Immune System Flashcards
Innate Immunity
: Defenses that are always active but NONSPECIFIC. Skin, mucus, stomach acid, tears etc
Adaptive Immunity:
Defenses that take time to activate and are
SPECIFIC to the invader.
List noncellular innate defenses
Skin, mucus, lysozymes, complement system, interferons
What does skin secrete in innate immunity?
antimicrobial enzymes
How is mucus propelled upward?
Through cilia via mucociliary escalator
Lysozymes
In tears and saliva. Antimicrobial compound
Complement
System
Can punch holes in the cell walls of bacteria making them
osmotically unstable, leading to lysis. Also triggers
opsonization
Interferons:
Given off by virally infected cells. Interfere with viral
replication and dispersion
Macrophages:
Ingest pathogens and present them on MHC-II. Secrete
Cytokines
MHC-I:
Present in all nucleated cells. Displays endogenous
antigen to cytotoxic CD8+ T-cells.
MHC-II
Present in professional antigen-presenting cells
(macrophages, dendritic cells, some B-cells, and certain
activated epithelial cells). Displays exogenous antigen to
helper CD4+ T-Cells.
Dendritic
Cells:
Antigen-presenting cells in the skin
Natural Killer
Cells:
Attack cells low on MHC, including virally infected cells and
cancer cell
List three types of granulocytes and list their functions and what activates them
Neutrophils: Activated by bacteria, conduct phagocytosis.
Eosinophil: Activated by parasites & allergens increase histamines
Basophils: Activated by allergens, inhibit blood clotting.
Describe the function of the lymphatic system
Circulatory system that consists of one-way vessels with
intermittent lymph nodes
• Provides for mounting immune responses
• Connects to the cardiovascular system via the thoracic duct in the
posterior chest
• Equalizes fluid distribution, transports fats and fat-soluble
compounds in chylomicrons
• Edema results when the lymphatic system is overwhelmed and
can’t drain excess fluid from tissues
Humoral Immunity:
Centers on antibody production by B-Cells. Kills
antigens while they are floating around in the fluid (humor)
B-Lymphocytes
(B-cells):
Made and mature in bone marrow. Activated in spleen
or lymph nodes. Express antibodies on its cell surface.
Antibodies (Ig):
Produced by plasma cells, which are activated B-Cells.
Target an antigen. Contain 2 heavy chains and 2 light
chains. Constant region & variable region. Tip of
variable region is the antigen-binding region.
Hypermutation:
Mutation of the antigen binding site on an antibody.
Results in varying affinities of antibodies for a specific
microbe. 5 diff isotypes (IgM, IgD, IgG, IgE, IgA)
Opsonization:
Antibodies mark pathogens for destruction.
Agglutination:
Pathogens clump together into insoluble complexes.
Caused by opsonizing pathogens
Memory B-Cells:
: Lie in wait for a second exposure to pathogen.
Secondary response is more rapid and vigorous.
Cell-Mediated (Cytotoxic) Immunity:
Centers on T-Cells. Responds to cells
once they have been infected by the antigen.
T-Lymphocytes
(T-cells):
Made in bone marrow, mature in Thymus. Coordinate
immune system and directly kill infected cells. Cellmediated immunity.
Positive/Negative
Selection:
Maturation of T-Cells. Facilitated by thymosin. Occurs
in Thymus.
Positive Selection:
Mature only T-cells that can
respond to the presentation of antigen on MHC.
Negative Selection
Causes apoptosis in T-cells that are
self-reactive
Helper T-Cells: Th of CD4+
Respond to antigen on MHC-II. Coordinate
rest of the immune system, secreting lymphokines to
activate immune defense.
Role of T 1 helper cells
secrete interferon gamma
Role of T 2 helper cells
activate B-Cells, in parasitic infections
Cytotoxic T-cells:
Tc, CTL, or CD8+. “Killer cells”. Respond to antigen on
MCH-I and kill virally infected cells
Suppressor T-Cells:
Treg. Down regulate the immune response after an
infection and promote self-tolerance. Defective
suppressor T-Cells lead to autoimmune conditions
Memory T-Cells
: Serve a similar function to memory B-Cells
Autoimmune
Conditions:
A self-antigen is recognized as foreign, and the
immune system attacks normal cells
Allergic Reactions:
Nonthreatening exposures incite an inflammatory
response
Immunization:
Induces active immunity (activation of B-Cells that
produce antibodes)
Passive Immunity:
Transfer of antibodies to an individual. Breast milk.
