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Chapter 16 Obj 02

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Chapter 16 Obj 02

  1. 1. 16.2
First
Lines
of
Defense
 List
and
describe
the
physical
factors
of
the
first
 line
of
defense
of
the
human
immune
system.

 a)  How
do
skin
and
the
mucous
membranes
 provide
immunity?
 b)  How
do
tears,
saliva,
urinaCon,
perspiraCon
 and
vaginal
secreCons
provide
protecCon?
 c)  How
is
the
protecCon
provided
by
hair
(nose
 hairs,
eyelashes)
different
from
that
provided
 by
cilia?

  2. 2. 1st
Lines
of
Defense:
 Skin
&
Mucous
Membranes
 •  Mechanical
protecCon
‐
Barrier
 –  skin
(epidermis)
closely
packed,

 
keraCnized
cells
 •  shedding
helps
remove

 
microbes
 •  Hard
to
penetrate
through
 –  mucous
membrane
secretes

 
mucus:
trap
&

 
move
microbes
 
as
a
“ciliary
 
escalator”

  3. 3. 1st
Lines
of
Defense:
Hair
 •  Mechanical
protecCon
–
Barrier
 •  Nose,
eyelashes,
eyebrows,
ear
 •  Block
entry
by
parCcles
into
the
moist
environments
 of
the
eye,
outer
ear
and
respiratory
tract
 Ear
hair
champion!

  4. 4. 1st
Lines
of
Defense:
 SecreCons
‐
Rinsing
 •  Tears,
vaginal

 
secreCons,
perspiraCon

 
&
saliva
conCnually

 
rinse
or
wash
surfaces

 
to
prevent
microbes
from
colonizing
 •  Expelling
of
materials
by
defecaCon,
urinaCon,
 emesis,
sneezing,
coughing
achieves
a
similar
 effect

  5. 5. 1st
Lines
of
Defense:


 SecreCons
‐
Chemical
 •  Some
secreCons
have
a
low
pH
that

 
creates
an
inhospitable
environment
 
for
many
microbes
 –  Gastric
juice:
pH
3
 –  Vaginal
secreCons/lacCc
acid:
pH
4.0
 –  Urine:
pH
6
 •  Lysozyme
is
an
enzyme
present
in
saliva,
tears,
urine,
 nasal
mucus,
sweat
 –  Enzyme
that
metabolizes
pepCdoglycan
 –  PepCdoglycan
is
a
component
of
bacterial
cell
walls
 –  More
effecCve
against
Gram
posiCve

  6. 6. 1st
Lines
of
Defense:
 Microflora
 •  10x
as
many
microbial
cells
colonizing
our

 
surfaces
as
there
are
human
cells
in
the
enCre
body
 •  Skin
&
hair
 –  Harmless
microbes
feed
on
sebum,
other
secreCons
&
dead
skin
 cells
 –  Acinetobacter
johnsonii,
Staphylococcus
aureus,
Candida
 albicans,
Demodex
folliculorum
 –  CompeCCon
for
territory
excludes
pathogens
 •  GI
tract
 –  Lactobacillus
acidophilus,
Escherichia
coli,
Bifidobacterium
 bifidum
 –  Acids
&
anCmicrobial
chemicals
released
to
prevent
pathogens
 •  Vagina
 –  Lactobacillus
acidophilus
 –  Produces
lacCc
acid
as
a
result
of
glycogen
metabolism


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