Summary
Summary Topic 2 Gas Exchange
Edexcel Biology Topic 2 Gas Exchange, Alveoli, Surface Area
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Gas exchange surfacesEpithelium Eithelial cells/tissuel
P
layer/lining
↳ alveoli
airways
+
S.I units Squamous -
flat cells - reduces
diffusion distance
Columnar -
>
airways
Simple
layered
=
Single epithelial tise
stratified ered epithelial tissue
Psuedostratified columnar -
appears
to be multiple layers but is
single
The
airways are
psuedostratified columnar epithelial cell which
are ciliated
Top membrane of epithelial cells is the apical membrane
Lower membrane is the basal membrane connected to the basement
membrane
Cilia -
hairlike structures on cells within
airways
Cells which ciliated
waft away from
-
are mucus
the to be
lungs coughed or swallowed
Mucus -produced and secreted
by goblet cells found in the airways
-
traps dust, debris and pathogens to protect longs
-
Mucus is H2O and Mucins (glycoproteins) gel
-
like substance
Villi hair like
projections formed by cells
folding the
lining of the
-
on
small intestine
-
Microvilli , found the cells
on he
in villi
byhe phospholipid membrane
folding
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