Chapter 26: Innate Immunity Flashcards
immunity
ability of organism to resist infection
innate immunity
built-in capacity of immune system of multicellular organisms to target pathogens that are seeking to colonize the host
does not require previous exposure to a pathogen
adaptive immunity
acquired ability to recognize and destroy a particular pathogen
dependent on previous exposure
directed toward individual molecular component of pathogen- antigen
natural host resistance
normal microbiota helps resist pathogens on skin and in gut
competitive exclusion
harmless microbes limit available nutrients and sites for infection
white blood cells
make up 0.1% of cells in blood
aka leukocytes (buff coat)
include lymphocytes, granulocytes, monocytes
lymphocytes
specialized leukocytes involved in adaptive immunity
B cells: originate and mature in bone marrow, produce antibodies
T cells: originate in bone marrow, mature in thymus, produce T cell receptors
Antigen-presenting cells
engulf, process, and present antigens to lymphocytes, monocytes, macrophages, dendritic cells
granulocytes
contains toxins or enzymes that are released to kill target cells
consist of neutrophils, basophils, eosinophils
microbial invasion
ability of a pathogen to enter host cells or tissues, multiply, spread, cause disease
cytokines
released by leukocytes and damaged cells
allow communication between WBCs
draws macrophages and neutrophils
large and diverse group of pro or anti inflammatory factors
genetic function is to induce cell migration
pathogen associated molecular patterns
pathogens have structures and molecules not found on host cells
ex. LPS common to all gram-neg bacterial outer membranes
Toll-like receptors (TLR)
send a signal to nucleus when encounterig a PAMP
phagocytes
engulf pathogens upon recognition of PAMPS by their TLRs
some pathogens can survive
some pathogens form capsule
inflammation
isolates and limites tissue damage, destroy damaged cells and pathogens
also inadverdently cause damage to healthy tissue in key organs
fever
caused by cytokines called pyrogens
increases circulation rates, allows WBCs to get to site of infection
some pathogens cannot tolerate healt
increase in transferrins which sequester iron, limiting pathogen growth
systemic inflammation
can lead to shock because of decreased blood pressure
gram neg bacteria contain LPS, triggers proinflammatory response –> cytokine storm which can be fatal
ex. salmonella or e. coli
signs of inflammation
widening of capillaries: increase vascular permeability
more blood flow: redness, pressure
water enters tissue (swelling): flush debris to lymphatic system, local pain
fever
genes induced by PAMP and TLRs
- cytokine production: attract immune cells
- phagocytosis: kill pathogen
- communication with adaptive immune cells: antigens
- inflammation: interleukins
- tissue healing
complement system activation
direct attack, recruitment of phagocytes, opsonization
opsonization
making a target easier to phagocytose
complement system
set of circulating inactive proteins tjay are activated in response to a pathogen
major histocompatibility complexes (MHC)
present small fragments of protein
every cell in body presents every protein it creates
inform immune system what is/isn’t foreign
natural killer cells kill everything w/o MHC
many viruses force body cells to decrease/stop expression of MHC
natural killer (NK) cells
cytotoxic lymphotcytes
recognize and kill cells that do not display MHC and have stress proteins: likely old, virally infected, cancer…)
granzyme
enzyme that induces apoptosis
interferons
small cytokine proteins produced by virally infected cells
serve as warning system, prevent viral replication by stimulating production of antiviral protein in uninfected cells once they receive signal from infected cell
infected cell induces apoptosis
MHC I
on every cell
present self-protein “I belong to the body”
MHC II
present antigens “I found this foreign thing”
only on special immune cells: phagocytes and B cells
perforin
pokes holes (perforates) target membrane
