Introduction to the Immune System Flashcards
The ___ system is a disparate set of organs and tissues that interact to protect the body from foreign pathogens and dysfunctional self cells.
immune
*disparate = doesn’t have single location
what is a pathogen?
an organism that has the potential to cause disease
what are the 5 classes of pathogens?
- bacteria
- viruses
- fungi
- protozoa
- parasites
what are the 5 roles of the immune system?
- kill or control pathogens
- control disease
- repair tissue damage
- organ development
- maintain organ integrity and function
___ was the first practice to provide immunity
variolation
what are some examples of variolation?
- powdered smallpox tissue inhaled or rubbed into scratches on the skin
- widely practiced in 16th century China
- introduced to britain by lady montagu in 1721
describe vaccination
- developed by edward jenner in 1796
- cowpox exposure prevented smallpox
- substantially safer than variolation/inoculation
vaccination was not expanded until louis pasteur and emile roux developed a ___ vaccine in 1865
rabies
the study of immunology demonstrated that our body has a responsive system for ___ and ___ pathogens that cause disease
targeting and eliminating
what are the most successful developments in public health to date?
vaccines
what are the 2 main physical barriers that the body is protected by?
skin and mucosal surfaces
name some examples of mucosal surfaces that provide physical barriers for the body
- respiratory tract
- sinuses
- trachea
- lungs
- urogenital tract
- kidneys
- bladder
- vagina
- gastrointestinal tract
- oral cavity
- esophagus
- stomach
- intestines
- mammary glands
what properties do protective physical barriers provide for the body?
- endogenous antimicrobial properties
- sebum
- low pH
- commensal organisms
how does the immune system respond when barriers are compromised?
describe how the immune system destroys pathogens
what are 3 common effector mechanisms utilized in the destruction of pathogens by the immune system?
- phagocytosis
- granule release
- targeted cell death
what are the 2 branches of the immune system?
innate immunity and adaptive immunity
describe innate immunity
- rapid response (hours)
- fixed response
- limited pathogen specificity
- consistent response
compare primary and secondary responses of the innate and adaptive immune systems
describe adaptive immunity
- slow response (days to weeks)
- flexible response
- very selective pathogen specificity
- response improves with exposure
- retains a memory of previous infection
how do the two branches of the immune system work together?
the adaptive immune system requires an innate response
what happens to the number of microorganisms and duration of infection when innate immunity is lacking? what about when adaptive immunity is lacking?
what are the principal components of innate immunity?
- epithelial barriers
- phagocytes
- dendritic cells
- complement
- NK cells
what are the principal components of adaptive immunity?
- B lymphocytes → antibodies
- T lymphocytes → effector T cells
immune cells function through ___ and ___ interaction
direct and indirect
describe direct interaction of immune cells
- phagocytosis
- pathogen internalization and destruction
- immune synapse
- T cell mediated killing
what 4 main components are involved in indirect interaction of immune cells?
- cytokines
- chemokines
- cytotoxins
- antibodies
describe how cytokines function in indirect interaction
- molecules that activate and regulate immune function through cell-surface receptors
- inflammatory: IL-1, IL-6, IL-8, TNF-alpha
- inhibitory: IL-4, IL-10, IL-6, TGF-alpha
describe how chemokines function in indirect interaction
- molecules that attract immune cells to a region of the body
- C, CC, CXC, CXXC families
describe how cytotoxins function in indirect interaction
- molecules that interact with cells and pathogens to kill them
- perforin
- granzyme
- TNF-alpha
describe how antibodies function in indirect interaction
- proteins targeted against specific pathogens to neutralize, remove, or kill
describe leukocyte blood distribution
- neutrophils: 40-75%
- eosinophils: 1-6%
- basophils: <1%
- monocytes: 2-10%
- lymphocytes: 20-50%
hematopoeitic stem cells make up the precursors for the adaptive and innate immune systems. What are the precursors for each?
- adaptive immune system
- common lymphoid precursor
- innate immune system
- common myeloid precursor
which innate immune cells are the “first responders”?
neutrophils
- large reserves are stored in the bone marrow and are released when needed to fight infection
- they travel and enter the infected tissue, where they engulf and kill bacteria/microorganisms
- they then die in the tissue and are engulfed and degraded by macrophages
what are the antigen presenting cells of the innate immune system?
- monocytes
- dendritic cells
- macrophages
describe how macrophages kill by phagocytosis and promote inflammation
- binding of bacteria to phagocytic receptors on macrophages induces their engulfment and degradation
- binding of bacterial components to signaling receptors on macrophages induces the synthesis of inflammatory cytokines
which 3 cells of the innate immune system serve in parasite control?
- mast cells
- basophils
- eosinophils
how do mast cells protect against parasites?
- antimicrobial filled granules (granulocyte)
- release immune mediators
- prominent at tissue boundaries
how do basophils protect against parasites?
- granulocyte
- target parasites
- increidbly rare; not well understood
- Fc receptors bind antibodies
how do eosinophils protect against parasites?
- granulocyte
- target helminth worms and intestinal parasites
- Fc receptors bind antibodies
what are the targeted killer cells of the adaptive immune system?
- T cells
- Th helper cell
- Tc cytotoxic T cell
- B cells
- plasma cell
- natural killer (NK) cells
___ drives B cell and T cell pathogen specificity
clonal expansion
describe clonal expansion that drives B cell and T cell pathogen specificity
- Fc receptors bind antibodies
- MHC class I and II stimulate T cell receptors
- nearly infinite targeting of pathogens
describe the basic anatomy of surface immunoglobulin or B-cell receptors, antibodies, and T-cell receptors
- Fc receptors bind antibodies
- MHC class I and II stimulate T cell receptors
- nearly infinite targeting of pathogens
describe the lineages of the innate and adaptive immune system cells starting with hematopoeitic stem cells
what are the 2 adaptive immunity responses?
- humoral
- antibody mediated
- cellular
- mediated by cell-cell interactions
describe the humoral and cellular responses of the adaptive immune system
describe how antibodies mediate humoral responses
which 5 antibody classes are involved with mediating humoral responses in the adaptive immune system?
- IgG - most abundant antibody
- IgM - first antibody produced and released
- IgA - secreted from mucosal glands
- IgD - B cell surface antibody
- IgE - basophil and mast cell surface antibody
describe how T cells resolve pathogens through direct killing and immune support
describe the 2 classes of T cells involved in resolving pathogens through direct killing and immune support
- cytotoxic (CD8) T cells
- kill latered self cells
- helper (CD4) T cells
- support the functions of the immune system and other organ systems
- several subtypes
- regulatory function
immune cells develop at and respond from ___ organs
lymphoid
describe primary lymphoid organs
- where immune cells develop
- bone marrow
- thymus
describe secondary lymphoid organs
- where adaptive responses initiate
- lymphoid system
- spleen
- mucosa-associated lymphoid tissue (MALT)
what important immunity activity occurs in the bone marrow?
myeloid propagation and B cell maturation
*T cells are produced in the bone marrow but migrate to the thymus for maturation
what important immunity activity occurs in the thymus?
T cell maturation
*T cells are produced in the bone marrow but migrate to the thymus for maturation
describe the lymphatic system
- collection of extracellular fluid
- system of lymphatic capillaries and lymph nodes make up the lymphatics that return lymphocytes and lymph to the blood
- they are regional/localized which is helpful for reactions
describe the role of the spleen as a lymphoid organ
- filters blood borne antigens
describe the role of mucosal tissues as lymphoid organs
- points of pathogen susceptibility
- function like lymph nodes in the absence of a lymphatic system
- MALT (think of peyer’s patches)
describe the generalized immediate innate immune response to infection
0-4 hours
describe the generalized induced innate immune response to infection
4 hours to 4 days
describe the generalized adaptive immune response to infection
4 days until defeat of the pathogen, defeat of the host, or the truce of chronic disease
what are the 9 steps in the basic process of pathogen resolution?
- injury/pathogen infiltraiton
- resident immune cells respond
- inflammatory response
- innate pathogen targeting
- pathogenic antigens presented in the lymph nodes
- adaptive immunity initiated
- ongoing immune response
- pathogen destroyed or sequestered
- memory cells formed
