Chapter 1: The Immune System Flashcards
What is the definition of the immune system?
The immune system is a network of cells and proteins that protect the body from infection and promote healing by generating inflammation, removing pathogens, expanding immune cell populations, developing memory, controlling inflammation, and repairing tissues.
What are the main functions of immunity?
Immunity involves generating inflammation, removing and destroying pathogens, expanding immune cell populations, developing memory against antigens, controlling inflammation, and repairing tissues.
How do innate and adaptive immunity differ?
Innate immunity provides an immediate, nonspecific response against pathogens, while adaptive immunity requires priming with pathogens, is specific, and develops memory for faster responses upon re-exposure.
What are the central organs of the immune system and their functions?
The central organs include the bone marrow, where immune cells are produced and undergo initial development, and the thymus, where T cells complete their maturation.
What are the peripheral organs of the immune system and their functions?
Peripheral organs include lymph nodes, spleen, and mucosa-associated lymphoid tissues (MALT, BALT, GALT) where immune cells complete their development and become activated upon encountering antigens.
What role do epithelial barriers play in immunity?
Epithelial barriers, such as skin and mucosa, protect against pathogens and toxins. They are reinforced by secretions like lysozymes in saliva and tears and physiological clearance mechanisms like the mucociliary system.
What are physiological barriers in the immune system?
Physiological barriers include secretions (e.g., lysozymes, low stomach pH) and clearance mechanisms (e.g., mucociliary system) that add protection against pathogens.
How do immune cells migrate in the body?
Immune cells circulate through blood and lymph, migrating to tissues and lymphoid structures. They can become resident cells or constantly recirculate, searching for antigens or sites of inflammation.
What is diapedesis?
Diapedesis is the process where leukocytes move from the bloodstream into tissues to respond to infections or inflammation.
What are sentinel cells and their functions?
Sentinel cells, such as macrophages and mast cells, reside in tissues and detect pathogens or tissue destruction, triggering inflammatory responses by secreting cytokines.
What are inflammatory cytokines and their effects?
Inflammatory cytokines, such as TNF-alpha, IL-1, and IL-6, attract inflammatory cells, cause fever, vasodilation, and increase capillary permeability, leading to clinical signs of inflammation.
What are myeloid cells and their types?
Myeloid cells include neutrophils, monocytes, macrophages, dendritic cells, eosinophils, basophils, mast cells, red cells, and thrombocytes. They play roles in phagocytosis and pathogen removal.
What is phagocytosis?
Phagocytosis is the process of engulfing and digesting particles, such as pathogens, cells, and molecules, by immune cells like macrophages and neutrophils.
What are pattern-recognition receptors (PRRs) and their types?
PRRs are receptors on phagocytes that recognize pathogen-associated molecular patterns (PAMPs). Types include Toll-like receptors (TLRs), NOD-like receptors, and RIG-1-like receptors.
How are phagocytes activated?
Phagocytes are activated upon recognizing pathogens through their PRRs, leading to cytokine secretion and an expanded inflammatory response.
What is a phagolysosome?
A phagolysosome is formed when a phagosome fuses with a lysosome inside a phagocyte, leading to the degradation of engulfed pathogens.
What are neutrophils and their function?
Neutrophils are short-lived immune cells that arrive quickly at infection sites to phagocytose and kill pathogens, often requiring opsonization for efficient function.
What are macrophages and their types?
Macrophages are tissue-resident cells derived from monocytes. They include pro-inflammatory (M1) macrophages involved in inflammation and anti-inflammatory (M2) macrophages involved in tissue repair.
What are dendritic cells and their role in immunity?
Dendritic cells are phagocytes that process and present antigens to T lymphocytes, particularly CD4+ T cells, to initiate and guide adaptive immune responses.
How do dendritic cells present antigens to T cells?
Dendritic cells present processed antigens via MHC class II molecules to CD4+ T cells, leading to T cell activation through receptor binding and co-stimulation.
