Cliffs AP Biology, 2nd Ed. vs.people.artcenter.edu/~jtsao1/m2/content/comm2_response... ·...
14
L L “The Digestive System” an excerpt from Cliffs AP Biology, 2nd Ed. vs. “Goodwork” by Julia Tsao julia_comm2_03.indd 1-2 julia_comm2_03.indd 1-2 4/16/08 2:34:38 AM 4/16/08 2:34:38 AM
Transcript of Cliffs AP Biology, 2nd Ed. vs.people.artcenter.edu/~jtsao1/m2/content/comm2_response... ·...
LL
“Th
e D
iges
tive
Sys
tem
” an
exc
erpt
fro
m
Clif
fs A
P B
iolo
gy,
2nd
Ed.
vs. “G
oodw
ork
” by
Ju
lia
Tsa
o
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Ms.
T w
aass m
y el
evenen
th g
rade
BBio
logy
teeac
ha
er.
She
S re
mai
nsns to
this
dayay o
ne o
f thhee
gre
ates
t dt es
igne
rs I’
vIe
ever
me
met
.
Whe
n I w
aw
as in
my
junni
or y
ear o
f hf hig
h sc
hoooo
l, M
s. T
hahad
grac
iousus
ly a
ccep
teded
the
ardu
ouous
task
of tf
each
ing
AAd-
vvanc
ed P
lacce
men
t Bioio
logy
to m
ym
y ov
erly
aanx
ious
and
sdlig
htly
nneu
re
otic
cla
sass
of o
verr-a-a
chie
vers
. I w
as d
ecid
eid
dly
outut o
f pla
ce. H. H
ard
ly a
n nov
erac
hieev
erv in
any
y se
nse
of tf t
he w
ord
, I wI
as a
lonne
lye d
rifttee
r in
the
mmid
st o
f a a se
a of
wwou
ld-b
e d
ocd
tors
aand
sur
geoeo
ns. T
o m
a
ke m
am
atte
rs w
ororse
,
I hhate
dd scc
iienc
ee.
12
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AM
The
Dig
esti
ve S
yste
m
Dig
estio
n is
the
chem
ical
bre
akdo
wn
of f
ood
into
sm
alle
r m
olec
ules
. In
an in
divi
dual
cel
l, di
gest
ion
is a
ccom
plis
hed
by in
trac
ellu
lar
dige
stio
n w
hen
a ly
osom
e co
ntai
ning
dig
estiv
e en
zym
es m
erge
s w
ith a
foo
d va
cuol
e. I
n m
ost a
nim
als,
how
ever
, the
foo
d in
gest
ed is
too
larg
e to
be
engu
lfed
by
indi
vidu
al c
ells
. Thu
s, f
ood
is fi
rst d
iges
ted
in a
gas
trov
ascu
lar
cavi
ty b
y ex
trac
ellu
lar
dige
stio
n an
d th
en a
bsor
bed
by in
divi
dual
cel
ls.
Dur
ing
dige
stio
n, f
our
diff
eren
t gro
ups
of m
olec
ules
are
com
mon
ly e
ncou
nter
ed. E
ach
is b
ro-
ken
dow
n in
to it
mol
ecul
ar c
ompo
nent
s by
spe
cifi c
enz
ymes
, and
fol
low
s:
1. S
tarc
hes
are
brok
en d
own
into
glu
cose
mol
ecul
es.
2. P
rote
ins
are
brok
en d
own
into
am
ino
acid
s.
3. F
ats
(or
lipid
s) a
re b
roke
n do
wn
into
gly
cero
l and
fat
ty a
cids
.
4. N
ucle
ic a
cids
are
bro
ken
dow
n in
to n
ucle
otid
es.
In h
uman
s an
d ot
her
mam
mal
s, d
iges
tion
follo
ws
the
follo
win
g se
quen
ce o
f ev
ents
. In
part
icu-
lar,
note
whi
ch k
inds
of
mol
ecul
es a
re d
iges
ted
(bro
ken
dow
n) a
nd b
y w
hich
enz
ymes
. Sin
ce
enzy
mes
are
spe
cifi c
for
dif
fere
nt b
onds
, onl
y a
repr
esen
tativ
e fe
w o
f th
e nu
mer
ous
enzy
mes
ar
e gi
ven.
1.
Mou
th.
Saliv
ary
amyl
ase,
sec
rete
d in
to th
e m
outh
by
the
saliv
ary
glan
ds, b
egin
s
the
bre
akdo
wn
of s
tarc
h in
to m
alto
se (
a di
sacc
hari
de).
Che
win
g re
duce
s th
e si
ze
of
food
par
ticle
s, th
ereb
y in
crea
sing
the
surf
ace
area
upo
n w
hich
am
ylas
e an
d su
b
s
eque
nt e
nzym
es c
an o
pera
te. F
ood
is s
hape
d in
to a
bal
l, or
bol
us, a
nd th
en s
wal
-
l
owed
.
2.
Pha
rynx
. Whe
n fo
od is
sw
allo
wed
and
pas
sed
into
the
thro
at, o
r ph
aryn
x, a
fl ap
of
t
issu
e, th
e ep
iglo
ttis
, blo
cks
the
trac
hea
so th
at s
olid
and
liqu
id m
ater
ial e
nter
onl
y
the
eso
phag
us.
3.
Eso
phag
us. F
ood
mov
es th
roug
h th
e es
opha
gus,
a tu
be le
adin
g to
the
stom
ach,
by
m
uscu
lar
cont
ract
ions
cal
led
peri
stal
sis.
4.
Sto
mac
h. T
he s
tom
ach
secr
etes
gas
tric
jui
ce, a
mix
ture
of
dige
stiv
e en
zym
e an
d
hyd
roch
lori
c ac
id, (
HC
l), a
nd s
erve
s a
vari
ety
of f
unct
ions
, as
follo
ws:
• S
tora
ge. B
ecau
se o
f its
acc
ordi
onlik
e fo
lds,
the
wal
l of
the
stom
ach
can
e
xpan
d to
sto
re tw
o to
fou
r lit
ers
of m
ater
ial.
• M
ixin
g. T
he s
tom
ach
mix
es th
e fo
od w
ith w
ater
and
gas
tric
juic
e to
pro
duce
a c
ream
y m
ediu
m c
alle
d ch
yme.
• P
hysi
cal b
reak
dow
n. M
uscl
es c
hurn
the
cont
ents
of
the
stom
ach,
phy
sica
lly
b
reak
ing
food
dow
n in
to s
mal
ler
part
icle
s. I
n ad
ditio
n, H
Cl f
rom
the
gast
ric
jui
ce d
enat
ures
(or
unf
olds
) pr
otei
ns a
nd lo
osen
s th
e ce
men
ting
subs
tanc
es
b
etw
een
cells
of
the
food
. Als
o, th
e H
Cl k
ills
mos
t bac
teri
a th
at m
ay
a
ccom
pany
the
food
.
• C
hem
ical
bre
akdo
wn.
Pro
tein
s ar
e ch
emic
ally
bro
ken
dow
n (d
iges
ted)
by
the
enzy
me
peps
in. S
tom
ach
cells
pro
duci
ng p
epsi
n ar
e pr
otec
ted
from
sel
f -d
iges
tion
beca
use
they
pro
duce
and
sec
rete
an
inac
tive
form
, pep
sino
gen.
Pep
sion
ogen
is a
ctiv
ated
into
pep
sin
by H
Cl,
whi
ch is
pro
duce
d by
othe
r st
omac
h ce
lls. T
hus,
onl
y af
ter
peps
inog
en is
sec
rete
d in
to th
e st
omac
h
ca
vity
can
pro
tein
dig
estio
n be
gin.
Onc
e pr
otei
n di
gest
ion
begi
ns, t
he s
tom
ach
is p
rote
cted
by
a la
yer
of m
ucus
sec
rete
d by
stil
l oth
er c
ells
in th
e hu
man
linin
g. F
ailu
re o
f th
e m
ucus
to p
rote
ct th
e st
omac
h ca
n le
ad to
lesi
ons,
or
pept
ic u
lcer
s. L
ong
belie
ved
to b
e ca
used
by
stre
ss, d
iet,
or o
ther
fac
tors
,
mos
t ulc
ers
are
now
kno
wn
to b
e ca
used
by
bact
eria
and
can
be
succ
essf
ully
trea
ted
with
ant
ibio
tics.
• C
ontr
olle
d re
leas
e. M
ovem
ent o
f ch
yme
into
the
smal
l int
estin
e is
reg
ulat
ed
by
a v
alve
at t
he e
nd o
f th
e st
omac
h, th
e py
lori
c sp
hinc
ter.
Gas
trin
is p
rod-
uced
by
cells
in th
e st
omac
h lin
ing
whe
n fo
od r
each
es th
e st
omac
h or
whe
n
the
nerv
ous
syst
em, t
hrou
gh s
mel
l or
sigh
t, se
nses
the
avai
labi
lity
of f
ood.
Gas
trin
ent
ers
the
bloo
d st
ream
and
stim
ulat
es o
ther
cel
ls o
f th
e st
omac
h to
prod
uce
gast
ric
juic
es.
5.
Sm
all i
ntes
tine
. The
fi rs
t tw
enty
-fi v
e m
eter
s of
the
smal
l int
estin
e, th
e du
oden
um,
con
tinue
s th
e di
gest
ion
of s
tarc
hes
and
prot
eins
(w
hich
beg
an in
the
mou
th a
nd
sto
mac
h, r
espe
ctiv
ely)
as
wel
l as
all r
emai
ning
foo
d ty
pes
(inc
ludi
ng fa
ts a
nd
nuc
leot
ides
). S
ecre
tin is
pro
duce
d by
the
cells
lini
ng th
e du
odeu
m w
hen
food
e
nter
s. S
ecre
tin s
timul
ates
the
panc
reas
e to
pro
duce
bic
arbo
nate
whi
ch, w
hen
de
p
osite
d in
to th
e sm
all i
ntes
tine,
neu
tral
ize
the
acid
ity o
f th
e ch
yme.
Foo
d le
aves
t
he d
uode
num
and
ent
ers
the
jeju
num
and
then
the
ileum
(th
e fi n
al p
art o
f th
e sm
all
int
estin
e). E
nzym
es f
or th
ese
vari
ous
proc
esse
s or
igin
ate
from
the
follo
win
g
s
ourc
es.
• S
mal
l int
esti
ne. T
he w
all o
f th
e sm
all i
ntes
tine
is th
e so
urce
of
vari
ous
enz
ymes
, inc
ludi
ng p
rote
olyt
ic e
nzym
es (
or p
rote
ases
, enz
ymes
that
dig
est
pr
otei
ns, s
uch
as a
min
opep
tida
se),
mal
tase
and
lact
ase
(for
the
dige
stio
n
o
f di
sacc
hari
des)
, and
pho
spha
tase
s (f
or th
e di
gest
ion
of n
ucle
otid
es).
Cho
lecy
stok
inin
is p
rodu
ced
by th
e sm
all i
ntes
tine
to s
timul
ate
the
gallb
lad
d
er to
rel
ease
bile
and
the
panc
reas
to r
elea
se it
s en
zym
es.
• P
ancr
eas.
The
pan
crea
se p
rodu
ces
vari
ous
enzy
mes
, inc
ludi
ng t
ryps
in
a
nd c
hym
otry
psin
(pr
otea
ses)
, lip
ase
(dig
estio
n of
fat
s), a
nd p
ancr
eati
c
am
ylas
e (d
iges
tion
of s
tarc
h). T
hese
and
oth
er e
nzym
es, p
acka
ged
in a
n
al
kalin
e so
lutio
n th
at s
erve
s to
neu
tral
ize
the
HC
l in
the
chym
e, e
nter
the
duo
denu
m th
roug
h th
e pa
ncre
atic
duc
t.
• L
iver
. The
live
r pr
oduc
es b
ile, w
hich
fun
ctio
ns to
em
ulsi
fy f
ats.
Em
ulsifi c
a-
tion
is th
e br
eaki
ng u
p of
fat
glo
bule
s in
to s
mal
ler
fat d
ropl
ets,
incr
easi
ng
th
e su
rfac
e ar
ea u
pon
whi
ch f
at-d
iges
ting
enzy
mes
(lip
ase,
or
exam
ple)
can
oper
ate.
Sin
ce b
ile d
own
not c
hem
ical
ly c
hang
e an
ythi
ng, i
t is
not a
n en
-
34
julia
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julia
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AM
zy
me.
Bile
is a
lso
alka
line,
ser
ving
to h
elp
neut
raliz
e th
e H
Cl i
n th
e ch
yme.
The
bile
is s
tore
d ad
jace
nt to
the
liver
in th
e ga
llbla
dder
and
fl ow
s th
roug
h
th
e bi
le d
uct w
here
it m
erge
s w
ith th
e pa
ncre
atic
duc
t.
The
rem
aind
er o
f th
e sm
all i
ntes
tine
(nea
rly
six
met
ers)
abs
orbs
the
brea
k-
do
wn
prod
ucts
of
food
. It i
s ch
arac
teri
zed
by v
illi a
nd m
icro
villi
, fi n
gerl
ike
proj
ectio
ns o
f th
e in
test
inal
wal
l tha
t inc
reas
e its
tota
l abs
orpt
ive
surf
ace
area
. Am
ino
acid
s an
d su
gars
are
abs
orbe
d in
to b
lood
cap
illar
ies,
whi
le m
ost
of
the
fatty
aci
ds a
nd g
lyce
rol a
re a
bsor
bed
into
the
lym
phat
ic s
yste
m.
6.
Lar
ge in
test
ine.
The
mai
n fu
nctio
n of
the
larg
e in
test
ine,
or
colo
n, is
the
reab
sorp
-
t
ion
of w
ater
to f
orm
sol
id w
aste
r, or
fec
es. V
ario
us h
arm
less
bac
teri
a liv
e in
the
l
arge
inte
stin
e, in
clud
ing
som
e th
at p
rodu
ce v
itam
in K
, whi
ch is
abs
orbe
d th
roug
h
the
inte
stin
al w
all.
At t
he b
egin
ning
of
the
larg
e in
test
ine,
ther
e is
a s
hort
bra
nch
to
a d
ead-
end
pouc
h w
hich
bea
rs a
fi ng
erlik
e pr
ojec
tion
calle
d th
e ap
pend
ix. O
ther
tha
n a
poss
ible
rol
e in
the
imm
une
resp
onse
, the
app
endi
x is
sig
nifi c
ant o
nly
whe
n
it b
ecom
es infl a
med
, cau
sing
app
endi
citis
. Foo
d th
en tr
avel
s up
war
d in
the
asce
nd-
ing
col
on. T
he f
ood
trav
els
acro
ss th
e ab
dom
en in
the
tran
sver
se c
olon
, goe
s ba
ck
dow
n th
e ot
her
side
of
the
body
in th
e de
scen
ding
col
on, a
nd th
en th
roug
h th
e si
g-
m
oid
colo
n.
7.
Fec
es a
re s
tore
d at
the
end
of th
e la
rge
inte
stin
e, in
the
rect
um, a
nd e
xcre
ted
thr
ough
the
anus
.
Too
mee,
B
ioolo
ggy
wwas
mm
errel
yy thh
e lee
sser
of tt
woo
evils
; 5
6ju
lia_c
omm
2_03
.indd
7-
8ju
lia_c
omm
2_03
.indd
7-
84/
16/0
8 2
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40 A
M4/
16/0
8 2
:34:
40 A
M
a w
eelco
mme
altte
r-na
tivve
to t
he pp
er-
pet
uual
head
aache
I
kknew
aw
aaite
d
me
in P
hhysi
cs..
Do
-in
g w
ell
in B
ioolo
gy,
th
ooug
h dd
esiraa
ble
too
m
ee in
the
abb
stra
ctt,
wass
ha
rdly
aa
hig
hh p
riiorit
y o
n mm
y si
xx-te
een y
eear-
oldd
ag
en-
daa.
MM
y p
lan
wwas
too
bre
eeze
bby
in tt
he
clas
s, g
et mm
y unn
its,
annd
get
thee
hel
l out
.
OOn
thhe
fi rrst
d
aay
of
cclas
s,
eacch
st
uuden
t ww
as
giv
enn
an
eig
ht--
ppo
unnd
te
xxtb
ooo
k an
dd
assi
ggne
d
four
ch
app-
tters
of
reead
ing
, d
uue
the
next
d
ay..
I w
as
aghaa
st——
my
“eass
y”
sciee
nce
class
s ww
as
turnn
ing
oout
too
be
wway
m
orre
woo
rk t
hhan
I ha
d
imaag
ined
. So
I d
id ww
hat
anyy
diss
inte
reest
ed
and
le
thar
gic
kid
wo
uld
do
:: I
dday
drre
ameed
m
yy w
ayy
thrro
ughh
clas
ss, to
sssed
the
boo
ok
in
myy
lockk
er
annd
w
eent t
oo g
o ww
atch
aa m
ovvi
e w
ith mm
y eq
ually
dis
intte
r-ess
ted
aand
letth
arg
ic fr
iennd
s.
TThhe
neextt
mmonn
th a
t sc
hoool
wwas
hel
l.MM
s.
TT’s
bbiw
eekkl
y ex
ams
hhad
me
teet
erin
g oo
n th
e eed
gee
of
ddis
astee
r—d
isas
terr
bei
ngg C
-mmin
us,
a m
ere
2%%
awayy
fro
mm th
e d
reaad
ed DD
. A
n dd I
waas
n’t aa
lonee
. Mo
re
thann
haa
lf oo
f m
yy cl
ass-
matt
es
wer
ee stt
rug
gllin
g
righht
thee
re ww
ith mm
e, s
oom
e fa
rinng
evve
n ww
ors
ee th
ann m
y ssh
ammef
ul
C-m
inuus
. So
me-
thin
gg h
add to
bbe
doo
ne. I
sw
oree
too
myys
elf t
hat I
wo
uuld
brrin
g u
pp
my
grra
de
beff
ore
the
midd
-see
mees
ter
grra
dinn
g pp
erio
d.
AAnd
sso
I fi
nnal
lyy u
neear
thhed
tth
e nee
glee
cteed
eei
ghht
-po
und
t ee
xtb
ooo
k aan
d d
raag
geed
it b
ackk
hoomm
e ww
ith m
ee. I
flfl ip
pped
it o
peen
, o
pptimm
isttic
aand
read
y too
read
, beef
ore
78
julia
_com
m2_
03.in
dd
9-10
julia
_com
m2_
03.in
dd
9-10
4/16
/08
2:3
4:41
AM
4/16
/08
2:3
4:41
AM
slam
mmin
g i
t shh
uut a
fter
aa m
ere
155 m
inut
ess o
f ef
-fo
rt.
Thee
text
bo
okk,,
an
agedd
,, d
ecre
ppiitt
thin
g,
wwas
a
nnig
htm
are;
aa g
litte
riinngg
sym
boo
ll o
f ev
erryyt
hing
II h
at-
e dd aa
bo
ut b
iolloo
ggy
and
ssci
ence
iinn
gen
eraal
. It
lacc
kked
an
y dd
iisstin
gui
shabb
llee c
larit
y, aa
nd w
as fifi
lled
wiitthh
pag
e aaf
-te
r p
agee
of
bo
ringg
sc
ienc
e-tte
xt
andd
co
mp
liccaat
ed
ddiiaa
-gg
ram
s. I
fel
tt ch
eate
d,
aannd
ro
yalllyy
scr
ewedd
.. H
ow
wwaas
I s
upp--
poo
ssed
to
dig
mmyys
elf
out
off
mmy
hole
wwith
suc
hh aa
shit
teexxt
bo
ok??
I wen
t too
ssch
oo
l the
neex
t day
, irr
ittaate
d a
ndd oo
n th
e o
ffffeens
ive.
I nne
ed-
ed to
kno
w ww
hat I
was
supp
ppo
sed
to dd
o; g
iven
mmy
sco
reess
in th
e ccll
ass
and
lack
ing
tthhe
res
our
cess
I ne
ededd
tto
stu
ddyy
on
my
oow
n. WW
hheen
Ms.
T w
alke
d in
ttoo o
ur s
ixth
ppeer
iod
Bio
lloogg
y cl
asss,
for
the
fifi rst
tim
ee,,
I sat
uupp
a li
ttle
str
aiigg
hter
. I h
add a
pur
po
ssee t
hat
ddaayy
. Ms.
T cc
olle
ctt-
ed h
er nn
otes
and
maadd
e he
r waayy
up
to thh
ee ov
erhhee
ad p
roojjee
ct
o
r,fl i
pp
ed thh
ee sw
itch,
andd
beg
an tthh
at d
ay’s
lleect
uree
oon th
e
dd
igess
tt-iv
e sy
stem
. SShe
beg
ann tt
he le
ssoo
n, a
nd II
wat
chheed
,
amm
azedd
, as
I wen
t ho
mme
that
nig
ht a
nd re
aad o
ver
my
lect
urree
not
e
ss se
vera
l tim
ees. I
had
a fe
w u
n-an
sswwer
ed q
uest
ions
I nee
eeded
ans
wer
ed, ss
o
I fl
ipppp
ed t
hro
ugghh
my
text
bo
ok
in a
hhaal
f-he
arte
d a
ttem
ptt
to fi
ll in
the
blaa
n
ks. T
o mm
y su
rpri
se, I
foun
d m
ysel
f geett
tting
lost
in t
he b
ooo
k. Im
ages
of
in
test
inee
ss an
d e
n-
zym
es d
ance
d t
hroo
uugh
my
head
, pai
nttiinn
g a
cle
ar
p
ictu
re o
f thhee
func
-tio
nalit
y, fl
uid
ity, a
n dd iill
lust
rious
ness
of t
hhee h
uman
bb
ood
y. I
was
amm
az-
ed a
t th
e p
ow
er o
f Ms.
T’s
lect
ure,
its
visu
aall c
lari
ty
, anndd
ho
w it
hadd
b
een
able
to
act
as
such
aa s
tro
ng c
om
ple
meenn
t
to
the
vver
bo
se
910
julia
_com
m2_
03.in
dd
11-1
2ju
lia_c
omm
2_03
.indd
11
-12
4/16
/08
2:3
4:43
AM
4/16
/08
2:3
4:43
AM
annd
onn
e-d
iime
siio
nal
te
xtbb
oo
k. H
er
teac
hin
g
mmet
hod
waas
so
absu
rdly
si mm
ple
: sshe
took
thee
fact
s la
id o
uut in
the
i
mpo
ssib
lee te
xt-
boo
ok
aand
ppre
seen
tedd
th
eem
in a
str
aig
htf
orr
ww
ard
, vis
uually
-co
mmp
eellin
gg w
ay.. I
hadd
nevv
er s
eeen
sciee
nce
in
tthi
s ki
nd o
f lig
ht,
andd
I w
aas in
trig
ued
andd
exc
itted
. Ms.
T’s
mmet
hod
s
wwe
re,
I q
uic
kly
learr
ned
, inv
aalua
ble
to
mmy
suucc
ess
in t
he c
our
se,,
aan
d in
lifee
. I
was
ins pp
iredd
. I w
aante
dd t
o lee
arn
eever
ythhi
ng I
ccoul
d a
bb
oout
the
lifee
sci
ence
s.
Latee
r thh
at y
eear,
aafte
r M
s. T
’s c
lass
, I s
eent
outt
mm
y un
iverr
sity
ap
plic
aa-tio
nns w
ith a
maj
oor in
BBio
logg
y. M
s. T
’s tee
achi
ngg
hhad
stir
reed
in m
e a
sens
e o
f pp
assii
on
ffor
thhe
sciie
ncees
tha
t I h
add n
ever
bb
efo
re k
no
wn
exi
ste
d.
Bio
log
y A
P ww
ith
Ms.
T t
auug
ht mm
e to
lloo
k foo
r
dd
esig
n in
the
mo
st uu
nexp
ecte
d o
f
pla
cces,
tto ta
ke ri
ggid
and
sttr
uctu
rred
exxp
erie
nc
ee
s an
d id
eeas,
and
imbb
ue in
them
a s
ense
Ms.
T11
12ju
lia_c
omm
2_03
.indd
13
-14
julia
_com
m2_
03.in
dd
13-1
44/
16/0
8 2
:34:
48 A
M4/
16/0
8 2
:34:
48 A
M
The
Dig
esti
ve S
yste
m
Dig
edi
geen
zyto
be
extr
Dur
ike
n
In h
ula
r, n
enzy
are
g
o
f fo
od p
artic
les,
ther
eby
incr
easi
ng
seq
uent
enz
ymes
can
ope
rate
. Foo
d is
sha
ped
into
a b
all,
or b
olus
, and
then
sw
al-
l
owed
.
2. P
hary
nx. W
hen
food
is s
wal
low
ed a
nd p
asse
d in
to th
e th
roat
, or
phar
ynx,
a fl
ap o
f
tis
sue,
the
epig
lott
is, b
lock
s th
e tr
ache
a so
that
sol
id a
nd li
quid
mat
eria
l ent
er o
nly
the
eso
phag
us.
3. E
soph
agus
. Foo
d m
oves
thro
ugh
the
esop
hagu
s, a
tube
lead
ing
to th
e st
omac
h, b
y
m
uscu
lar
cont
ract
ions
cal
led
peri
stal
sis.
4. S
tom
ach.
The
sto
mac
h se
cret
es g
astr
ic j
uice
, a m
ixtu
re o
f di
gest
ive
enzy
me
and
h
ydro
chlo
ric
acid
, (H
Cl)
, and
ser
ves
a va
riet
y of
fun
ctio
ns, a
s fo
llow
s:
•
Sto
rage
. Bec
ause
of
its a
ccor
dion
like
fold
s, th
e w
all o
f th
e st
omac
h ca
n ex
pand
to s
tore
two
to f
our
liter
s of
mat
eria
l.
•
Mix
ing.
The
sto
mac
h m
ixes
the
food
with
wat
er a
nd g
astr
ic ju
ice
to p
rodu
ce
a c
ream
y m
ediu
m c
alle
d ch
yme.
•P
hysi
cal b
reak
dow
n. M
uscl
es c
hurn
the
cont
ents
of
the
stom
ach,
phy
sica
lly
bre
akin
g fo
od d
own
into
sm
alle
r pa
rtic
les.
In
addi
tion,
HC
l fro
m th
e ga
stri
c
juic
e de
natu
res
(or
unfo
lds)
pro
tein
s an
d lo
osen
s th
e ce
men
ting
subs
tanc
es
betw
een
cells
of
the
food
. Als
o, th
e H
Cl k
ills
mos
t bac
teri
a th
at m
ay
Dig
estio
n is
the
chem
ical
bre
akdo
wn
of f
ood
into
sm
alle
r m
olec
ules
. In
an in
divi
dual
cel
l,di
gest
ion
is a
ccom
plis
hed
by in
trac
ellu
lar
dige
stio
n w
hen
a ly
osom
e co
ntai
ning
dig
estiv
ege
stiv
een
zym
es m
erge
s w
ith a
foo
d va
cuol
e. I
n m
ost a
nim
als,
how
ever
, the
foo
d in
gest
ed is
too
larg
el
to b
e en
gulf
ed b
y in
divi
dual
cel
ls. T
hus,
foo
d is
fi rs
t dig
este
d in
aga
stro
vasc
ular
cavi
tyca
vity
by
by
extr
acel
lula
rdi
gest
ion
and
then
abs
orbe
d by
indi
vidu
al c
ells
.
Dur
ing
dige
stio
n, f
our
diff
eren
t gro
ups
of m
olec
ules
are
com
mon
ly e
ncou
nter
ed. E
ach
is b
ro-
ach
is b
roac
his
bro
ken
dow
n in
to it
mol
ecul
ar c
ompo
nent
s by
spe
cifi c
enz
ymes
, and
fol
low
s:
1. S
tarc
hes
are
brok
en d
own
into
glu
cose
mol
ecul
es.
ecul
es
2P
rote
ins
are
brok
endo
wn
into
amin
oac
idss
hyd
roch
lori
c ac
id, (
HC
l), a
nd s
erve
s a
vari
ety
of f
unct
ions
, as
follo
ws:
gp
yp
yd
ih
di
tb
llt
bl
dth
ld
thon
s, a
s fo
llow
s:tio
ns, a
s fo
llow
s:
• S
tora
ge. B
ecau
se o
f its
acc
ordi
onlik
e fo
lds,
the
wal
l of
the
stom
ach
can
hew
all
expa
nd to
sto
re tw
o to
fou
r lit
ers
of m
ater
ial.al
•ch
easo
that
solid
ad
Mix
ing
ndliq
uind
liqui
. The
sto
mac
h m
ixes
the
food
with
wat
er a
nd g
astr
ic ju
ice
to p
rodu
ce
,p
y,
pp
y,
pid
mat
eria
lent
eron
lyid
mat
eria
lent
eron
lyd
gast
ric
juic
e to
pro
er a
nd g
astr
ic ju
ice
to p
rodu
ce
er a
nd g
astr
ic ju
ice
to p
rodu
c a
cre
am y
med
ium
cal
led
qqch
yme
yy.
• P
hysi
cal b
reak
dow
nl
dit
tht
. Mus
cles
chu
rn th
e co
nten
ts o
f th
e st
omac
h, p
hysi
cally
h
bof
the
stom
ach,
phy
sica
llynt
ents
of
the
stom
ach,
phy
sica
lly
brea
king
foo
d do
wn
into
sm
alle
r pa
rtic
les.
In
addi
tion,
HC
l fro
m th
e ga
stri
c
e le
adin
g to
the
stom
ach,
by
e
lead
ing
to th
e st
omac
h, b
y
addi
tion,
HC
l fro
m th
e ga
stri
addi
tion,
HC
l fro
m th
e ga
stri
c
juic
e de
natu
res
(or
unfo
lds)
pro
tein
s an
d lo
osen
s th
e ce
men
ting
subs
tanc
es
astr
icju
ice
am
ixt
betw
een
cells
of
the
food
. Als
o, th
e H
Cl k
ills
mos
t bac
teri
a th
at m
ay
ure
ofdi
gest
ive
enzy
me
and
ure
ofdi
gest
ive
enzy
me
and
llsm
ostb
acte
ria
that
may
llsm
ostb
acte
ria
that
may
1314
est
sti
ym e e ac ing
do
uma
note
yme
give
offo
odpa
rtic
les,
ther
eby
incr
easi
ngth
esu
rfac
ear
eaup
onw
hich
amyl
ase
and
sub
2.P
rote
ins
are
brok
endo
wn
into
amin
oac
ids.s
ubub al-
p of
fp
of ff
nly
nly
nly by
by
mix
ture
of
dige
stiv
e en
zym
e an
d
ure
of d
iges
tive
enzy
me
and
i
tf
fti
fll
gth
esu
rfac
ear
eaup
onw
hich
amyl
ase
and
sub
ear
eaup
onw
hich
amyl
ase
an
c g
GE
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diff
eren
t gro
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olec
ular
com
pon
tarc
hes
are
brok
en d
ow
are
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mam
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yen
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NNoooo
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Cthe
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ase,
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mal
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se
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hari
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h se
cret
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an
julia
_com
m2_
03.in
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2_03
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-16
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/08
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AM
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AM
The Digestive System
Digestion is the chemical breakdown of food into smaller molecules. In an individual cell, digestion is accomplished by intracellular digestion when a lyosome containing digestive enzymes merges with a food vacuole. In most animals, however, the food ingested is too large to be engulfed by individual cells. Thus, food is fi rst digested in a gastrovascular cavity by extracellular digestion and then absorbed by individual cells.
1516
high
light
, and
you
will
suc
ceed
.
co
rnel
l sty
le n
otes
: fol
d th
e pa
ge in
to tw
o co
lum
ns.
voca
bula
ry w
ords
go
on th
e le
ft, d
efi n
itio
ns g
o on
the
righ
t.
fl
ash
card
s ar
e th
e be
st w
ay to
mem
oriz
e an
ythi
ng.
clus
ters
! whe
n yo
u th
ink
of in
form
atio
n du
ring
the
exam
, you
’ll im
agin
e an
imag
e of
the
clus
ter
in y
our
min
d. it
’s vi
sual
lear
ning
. if y
ou w
rite
it e
noug
h ti
mes
, you
’ll re
mem
ber
it.
the
fi rst
lett
er w
ill c
ue y
ou in
. tak
e al
l the
fi rs
t let
ters
and
mak
e a
sent
ence
out
of t
hem
. you
’ll re
mem
ber
it fo
reve
r.
julia
_com
m2_
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-18
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/08
2:3
5:11
AM
Dig
esti
on
Ext
race
llu
lar
dige
stio
n
Per
ista
lsis
Ch
yme
Intr
acel
lula
rdi
gest
ion
Sal
ivar
y am
ylas
e
Hyd
roch
lori
c ac
id
Pep
sin
1718
Diges
tion
Intr
acellu
lar
Diges
tion
Extr
acellu
lar
Diges
tion
4 gr
oups
of m
olec
ules
in d
igest
ion
Star
ches
Prot
eins
Fats
Nucle
ic Ac
ids
chem
ical b
reak
down
of f
ood
into
sm
aller
mol
ecul
es
indiv
idual c
ell
lyso
som
e m
erge
s with
a f
ood
vacu
ole
mos
t an
imals
food
mus
t be
bro
ken
down
food
f ir
st t
aken
into
gas
trov
ascu
lar
cavit
yth
en d
igest
ed a
nd a
bsor
bed
Each
is b
roke
n do
wn
into
it m
olec
ular
com
pone
nts
by s
pecif
ic e
nzym
es
Brok
en d
own
into
glu
cose
mol
ecul
es.
Brok
en d
own
into
am
ino
acids
.
(Lipi
ds) B
roke
n do
wn
into
gly
cero
l and
fat
ty a
cids.
Brok
en d
own
into
nuc
leot
ides.
julia
_com
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03.in
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-20
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5:11
AM
4/16
/08
2:3
5:11
AM
In a
n i
ndi
vidu
al c
ell,
dig
esti
on
is a
ccom
plis
hed
by
intr
acel
lula
r di
gest
ion
wh
en a
lyo
som
e co
nta
in-
ing
dige
stiv
e en
zym
es m
erge
s w
ith
a
food
vac
uol
e
secr
eted
in
to t
he
mou
th b
y th
e sa
liva
ry g
lan
ds, b
egin
s th
e br
eak
-do
wn
of
star
ch i
nto
mal
tose
Th
e st
omac
h s
ecre
tes
gast
ric
juic
e,
a m
ixtu
re o
f di
gest
ive
enzy
me
and
hyd
roch
lori
c ac
id, (
HC
l), a
nd
serv
es a
var
iety
of
fun
ctio
ns
the
chem
ical
bre
akdo
wn
of
food
in
to s
mal
ler
mol
ecu
les
the
chem
ical
bre
akdo
wn
of
food
in
to s
mal
ler
mol
ecu
les
In m
ost
anim
als,
how
ever
, th
e fo
od i
nge
sted
is
too
larg
e to
be
en-
gulf
ed b
y in
divi
dual
cel
ls. T
hu
s,
food
is
firs
t di
gest
ed i
n a
gas
tro-
vasc
ula
r ca
vity
by
extr
acel
lula
r di
gest
ion
an
d th
en a
bsor
bed
by
indi
vidu
al c
ells
.
Mu
scu
lar
con
trac
tion
s
Pro
tein
s ar
e ch
emic
ally
bro
ken
do
wn
(di
gest
ed)
by t
he
enzy
me
peps
in
Sm
all
Inte
stin
e
Du
oden
um
: con
tin
-u
es t
he
dige
stio
n o
f st
arch
es, p
rote
ins,
fat
s,
nu
cleo
tide
s.
Bic
arbo
nat
e:
neu
tral
ize
the
acid
-it
y of
th
e ch
yme
Sec
reti
n: p
rodu
ced
by t
he
cell
s li
nin
g th
e du
odeu
m w
hen
fo
od e
nte
rs
Pan
crea
s: p
rodu
ces
vari
ous
enzy
mes
, in
clu
din
g tr
ypsi
n a
nd
chym
otry
psin
, lip
ase,
an
d pa
ncr
eati
c am
y-la
se
Wal
l of
th
e sm
all
inte
stin
e:so
urc
e of
var
iou
s en
zym
es t
o di
gest
pr
otei
ns
Sec
reti
n:
stim
ula
tes
the
pan
-cr
ease
to
prod
uce
bi
carb
onat
e
1920
julia
_com
m2_
03.in
dd
21-2
2ju
lia_c
omm
2_03
.indd
21
-22
4/16
/08
2:3
5:12
AM
4/16
/08
2:3
5:12
AM
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyl
ase:
beg
ins th
e br
eakd
own
of s
tarc
h int
o m
altos
e
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyl
ase
Saliv
ary
amyl
ase
Saliv
ary
amyl
ase
Saliv
ary
amyl
ase
SALIV
ARY
AMYL
ASE
SALIV
ARY
AMYL
ASE
Saliv
ary
amyl
ase
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
SALIV
ARY AMYL
ASE
Saliv
ary
amyl
ase
Saliv
ary
amyl
ase
begi
ns th
e br
eakd
own
of s
tarc
h in
to m
altos
e
begi
ns th
e br
eakd
own
of
star
ch in
to m
altos
e
begin
s
th
e
brea
kdow
n
o f st
arch
into
m
altos
e
star
ch in
to m
altos
e
begi
ns th
e br
eakd
own
of
star
ch in
to m
altos
e
BEGINS T
HE BRE
AKDOWN
O
F STA
RTCH
Int
o
MALT
OSE
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyl
ase:
beg
ins th
e br
eakd
own
of s
tarc
h int
o m
altos
e
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
star
ch in
to m
altos
e
Saliv
ary
amyl
ase
SALIV
ARY
AMYL
ASE
SALIV
ARY
AMYL
ASE
begi
ns
th
e br
eakd
own
of
sta
rch
into
m
altos
e
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
sta
rch
into
malt
ose
Saliv
ary
amyl
ase:
beg
ins
the
brin
to m
altos
eea
kdow
n of
sta
rch
SALIV
ARY
AMYL
ASE
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sta
rch
into
malt
ose
BEGIN
S The
brea
kdow
n of s
tarch
into
maltos
e
Begin
s the
break
down o
f star
ch in
to malto
se
begins
the b
reakdo
wn of s
tarch
into m
altose
BEGIN
S The
brea
kdow
n of s
tarch
into
maltos
e
BEGIN
S The
brea
kdow
n of s
tarch
into
maltos
e
Saliv
ary
amyla
se: b
egins
the
brea
kdow
n of
sST
ARCH
INTO
MAL
TOSE
Saliv
ary
amyl
ase:
beg
ins
the
brea
kdow
n of
sta
rch
into
malt
ose
2122
julia
_com
m2_
03.in
dd
23-2
4ju
lia_c
omm
2_03
.indd
23
-24
4/16
/08
2:3
5:12
AM
4/16
/08
2:3
5:12
AM
OR
DE
R:
Mea
n
Pu
rple
Egg
plan
ts
Saw
Sal
ty
Lem
ons
OR
DE
R:
Mou
th
Ph
aryn
x
Eso
phag
us
Sto
mac
h
Sm
all
Inte
stin
e
Lar
ge I
nte
stin
e
M P E S S L
2324
julia
_com
m2_
03.in
dd
25-2
6ju
lia_c
omm
2_03
.indd
25
-26
4/16
/08
2:3
5:12
AM
4/16
/08
2:3
5:12
AM
Mo
uth
Ch
ewin
g!
Sta
rch
Mal
tose
Fo
od
bec
om
es B
olu
s,
and
Sw
allo
wed
.
Sto
ma
chG
astr
ic J
uic
em
ixtu
re o
f d
iges
tive
en
zym
e an
d
hy
dro
chlo
ric
acid
.
OU
TR
ectu
mF
eces
are
sto
red
at
th
e en
d o
f th
e la
rge
inte
stin
e, i
n
the
rect
um
, an
d
excr
eted
th
rou
gh
th
e an
us.
La
rge
Inte
stin
eC
olo
nR
eabs
orp
tio
n o
f w
ater
to
fo
rm s
oli
d w
aste
, or
fece
s.
Sm
all
Inte
stin
eD
iges
tio
n o
f st
arch
es
and
pro
tein
s.S
ecre
tin
- to
neu
tral
ize
acid
.
Ph
ary
nx
Ep
iglo
ttis
Blo
cks
the
trac
hea
so
mat
eria
l en
ters
on
ly
the
Eso
ph
agu
s.
Eso
ph
ag
us
Tu
be l
ead
ing
to
th
e st
om
ach
.M
ove
s by
Per
ista
lsis
(m
usc
ula
r co
ntr
acti
on
s)
julia
_com
m2_
03.in
dd
27-2
8ju
lia_c
omm
2_03
.indd
27
-28
4/16
/08
2:3
5:12
AM
4/16
/08
2:3
5:12
AM
