Biology Chapter 8: The Immune System Flashcards
Innate immunity
composed of defenses that are always active but that cannot target a specific invader and cannot maintain immunologic memory, also called nonspecific immunity.
Adaptive immunity
Composed of defenses that take time to activate, but that target a specific invader and can maintain immunologic memory; also called specific immunity.
Where do immune cells come from?
Bone marrow
Where are B-cells activated
Spleen and lymph nodes (immune responses can be mounted here)
Thymus
Site of T-cell maturation
Gut-associated lymphoid tissue
includes tonsils and adenoids
Immune role of skin
acts as a physical barrier and secretes antimicrobial compounds like defensins
Immune role of mucus
traps pathogens; in the respiratory system, the mucus is propelled upward by cilia and can be swallowed or expelled.
Immune role of tears and saliva
contain lysozome, an antibacterial compound
Immune role of stomach
produces acid, killing most pathogens. Colonization of the gut helps prevent overgrowth by pathogenic bacteria through competition.
Immune role of the complement system
can punch holes in the cell walls of bacteria, making them osmotically unstable.
Immune role of inferons
Given off by virally infected cells and help prevelt viral replication and dispersion to nearby cells.
Macrophages
ingest pathogens and present them on major histocompatibility complex molecules. They also secrete cytokines.
MHC class I
present in all nucleated cells and displays endogenous antigen (proteins from within the cell) to cytotoxic T-cells (CD8+ cells)
MHC class II
present in professional antigen-resenting cells (macrophages, dentritic cells, some B-cells & 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 not presenting MHC molecules. Including virally infected cells and cancer cells.
Granulocytes
include neutrophils, eosinophils and basophils
Neutrophils
ingest bacteria, particularly opsonized bacteria (those marked with 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 are related cells found in the skin.
Humoral immunity
centered on antibody production by plasma cells, which are activated B-cells.
Antibodies
- target a specific antigen
- Contain 2 heavy and 2 light chains
- They have a constant region and a variable region; tip of the variable is the antigen-binding protein.
What happens when the antigen-binding region is activated?
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
mark for destruction
What are three ways that circulating antibodies work?
- opsonize for destruction
- cause clumping into insoluble complexes that are degraded
- neutralize pathogens
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
What hormone promotes T-cell development?
Thymosin
Why do T-cells undergo maturation?
Positive and negative selection
Positive T-cell selection
Only selecting t-cells that can react to antigen presented on MHC.
Negative T-cell selection
causing apoptosis in self-reactive T-cells
Helper T-cells
respond to antigen on MHC II and coordinate the rest of the immune response, secreting lymphokines to activate various arms of immune defense.
Tb1 cells
secrete interfoeron gamma which activates microphages
Tb2 cells
activate B-cells
Cytotoxic T-cells
respond to antigen on MHC-I and kill virally infected cells.
Supressor T-cells
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
self-antigen is recognized as foreign and the immune system attacks normal cells
allergic reactions
incite an inflammatory response
Active immunity
Activation of B-cells that produce antibodies to an antigen
Immunization is creating
active immunity
Passive immunity
transfer of antibodies to an individual
Lymphatic system
a circulatory system that consists of one-way vessels with intermittent lymph nodes
thoracic duct
connects the lymphatic system to the cardiovascular system
chylomicrons
equalizes fluid distribution, transports fats and fat-soluble compounds in chylomicrons
