Ch. 8: The Immune System Flashcards
Divisions of Immune Sys
Innate and Adaptive Immunity
Innate immunity or Nonspecific immunity
Composed of defenses that are always active, but that cannot target a specific invader and cannot maintain immunologic memory.
Adaptive immunity or Specific immunity
Composed of defenses that take time to activate, but that target a specific invader and can maintain immunologic memory
Bone marrow
Immune cells come from the bone marrow
Spleen and Lymph Nodes
Sites where immune responses can be mounted, and in which B-cells are activated
Thymus
Site of T-cell maturation
Gut-associated lymphoid tissue (GALT)
Includes tonsils and adenoids
Leukocytes
White blood cells, are involved in immune defenses
Skin
Acts as a physical barrier and secretes antimicrobial compounds like defensins.
Mucus
On mucous membranes traps pathogens; in the respiratory system, the mucus is propelled upward by cilia and can be swallowed or expelled
Lysozyme
Tears and Saliva contain lysozyme an antibacterial compound
Stomach
The stomach produces acid, killing most pathogens; Colonization of the gut helps prevent overgrowth by pathogenic bacteria through competition
Complement system
Can punch holes in the cell walls of bacteria, making them osmotically unstable
Interferons
Given off by virally infected cells and help prevent viral replication and dispersion to nearby cells
Macrophages
Ingest pathogens and present them on major histocompatibility complex (MHC) molecules. They also secrete cytokines
MHC class I (MHC-I)
Present in all nucleated cells and displays endogenous antigen (proteins from within the cell) to cytotoxic T-cells
MHC class II (MHC-II)
Present in professional antigen-presenting cells (macrophages, dendritic cells, some B-cells, and certain activated epithelial cells) and displays exogenous antigen (proteins from outside the cell) to helper T-cells (CD4+ cells)
Dendritic Cells
Antigen-presenting cells in the skin
Natural killer cells
Attack cells presenting MHC molecules, including virally infected cells and cancer cells
Granulocytes
Include neutrophils, eosinophils, and basophils
Neutrophils
Ingest bacteria, particularly opsonized bacteria (those marked w antibodies). They can follow bacteria using chemotaxis
Eosinophils
Used in allergic reactions and invasive parasitic infections. They release histamine, causing an inflammatory response.
Basophils
Used in allergic reactions
Mast Cells
Related to basophils, found in the skin
Humoral immunity
Centered on antibody production by plasma cells, which are activated B-cells
Antibodies
Target a particular antigen. Containm 2 heavy chains and 2 light chains. They have a constant region and a variable region; the tip of the variable region is the antigen binding region
Hypermutation
When activated, the antigen-binding region undergoes hypermutation to improve the specificity of the antibody produced. Cells may be given signals to switch isotypes of antibody (IgM, IgD, IgG, IgE, IgA)
Opsonize and Agglutination by Antibodies
Circulating antibodies can opsonize pathogens (mark them for destruction), cause agglutination (clumping) into insoluble complexes that are ingested by phagocytes, or neutralize pathogens
Cell surface antibodies can
Activate immune cells or mediate allergic reactions
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)
Cell-mediated (cytotoxic) immunity
Centered on the functions of T-cells
T-cells undergo maturation in the thymus through
Positive selection: only selecting for T-cells that can react to antigen presented on MHC)
Negative selection: causing apoptosis in self-reactive T-cells
Thymosin
Promotes T-cell development
Helper T-cells
Aka Th or CD4+; respond to antigen on MHC-II and coordinate the rest of the immune system, secreting lymphokines to activate various arms of immune defense
Th1 cells
Secrete interferon gamma which activates macrophages
Th2 cells
Activate B-cells, primarily in parasitic infections
Cytotoxic T-cells (Tc, CTL, or CD8+)
respond to antigen on MHC-I and kill virally infected cells
Suppressor (regulatory) T-cells (Treg)
tone down the immune response after an infection and promote self-tolerance
Memory T-cells
Serve a similar function to memory B-cells
Autoimmune conditions
A self-antigen is recognized as foreign and the immune sys attacks normal cells
Allergic reactions
Nonthreatening exposures incite an inflammatory response
Immunization
Method of inducing active immunity (activation of B-cells that produce antibodies to an antigen) prior to exposure to a particular pathogen
Passive immunity
Transfer of antibodies to an individual
Lymphatic system
Circulatory sys that consists of one-way vessels with intermittent lymph nodes
Thoracic duct
In the posterior chest, connects lymphatic sys to the cardiovascular sys
Chylomicrons
Lymphatic sys equalizes fluid distribution, transports fats and fat soluble compounds in chylomicrons, and provides sites for mounting immune responses
