Microbiology Ch16 Innate Immunity

Immunity

ability to ward off disease

susceptibility

lack of resistance to a disease

Innate immunity

defenses against any pathogen; rapid & present at birth

Types of innate immunity (6)

- physical barriers

- chemicals

- cells that can phagocytize

- inflammation

- fever

- molecules

Adaptive immunity

immunity/resistance to a specific pathogen; slow & has memory component

Physical factors of innate immunity (7)

- skin

- mucous membranes

- ciliary escaltor

- earwax

- urine

- vaginal secretions

-lacrimal apparatus

dermis of skin

inner portion made of CT

epidermis of skin

outer portion made of epithelial cells w/keratin

how does skin provide immunity

shedding & dryness inhibits microbial growth & penetration

mucus of mucous membranes

viscous glycoproteins that trap microbes & prevent tracts from drying out

lacrimal apparatus of mucous membranes

drains tears; washes eye

where are mucous membranes

epithelial layer lining gastrointestinal, respiratory, & genitourinary tracts

ciliary escalator as physical factor of innate immunity

transports microbes trapped in mucus away from lungs

epiglottis as physical factor of innate immunity

prevents microbes from entering lower respiratory tract

earwax as physical factor of innate immunity

prevents microbes from entering ear

urine as physical factor of innate immunity

cleans the urethra via flow

vaginal secretions as physical factor of innate immunity

move microbes out of the vaginal tract

Types of chemical factors of innate immunity (4)

- sebum

- lysozyme

- low pH of 1.2 - 3.0 of gastric juice

- low pH 3.0 - 5.0 of vaginal secretions

sebum as chemical factor of innate immunity

forms a protective film & lowers pH of skin to 3.0 - 5.0

lysozyme as chemical factor of innate immunity

in perspiration, tears, saliva, & urine; destroys bacterial cell walls

low pH of 1.2 - 3.0 in gastric juice as chemical factor of innate immunity

destroys most bacteria & toxins

low pH of 3.0 - 5.0 in vaginal secretions as chemical factor of innate immunity

inhibits microbial growth

Types of cells that can phagocytize in innate immunity (3)

- normal microbiota

- formed elements in blood

- lymphoid system

how do normal microbiota provide innate immunity

compete with pathogens via microbial antagonism (competitive exclusion)

microbial antagonism of normal microbiota (5)

- compete for space & nutrients

- prod. substances harmful to pathogens

- alter conditions affecting pathogen survival

- prevents overgrowth of harmful microbes

- help develop immune system

commensalism of normal microbiota of innate immunity

1 organism benefits while the other (host) is unharmed

Opportunistic pathogens among normal microbiota (6)

- e. coli

- s. aureus

- s. epidermidis

- enterococcus

- faecalis

- pseudomonas aeruginosa

probiotics of normal microbiota of innate immunity

live microbial cultures administers to exert a beneficial effect

prebiotics of normal microbiota of innate immunity

chemicals (nutrients) that selectively promote the growth of beneficial bacteria

types of formed elements in blood of cells that phagocytize of innate immunity (2)

- granulocytes

- agranulocytes

granulocytes of formed elements in blood

leukocytes with granules in their cytoplasm that are visible with a light microscope

types of granulocytes of formed elements in blood (3)

- neutrophils

- basophils

- eosinophils

neutrophils of granulocytes of formed elements in blood

phagocytic; work in early stages of infection

basophils of granulocytes of formed elements in blood

release histamine; work in allergic responses

eosinophils of granulocytes of formed elements in blood

phagocytic; toxic against parasites & helminths

Agranulocytes of formed elements in blood

leukocytes with granules in their cytoplasm that are not visible with a light microscope

types of agranulocytes of formed elements in blood (3)

- monocytes

- dendritic cells

- lymphocytes

monocytes of agranulocytes of formed elements in blood

mature into macrophages in tissues where they are phagocytic

dendritic cells of agranulocytes of formed elements in blood

found in the skin, mucous membranes, & thymus; phagocytic

lymphocytes of agranulocytes of formed elements in blood

t cells, b cells, & NK cells; involved in adaptive immunity

Lymphoid system of cells that phagocytize of innate immunity

carries microbes to lymph nodes where B & T lymphocytes, macrophages (lymphocytes/phagocytic cells) encounter & destroy the pathogen

Mechanisms of phagocytosis (4)

- chemotaxis

- adherence

- ingestion

- digestion

chemotaxis (2)

- chemical signals attract phagocytes to microbes

- include microbial products, components of WBCs, damaged cells, complement

adherence (3)

- attachment of a phagocyte to the surface of the microbe

- PAMPs on microbes attach to TLRs on phagocyte surfaces

- opsonization

opsonization of adherence

microbe is coated w/ serum proteins, making adherence easier

ingestion (3)

- pseudopods (projections on phagocyte) extend out & engulf the microbe

- engulfed. microbe is enclose in a phagosome

- phagosome becomes acidic (pH 4) - activates hydrolytic enzymes

digestion (3)

lysosome fuses with phagosome to form phagolysosome which breaks down and destroys pathogens, leftover material forms a residual body that is removed by exocytosis

inflammation as innate immunity

- destroys injurious agent or limits its effects on the body

- repairs & replaces tissue dmged by injurious agent

fever as an innate immunity

- cytokines cause hypothalamus to release prostaglandis that reset hypothalamus to higher temp (maintained until cytokines are eliminated)

what happens when body temp falls during a fever

vasodilation & sweating

factors that make a fever a defense (4)

- phagocytes & t cells work better at higher temp

- higher temp intensifies effect/production of other antimicrobial substances (interferons, transferrins)

- higher temp slows pathogen growth

- increase metabolic rate repair process

what the complement system in innate immunity

serum proteins prod. by the liver that enhances the immune system in destroying microbes

how are proteins in the complement system organized and named

- uppercase C & numbered in order of discovery (C1, C2, C3)

- activated fragments indicated with lowercase a & b (C3a, C3b)

Pathways for the complement system (3)

- classical

- alternative

- lectin

complement system; the classical pathway (5)

- antibodies bind to antigens (activating C1)

- C1 splits (activating C2 & C4)

- C2a & C4B combine & activate C3

- C3a functions in inflammation

- C3b functions in cytolysis & opsonization

complement system; alternative pathway (2)

- C3 present in blood combines with factors B, D, & P on microbe surface

- C3 splits into C3a & C3b, functioning the same in the classical pathway

complement system; lectin pathway (3)

- macrophages ingest pathogens, releasing cytokines that stim. lectin prod. in liver

- mannose-binding lectin (MBL) binds to mannose, activating C2 & C4

- C2a & C4b activate C3, which functions the same as the classical & alternative pathways

Outcomes of complement activation (3)

- cytolysis

- opsonization

- inflammation

cytolysis of complement activation

activated complement proteins create a membrane attach complex (MAC)

opsonization of complement activation

promotes attachment of phagocyte to microbe by “tagging it”

inflammation of of complement activation

activated complement proteins bind to mast cells, releasing histamine

interferons of innate immunity

cytokines prod. by cells; have antiviral activity

types of interferons (3)

- IFN-a

- IFN-b

- IFN-Y

IFN-a & IFN-b

triggers neighboring cells to prod. antiviral proteins (AVPs) that stop viral replication

IFN-y

cause neutrophils & macrophages to kill bacteria

Iron-binding proteins as an innate immunity

host proteins bind iron tightly with these proteins bc pathogen compete with host for iron (needed for growth & reproduction)

Types of iron-binding protein (4)

- transferrin

- lactoferrin

- ferritin

- hemoglobin

transferrin

in blood & tissue fluids

lactoferrin

in milk, saliva, mucus

ferritin

in liver, spleen, red bone marrow

hemoglobin

in RBCs

Bacteria response to compete with iron-binding proteins

siderophores

antimicrobial peptides as an innate immunity

short peptides prod. in response to protein & sugar molecules on microbes

antimicrobial peptides functions (4)

- broad spectrum of activity (600+)

- inhibit cell wall synthesis

- form pores in plasma membrane causing lysis

- destroy DNA & RNA

Examples of antimicrobial peptides (3)

- dermicidin (skin)

- cathelicidins (neutrophils, macrophages)

- thrombocidin (platelets)