Biology Ch 8. The Immune System Flashcards
Innate immunity
Composed of defenses that are always active, but they cannot target a specific invader and cannot maintain immunological memory, also called non-specific immunity, typically acts near entry points of the body
Immune system divisions
Innate and adaptive immunity
Nonspecific immunity
Composed of defenses that are always active, but they cannot target a specific invader and cannot maintain immunological memory (makes response faster next time), also called innate immunity, typically acts near entry points of the body
Adaptive immunity
Composed of defenses that take time to activate, but that can target a specific invader and can maintain immunological memory (makes response faster next time), also called specific immunity
Specific immunity
Composed of defenses that take time to activate, but that can target a specific invader and can maintain immunological memory, also called adaptive immunity
Skin innate immune system
Access a physical barrier and secretes antimicrobial compounds, like defensins, secretes sweat which has antimicrobial properties, first line of defense
Defensins
Antimicrobial compounds/antibacterial enzymes that can be found secreted from the skin
Bone marrow
Where immune cells come from –> where hematopoiesis takes place
Spleen
Location of blood storage, one site where immune responses can be mounted, where B-cells are activated
Lymph nodes
Major components of lymphatic system, one site where immune responses can be mounted, where B-cells are activated
Thymus
Site of T-cell maturation, small gland just in front of the pericardium
Gut-associated lymphoid tissue
GALT - Includes the tonsils, adenoids, Peyer’s patches in the small intestine, and lymphoid aggregates in the appendix, in close proximity to digestive system which is a site of potential pathogen invasion
Leukocytes
White blood cells involved in immune defense, divided into granulocytes and agranulocytes
Mucus innate immune system
Present on mucous membranes to trap pathogens, in the respiratory system the mucus is propelled upward by cilia and can be swallowed or expelled
Lysozyme
An antibacterial compound found in saliva and tears, a nonspecific bacterial enzyme
Stomach innate immune system
Produces acid killing most pathogens, colonization of the gut helps prevent overgrowth of pathogenic bacteria through competition
Complement system
Consists of a number of proteins in the blood that act as a nonspecific defense against bacteria, can punch holes in the cell walls of bacteria, making them osmotically unstable, can be activated through classical or alternative pathway, cannot be modified to target specific organism so still considered nonspecific defense
Interferons
Proteins given off by virally infected cells and help prevent viral replication and dispersion to nearby cells, causes nearby cells to decrease production of viral and cellular proteins, decrease permeability of cells making it harder for a virus to infect them, up regulate MHC molecules which increases antigen presentation and better detection of infected cells, responsible for many “flu like” symptoms
Noncellular innate immune system components
skin & defensins, mucus, lysozyme, GALT, complement system, interferons
Cellular innate immune system components
Macrophages, dendritic cells, natural killer cells, granulocytes including neutrophils, eosinophils, basophils
Macrophages
Ingest pathogens via endocytosis, digests them, and presents little pieces of them on major histocompatibility complex molecules, are one of the cell types that displays MHC-2 also (exogenous pathway), also secrete cytokines, derived from monocytes, resident populations called microglia in CNS, Langerhans cells in skin, osteoclasts in bone, etc, have special pattern recognition receptors
Cytokines
Secreted by macrophages, chemical substances that stimulate inflammation and recruit additional immune cells to the area
Major histocompatibility complex
MHC - proteins that present pathogens peptides (antigens) on, class I and class II exist, allows for antigens to be recognized by cells of the adaptive immune system
MHC Class I
Present in all nucleated cells and displays endogenous antigen to cytotoxic T cells, any cell in the body that has been infected with a virus/pathogen can display an antigen on MHC-1
Endogenous antigen
Proteins from within a cell, antigens presented on MHC-1
CD8+ cells
Cytotoxic T-cells, respond to antigens on MHC-1 (endogenous) and kill virally infected cells by injecting chemicals that promote apoptosis, most effective against viral (and intracellular bacterial or fungal) infections
MHC Class II
Present on professional antigen presenting cells and displays exogenous antigen to helper T cells after they phagocytize and process the pathogen from the outside environment, can result in activation of both innate and adaptive immune sys
Professional antigen presenting cells
Macrophages, dendritic cells, some B cells, and certain activated epithelial cells
Exogenous antigen
Proteins from outside the cell, present on MHC-II, can result in activation of both innate and adaptive immune sys
CD4+ cells
Helper T cells, respond to antigen on MHC II (exogenous antigens) and coordinate the rest of the immune system, secrete lymphokines, includes Th1 and Th2 cells, most effective against bacterial, fungal, and parasitic infections
Dendritic cells
Antigen-presenting cells in the skin
Natural killer cells
Attack (induces apoptosis in) cells not presenting MHC molecules (senses downregulation), including virally infected cells and cancer cells
Neutrophils
Ingest bacteria, particularly opsonized bacteria, use chemotaxis to follow bacteria, most populous leukocyte in the blood, dead collections forms pus during an infection
Opsonized bacteria
Those marked with antibodies from a B-cell
Eosinophils
Contain bright red-orange granules, used in allergic reactions and invasive parasitic infections, release histamine causing vasodilation and increased leakiness of blood vessels allowing more immune cells to move into tissues from bloodstream
Histamine
Triggers inflammatory response, released by eosinophils and basophils, results in vasodilation and increased leakiness of the blood vessels allowing additional immune cells to move out of the bloodstream and into the tissue
Basophils
Contain large purple granules, used in allergic reactions to release histamine, similar to mast cells
Mast cells
Related to basophils but have smaller granules and are found in the skin, release histamine in response to allergens
B-cells
Turn into plasma cells to produce antibodies as a part of adaptive immunity, created and mature in bone marrow, activated in spleen or lymph nodes and proliferate into plasma and memory B-cells, each can only produce one type of antibody at a time
Plasma cells
Produce antibodies after forming from B-cells as a part of adaptive immunity
Humoral immunity
Division of adaptive immunity that involves antibodies production by plasma cells (activated B-cells)
Cell-mediated immunity
aka cytotoxic immunity, division of adaptive immunity that is driven by T-cells because they coordinate the immune system and directly kill virally infected cells
Granules
Present in the cytoplasm of granulocytes, contain toxic enzymes and chemicals which can be released by exocytosis, particularly effective against bacterial, fungal, and parasitic pathogens
Hematopoietic stem cell
Precursor to all of hematopoiesis including all lymphoid stem cells and myeloid stem cells
Lymphoid stem cells
Precursor to B cells and T cells in hematopoiesis
Myeloid stem cells
Precursor to leukocytes, erythrocytes, and platelets in hematopoiesis
Granulocytes
Contain granules in cytoplasm, examples include neutrophils, eosinophils, and basophils
Agranulocytes
Lack granules, include lymphocytes and monocytes
Lymphocytes
Responsible for antibody productions, immune system modulation, and targeted killing of infected cells, includes T-cells and B-cells, both created in bone marrow
Monocytes
Phagocytic cells in the bloodstream, become macrophages in tissues
Classical pathway
Requires the binding of an antibody to a pathogen, actives complement system
Alternative pathway
Does not require antibodies, activates complement system
Antigen
Pathogenic peptide that can be presented on MHC, recognized by cells of the adaptive immune system, can be targeted by an antibody
Pattern recognition receptors
PRR - present in macrophages and dendritic cells, able to recognize the category of the invader and allows fo the production of appropriate cytokines to recruit the right type of immune cells, one type is toll-like receptors
Toll like receptors
TLR - type of pattern recognition receptor
Chemotaxis
The movement of an organism according to chemical stimuli
Pus
Formed because of dead neutrophil collections during an infection
Inflammation
Mediated by histamine release, useful against extracellular pathogens such as bacteria, fungi, and parasites, causes vasodilation and increased leakiness of blood vessels allowing additional immune cells to move out of the bloodstream and into tissue
Antibodies
aka immunoglobulins, produced by B-cells, target a particular antigen, contain two heavy chains and two light chains, have a constant region and variable region (whose tip is the antigen-binding region), types include circulating and cell surface antibodies
Constant region
Region of an antibody, cells such as natural killer cells, macrophages, monocytes, and eosinophils have receptors for this reason and can initiate the complement cascade
Variable region
Tip of which is the antigen-binding region, region of an antibody, contains specific polypeptide sequences that will bind only one specific antigenic sequence
Antigen binding region
Part of the variable region of an antibody, undergoes hypermutation which activated
Hypermutation
Occurs when the antigen binding region is activated, improves the specificity of the antibody products
Isotypes
Includes IgM, IgD, IgG, IgE, IgA
Opsonization
Marking pathogens for destruction, can be done by antibody
Agglutination
Clumping of insoluble complexes that are ingested by phagocytes, can be done by antibodies
Circulating antibodies
Can opsonize pathogens, cause agglutination, or neutralize pathogens by blocking their ability to invade tissues
Cell-surface antibodies
Can activate immune cells or mediate allergic reactions when an antigen binds to the B-cell by triggering proliferation and formation of plasma and memory cells, on a mast cell, antigen binding to an antibody causes degranulation
Memory B-cells
Lie in wait for a second exposure to a pathogen and can then mount a more rapid and vigorous immune response
Secondary response
More rapid and vigorous immune response to second exposure of a pathogen because of memory B and T cells
T-cells
Undergo maturation in the thymus through positive selection or negative selection, created in bone marrow
Thymosin
A peptide hormone that promotes T-cell development, secreted by thymus cells
Positive selection
Method of T-cell selection where only T-cells that can react to an antigen presented on MHC mature
Negative selection
Method of T-cell maturation that causes apoptosis in self-reactive T-cells
Lymphokines
Activate various arms of the immune defense, secreted by helper T-cells, recruit immune cells such as plasma cells, cytotoxic T cells and macrophages
Th1 cells
Helper T cells that secrete interferon gamma
Interferon gamma
Secreted by Th1 cells, activates macrophages
Th2 cells
Helper T cells that activate B cells primarily during parasitic infections
Suppressor T cells
aka regulatory T cells, tone down the immune response after an infection and promote self-tolerance, express CD4 but are differentiated by Foxp3
Memory T cells
Lie in wait for a second exposure to a pathogen and can then mount a more rapid and vigorous immune response
Autoimmune conditions
A self-antigen is identified as foreign and the immune system attacks the body’s own cells
Allergic reactions
Nonthreatening exposures incite an inflammatory response
Immunization
A method of inducting active immunity prior to exposure to a particular pathogen
Active immunity
Activation of immune system B cells that produce antibodies to an antigen
Passive immunity
Transfer of antibodies to an individual, transient because individual does only gets antibodies and not plasma cells, natural examples include transfer from mom to fetus/baby via placenta or breast milk
Adaptive immune system divisions
Humoral and cell-mediated (cytotoxic) immunity
Lymphocyte types
T-cells and B-cells
Degranulation of mast cells
Occurs when an antigen binds to an antibody on a mast cell, exocytosis of granule contents which releases histamine and causes and inflammatory response
Clonal selection
Mechanism where B-cells and T-cells that are able to bind an antigen with high affinity are the only ones to survive and proliferate
Isotypes
The five different types of antibodies - IgM, IgD, IgG, IgE, IgA
Isotype switching
Mechanism in which cells change which isotope of antibody they produce, stimulated by specific cytokines
Naive B and T cells
Cells that are mature but have not yet been exposed to an antigen
Primary response
The initial immune response to a pathogen, takes 7-10 days approximately
Human immunodeficiency virus
HIV - loss of helper T-cells which prevent the immune system from mounting an adequate response to an infection
Acquired immunodeficiency syndrome
AIDS - advanced HIV infection
Self tolerance
When suppressor or regulatory T cells tone down the immune response (including turning off self reactive lymphocytes) to prevent autoimmune disease
Types of infectious pathogens
Bacteria, virus, fungi, parasites, prions
Self antigens
Proteins and carbohydrates present on the surface of every cell in the body
Autoimmunity
When the immune system fails to make the distinction between self and foreign and attacks cells expressing particular self antigens
Hypersensitivity reactions
Family of immune reactions that includes autoimmunity and allergies
Treatment of autoimmune diseases
Administration of glucocorticoids because they have potent immunosuppressive qualities
Autoimmune prevention
Negative selection of T-cells and eliminations of B-cells that respond to self antigens prior to leaving bone marrow
Lymphatic system
Circulatory system that consists of one-way vessels with intermittent lymph nodes, equalizes fluid distribution, transports fats and fat soluble compounds in chylomicrons, and provides sites for mounting immune responses
Thoracic duct
In posterior chest, connects the lymphatic system to the cardiovascular system
Chylomicrons
What fat is packaged into by intestinal mucosal cells in the small intestine
Lymph
Lymphatic fluid
Lymph nodes
Small, bean-shaped structures along the lymphatic vessels, contain a lymphatic channel, artery, and vein, provides a space for immune system cells to be exposed to possible pathogens
Edema
Swelling due to fluid collecting in tissue when the lymphatics are overwhelmed
Lymphatic system fluid equalization
Lymphatic system returns fluid to bloodstream that was taken out because of hydrostatic forces and not pulled back in because net osmotic pressure puling back into the venule end of the capillaries is slightly less than thehydrostatic pressure
Lacteals
Small lymphatic vessels located at the center of each chills in the small intestine, where fats packaged into chylomicrons enter from transport
Chyle
Lymphatic fluid carrying many chylomicrons with a milky white appearance
Germinal centers
Location in the lymph nodes where B-cells proliferate and mature
