Pathophysiology
Small
(
?
1
?
m
)
particles
are
more
dangerous
because
they
are
more
likely
to
be
____________________
distally
in
the
respiratory
bronchioles
,
alveolar
ducts
,
and
____________________
.
The
surface
of
these
particles
generates
silicon
-
based
radicals
____________________
lead
to
the
production
of
hydroxyl
,
hydrogen
peroxide
,
and
other
____________________
radicals
that
damage
cell
membranes
by
lipid
peroxidation
and
____________________
essential
cell
proteins
.
Alveolar
macrophages
ingest
the
particles
,
____________________
activated
,
and
release
cytokines
,
including
tumor
necrosis
____________________
,
interleukin
-
1
,
and
leukotriene
B
-
4
,
as
well
as
chemotactic
factors
that
____________________
other
inflammatory
cells
.
The
ensuing
inflammation
damages
____________________
cells
and
the
extracellular
matrix
.
Transforming
growth
factor
?
alpha
____________________
proliferation
of
type
2
pneumocytes
,
and
other
cytokines
(
eg
,
platelet
-
derived
growth
factor
,
insulin
-
like
growth
factor
)
stimulate
fibroblasts
____________________
proliferate
and
produce
collagen
;
fibrosis
results
.
Silica
particles
____________________
the
alveolar
macrophages
that
ingested
them
,
thereby
continuing
the
____________________
of
injury
.
