Podcast
Questions and Answers
What is the primary function of cytokines in the immune system?
What is the primary function of cytokines in the immune system?
- They are responsible for producing antibodies.
- They eliminate cell debris.
- They directly kill pathogens.
- They drive and orchestrate immune responses. (correct)
Which of the following organs is NOT considered a primary lymphoid organ?
Which of the following organs is NOT considered a primary lymphoid organ?
- Spleen (correct)
- Lymph nodes (correct)
- Bone marrow
- Thymus
Which type of immunity is characterized by immediate response to infection?
Which type of immunity is characterized by immediate response to infection?
- Specific immunity
- Adaptive immunity
- Innate immunity (correct)
- Passive immunity
What role do dendritic cells play in the immune system?
What role do dendritic cells play in the immune system?
Which of the following cells is primarily involved in phagocytosis?
Which of the following cells is primarily involved in phagocytosis?
Which cytokine is primarily associated with inducing inflammation?
Which cytokine is primarily associated with inducing inflammation?
What is the function of Natural Killer (NK) cells in the immune system?
What is the function of Natural Killer (NK) cells in the immune system?
Which of the following is a characteristic function of adaptive immunity?
Which of the following is a characteristic function of adaptive immunity?
What is present on all Gram-negative bacteria?
What is present on all Gram-negative bacteria?
Which cells play a crucial role in phagocytosis during an immune response?
Which cells play a crucial role in phagocytosis during an immune response?
Which process accurately describes the sequence of phagocytosis?
Which process accurately describes the sequence of phagocytosis?
What do identical Toll-like receptors recognize in different microbes?
What do identical Toll-like receptors recognize in different microbes?
What do neutrophils and macrophages do after detecting an infection?
What do neutrophils and macrophages do after detecting an infection?
Which cytokines are specifically mentioned as mediators of inflammation?
Which cytokines are specifically mentioned as mediators of inflammation?
What is the primary function of natural killer (NK) cells?
What is the primary function of natural killer (NK) cells?
What role does perforin play in the immune response?
What role does perforin play in the immune response?
How do neutrophils and macrophages eliminate pathogens?
How do neutrophils and macrophages eliminate pathogens?
What is the membrane attack complex primarily associated with?
What is the membrane attack complex primarily associated with?
What role does C3a play in the complement system?
What role does C3a play in the complement system?
Which pathway is activated by an antigen-antibody complex?
Which pathway is activated by an antigen-antibody complex?
What is the primary function of the activated complement proteins during opsonisation?
What is the primary function of the activated complement proteins during opsonisation?
Which component acts as the central element of the complement system?
Which component acts as the central element of the complement system?
What is the result of the membrane attack complex (MAC)?
What is the result of the membrane attack complex (MAC)?
What form does the C3 convertase take in the classical pathway?
What form does the C3 convertase take in the classical pathway?
Which of the following features is characteristic of innate immunity?
Which of the following features is characteristic of innate immunity?
Which component is involved in the formation of C5 convertase?
Which component is involved in the formation of C5 convertase?
What type of cells are primarily involved in the adaptive immune response?
What type of cells are primarily involved in the adaptive immune response?
The alternative pathway primarily provides a mechanism for which aspect of the immune response?
The alternative pathway primarily provides a mechanism for which aspect of the immune response?
Which statement about the adaptive immune system is true?
Which statement about the adaptive immune system is true?
Which are included in the cells of the innate immune system?
Which are included in the cells of the innate immune system?
What role do Pathogen Recognition Receptors (PRRs) play in the innate immune response?
What role do Pathogen Recognition Receptors (PRRs) play in the innate immune response?
Which of the following statements correctly describes the innate immune response compared to the adaptive immune response?
Which of the following statements correctly describes the innate immune response compared to the adaptive immune response?
Which cell type is NOT part of the adaptive immune system?
Which cell type is NOT part of the adaptive immune system?
What distinguishes the adaptive immune system's memory function?
What distinguishes the adaptive immune system's memory function?
Study Notes
Functions of the Immune System
- The immune system protects the body from pathogens and disease
- It fights cancer
- It promotes wound healing and tissue regeneration
- It removes cellular debris
Tissues of the Immune System
- Primary Lymphoid Organs : Where immune cells are formed and mature
- Bone Marrow
- Thymus
- Secondary/Peripheral Lymphoid Organs: Where immune cells are concentrated and function
- Lymph Nodes
- Spleen
- Mucosal Immune System
Cells of the Immune System
- Circulating Cells: Travel between the blood and tissues:
- Neutrophils, Monocytes/Macrophages, Eosinophils, Lymphocytes
- Resident Cells: Remain in tissues:
- Dendritic cells, Macrophages, Mast cells
Cytokines: Important Effectors of Immune Function
- They are small proteins (5-20kDa)
- They are secreted by cells and can act on the cell that produced it (autocrine) and nearby cells (paracrine)
- They bind to specific receptors on cells
- Key types: Interleukins (IL-1-IL-22); Interferons (IFN-α, β, γ); tumour necrosis factors (TNF- α, β), transforming growth factor-β (TGF-β)
- Each immune cell secretes a characteristic profile of cytokines that determine the function of that cell
- They drive and orchestrate immune responses
The Two Main Branches of the Immune System
- Innate Immunity:
- Physical barriers (skin, lysozyme in secretions)
- Phagocytosis
- NK cells
- Complement
- Inflammatory mediators and antimicrobial peptides released from innate cells
- Adaptive Immunity:
- Antibodies: B cells (B lymphocytes)
- Cell-mediated Immunity: T cells (T lymphocytes)
Cells of the Innate and Adaptive Branches
- Innate: Monocytes/Macrophages, Neutrophils, Eosinophils, Basophils, Mast Cells, Dendritic Cells, Natural Killer Cells
- Adaptive: Lymphocytes, B cells, T cells
Features of Innate/Natural Immunity
- Present at birth
- Always active
- Responds immediately
- Instructs the adaptive immune system
- Recognizes non-self in a non-specific way
- No memory function
Features of Adaptive/Acquired Immunity
- Develops over a lifetime
- Slower response time than innate
- Recognizes antigens with high specificity
- Has a memory function
Innate Immune System
Pathogen Recognition by Cells of the Innate System
- Non-specific recognition
- Innate cells express Pathogen Recognition Receptors (PRRs)
- Toll-like receptors
- They bind to pathogen-associated molecular patterns (PAMPs)
- Structures on microbes
- Shared by groups of microbes
Innate Immune Recognition of Bacterial Cell Wall Components
- Gram-negative bacteria: TLRs recognize lipopolysaccharides (LPS)
Innate Functions: Phagocytosis & Destruction of Pathogens
- Neutrophils and macrophages are key phagocytes
- They leave the blood and travel to sites of infection
- Phagocytosis involves recognition, ingestion, and digestion
Complement
- 30 plasma proteins that circulate in an inactive state
- They become activated at sites of infection and trigger inflammatory events
- C3 is the central component
- ** Pathways:**
- Classical pathway (activated by antigen-antibody complexes)
- Alternative pathway
- Lectin pathway
- ** Functions:**
- Inflammation (C3a, C4a, C5a)
- Opsonisation (C3b, C4b bind to pathogen surface and increase phagocytosis)
- Cell lysis (Membrane Attack Complex, MAC)
Natural Killer Cells
- Lymphocytes (10-15% of blood lymphocytes)
- Recognize cells infected with viruses or become cancerous
- These cells have lost or modified surface structures
- They kill infected cells through the release of:
- Perforin: Punches holes in the cell membrane
- Granzyme: Enters cells via perforin pores and induces apoptosis (cell death)
Summary of Main Points
- The immune system is made up of cells and tissues that protect the body
- Cytokines are small proteins crucial for immune cell communication and response
- The innate and adaptive immune systems differ in their speed of response and specificity
- Phagocytosis is a key function of innate immunity, carried out by neutrophils and macrophages
- Complement system contributes to opsonisation, inflammation, and cell lysis.
- Natural Killer Cells use perforin and granzyme to target pathogens
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Description
Test your knowledge on the immune system's functions, tissues, and cellular components. This quiz will cover the different types of lymphoid organs, immune cells, and the role of cytokines in immune response. Perfect for students studying immunology.
