vital for cell-to-cell combat.
• T-cells cannot recognize antigens without antigen-presenting cells.
• T-cells develop responses after exposure to antigens.
• T-cells have cytotoxic and helper roles.
• Activated T-cells multiply into thousands of cells capable of releasing cytotoxic chemicals.
• Helper T-cells recruit other lymphocytes for battles.
• Memory T-cells remain in the body to initiate a stronger, faster secondary response to any future infection.
• Suppressor T-cells eventually end the immune response.

B-Cells and Antibodies

• B-cells directly recognize antigens and change into plasma cells.
• Plasma cells secrete antibodies.
• Antibodies eliminate antigens and are also known as immunoglobulins.

Immunoglobulins (Major Functions)

• IgG is the main antibody in the secondary immune response.
• IgA helps prevent bacterial and viral attachment.
• IgM is produced in the primary immune response.
• IgD serves as an antigen receptor on B cells.
• IgE mediates immediate hypersensitivity response and defends against worm infections.

B and T Cell Development

• Stem cells develop into specific B and T cells.
• Pre-B cells and pre-T cells mature into B and T cells, respectively, following exposure to antigens in the thymus.
• Stem cells develop from bone marrow.

Immune Response

• The body responds to an initial exposure to antigens leading to a primary response.
• The body's response to subsequent exposure to antigens leading to secondary response which is faster and stronger.

Principles of Vaccination

• Antigens are live or inactivated substances that can stimulate an immune response.
• Antibodies are proteins produced by B-lymphocytes to target specific antigens.

Antibody Actions

• Antibodies neutralize, agglutinate microbes, precipitate antigens, and activate the complement system.
• Antibody binding and other actions lead to cell lysis—cells rupturing or breaking open.

Hypersensitivity Reactions

• Hypersensitivity is an exaggerated response to a foreign substance or perceived foreign substance and damages the body.
• Type I hypersensitivity (Allergic Anaphylaxis and Atopy).
• Type II hypersensitivity (Antibody).
• Type III hypersensitivity (Immune Complex).
• Type IV hypersensitivity (Delayed).

Local Anaphylaxis

• Two-phase reaction involving a late-phase reaction that may appear 2-8 hours after exposure to antigen.
• This late-phase reaction involves a more intense infiltration of tissues with eosinophils, neutrophils, and basophils with CD4+ T-cells.

Signs of Anaphylaxis

• Anaphylaxis can manifest in various areas of the body, most often in skin, airways, central nervous system, or GI tract.

Allergy and Atopy

• Atopy is a genetic predisposition for IgE-mediated diseases.
• Atopy involves nonatopic allergic diseases, such as contact dermatitis and hypersensitivity pneumonitis.

Type II Hypersensitivity- Antibody-Mediated Cellular Dysfunction

• Antibody-mediated cellular dysfunction occurs when target cells are coated with antibodies.
• Cells are lysed by neutrophils, eosinophils, macrophages, or natural killer (NK) cells.
• Examples include myasthenia gravis and Graves disease.

Type III Hypersensitivity – Immune Complex

• Immune complexes (antigen-antibody complexes) deposit in tissues during type III hypersensitivity reactions.
• Immune complexes activate the complement system, attracting neutrophils and leading to inflammation.

Type IV Hypersensitivity – Cellular

• Type IV hypersensitivity is a delayed-type hypersensitivity reaction involving T-cells, monocytes, and macrophages.
• The body must have previous contact and sensitization.
• Examples include chronic graft rejection, PPD tests, latex reactions, nickel allergies, and poison ivy.

Test your knowledge on immune defenses and hypersensitivity reactions with this quiz. Explore key concepts such as inflammation signs, antibody functions, and the role of the thymus gland. Perfect for students studying immunology or related fields.