Animal exchange and transport

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Module 2 ­ Exchange and transport
I
n or
der t
o s
u r
vive,
l
ivi
ng cel
ls
need a
sup pl
y of
oxygen
and nut
ri
ent
s.
In
singl
e cel
l
and
smal
l
or
ganisms t
hese ma t
eri
als
can enter
by
pa ssi
ve
processes.
However
once
a n
organism
r
eaches a
cri
ti
cal
size
it
r
equ i
res
special
ised
exchange sur
faces
and
tr
ansport
syst
e ms.
1.2.1 Exchange surfaces and breathing
Single cell and small organisms
large sur
face
area
to vol
ume rat
io.
g ases
nutr
ient
s and
w ast
e can
be exchanged
across
thei
r
out
er
sur
faces
Sma l
l
dist
ance bet
w een
surf
ace and cent
re
of
organi
sm.
Multicellular organisms
Small
surf
a ce
area t
o vol
ume
rat
io
Outer
surf
ace not
lar
ge enough f
or
substance
to
dif
fuse
fast
enough
to
keep
cel
l
ali
ve
Lar
ge
dist
ance between sur
face
and cent
re
of or
ganism
Requir
e speci
a l
i
sed
exchange sur
face
Exchange surface
A speci
ali
sed area
that
is
a dapt
ed t
o make i
t
easi
er
for
mol
ecul
es
to
cross
fr
om
one
si
de of
t
he surface
to t
he other
.
Good exchange surface:
L ar
ge surface
area
Mo re space f
or
mo l
e cul
es t
o pass
thr
ough
T hi
n barri
er
T o
reduce
dif
fusi
on dist
ance
F r
esh supp l
y of
mo l
ecules
on one
side
T o
k eep
con cent
rat
ion hi
gh
R emo val
of
mo l
e cul
es
from other
si
de
T o
k eep
con cent
rat
ion l
ow
Examples
Wa ll
s of
alveol
i
in l
ungs
S mall
i
n t
esti
ne s
L i
ver
R oot
ha i
rs
of
p l
ants
Gaseous exchange
The
mo vement
of
gases
by di
ff
usi
o n
bet
w een
an
organi
sm
and
it
s envi
ronment
acr
oss
a
barr
ier
such
as
the
alveol
us
w al
l.
The lungs
TracheaB ronchiB r
onchi
olesalveol
i
Prot
ected
by
the r
ibs
Moveme nt
of
r
ibs
and di
aphr
a gm
aid
vent
il
ati
on.
Transport and exchange in animals

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Inhalation
Di
aphragm cont
racts
to
become
fl
att
er
a nd
pushes
ribs
down
Ext
ernal
i
nter
costal
muscles
contr
act
to
rai
se r
ibs
Vol
ume
of
chest
cavit
y i
ncreases
Pr
essure
in
chest
cavit
y dr
ops bel
ow atmospheri
c pr
essure
Ai
r
mo ves
int
o l
ungs
Exhalation
Diaphr
agm r
elaxes
and i
s pushed
up by
displ
ace
organs
underneath
Exter
nal
int
ercost
al
mu scl
es r
elax
and r…read more

Page 3

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E nsures
C oncent
rat
ion of
oxygen
is
higher
i
n al
veol
i
than
in
blood
Removes
air
cont
acti
ng CO 2
E nsures
concentr
ati
on of CO2 i
s hi
gher
i
n t
he bl
ood t
han i
n al
veol
i
Trachea and Bronchi
These
are
air
w ays
that
all
ow a
passage of
ai
r
int
o and out
of
t
he
lungs
To
be ef
fect
ive
T he l
arger
air
w ays…read more

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Ast
hma
can
be caused
by t
he const
ri
cti
on
of
the
ai
rways
due
to
an al
ler
gic
react
ion
to
somethi
ng i
n
t
he ai
r.…read more

Page 5

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Thi
s i
s necessary
as when a
person
breaths
in and
o ut
over
a
p er
iod of
t
ime t
he l
evel
of
car
bo n
dioxi
de i
ncreases
dangerousl
y.…read more

Page 6

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An
examp l
e i
s f
ish
They
are
less
acti
ve t
ha n
ma mma ls
so t
his
eff
ici
ent
but
T he bl
ood
pressure
is
reduced as
blood passes
thr
ough the
ti
ny capi
ll
ari
e s
of
the
gil
ls
T hi
s me ans
that
blood does
not
fl
o w ver
y qui
ckl
y t
o
t
he rest
of
t
h e
body
T hi
s l
imit
s t
he…read more

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Fi
sh
H eartarter
iesg i
l
lsv einsbo dy
ti
ssuev ei
nsh ear
t
T her
e must be
exchange
sur
faces
at
the
gil
l
s and
the
bod y
ti
ssue
to
all
ow
mater
ial
s t
o be
exchanged
between bl
ood
and t
issue
fl
uid
The Heart
The
mamma li
an hear
t
is
a muscul
ar
double
pump
that
cr
eates
pressur
e (
blood
pressur
e)
t
o pr
opel
t
he bl
ood t…read more

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At
ri
a
Mu scl
es are
very t
hin
D o not
ne ed
to cr
eate much pressur
e
F uncti
on
is
to
pu sh
blood i
nto
ventri
cl
e s
Ri
ght
ventri
cle
T hi
cker
than wall
s of
atr
ia
E nab l
e r
ight
ventri
cl
e
to
pump bl
ood out
of
the hear
t
T hinner
than r
ight
ventri
cl
e because
t hey
on l
y need t
o pump
blood…read more

Page 9

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How valves work
At
ri
oven t
ricular
val
v e s
P r
essu re
in ventricl
es drops
be l
ow
pressure
in
a t
ri
a af
ter
ventri
cular
w al
ls
co ntr
a ct
and r
eco i
l
T h i
s cause s
valve s t
o open
B l
oo d enter
ing heart
f
lows st
raight
t
h ough at
ri
a and i
nto
ven t
ri
cles
P r
e ssure i…read more

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I f
t
h e
contract
ion
o f
t
he chamb ers
are not
synchronized
then i
t
can cause i
neff
ici
ent
pump ing
(fi
bri
ll
ati
on)
T h e
heart
nee ds
a me chani
sm t
hat
ca n
coordinat
e
the
con t
ract
ion
of al
l
4
chamb ers
how t
he heart
beat
start
s
T h e
sinoat
rial
node (
S AN) i
d t
he heart
s pacema ker.…read more

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