Immunity definitions Flashcards
What are leukocytes?
White blood cells that circulate in the blood and divide into innate & adaptive immune cells
Leukocytes play a crucial role in the immune response.
Define innate immunity.
Barrier defences & molecular recognition of traits shared by a broad range of pathogens
Innate immunity is the first line of defense against pathogens.
What characterizes adaptive immunity?
Specific recognition of pathogens using receptors that recognize features found on specific pathogens (B/T)
Adaptive immunity provides a targeted response and memory for future infections.
What is a pathogen?
A disease-causing organism
Pathogens can include bacteria, viruses, fungi, and parasites.
What is the immune system?
The body’s defense against invading pathogens
The immune system includes various cells, tissues, and organs.
What is a phagocyte?
A specialized white blood cell that carries out phagocytosis as a defense mechanism
Phagocytes are essential for engulfing and destroying pathogens.
What is the function of the lymphatic system?
A vascular network used for transport of immune cells & antigens (e.g. to site of activation)
The lymphatic system plays a critical role in immune surveillance.
What is the humoral response?
Antibodies respond to defend against infection in body fluids
The humoral response is primarily mediated by B cells.
What is the cell-mediated response?
Cytotoxic cells respond to defend against infection in body cells
This response is primarily mediated by T cells.
What are immunoglobulins?
Glycoproteins from B (plasma) cells that bind to specific antigens
Immunoglobulins are also known as antibodies.
What are T lymphocytes?
Cells that originate in bone marrow and mature in the thymus, including Helper (CD4), cytotoxic (CD8), and regulatory T cells
T lymphocytes play a key role in adaptive immunity.
What are B lymphocytes responsible for?
Developing and maturing in bone marrow, involved in the humoral immune response, and can differentiate into antibodies & memory cells
B lymphocytes are crucial for antibody production.
What is the role of macrophages?
Derived from monocytes, they ingest pathogens & debris and secrete cytokines
Macrophages are important for both innate and adaptive immunity.
What characterizes the primary immune response?
Adaptive response with a lag phase that is slower and less robust, produces memory cells that are dormant
The primary immune response establishes memory for future encounters with the same pathogen.
What is the secondary immune response?
Faster, stronger & more specific response upon 2nd exposure to the same antigen, mediated by memory B & T cells
The secondary immune response is more efficient due to memory cells.
What are antigens?
Substances that can elicit a response from a B or T cell
Antigens are typically proteins or polysaccharides found on pathogens.
What are cytokines?
Small signaling proteins with a regulatory role
Cytokines mediate communication between cells in the immune system.
What are antigen-presenting cells (APC)?
Cells that process & display antigens on MHC molecules to activate T cells (e.g. macrophages, B cells, dendritic cells)
APCs are essential for the activation of T lymphocytes.
Define clonal selection.
Process where lymphocytes with receptors to specific antigens proliferate & differentiate during an immune response
Clonal selection ensures a targeted immune response.
What are plasma cells?
Differentiated B cells responsible for antibody production
Plasma cells are crucial for the humoral immune response.
What are memory cells?
B/T lymphocytes that provide a rapid & strong response upon re-exposure to the same antigen
Memory cells are key for long-term immunity.
What is a T cell receptor?
Molecule that recognizes processed antigen fragments presented by MHC molecules on APCs
T cell receptors are essential for T cell activation.
What are natural killer (NK) cells?
Immune cells that target virus-infected/tumor cells, particularly if lacking MHC I
NK cells play a role in the innate immune response.
What is the Major Histocompatibility Complex (MHC)?
Cell surface proteins that present antigens to T cells; MHC I presents to CD8 and MHC II presents to CD4
MHC molecules are critical for T cell recognition.
