Immune System Flashcards
The immune system protects against assaults on the body. Including external assaults and internal assaults. External assaults are:
microorganisms - protozoans, bacteria, and viruses
The immune system protects against assaults on the body. Including external assaults and internal assaults. Internal assaults are:
abnormal cells that reproduce and form tumors that may become cancerous and spread
a protein marker on the surface of cells to identify them. They stimulate the production of antibodies
antigens
the ability to activate an effective response to a foreign antigen
immunocompetence
molecules on the surface of human cells that are unique to an individual, thus identifying the cells as “self” to the immune system
self markers
molecules on the surface of foreign or abnormal cells or particles that identify the particle as “non-self” to the immune system
non-self markers
the ability of our immune system to attack abnormal or foreign cells, but spare our own normal cells
self-tolerance
2 major categories of immune mechanisms:
innate/nonspecfic immunity adaptive/specific immunity
- immunity that is present at birth - built in and ready fr action providing the initial defense mechanism
innate immunity/ nonspecific
- mechanisms that develop in response to specific threatening agents or specific abnormal cells
adaptive immunity/specific
broad and loose category of small proteins that are important in cell signaling - they are released by cells and affect the behavior of other cells or the cells that release them - they regulate or initiate innate or adaptive immunity
cytokines
examples of cytokines:
- interleukins - leukotrienes - interferons - growth factors
7 components of innate immunity
- epithelial barrier cells - inflammation - phagocytic cells - natural killer cells - interferon - complement - toll-like receptors
innate immunity: first line of defense
skin and mucous membranes - sebum, mucus, enzymes, and hydrochloric acid in stomach
innate immunity: second line of defense
inflammatory response
tissue damage leads to release of inflammation mediators (histamine, kinins, prostaglandins, leukotrienes, and interleukins) many of these mediators are chemotactic factors: subtances that attract WBCs to the area. This process in known as
chemotaxis
4 signs of inflammation:
- redness -warmth - pain - swelling (edema)
Due to increase blood flow and vascular permeability in the affected region, which help phagocytic WBCs reach the general area and enter the affected tissue
inflammation
A major component in the 2nd line of defense, but also plays a role in adaptive immunity the ingestion and destruction of microorganisms or other small particles by phagocytes
phagocytosis
cells that perform phagocytosis are called
antigen-presenting cells
phagocytes that ingest foreign particles, isolate protein segments, and display them as antigens on their surfaces These peptides are then recognized by cells of the adaptive immune system as antigens and trigger an immune response by a specific (adaptive) immune cell
Antigen-presenting cells
part of phagocytosis: most numerous, “first responder”
neutrophils
take part in phagocytosis: “large eaters”; phagocytic monocytes that have grown to several times their original size after migrating out of the bloodstream
macrophages
take part in phagocytosis: cells with many extensions; found in many body tissues that are in contact with the external environment, such as the skin and mucous membranes
dendritic cells
lymphocytes (not T nor B) that kill tumor cells and cells infected by viruses - chemically triggers cell death and destruction - must have direct contact with target cell
Natural killer cells (NK cells)
NK cells recognize abnormal cells by using 2 different recognition receptors:
killer-activating receptor killer-inhibiting receptor
NK cells that bind to any of several common surface molecules found in cells
killer-activating cells
NK cells: - if the NK cell also binds to a protein found on the surface of normal cells, then the killing action is stopped
killer-inhibiting cells
only abnormal and foreign cells fail to bind to the _________ centers, so they are destroyed
killer-inhibiting centers
a protein synthesized by lymphocytes, macrophages, and fibroblasts that have been invaded by viruses
interferon
_____ diffuses into the circulation and to nearby cells
interferon
______ proteins interfere with the ability of viruses to cause disease by preventing replication
interferon
a group of enzymes that produce a cascade of reactions resulting in a variety of immune responses lyse cells when activated by either adaptive of innate mechanisms enhances inflammation and phagocytosis
complement
pattern-recognition receptors that identify a large variety of different bacterial moecules such as toxins and flagella proteins, viral RNA, and glycoproteins, and fungal molecules when triggered, they facilitate the nonspecfic/innate immune mechanisms
toll-like receptors
______ are found in the membranes of host cells. They do not identify specific antigens
toll-like receptors
- 3rd line of defense - mechanisms attack specfic agents that the body recognizes as abnormal or non-self - consists of 2 different classes of lymphocytes: B and T cells
Adaptive immunity
adaptive immunity requires activation of _______ populations, which then begin their immune attack of specific antigens. requires a specific antigen and activating chemicals
lymphocytes
Cells that do not attack pathogens themselves but instead produce molecules called antibodies that attack the pathogens
B lymphocytes (B cells)
______ mechanisms are classified as antibody-mediated immunity or humoral-mediated immunity
B cell
______ react to antigens in the plasma
B cells
B cells develop in 2 stages:
- Pre B cells (naive cells) develop by a few months of age 2. the 2nd stage occurs in lymph nodes and spleen with activation of a naive B cell after it binds a specfic antigen 3. Activated B cells become antibody-secreting plasma cells 4. Inactive B cells are memory B cells
the function f antibody molecules is to produce _________ immunity (humoral immunity) by disabling antigens: - antigen-antibody reactions - complement activation - primary and secondary responses
antibody-mediated
the binding of the antigen to antibody forms an antigen-antibody complex that may produce one more effects (2):
- transforms toxins into harmless substances - clumps antigens together (agglutination), making it possible for macrophages to dispose of them more rapidly
_______ attack pathogens more directly. They are classified as cell mediated immunity or cellular immunity
t cell mechanisms
______ go through the thymus gland before migrating to the lymph nodes and spleen
T lymphocytes
function of T cells:
- produce cell mediated immunity - help to regulate adaptive immunity in general
4 types of T cells:
- Helper T cells - cytotoxic T cells - suppressor T cells - memory T cells
Type of T cell: regulate the function of B cells, T cells, phagocytes, and other WBCs
helper T cell
Type of T cell: an effector T cell that causes contact killing of a target cell
cytotoxic T cell
Type of T cell: regulatory T cells that suppress lymphocyte function, thus regulating immunity and promoting self-tolerance
suppressor T cells
_____ T cells act to inhibit cytotoxic T cell activity once the virus has been killed (they are the off switch)
suppressor T cells
Type of T cell: inactive T cells that stay in the circulation; if the same antigen enters the body again, these cells can be activated and proliferate to respond to the antigen quickly
memory T cells
a component of blood plasma consisting of several protein compounds. It causes vasodilation, enhances phagocytosis, and other functions
complement
______ kills foreign cells by cytolysis or apoptosis.
complement
_____ activity can also be initiated by innate immune mechanisms
complement
initial encounter with a specific antigen trigger the formation and release of specific antibodies that reaches its peak in a few days
primary response
a later encounter with the same antigen triggers a much quicker response; B memory cells rapidly divide, producing more plasma cells and thus more antibodies
secondary response
Adaptive immunity review: 4 key points
- adaptive immunity is a specific immunity targeting specific antigens - adaptive immunity involve 2 classes of lymphocytes: B cells and T cells - B cells are antibody-mediated (humoral) immunity - T cells are cell-mediated (cellular) immunity
2 types of adaptive immunity:
- natural immunity - artificial immunity
immunity that results from non-deliberate exposure to antigens occurs in the course of everyday living
natural immunity
immunity that results from deliberate exposure to antigens, called immunization
artificial immunity
when the immune system responds to a harmful agent; lasts longer than passive
active immunity
developed when immunity from another individual is transferred to an individual who was not previously immune; it is temporary but provides immediate protection
passive immunity
