Chapter 43 Key Terms Flashcards
agents that cause disease such as bacteria, viruses, fungi or others
pathogens
system that enables animals to avoid or limit many infections
immune system
two types of molecular recognition
innate immunity and adaptive immunity
a defense active immediately upon infection
innate immunity
a response activated after the innate response and develops more slowly
adaptive immunity
what kind of immunity are barrier defenses?
innate
enzyme that breaks down bacterial cell walls (defense of invertebrates)
lysozyme
major immune cells of insects
hemocytes
process of cells breaking down microorganisms
phagocytosis
transmembrane receptor activated by binding of recognition proteins to fungal cell wall molecules (invertebrates)
Toll
activate production and secretion of antimicrobial peptides that kill fungal cells (invertebrates)
Toll
innate defenses of vertebrates similar to invertebrates
barrier defenses, phagocytosis, and antimicrobial peptides
innate defenses unique to vertebrates
natural killer cells, interferons, inflammatory response
barrier defenses include:
skin and mucous membranes
how does the skin and digestive system defend against the growth of bacteria
low pH of skin
innate immune cells in mammals detect, devour, and destroy invading pathogens using ___________ to recognize groups of pathogens
TLRs (toll like receptors)
recognize fragments of molecules characteristic of a set of pathogens
toll like receptors (TLR)
two MAIN kinds of phagocytic cells
neutrophils and macrophages
engulf and destroy pathogens
phagocytic cells
phagocytic cells that circulate in the blood
neutrophils
phagocytic cells that migrate through the body or reside permanently in organs and tissues
macrophages
two ADDITIONAL types of phagocytic cells
dendritic cells and eosinophils
phagocytic cells that stimulate development of adaptive immunity
dendritic cells
phagocytic cells that discharge destructive enzymes against parasites
eosinophils
type of innate defense; these circulate the body and detect abnormal cells; release chemicals leading to cell death, inhibiting the spread of virally infected or cancerous cells
natural killer cells
immune cells found in connective tissue; discharge cytokines (part of inflammatory response)
mast cells
signaling molecules that recruit neutrophils to an inflamed site
cytokines
chemical that triggers blood vessels to dilate and become more permeable
histamine
__________migrate to lymph nodes after interacting with pathogens to stimulate adaptive immunity
dendritic cells
proteins that provide innate defense by inhibiting the replication of viruses
interferons
system that consists of about 30 proteins in blood plasma; activated by substances on the surface of many pathogens; resulting cascade of reactions lead to lysis of invading cells
complement system
adaptive response relies on 2 types of lymphocytes:
T cells and B cells
lymphocytes that mature in the thymus
t cells
lymphocytes that mature in bone marrow
b cells
lymphocytes are?
a type of white blood cell
substances that can elicit a response from b or t cells
antigens
t or b cells bind to antigens via ____________ specific to part of one molecule of that pathogen
antigen receptors
small accessible part of an antigen that binds to an antigen receptor
epitope
soluble form of the receptor
antibody or immunoglobulin (Ig)
__________bind only to antigen fragments displayed or presented on a host cell
T cells
cell surface proteins that antigen fragments are bound to, the antigen fragment bound to T cells
Major histocompatibility complex molecules (MHC)
a process in which MHC molecules bind and transport antigen fragments to the cell surface
antigen presentation
the ________ immune system has 4 major characteristics:
- immense diversity of lymphocytes and receptors
- self tolerance: lack of reactivity against an animal’s own molecules and cells
- B and T cells proliferate after activation
- immunological memory
adaptive
light chain (in b and t cells) is encoded by 3 segments:
V (variable), J (joining), and (c) constant
enzyme that acts randomly to connect different V and J segments in each B cell
recombinase
multiple cell divisions that a B or T cell undergoes to produce a clone of identical cells
clonal selection
cells from the clone that act immediately against the antigen; plasma cells that secrete antibodies
effector cells
remaining cells in the clone; long lived and can give rise to effector cells if the same antigen is encountered again
memory cells
responsible for long term protection against diseases
immunological memory
first exposure to a specific antigen represents the
primary immune response
when memory cells facilitate a faster, greater and more prolonged response from a reservoir of T and B memory cells
secondary immune response
two kinds of defenses provided by B and T lymphocytes
humoral immune response and cell-mediated immune response
antibodies help neutralize or eliminate toxins and pathogens in the blood and lymph
humoral immune response
specialized T cells destroy infected host cells
cell mediated immune response
what kind of cell activates both the humoral and cell mediated immune response
helper t cell
antibodies bind to antigens on bacteria promoting phagocytosis (marking them)
opsonization
cells that use toxic proteins to kill cells infected by viruses or other intracellular pathogens
cytoxic t cells (killer t cells)
protection provided by a second immune response provides the basis for immunization
immunization
develops naturally when a pathogen invades the body and elicits a primary or secondary immune response
active immunity
provides immediate, short term protection
passive immunity
life threatening reaction to allergen
anaphylactic shock
the immune system loses tolerance for self and turns against certain molecules of the body
autoimmune diseases
some pathogens can change epitope expression and prevent recognition by the host
antigenic variation
inactive state of virus
latency
