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Final

IMM250H1 Study Guide - Final Guide: Genitourinary System, Commensalism, Antibody


Department
Immunology
Course Code
IMM250H1
Professor
Dana Philpott
Study Guide
Final

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Lecture TWO: INNATE BARRIERS TO INFECTION
overview
x barriers & their medium
x epithelial cells = lining on the skin; are the first to come in contact with bacteria; need to be able to defend themselves and initiate immune responses
x commensal flora ± natural microbes on/in us
x pathogens ± microbes that initiate disease & immune responses
innate barriers ------ > ------ once broken ------ > ------ innate immunity ------ > ------ inflammation occurs ------ > ------ adaptive immunity
skin & mucous membrane cellular & humoral defenses cellular & humoral defences
Ærapidly regenerating surfaces Æcomplement proteins Æantibodies
Æperistallic movement Æphagocytosis Æcytokines
Æmucosillary escalator Æmacrophages ÆT helper cells
Ævomiting Æneutrophils Æcytotoxic T cells
Æflow of tears/urine ÆNK cells
Æcoughing ÆNO
Ælysozyme ÆROS
Æsebaceous/mucous secretions Æcytokines
Æantimicrobial peptides
Æstomach acid
Æcommensal organism
innate immunity
Æimmediately recognizes foreign agents & initiates response
Æsets up adaptive immunity response (T cells, B cells, antibodies etc requires initiation by innate immunity)
innate host defences against infections
anatomical barriers/physical barriers humoral components/blood-borne factors cellular components/innate cellV³GHIHQGHU
Æmechanical factors Æcomplement Æneutrophils
Æchemical factors Æcoagulation system Æepithelial cells
Æbiological factors Æcytokines Æmonocytes & macrophages
ÆNK cells
Æeosinophils
musical surfaces = sites of microbial encounters
Æmouth/nose Æoesophagus Ætrachea/upper respiratory tract Æstomach
Ælarge intestine Æsmall intestine Æurogenital tract
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FIRST LINE DEFENCE STRATEGIES
Location
Defence
Function
eyes
- lysozymes/tears
dissolves cell walls of bacteria
oral cavity
- normal flora
competes with other pathogens
all over body
- skin
physical barrier; produces antimicrobial fatty acids; normal flora inhibits pathogen
colonization
trachea/respiratory tract
- mucous, cilia
lines the trachea suspend and move microorganisms out of the body
all inside body
- blood proteins
inhibit microbial growth
lungs
- mucous & phagocytes
prevent colonization
stomach
- pH (2)
inhibits microbial growth
duodenum
- pH
rapid change inhibits microbial growth
large intestine
- normal flora
competes with pathogens
urogenital tract
- flushing
prevents colonization
ANATOMICAL BARRIERS
System/Organ
Cell Type/Component
Mechanism
MECHANICAL FACTORS
skin
- squamous epithelium
physical barrier
desquamation ± high cell cycle turnover rate allows for high rates of skin
sloughing
mucous membranes
- non-ciliated epithelium (GI tract)
peristalsis ± squeezing of intestine that moves food down, movement
allows for high turnover rate
in GI tract, cells only survive ~3 days, allows for high turnover rate
- ciliated epithelium (respiratory tract)
musociliary escalator
cilia constantly move foreign agents to upper tract to be expelled
- epithelium (nasopharynx)
flushing action of tears, saliva, mucous, urine
CHEMICAL FACTORS
skin
- sweat
antimicrobial fatty acids
mucous membranes
- HCl
low pH
- tears & saliva
lysozymes dissolve bacterial cell walls
phospholipase A dissolves bacterial cell walls
- antimicrobial peptides
- defensisns (respiratory tract & GI tract)
antimicrobial
pokes holes in membranes of bacteria
- surfactants (lung)
opsonin ± enhances phagocytic uptakes by coating bacterial agents for
easier identification
BIOLOGICAL FACTORS
skin & mucous membranes
- normal flora
antimicrobial substances (fungi, bacteria, protozoa, archae) compete for
nutrients and colonization
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