unit 6 (nonspecific innate immunity) Flashcards
population
a group of individual organisms belonging to the same species and limited to a certain geographic area
symbiosis
any interaction between different species within a community, may be beneficial, harmful, or have no effect on species involved
mutualism
symbiosis in which two species benefit from each other
commensalism
symbiosis in which one organism benefits and the other is uneffected
parasitism
symbiosis in which one organism benefits and the other is harmed
microbiome definition
refers to all prokaryotic and eukaryotic microorganisms that are associated w/ a certain organism
human microbiome is composed of what types of microbiota
resident microbiota and transient microbiota
resident microbiota
consists of microorganisms that constantly live on our bodies
transient microbiota
consists of microbes that are only temporarily found in or on the body and may include pathogenic organisms
reservoir of infection
location where the microorganism normally resides and can be living or nonliving
zoonosis
a microbe that is normally found in an animal
zoonotic disease
any disease coming from transmission to humans
contact transmission types
direct and indirect
direct contact transmission types
person-to-person, vertical, horizontal, droplet
indirect contact transmission
fomites can become contaminated by pathogens from an infected individual or reservoir
person-to-person transmission
touching, kissing, sex, droplet sprays
vertical transmission
mother to child during pregnancy, childbirth, or breastfeeding
horizontal transmission
mucous membrane contact, possibly skin-to-skin
droplet transmission
transmission of pathogen to new host over one meter or less
vehicle transmission
refers to transmission of pathogens over air, food, and water
vector transmission types
diseases can be transmitted through a mechanical or biological vector
mechanical transmission
transmitted by a mechanical vector which is an animal that carries a pathogen from one host to another without being infected itself
biological transmission
disease transmitted biological vector that the pathogen reproduces in and transmits pathogen from one host to another
nonspecific innate immunity definition
multifaceted system of defenses that targets invading pathogens in a nonspecific manner
3 categories of nonspecific innate immunity
physical defenses, chemical defenses, cellular defenses
physical defense types
physical barriers, mechanical defenses, microbiome
types of physical barriers
skin barrier, mucous membranes, endothelia
physical barrier function
consists of tightly packed cells that prevent invaders from crossing through to deeper tissues
skin barrier functions/mechanisms
epidermis consists of dead and tightly packed keratin which is tough and resistant to degradation of bacterial enzymes, fatty acids create dry, salty, acidic environment, skin cells shed often and take microbes clung to them (mechanical defense)
mucous membranes comprised of
consists of a layer of epithelial cells bound by tight junctions that secrete a mucus
mucus function
covers and protects more fragile cell layers beneath it and traps debris and particulate matter, including microbes and also contain antimicrobial peptides
endothelia
epithelial cells lining the urogenital tract, blood vessels, lymphatic vessels, and certain other tissues that are tightly packed to create barrier against invaders
mechanical defenses
shedding of skin cells, expulsion of mucus (mucociliary elevator), excretion of feces, flushing action of urine and tears, eyelids/eyelashes
microbiome function in innate immunity
resident microbiota occupy cellular binding sites and compete for available nutrients prevent early steps of pathogen attachment and proliferation required for the establishment of an infection
chemical defense types
chemicals and enzymes in bodily fluids, antimicrobial peptides, plasma protein mediators, cytokines, inflammation-eliciting mediators
chemical mediators definition/function
encompass a wide variety of substances found in various body fluids and tissues throughout the body that may work alone or in conjunction with each other to inhibit microbial colonization and infection
endogenous
chemical mediators produced by human body cells
exogenous
chemical mediators produced by certain microbes that are part of the microbiome
chemical and enzymatic mediators found in bodily fluids examples
sebum eaten by normal microbiota that produces oleic acid, saliva contains lactoperoxidase, mucus in esophagus contains lysozyme, acidity of urine, tears contain lysozyme and lactoferrin, earwax lowers pH, mucus contains lysozyme, lactoferrin, and lactoperoxidase
antimicrobial peptides (AMPs) definition
a special class of nonspecific cell derived mediators with broad spectrum antimicrobial properties
AMP function/mechanism
may induce cell damage by inflicting damage to membranes, destroying DNA and RNA, or interfering with cell-wall synthesis
defensins
family of AMPs that are produced by epithelial cells throughout the body as well as by macrophages and neutrophils and may be secreted or act inside host cells by disrupting their membranes
bacteriocins
family of AMPs produced exogenously by certain members of resident microbiota in gastrointestinal tract, and the genes are that encode for them are found on plasmids for HGT
plasma protein mediator types
acute-phase proteins, complement proteins, and cytokines that are all involved in innate immune response
acute phase proteins function
antimicrobial mediators that respond to inflammatory molecules from the immune system and inhibit or destroy microbes in some way
acute phase protein types
C-reactive protein, Serum amyloid A, Ferritin, transferrin, fibrinogen, and mannose-binding lectin
the complement system definition
a group of proteins found in bloodstream that are a part of the innate nonspecific immune defense and serve as a bridge connecting innate and adaptive immunity
complement activation definition
process by which circulating complement precursors become functional that can be triggered by three different pathways: alternative, classical, and lectin pathways
alternative pathway complement activation
initiated by spontaneous activation of C3: C3 hydrolyzes to produce C3a and C3b, C3b attaches to surface of invader microbes and recruit other complement proteins in a cascade
classical pathway complement activation
an antibody-antigen complex must form which activates the C1 complex and then the remaining classical pathway complement proteins are recruited and activated in a cascading sequence
lectin pathway complement activation
triggered by binding of mannose-binding lectin (acute phase protein) to carbohydrates on microbial surface
outcomes of complement activation
opsonization, inflammation, chemotaxis, and cytolysis
chemotaxis definition
migration of cells towards attractant chemicals
opsonization definition
coating of a pathogen by a chemical substance that allows phagocytic cells to recognize, engulf, and destroy it more easily
opsonins examples
complement proteins C1q, C3b, C4b; mannose-binding proteins; antibodies
anaphylatoxins definition
complement fragments C3a and C5a that activate mast cells, causing degranulation and release of inflammatory chemical signals
C5a attracts
neutrophils and other white blood cells
membrane attack complex (MAC)
C6, C7, C8, and C9 assemble into a MAC, which allows C9 to polymerize into pores in the membranes of gram- bacteria, leading to cell lysis
cytokine definition
soluble proteins that act as communication signals between cells
cytokine function in innate immunity
stimulate production of chemical mediators or other cell functions, such as cell proliferation, cell differentiation, inhibition of cell division, apoptosis, and chemotaxis.
autocrine function of cytokines
same cell that releases the cytokine is the recipient of the signal, self-stimulation
paracrine function of cytokines
involves release of cytokines from one cell to other nearby cells, stimulating some response in the recipient cells
endocrine function in cytokines
occurs when cells release cytokines into the bloodstream to be carried away to target cells much further away
classes of cytokines
interleukins, chemokines, and interferons
interleukins function
involved in modulating almost every function of the immune system, produced by and stimulate a variety of cells unrelated to immune defenses
chemokines function
chemotactic factors that recruit specific subsets of leukocytes to site of infection, inflammation, and tissue damage
Interferons types
Type I interferons (interferon alpha and interferon beta), Type II interferons (interferon gamma)
Type I interferon function
produced and released by cells infected w/ virus, stimulate nearby cells to stop production of mRNA, destroy RNA already produced, and reduce protein synthesis. also stimulate immune cells to more aggressively attack virus-infected cells.
Type II interferon function
alerts neighboring immune cells to attack (activates immune cells)
inflammation-eliciting mediators examples
histamine, leukotrienes, prostaglandins
histamine released by and cause
released by degranulation of mast cells and basophils, cause vasodilation, bronchoconstriction, smooth muscle contraction, increased secretion and mucus production
leukotrienes released by and cause
released by mast cells and promote inflammation which is stronger and longer lasting than histamine
prostaglandins released by and cause
cytokines stimulate their production, promotes inflammatory effects of histamines and promote inflammation and fever
formed elements definition/types
are all formed from the same stem cell in the bone marrow: red blood cells, platelets (thrombocytes), and white blood cells (leukocytes)
hematopoietic stem cells (HSCs)
where all formed elements of blood are derived from
hematopoiesis
process of HSCs differentiating into different types of blood cells
granulocyte definition
leukocyte that have numerous granules visible in their cytoplasm
agranulocyte definition
leukocytes that lack granules
types of granulocytes
neutrophils, basophils, eosinophils, mast cells
neutrophils function
involved in the elimination and destruction of extracellular bacteria, contain defensins that help them destroy bacteria through phagocytosis, capable of degranulation to clear infectious agents
eosinophils function
protect against protozoa and helminths. granules contain histamine and major basic protein that binds to the surface of parasites, disrupting their cell membrane
basophils function
important in allergic reactions and other responses involving inflammation. granules contain histamine and other chemical factors that are released when basophil is stimulated by complement proteins or assistance of antibodies
mast cells function
function similarly to basophils except they are most frequently found residing in tissues rather than the bloodstream
categories of agranulocytes
lymphocytes and monocytes
lymphocyte types
natural killer cells, B and T cells (adaptive immunity)
monocyte types
macrophages, dendritic cells
natural killer cell function
use nonspecific mechanisms to recognize and destroy abnormal cells
NK cell activation
when MHC marker are diminished or absent, NK cell interprets it as an abnormality and binds to activating molecular molecules on target cells and destroys the cell
major histocompatibility complex
molecular markers displayed on healthy cells as an indication of “self”
activating molecular molecules function
infected cell display “altered” self or “non-self” molecules on cell surface for NK cells to recognize
NK cell mechanisms to kill target
binds to target cell and expresses cytokine and cytotoxins to stimulate target cell into apoptosis or perforin-mediated cytotoxicity to induce apoptosis
perforin-mediated cytotoxicity
NK cell releases perforin, creates pores in target cell, and granzymes, that enter into the pores and trigger a cascade of protein activation that leads to apoptosis
monocytes function
effective phagocytes that engulf pathogens and apoptotic cells, release cytokines, and are an important bridge between innate and adaptive immunity
monocyte differentiation definition
when they leave the bloodstream and enter a specific body tissue they differentiate into tissue specific phagocytes: macrophages and dendritic cells
phagocyte definition
cells whose main function is to seek, ingest, and kill pathogens
diapedesis process is
which leukocytes pass through walls of small capillary blood vessels within tissues
transendothelial migration
process in which leukocytes flatten and squeeze through a cellular junction to exit the bloodstream
Pathogen-associated molecular patterns (PAMPs) definition
molecular structures that are common to many groups of pathogenic microbes that phagocytes can recognize
common PAMPs
peptidoglycan, flagellin, lipopolysaccharide, lipopeptides, nucleic acids (viral DNA or RNA)
pattern recognition receptors (PRRs)
structures that allow phagocytic cells to detect PAMPs
toll-like receptors (TLRs)
group of PRRs that bind to various PAMPs and communicate w/ nucleus of the phagocyte to elicit a response
interaction between PAMPs and PRRs on macrophages activates phagocyte into state of
hyperactivity, proliferation, production/secretion of cytokines, and enhanced intracellular killing
phagocytosis
process by which a pathogen is engulfed in a vesicle and brought into the internal compartment of the phagocyte
phagosome
membrane vesicle; the phagocyte forms pseudopod around the pathogen and pinches it off
phagolysosome
phagosome containing pathogen fuses with one or more lysosomes
enzymes and factors in phagocytosis that kill pathogens
low pH, lysozyme, phospholipase, proteases, and respiratory burst enzymes
respiratory burst (process)
phagocytes increase their uptake and consumption of oxygen to produce ROS that are antibacterial (can be released into the area around the cell to degrade microbes externally)
exocytic vescile
what leftover waste products from pathogen degradation are excreted from the cell in
inflammation triggered by
a cascade of chemical mediators and cellular responses that may occur when cells are damaged or stressed or when pathogen successfully breach the physical barriers of the innate immune system
inflammation function
recruits cellular defenses needed to eliminate pathogens, remove damaged and dead cells, and initiate repair mechanisms
five observable signs associated w/ inflammatory response
erythema (redness), edema, heat, pain, and altered function
acute inflammation
early/immediate response to tissue injury. vasoconstriction/vasodilation
chronic inflammation
when acute inflammation is unable to clear pathogen; an ongoing lower level battle between host organism and pathogen
granulomas
pockets of infected tissue walled off and surrounded by WBCs
fever
an inflammatory response that extends beyond the site of the infection and affects the entire body, resulting in an overall increase in body temperature
fever activation
bacterial and viral infections produce pyrogens which stimulate hypothalamus to increase body temp
pyrogens
chemicals that stimulate increase in body temp that may be endogenous or exogenous
fever function
stimulate leukocytes to kill pathogens, temps inhibit growth of pathogens, starve iron-dependent microbes
superantigens
bacterial or viral proteins that can cause an excess activation of T cells and an excessive release of cytokines that overstimulates the inflammatory response
disease definition
any condition in which the normal structure or functions of the body are damaged or impaired
causes for disease
infection by a pathogen, genetics, noninfectious environmental factors, or inappropriate immune responses
infection definition
successful colonization of a host microorganism
signs of disease definition
objective and measurable, directly observed by a clinician
signs of disease examples
body temp, heart rate, breath rate, and blood pressure
symptoms of disease definition
subjective, felt or experienced by patient but not clinically confirmed or objectively measured
syndrome definition
specific group of signs and symptoms characteristic of a particular disease
asymptomatic or subclinical disease definition
disease that do not present any noticeable signs or symptoms
morbidity definition
number of cases of a disease
mortality definition
number of deaths due to a disease
infectious disease definition
any disease caused by the direct effect of a pathogen
noncommunicable disease definition
disease not spread from one person to another
communicable disease definition
capable of being spread person-to-person through direct or indirect mechanisms
contagious disease definition
disease easily spread from person-to-person
iatrogenic disease definition
diseases that are contracted as the result of a medical procedure
nosocomial disease definition
diseases acquired in hospital settings
zoonotic disease definition
disease that occurs when a pathogen is transferred from an animal to a human
noninfectious disease definition
those not caused by pathogens but caused by genetics, the environment, or immune system dysfunction
five periods of disease
incubation, prodromal, illness, decline, convalescence
period of convalescence
host generally returns to normal function
incubation peroid
initial entry of pathogen into host, pathogen begins multiplying in host but has insufficient numbers to cause signs and symptoms
prodromal period
pathogen continues to multiply and host beings to experience general signs and symptoms of nonspecific illness
period of illness
host’s signs and symptoms are most severe
period of decline
number of pathogen particles begins to decrease, and signs and symptoms begin to decline, patients may be susceptible to developing secondary infection
primary pathogen definition
cause disease in host regardless of host’s resident microbiota or immune system
opportunistic pathogen definition
can only cause disease in situations that compromise the host’s defenses; protective barriers, immune system, or normal microbiota
stages of pathogenesis
to cause disease a pathogen must achieve: exposure (contact), adhesion (colonization), invasion, and infection
portal specificity
most pathogens are suited for a particular portal of entry
most important portal of entry for pathogens
mucosal surfaces (eyes, nose, mouth, urethra, anus)
to cause disease a pathogen must be able to:
gain entry to the host, travel to the location where it can establish an infection, evade or overcome the host’s immune response, and cause damage (disease) to the host
exposure
an encounter with a pathogen
portal of entry
an anatomic site at which pathogens can pass into host tissue and are in direct contact w/ the external environment
parenteral route of entry
pathogens that enter through a breach in protective barriers of skin and mucous membranes
invasion
involves the dissemination of a pathogen throughout local tissues or the body
inflammation occurs when
TORCH definition
pathogens that can cross the placental barrier: toxoplasmosis (T), HIV/chickenpox/syphilis (O), rubella (R), cytomegalovirus (C), herpes (H)
adhesion definition
refers to the capability of pathogenic microbes to attach to the cells of the body using adhesion factors
Infection
successful multiplication of pathogen leads to infection
adhesins
molecules (proteins or carbs) that are found on the surface of certain pathogens and bind to specific receptors (glycoproteins) on host cells
first method of endocytosis (membrane ruffling)
effector proteins are secreted by pathogen that cause protrusion of membrane ruffles that bring the bacterial cell in
second method of endocytosis
surface proteins expressed on the pathogen bind to receptors on the host cell, resulting in entry
local infection definition
confined to a small area of the body, typically near the portal of entry
focal infection definition
a localized pathogen, or the toxin it produces, spreads to a secondary location
virulence factors definition
factors that determine the extent and severity of disease they may cause
systemic infection definition
when an infection becomes disseminated throughout the body
bacteremia definition
presence of bacteria in the bloodstream
portal of exit
site where pathogen exits body to transmit to a new host
Opa proteins
adhesion factor that aids the pili in adhesion and invasion of epithelial cells in the lining of the genital tract (N. gonorrhoeae)
common portals of exit
skin, respiratory, urogenital, gastrointestinal tracts, excretions, blood
types of virulence factors
adhesion factors, exoenzymes and toxins, factors for survival and immune evasion
pyemia definition
bacteremia involving pyogens (pus forming bacteria)
viremia definition
presences of viruses in the blood
toxemia definition
describes the condition when toxins are found in the blood
septicemia definition
bacteria are both present and multiplying in the blood
four examples of A-B exotoxin
diphtheria, cholera, botulinum, and tetanus toxins
membrane disrupting toxins function
form pores or disrupt the phospholipid bilayer in host cell membranes
examples of membrane disrupting toxins
hemolysins and leukocidins
streptolysins
hemolysins that bind to cholesterol in host cell membrane to form a pore
beta hemolysis
complete lysis of blood cells on blood agar plate
alpha hemolysis
partial lysis of blood cells, more accurately a bruising of blood cell membranes on blood agar plate
gamma hemolysis
no lysis, no effect on red blood cells
phospholipases
membrane-disrupting toxins that degrade the phospholipid bilayer of membranes instead of forming pores
cytokine storm
excessive production of cytokines induced by superantigens, elicits a strong immune and inflammatory response that can cause life-threatening high fevers, low blood pressure, multi-organ failure, shock, and death
virulence factors for immune evasion
capsules, production of proteases to attack antibodies to prevent phagocytosis, fimbriae, mycolic acid (acid-fast), and antigenic variation
