L1 online Flashcards
(16 cards)
What are the two types of immunity, and how do they differ?
Innate immunity: Rapid, non-specific, no memory.
Adaptive immunity: Specific, slower, generates memory (e.g., B cells produce antibodies, T cells direct immune responses).
What are the physical and chemical barriers in innate immunity?
Physical barriers: Skin, mucous membranes, cilia.
Chemical barriers: Lysozyme, defensins, low pH in the stomach.
How does lysozyme function as an antimicrobial agent?
Lysozyme cleaves bonds in peptidoglycan, breaking bacterial cell walls (most effective against Gram-positive bacteria).
What is the role of defensins in immunity?
Defensins are antimicrobial peptides that disrupt microbial membranes by forming pores, leading to cell death.
What are primary and secondary lymphoid organs?
Primary: Bone marrow (B cell maturation), thymus (T cell maturation).
Secondary: Spleen, lymph nodes, mucosa-associated lymphoid tissue (MALT).
What is opsonization, and why is it important?
The process where pathogens are coated with antibodies or complement proteins to enhance phagocytosis by immune cells.
Name the three types of granulocytes and their primary functions.
Neutrophils: Phagocytosis and first responders to infection.
Eosinophils: Combat parasites and mediate allergic responses.
Basophils: Involved in allergic reactions via histamine release.
What are dendritic cells, and what role do they play in immunity?
Dendritic cells are antigen-presenting cells (APCs) that activate T cells by presenting antigens.
What are the steps of phagocytosis?
- Attachment: Pathogen adheres to phagocyte.
- Ingestion: Formation of a phagosome.
- Fusion: Phagosome fuses with lysosome, forming a phagolysosome.
- Digestion: Pathogen is degraded by enzymes.
- Release: Debris is expelled.
What is the respiratory burst in phagocytes?
A process where phagocytes produce reactive oxygen species (e.g., hydrogen peroxide) to kill engulfed microbes.
Compare innate and adaptive immunity, highlighting their characteristics and overlap.
Innate immunity: Non-specific, rapid, germline-encoded receptors, no memory. Key components: barriers, phagocytes, and antimicrobial peptides.
Adaptive immunity: Specific, slower, involves clonal expansion and memory generation. Key components: B cells (antibody production) and T cells (cytokine production, cytotoxicity).
Overlap: APCs (e.g., dendritic cells) link innate and adaptive immunity by presenting antigens to T cells.
Explain how antimicrobial peptides like defensins work and their role in innate immunity.
Defensins disrupt microbial membranes by inserting their amphipathic regions, forming pores that cause leakage and cell death.
Produced by epithelial cells and immune cells, they target bacteria, fungi, and enveloped viruses.
What are the roles of monocytes and macrophages in the immune system?
Monocytes circulate in blood and differentiate into macrophages in tissues.
Macrophages perform phagocytosis, act as APCs to activate T cells, and regulate immune responses through cytokine production.
Describe the process of phagocytosis and its significance in innate immunity.
Steps: Attachment, ingestion (phagosome formation), fusion (phagosome-lysosome), digestion (pathogen degradation), and release of debris.
Significance: Clears pathogens, presents antigens to adaptive immune cells, and produces reactive oxygen species during respiratory burst to kill microbes.
How do T cells and B cells differ in their roles within adaptive immunity?
T cells:
CD4+ T cells (Helper): Activate macrophages, B cells, and other T cells.
CD8+ T cells (Cytotoxic): Kill infected or cancerous cells.
B cells: Produce antibodies for neutralizing pathogens and opsonization. Also act as APCs to activate T cells.
