Questions and Answers
What type of lymphocytes are predominantly found in the marginal zone of the white pulp?
Which part of the MALT system includes the tonsils and adenoids?
Which cells are responsible for capturing antigens from the intestinal lumen in Peyer patches?
What percentage of leukocytes do eosinophils constitute?
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What is the primary function of neutrophils?
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Which of the following characteristics is TRUE regarding neutrophils?
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What type of immune response do eosinophils primarily target?
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What is the primary function of bone marrow in relation to B lymphocytes?
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Which types of granules do neutrophils contain that are involved in their phagocytic activity?
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Which of the following correctly describes lymph nodes?
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What component of lymph nodes is primarily associated with B cells?
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Which lymphatic structure drains lymph into the superior vena cava?
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How does the lymphatic system contribute to immune function?
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What is the role of macrophages in the spleen?
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Which tissues or organs are classified as secondary lymphoid organs?
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What is the significance of the primary and secondary lymphoid follicles in lymph nodes?
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Which organ is responsible for the maturation of T lymphocytes?
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Where do B lymphocytes mature in adults?
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Which of the following structures predominantly contains thymocytes?
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What is the primary function of negative selection in the thymus?
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Which of the following is NOT considered a secondary lymphoid organ?
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What is hematopoiesis primarily associated with?
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During fetal life, where does the maturation of lymphocytes take place?
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Which type of immune system cells are classified as innate?
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What is the primary function of basophils?
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Which of the following best describes mast cells?
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Which structures are associated with monocytes when they migrate to tissues?
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What components are primarily found in the granules of mast cells?
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What is a key feature of macrophages compared to monocytes?
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What is the primary role of platelets in the immune system?
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Which cytokines do activated macrophages produce to promote T CD4+ lymphocyte differentiation?
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What kind of nucleus do monocytes have?
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What distinguishes classic dendritic cells from follicular dendritic cells?
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What role do IL-10 and TGF-β play in the immune response?
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Which of the following is a characteristic of B lymphocytes?
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What triggers the proliferation of T, B, and NK lymphocytes?
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What unique feature do plasma cells possess compared to B lymphocytes?
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Which percentage of total lymphocytes do B lymphocytes typically represent?
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Which of the following is NOT a characteristic of T lymphocytes?
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What is the primary immunoglobulin produced during the primary immune response by B lymphocytes?
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Study Notes
Immune System Overview
- Comprises primary and secondary organs
- Primary organs: Thymus and Bone Marrow
- Secondary organs: Spleen, lymph nodes, MALT (mucosa-associated lymphoid tissue)
Primary Immune System Organs
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Thymus:
- Located in the thorax, bilobed structure, regresses after puberty
- Divided into cortex (many thymocytes) and medulla (few thymocytes)
- Contains epithelial cells, dendritic cells, and macrophages
- Over 95% of cortical lymphocytes undergo negative selection for self-tolerance
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Bone Marrow:
- Source of hematopoietic cells for lymphocyte precursors
- Location: "islands" of hematopoietic tissue amidst fat in long and flat bones
- Maturation of B lymphocytes occurs here
Hematopoiesis
- Self-renewing process from pluripotent stem cells
- Generates various blood and immune cells
Secondary Immune System Organs and Tissues
- Locations for mature lymphocytes to encounter antigens
- Composed of lymph vessels and lymphoid organs
Lymphatic System
- Lymphatic capillaries extract interstitial fluid, forming lymph
- Converge at lymph nodes where antigens and antigen-presenting cells arrive via afferent vessels
- Thoracic duct drains lymph into the superior vena cava
Lymph Nodes
- Functions: antigen contact and T-B cooperation
- Structures:
- Cortex: B cells (with primary and secondary follicles)
- Paracortex: T cells
- Medulla: Activated T and B cells, macrophages
Spleen
- Functions: elimination of old red blood cells and filtration of blood antigens
- Histology:
- Red pulp rich in macrophages for erythrocyte clearance
- White pulp functions similarly to lymph nodes with PALS (T lymphocytes) and a marginal zone for B lymphocytes
Mucosal Immunity (MALT)
- Includes Waldeyer’s ring (tonsils, adenoids) and MALT tissues in respiratory, genitourinary, and gastrointestinal tracts
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Peyer patches: Specialized lymphoid tissue in the small intestine
- Houses T and B lymphocytes, involved in IgA production
Immune Cells
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Neutrophils:
- 90% of granulocytes, short lifespan (2-3 days)
- Key function: phagocytosis, increases during bacterial infections
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Eosinophils:
- 1-3% of leukocytes, defense against helminths
- Contain bilobulated nucleus and granules that bind acidic dyes
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Basophils:
- <1% of leukocytes, involved in defending against parasites and allergy reactions
- Contain granules with histamine, heparin, and serine proteases
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Mast Cells:
- Derived from bone marrow, found in skin and mucosal epithelium
- Release cytokines and histamine, linked to allergic responses
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Monocytes:
- Horseshoe-shaped nucleus, migrate to tissues to become macrophages
- Functions include phagocytosis and acting as antigen-presenting cells (APCs)
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Dendritic Cells:
- Major APCs with phagocytic activity
- Classify into classic DCs (myeloid origin) and follicular DCs (not phagocytic)
Lymphocytes
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Comprise 20-40% of total leukocytes
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B Lymphocytes:
- Mature in bone marrow and recognize soluble antigens via B cell receptors (BcR)
- Activate, proliferate into memory B cells and plasma cells producing specific immunoglobulins (IgM, IgG, IgA, IgE)
-
T Lymphocytes:
- Differentiate in the thymus, participate in cell-mediated immunity
- Require activation by antigens and cytokines from helper T cells for effective immune response
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Natural Killer (NK) Cells:
- Part of innate immune response, responsible for targeting and destroying infected or cancerous cells
Cytokine Production
- Activated macrophages produce various cytokines (e.g., IL-1, IL-6, TNF-α) for inflammatory responses
- Promote differentiation of T lymphocytes and recruit various leukocyte populations to infection sites
- Anti-inflammatory cytokines (e.g., IL-10, TGF-β) mediate tolerance and inflammatory response downregulation
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Description
Test your knowledge on the immune system with this quiz. Topics cover primary and secondary organs, including the thymus, bone marrow, spleen, and other lymphoid tissues. Challenge yourself on hematopoiesis and the processes by which the immune system functions.
