Questions and Answers
Which of the following is classified as an infectious non-self?
The immune system has a specific memory for pathogens.
True
What are the primary lymphoid organs?
Bone marrow and thymus
The ___________ is the largest lymphatic organ.
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What is the role of bone marrow in the immune system?
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Which immunity type involves T lymphocytes?
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Match the following lymphoid organs with their functions:
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What is humoral immunity mediated by?
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All organisms possess innate immunity.
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The ___________ secretes thymus hormones and regulates T cell development.
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What is commensalism?
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Study Notes
Fundamental Functions of the Immune System
- Differentiates between SELF and NON-SELF entities.
- Classifies non-self entities into infectious (pathogens: viruses, bacteria, fungi, parasites) and non-infectious (food, pollen, dust).
- Recognizes infectious self (cancer) and non-infectious self (body cells and proteins).
Mode of Operation of the Immune System
- Identification: Distinguishes non-infectious self and infectious non-self.
- Recruitment: Mobilizes immune effectors.
- Elimination: Clears pathogens from the body.
- Prevent Recurrence: Establishes immunological memory to prevent future infections.
- Deactivation: Stops immune response to prevent collateral damage.
Types of Immunity
- Innate Immunity: Non-specific response, immediate maximal reaction, no immunological memory.
- Adaptive Immunity: Specific response, delayed maximal reaction, leads to immunological memory.
- Humoral Immunity: Mediated by macromolecules in body fluids.
- Cellular Immunity: Involves activation of phagocytes, T-lymphocytes, and cytokines without antibodies.
Components of the Immune System
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Innate Immune System
- Non-specific, immediate response.
- Present in nearly all life forms.
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Adaptive Immune System
- Specific to pathogens, has a lag time for maximal response.
- Found only in jawed vertebrates and induces immunological memory.
Surface Barriers
- Skin acts as a primary barrier against infections.
- Additional defenses include:
- Gastric acid and proteases in the stomach prevent ingested pathogens.
- Flushing actions of tears and urine expel pathogens.
- Mucus in respiratory and gastrointestinal tracts traps microorganisms.
- Enzymes like lysozyme serve antibacterial functions.
Commensalism
- A relationship where one organism benefits without affecting the other.
- Commensal flora can assist in nutrition, pathogen exclusion, and contribute to immune defense.
- Lactobacillus in the vagina inhibits other bacteria by reducing pH.
Organs of the Immune System
Primary Lymphoid Organs
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Bone Marrow
- Source of all circulating blood cells and B cell maturation.
- Contains red marrow (hematopoietic tissue) and yellow marrow (fat cells).
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Thymus
- Located behind the sternum, responsible for T cell differentiation and maturation.
- Contains thymic stromal and cortical cells which support T cell development.
Secondary Lymphoid Organs
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Lymph Nodes
- Oval structures that filter lymph fluid, containing germinal centers for lymphocyte production.
- Enclosed by a fibrous capsule, with afferent and efferent lymphatic vessels.
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Spleen
- Largest lymphatic organ, filters blood, and contains red pulp (blood components) and white pulp (lymphatic nodules).
- Plays a critical role in managing aged erythrocytes and immune responses.
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MALT (Mucosa-Associated Lymphoid Tissue)
- Protects mucous membranes in areas such as the gut and respiratory tract.
Function of the Lymphatic System
- Provides defense against harmful organisms and chemicals through two types of defense: nonspecific and specific (immunity).
- Humoral immunity involves B cells which transform into plasma cells and produce antibodies.
- Cell-mediated immunity entails T cells that directly destroy infected cells.
Thymus Microenvironment
- Consists of thymic stroma and thymocytes, facilitating T cell development.
- The blood-thymus barrier protects immature T cells from foreign antigens.
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Description
Explore the fundamental functions of the immune system and how it distinguishes between self and non-self entities. This quiz delves into the various types of pathogens and non-pathogens that interact with the immune system, covering both infectious and non-infectious agents. Test your knowledge on the mechanisms of immune identification and response.
