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Flashcards in Immune System Deck (67)
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What are the two divisions of the immune system?

-innate immunity
-adaptive immunity


Innate Immunity

-composed of defenses that are always active against infection but lack the ability to target specific invaders over others
-called non-specific immunity


Adaptive Immunity

-the defenses that target a specific pathogen
-slower to act but can maintain immunological memory of an infection to be able to mount a faster attack in subsequent infections
-called specific immunity
-can be divided into two parts: humoral immunity (driven by B-cells and antibodies) and cell-mediated immunity (provided by T-cells)


How does the Innate Immune System work?

includes cells that ingest and destroy pathogens (like dendritic cells and macrophages), and also activate an inflammatory response, secreting cytokines that trigger an influx of immune cells from the blood, and recruit more phagocytes -- monocytes and neutrophils


How does the Adaptive Immune System work?

-activated B-cells secrete antibody molecules that bind to antigens and destroy the invader directly or mark it for attack by others
-T cells recognize antigens displayed on cells or help activate B-cells and other T-cells which can directly attack infected cells


What organs are included in the immune system?

-lymph nodes
-peyer's patches (small intestine)
-lymphatic vessel
-bone marrow


Bone Marrow

produces all of the leukocytes (WBCs) that participate in the immune system through the process of hematopoiesis



location of blood storage and activation of B-cells, which turn into plasma cells to produce antibodies as part of adaptive immunity



-small gland in front of the pericardium (sac that protects the heart)
-where T-cells mature


Lymph Nodes

-provide a place for immune cells to communicate and mount an attack
-B-cells can be activated here


Gut-Associated Lymphoid Tissue (GALT)

-immune tissue that is found in close proximity to digestive system
-sites of potential invasion by pathogens
-includes: tonsils, adenoids, peyer's patches, lymphoid aggregates in the appendix


1. Site of Development:
2. Site of Maturation:
3. Major Functions:
4. Specific or Non-Specific?
5. Humoral or Cell-Mediated?

1. bone marrow
2. bone marrow (but are activated in the spleen or lymph nodes)
3. produce antibodies
4. specific
5. humoral


1. Site of Development:
2. Site of Maturation:
3. Major Functions:
4. Specific or Non-Specific?
5. Humoral or Cell-Mediated?

1. bone marrow
2. thymus
3. coordinate immune system and directly kill infected cells
4. specific
5. cell-mediated


What is the first line of defense in the innate immune system?

skin (integument) -- provides a physical barrier, contains defensins (antibacterial enzymes)


What are other physical barriers of the immune system?

-mucus (lines respiratory tract, covers the eye, oral cavity) which produces a nonspecific bacterial enzyme called lysozyme


What role does the GI Tract play in nonspecific immunity?

-stomach secretes acid which eliminates most pathogens
-potential invades not able to compete against the large bacterial population in the gut


What role does the Complement System play in nonspecific immunity?

-system consists of many proteins in the blood that act as a nonspecific defense against bacteria
-activated through a classical pathway (requires binding of antibody to a pathogen) or an alternate pathway (does not require antibodies)
-complement proteins put holes in cell walls of bacteria making them osmotically unstable


What role do Interferons play in nonspecific immunity?

-these are proteins that prevent viral replication and dispersion
-cause nearby cells to decrease production of viral and cellular proteins, and decrease the permeability of these cells making a virus harder to infect them
-upregulate MHC class I and II molecules, resulting in increased antigen presentation and better detection of infected cells by immune system
-cause "flu-like" symptoms


What cells comprise the Innate Immune System?

-natural killer cells
-mast cell
-dendritic cell



-type of agranulocyte
-derive from blood-borne monocytes and can become resident population in a tissue (permanent)
-immune defender that engulfs and consumes pathogens
-release cytokines (chemical substances that stimulate inflammation and recruit additional immune cells)


What 3 things does a macrophage do when activated?

1. phagocytizes bacteria invader through endocytosis
2. digests the invader using enzymes
3. presents little peptide pieces of the invader to other cells using a protein called major histocompatibility complex (MHC) -- which binds to a pathogenic peptide (antigen) and carries it to the cell surface where it can be recognized by cells of the adaptive immune system


MHC Class I Molecules

-displayed by all nucleated cells in the body
-any protein produced within a cell can be loaded onto MHC-1 and presented on the surface of the cell, allowing immune system to detect if these cells have been infected -- if infected cells present an unfamiliar protein on their surface
-considered an endogenous pathway because it binds antigens from inside the cell


MHC Class II Molecules

-mainly displayed by professional antigen-presenting cells like macrophages, dendritic cells, some B-cells, and certain activated epithelial cells
-considered an exogenous pathway fir antigen presentation because the exogenous antigen picked up from the environment, processed inside the cell, then presented on MHC-2


Pattern Recognition Receptors

-specialized cells found on macrophages and dendritic cells
-recognize the category of the invader and produce appropriate cytokines to recruit the right type of immune cells


Natural Killer Cells

-type of nonspecific lymphocyte
-can detect the down-regulation of MHC and induce apoptosis in these virally infected cells (cancer cells often do not present MHC-antigen complexes)
-cell that destroys the body's own cells that have become infected



-three cell types with tiny granules in their interiors -- neutrophils, eosinophils, basophils -- that participate in the inflammatory response



-short-lived (last about 5 days)
-phagocytic cells that target bacteria
-follow bacteria using chemotaxis (sensing of certain products given off by bacteria and migration of neutrophils to follow these products back to the source )
-can also detect bacteria once it has been opsonized (marked with an antibody from a B-cell)
-when these are dead they form pus



-contain bright orange granules
-primarily involved in allergic reactions and invasive parasitic infections
-once activated they release large amounts of histamine


How does histamine cause inflammation?

it induces vasodilation and the movement of fluid and cells (especially macrophages and neutrophils) from the bloodstream into tissues



-contain large purple granules
-involved in allergic responses
-least populous leukocyte in the bloodstream