LAB TOPIC 22
VertebrateAnatomy II:
The Circulatory and RespiratorySystems
Laboratory Objectives
After completingthis lab topic, you should be ableto:
1. Identify and describethe function of the main organsand structuresin
the circulatory systemand trace the flow of blood through the pulmonary and systemrccrrcurts.
2. Identify and describethe function of the main organsand structuresin
the respiratorysystemand descnbethe exchangeof oxygenand carbon dioxide in the lungs.
3. Describehow the circulatoryand respiratorysystemswork togetherto
bnng about the integratedfunctioningof the body.
4. Apply knowledgeand understandingacquiredin this lab to probiems
in human physiology.
5. Apply knowledge and understandingacquiredin this lab to explain
organismaladaptivestrategies.
Introduction
In Lab Topic21, VertebrateAnatomyI, you learnedthat nutrientsaretaken
into the digestivetract, where they areprocessed:chewed,mixed with water
and churned to a liquid, mixed with digestiveenzlrrnes,and finally digested
into the componentmonomers,or building blocks, from which they were
slmthesized.For an animal to receivethe benefitsof thesenutrients,these
productsof digestionmust passacrossintestinalcellsand into the circulatory
systemto be transportedto all the cel1sof the animal'sbody Oxygen ls necessaryfor the releaseof energyfrom thesedigestedproducts.Oxygenfrom
the atmospherepassesinto the respiratorysystemof the animal,whereit ultimately crossescellsin the lungs (i.na terrestrialvertebrate)or gills (in an aquatic
vertebrate)and entersthe circulatory systemfor transport to cells of a1l
organs,to be utilized in nutrient metabolism.Wasteproducts of cellular
metabblism-carbon dioxide and ulea-are transDortedfrom the dssues
that producethem via the blood and areeliminatedfrom the body through
the lungs of the respiratorysystemand the kidney of the excretorysystem,
respectivelyThus, the circulatoryrespiratory,and excretorysystemsfunction collec[ively,utilizing environmentalmateria]s,eliminatingwastes,and
maintaini.nga stablei.nternalenvironment.
ln this and the following lab topic, you will investigatethe morphologyof
the circulatory,respiratory,and excretorysystemsin the fetal pig. As you
dissect,relatethe structureand specificfunction of eachsystemto its role
in the integratedbody
58r
22: Vefl"ebrate
AnaromyIl: The Circularo
E X E R C I S E2 2 . I
Glands and RespiratoryStructures
of the Neck and Thoracic Cavitv
Materials
Thesematerialswill be used for the entirelab tonic.
fetal pig
disposablegloves
dissectingpan
plasticbag with twrst tie and rabels
dissectinginstruments
preservattve
twrne
Introduction
To study the glandsand respiratorystructureso[ the neck, you must firsr
open the thoraciccavityand then removethe skin and musciesin the neck
region.This will exposeseveralmajor glandsthat lie in the neck regionin
closeproximity to the respiratorystructures.
Procedure
r\
1Q'
Weardisposable
gloveswhendissecting
preserved
animals.
L. Begin the dissectionby opening the thoracic cavity,which housesthe
heart and lungs, and making an incision thar extendsto the jaw.
a. Usescissorsto deepenthe superficialincisionprer.rouslymadeanterior to the abdominarcavity,and conrinuedeepeningthis incision
to the baseof rhe lower jaw.
b. Cut through the body wall in the region of the rhorax, clipping
through the ribs slightly to the right or left of rhe srernum (the nai
bone lying midventrally to which ribs atrach).
c. continue the incisionpast the rib cageto the baseof the lower jaw.
using the blunt probe ro separaterissues,carefullyremovethe skin and
musclesin the neck region.Youwill exposethe th)rmus gland on each
side of the neck (Figure22.1). This glandis largein the fetarpig and in
young mammals,but regresses
with age.It plays an important role in
the developmentof the body'simmune system.
3 . Push the two th).rynusmassesto the side to exposethe laDmx and trachea
lying deep to the masses.Recallyour knowledge about the glottis,
observedin the dissecrionof rhe mouth in Lab Topic 21. The glotris
leadsinto the lanrnx, an expandedstructurerhrough which air
fasses
from the mouth to the narrower trachea.The larlnx housesvocaltords.
4 . A small reddish gland, the thyroid gland, coversrhe rrachea.The thyroid gland secreteshormonesthat influencemerabolism.push this gland
asideand observethe rings of cartilagerhat prevenrthe collapseof the
tracheaand allow air to passro the lungs. push asidethe tiachea to
observethe dorsallylocatedesophagus.
r
l.
Lab Topic 22:YertebrateAnatomy ll: The Circulatory and RespiratorySystems 583
Larynx
Trachea
Thyroidgland
Cranialvenacava
Thrrmrrc
Pericardialsac
Heart
Figure22.1.
Ventralview of the anterior region of the pig, showingstructuresin theneck
the heart.
regionand the thoraciccavityThepericardialsacencloses
5. Do not continuethe dissectionof the neck and thoracicregionsat this
time. To prevent damageto blood vessels,you will completethe dissectionof the remainderof the respiratorysystem(Exercise22.5) following the dissectionof the circulatorysystem.
E X E R C I S E2 2 . 2
The Heart and the
Pulmonary Blood Circuit
"rib")
caviThe heart and iungs lie in the pericardial and pleural (Gk. for
ties, respectively,within the thoracic car,rty.In your dissectionof the heart
and blood vessels,you will distinguish the two circulatory pathwaysfound
in mammaliancirculation:the pulmonary circuit, which carriesblood from
the heart to the Jungsin arteriesand back to the heart in veins; and the
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Lab Topic 22'.Yertebrate
Anatom
systemic circuit, which carriesblood from the heart in arteriesto all organs
but thelungsandback to the heart in veins.This exerciseinvestigatescirculation
in fetal and adult pig hearts and the pathway of blood to the lungs in the
pulmonary circuit.
Materials
isolatedadult pig heart dissectedto show chambersand valves,demon,
strationonly
suppliesfrom Exercise22.I
Procedure
Although,generally,veins containblue latexand arteries
containred latex,the colorscan vary and should not be
used as guidesto distinguishveinsfrom arteriesor vessels
carryingoxygenatedblood from vesselscarryingdeoxygenatedblood.
1 . In the fetalpig, exposethe heart lying in the pericardial cavity berween
the two pleural cavities.Gently push open the rib cage,using scissors
and a probeto cut through muscleand connectivetissue.Another lobe
of the thymus gland will be seenlying over rhe pericardial sac housing the heart.The wall of rhe pericardialsacis a tough membranecomposedof two fusedcoelomicepitheliallinings, the parietal pericardium
and the parietal pleura.
2 . Cut into and push asidethe pericardialsac.Carefullydissectawaymembranes adhering to the heart until you can identily the four chambers
of the heart (Figure22.2 and Color Plate61).
Eigare 22.2.
Enlarged ventral view of a fetal
heart, showing the four chambers
and the major associated
blood
vessels.Comparethis anatomywith
that of an adult heart.
Aortic arch (aorta)
Cranialvena cava
Ductusarteriosus
Rightatrium
Pulmonary
trunk
Pulmonary
artery
Rightventricle
Leftatrium
Coronaryartery
and vein
Left ventricle
Caudalvena cava
a. The right atrium and left atrium are small, dark, anteriorrylocated
heart chambers that receive blood from the venae cavae and the
pulmonary veins, respectively
b. The right ventricle and left ventricle are large muscular heart chambers that contract to pump blood. A branch of the coronary artery
may be seenon the heart surfacewhere the left and right ventricres
sharea common wall.
what is the name of the epithelial lining adhering to the hearr surface?
3 . Tiacethe pulmonary circuit. fu the heart contracts,blood is forcedfrom
the right ventricle into the pulmonary trunk, alarge vessellying on
the ventral surfaceof the heart. Another largevessel,ihe aorta, iies lust
dorsal to the pulmonary trunk
a. Use forceps to pick away tissue around the pulmonary trunk and
trace the pulmonary trunk as it curves cranially, giving off three
branches:the right and left pulmonary arteries and the ductus
arteriosus.
b. Identift the ductus arreriosusand the left pulmonary arLery(the right
pulmonary artery is not readily visible).
The.right and left pulmonary arteriesare relativelysmall at this stage
of developmenr.They conducr blood ro rhe right and left lungs,
respectivelyThe ductus arteriosusis the short, large-diametervesiel
that connectsthe pulmonary trunk to the aona. Beciusethe small right
and left pulmonary arteries and compact lung tissue present an
extremelyresistantblood pathway,the grearestvolume ofblood will
flowfrom the pulrnonarytrunk*rough the ducnrsarteriosusand directly
into the aorta and systemic circulation, bypassing the pulmonary
arteriesand lungs. At the time of the fetui's birth]when air enrers
the lungs and the tissuesexpand, blood will more easily flow into
the lungs. The ductus arteriosusclosesoff and eventualiy becomes
a ligament.
1 . observe the isolatedadult pig heart on demonsrrationand locatethe dorsal and ventralsurfaces(Figure22.2 and Color plate 6l).
a. Identify the right atrium with associatedcranial and caudal venae
cavae and the left atrium with associatedpulmonary veins.
b. Locatethe right and left ventricles and the atrioventricular valves
between the atria and the ventricles.
c. Locate the pulmonary trunk, which carries blood from the right
ventricle, and the aorta, carrying blood from the left ventricle. ihe
first two small branchesof the aortaarecoronary arteries. locate these
vesselsand the coronary veins lying on the surfaceof the heart
between the left and right venrricles.
22: Yertebrate
Results
Reviewthe heart chambers,blogd
vessels,
in the pathway of
the pulmonary circuir in the adult
h"il. T" 1n{organs
facilitate rhis review,fill in the
blanks in rhe next paragraph.
Blood entering the heaft passes
first into the right atrium. From
there it
flows into the right ventricre.when
the heart conrracrs,this brood is forced
out of the ventricleinto the
trunk. Branchesof this trunk
called
carryblood to the lungs.After birth,
the blood
will be oxygenatedin the lungs. Blood
from the lungs passesback to the
heartthrough
, thus completingthe circuit. Ir enters
the left aftium of the heart.
Discussion
L
Defineartery.Definevein.
2. Why would pulmonary afteries
be relativelysmall at the fetal saqe
of
development?
3' Although a pulmonary circuir
exists,the heart in amphibiansand
mosr
reptiles j-smade up of onry th.e"
chumbers-two atria and.oneventrlcle' The larterreceivesblood r."u"irr urria.Specurate
about possibre
disadvantagesto thrs circulatory putt
*u1.
EXERCISE
22.3
The Heartand rhe
SystemicCircuit in the Thorax
Biood returninq from the lungs collecrc
in the left atrium and flows into the
left ventricle.wh".r the hearico;;;;i;"d
is forcedout the aorta, rhe
origin of which is obscuredby the
put-o.rury trunk. The first branch
from
the aortais the small c
r,"u.,-*.r":"#ilr::T;T*T,T,ffiH'*'ffi:,ih*"jji,:::
organsof the body bur the lungs. Brood."iu'r*
to the he-artf.o,o orga.r, ot
the body throughrtwo ru.g" rr.i.,r,1h.
.r**r and caudarvenaecavae.
VertebrateAnatomy II: The Circ
External
jugular
Internal
jugular
Subclavian
vein
Subscapular
vein
R
Cranialvena cava
Right
atrium
Right
ventricle
F=SR+
\
\
Rib
cage
Subclavian
vetn
jugular
External
Cephalic
vetn
Axillaryvein
Left
atnum
Coronary
vein
Leftventricle
Figure 22.3.
veins near the heart. The subclavianvein and the external and internaljugulars
carry blood to the brachiocephalicveins, which unite into the cranial vena cava.
The caudal vena cavacarriesblood from the posterior regionsof the body.
Procedure
1. Identify rhe venaecavaeand their major branches.
a. Pushthe heart to the pigs ieft to seetwo rargeveins enreringthe right
atrium; thesearethe cranial and caudal .'r"ru" cavae(Figirre zz.l)
I^
I^
5
Internaljugular
b. using the blunt probe_toseparatethe vessersfrom surroundingtissues,follow the cranial vena cavaroward the head and identiff the
two largebrachiocephalic veins, which unite in the cranialvenacava.
c. Identify the threemajor veins that unite to form eachbrachiocenhalic
vein: the external and internal jugulars that carry blood returning
from the head, and the subclavian vein that drains brood from the
front leg and shoulder.Follow the subclavianvein into the front leg.
deep into rhe.muscle coveringthe undersideof rhe ,.uprrl-u
flobe_
(shoulderblade)and you should seerhe subscapularvein, draining
blood from the shoulderregion.The axillary veiln carriesbiood from
the front ieg,becomingthe subclavianvein at the subscapularbranch.
Another vein that is often injected and prominent in ihe shoulder
areais the cephalic vein. This vein hesjust beneaththe skin on the
upper front leg. It typicallyentersthe externaljuguiar near its base.
Subscapular
vein
Axillaryvein
7-
ic 22: YertebrateAnat
Right
subclavian
artery
Common
carotid
artenes
Aortic
arch
Right
atnum
Right
ventricle
Coronary
Commoncarotid
artery
Subscapular
artery
trunk
Rib
cage
II: The Ci
R
Axillaryartery
Subscapular
artery
Axillaryartery
Leftsubclavian
artery
Left
subclavian
artery
Aorticarch
Left
atrium
Left ventricle
Dorsal
aona
a,
Figure22.4.
Branchesof the aorta.Branches
from the aorticarchcarryblood to the head
and anteriorlimbs.Thefirst branch,the brachiocephalic
trunk, branchesinto
the right subclavianarteryro the right limb and two commoncarotidarteries
to the head.Thesecondbranchis the left subclavianto the left limb.
2. Identify branchesof rhe aorranear rhe heart (Figure 22.4).
a. Push the pulmonary trunk ventrally and posteriorly to observethe
curve of the aorta, the aortic arch, lying behind.
b. Removeobscunng tissueand exposethe first two major branchesof
the arch, which carry blood anteriorly It may be neceisaryro remove
the veirs to do so.The largerof the branches,the brachiocephalic trunk,
branchesoff first. The left subclavian ^rtery brancheJoff second..
c. Identify the three major branches from the brachiocephalictrunk:
the right subclavizrn ^rtery, which gives off severalbranches that
serve the right shoulder and limb area, and two common carotid
arteries, which carry blood to the head.The common carotid arteries
lie adjacentro the internaljugular veins.
d. Tiacethe branchesof the left subclavianailery inro the left shoulder
and front leg. The branch that passesdeep toward the underside of
the scapulais the subscapular ^rtery. After the subscapularartery
branchesoff, rhelelt subclavianconrinuesinto the front leg asthe left
axillary afiery. Additional branchesof this arrery compl& may also
be visible.
22:YertebraLe
Anatom
ms 589
P u l l t h e l u n g sr o t h e p i g s r i g h rs i d ea n d r r a c et h e d o r s a a
l o r t aa s i r
extendsposteriorly from the aor[ic arch along the dorsal thoracic
wall. Notice againthe ductus arteriosus connectingfrom the pulmonary trunk.
Note the sma11
branchesof the dorsalaorracarryingblood to the ribs.
A largeconspicuousvein, the azygosvein, lies near this reglonof the
aorta.This vein carriesblood from the ribs back to the heart.
Results
Modify Figures22.3 and22.4 or sketchadditionaldetails in the margin of
your lab manualto indicateparticularfea[uresof your prg'scirculatorysys,
tem for fu[ure reference.
E X E R C I S E2 2 . 4
The Systemic Circuit in the
Abdominal Cavity
The dorsalaoftapassesinto the abdominalcavity whereit branchesinto arteries supplyingthe abdominalorgans,the legs,and rhe tail. In feralcirculation, it also branches into two large umbillcal arteries to the placenta. Blood
from the 1egs,tail, and organs collects in veins that ultimately roin the caudal vena cava to return to the heart. Blood draining from organs of the diges-
tivesystempassesthroughadditionalvessels
in rhehepaticporralsystembefore
emptyingrnto the caudalvenacava.
Lab Studv A. Major Branchesof the Dorsal
Aorta and the Caudal Vena Cava
In this lab study,you will identify the major blood vesselsbranchingfrom
the dorsalaortaand thoseemptyinginto the caudalvenacava.
Procedure
Identily branchesof the dorsalaorta(Figures22.5 and 22.7).
I
n ,J
R
,11
a. The first largebranchof the aortain the abdominalcar,rtyexitsthe aorra
at approximatelythe levelof the diaphragm.Clip rhediaphragmwhere
it joins the body wal1,pull al1the organs(lungsand digestiveorgans)
to thepigsright, andsearchfor thecoeliacartery,which carriesblood
to the stomachand the spleen.You may haveto pick awaypiecesof
the diaphragmthat areattachedto the aortato seethis vessel.
b. Onceyou haveidentifiedthe coeliacartery,lookfor the next branch
of the aorta,the cranial mesenteric artery, arisingslightly caudal
to the coeliacarteryand carryingblood to the small intestine.The cranial mesentericarteryultimatelybranches[o the mesenteric arteries you observedwhen you studiedthe digestivesysrem.
c. Followingthe dorsalaortaposteriorlyidentifythe two renal arteries
leadingto the kidneys.
i
590
Lab Topic 22: YertebrateAnatomy II: The Circulatory and RespiratorySystems
Coeliacartery
Cranial
mesenteric
artery
Renal
artery
andvein
Common
iliacvein
Externaliliac
arteryand
vein
Umbilical
artery
Femoral
arteryand
vein
Deep femoral
arteryand
vein
Figure 22.5.
Branches of the aorta and caudal vena cava in the abdomen. Branchesof the
aorta supply blood to the stomach (the coeiiacarter/), the small intestine (the
cranial mesentericartery), the kidney (renal arteries),the hind limbs (iliac arteries), and the placenta(umbilical arteries).Branchesofthe caudalvena cavadrain
blood from the kidney (renal veins) and posterior limbs (common iliac veins).
You will observethe posterior branchesof the aorta after
the dissectionof the reproductivesystem.
The dorsalaortasendsbranchesinto the hind legs(the external iliac
arteries) and to the placenta (the umbilical arteries) through the
umbilical cord.
Separatethe musclesof the leg to seethat the externaliliac artery
divides into the femoral artery and the deep femoral artery. The
femoral artery carriesblood to the musclesof the lower leg, and the
deep femoralarterycarriesblood to the thigh muscles.
Lab Io
VertebrateAnatorn-
2. Identify branchesof the caudal vena cava.
a. Using Figure 22.5 as a reference,push the digestive organs to the
pig's left and trace the caudal vena cavainto the abdomin"alcavit;r It
Iiesdeep to the membranelining the wall of the abdominalcavity the
parietal peritoneum. peel off this membrane to seethe vena cava,
the dorsal aorta, and the kidneys.
b. Identify renal veins_carryingblood from the kidneys.common iliac
veins (to be identified in Lab Topic 23) carry blood from the hind
legs,and hepatic veins carryrblood from the iiver to the caudalvena
cava.Hepatic veins are presentedin Lab Study B.'
Lab Study B. The Hepatic portal Sysrem
In the usual pathwayof circulation, blood passesfrom the heart to
arteries,
to capillaries an organ, and to veins leading from the organ back
to the
-in
heart (Figure22.6a).Ina few rareinstances,a se"cond
capillaribed is inserted
in a second organ in the circulation pathway (Figure 22.6b). when
this
I
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-:.
"fj,r,?r.i.1"
.-----=-fu*--/
nousportatcircuration
ffi
-/
<-:
c^0,r1i1,19;;@4
__I---{
."-*;;b.i.i*i
b.
_
I
ft_
try
,/
7-
I
-
-**,,x
{6#dfu"
L:nn"*n-mq:r
in
{ Capiilaries
HepaticPortat
Gircurarion
ffi*7
w
\_
c ffi:ijfif,::g-ry
/
I
*,.
Figure 22.6.
Circulatory pathways. (a) General
circulatory pathway; (b) circularion in
a portal system;and (c) circulation in
the hepatic portal system.Arteries are
depicted in dark blue; veins are gray;
portal veins are grayoutlined in dark
blue.
j
occurs,the circulatorycircuit involved is called a portal
system. such a
systemof portal circularionexisrsin the digesriv.iyrt"- (rigure
22.6c).
An unders^randing
of this circulation parhway wil increas.
underio*
standingof the absorptionand pro."rrirg of nutrients.
You have previouslyexposedthe coeliacand cranial
mesentericarteries,
which send branchesto the stomach,spieen,and smail
intestine.These
arteriesdivide into smallerarreries,to arierioles,and, finally,
to capillaries,
thin-wailedvesselsrhararethe sireof exchangebetween
ulooa ana the ris_
suesof the organs.Arteriesassociaredwith ihe small intestine
are called
mesenteric arteries; veins leavingthe small intestineare
calledmesenteric
veins, and they unite to form one largemesenteric vein.
veins from the
stomach-andspleenunite to form the largerlienogastric
vein. ih. -.r"rrteric and lienogastricveins unire to form the heiatic portal
vein, which
entersthe hver (Figure22.7). rn the fetalpig, smallbraiches
of the umbilical vein join the heparicportar vein aslt'enters the liver.
However,rhe
greatesrvolume of blood in the umbilicai vein passes
directly through the
liver into the caudal veta caya.
In the live-r,the hepaticportal vein branchesinto a second
capilary bed,
whereexchangetakesplacebetweenbrood and river tissue.
Thesecapiilarresreuniteinto hepatic veins, which join the caudalvena
cava.To identify
thesevessels,begin by dissectingthe veins.
Figure 22.7.
The hepatic portal system. Blood
flromihe small intestinepasses
into
the mesentericvein, which unites
with the lienogastricvein to form the
hepaticportal vein. This vesselleads
to the liver, where it breaks into a
capillarybed. Biood leavesthe liver
through the hepatic veins.
Hepatic
portal
vetn
Coeliacartery
Lienogastric
vein
Mesentenc
vern
Cranial
mesenteric
artery
Mesenteric
and veins
Renal
arteryand
vein
Lab Topic 22:YertebrateAnatomy II: The Circulatory and RespiratorySystems 593
Procedure
I.
Pushthe stomachand spleenanteriorlyand dissectawaythe pancreas.
2. Use the blunt probe to exposea vein (it wrli probablynot be injected)
leading from the mesenteriesof the small intestine. This is the mesenteric vein. It is joined by a vein leadingfrom the stomachand spleen,
the lienogastric vein. The two fuseto form the hepatic portal vein, which
continues to the hver.
3. Reviewthe flow of blood from the mesentericarteriesto the liver.
Results
Review the blood vesselsand organsin the pathway of blood through the
hepatic portal systemof an adult pig with functioning digestiveorgans.Fill
in the blanks in the next paragraph:
R
R
Blood that is poor in nutrients is carried from the aorta to the arLeryLosmallermesentericarteries,which divide to a cap1llary
bed in the wall of the
, where, in the processof
I
absorption,nutrients enter the blood. This nutrient,rich blood now flows
\
into the
3
vein from the spleen and stomach and becomesthe
la
t;
tu
6
p
t0
9
I
p
p
vein. which ioins with the
vein. This vein now carriesblood to the liver. where it breaksinto a second
capillarybed. Capillariesin the liver convergeinto the
VCINS,
which empty into the caudal vena cavafor transport back to the heart.
Discussion
Referringto your text, review the function of the liver in nutrient metabolism and relatethis to the function of the hepatic portal sysrem.Include
information on digestiveproducts, drugs, and toxins.
594
Lab Topic 22: VertebrateAnatoqy II: The Circulatory and RespiratorySystems
E X E R C I S E2 2 . 5
Fetal Pig Circulation
As you dissectedthe circulatory sysremin the fetal pig and observedthe
adult pig heart, you noted differencesberweenthe fetal heart and the adult
heart, and you identified blood vesselsfound in the fetus but not in the
adult. In this exerciseyou will review thesevesselsand structures,tracing
blood flow through the fetal pig.
Procedure
1. Returnthe umbilical cord to rhe positionit occupiedbeforeyou began
your dissection.Locate again rhe umbilical vein as it passesfrom the
umbilical cord toward the liver. You cut through this vein when you
openedthe abdominal cavity The umbilical vein carriesblood from the
umbilical cord into the liver. ln the liver, small branches of this vein
join the hepaticportal vein, passingblood into the liver rissue.However,
the majority of the blood passesrhrough a channelin rhe liver calledthe
ductus venosusinto the caudaivena cava.Would blood be highorlow
in oxygen in the caudalvena cava?
z.
Reviewthe anatomyof the heart, and rerracethe flow of blood through
the heart into the dorsal aortaby way of the ductusarteiosus.This representsone pathway of blood through the fetal heart.
A secondpathwayof blood through the heart is createdby a structure
in the fetal heart called the foramen ovale. To study this pathway,use
your scalpelto open the pig heart by cutting it along a fronral plane,
dividing it into dorsal and ventral portions. Begin at the caudal end of
the heart and carefullyslicealongthe frontal plane, cutting just through
the ventricles,keeping the atria inract. Carefully lift the ventricles and
look inside the heart for the wall between the two atria. Using your
blunt probe, carefully feel along rhis wall for an opening between the
two atria. This hole is the foramenovale,which makespossiblethe second pathwayof blood through the heart.How would this hole change
the flow of blood through the heart?
In fact, most blood coming into the heart from the caudalvena cava
passesfrom the right atrium through this hole into the left atrium. After
leaving the left atrium, where would blood go next?
4 . Follow the dorsalaoria into the abdominalcavity to the umbilicalanery
branches.Thesebranchespassthrough the umbilical cord to the placenta.Would blood in thesebranchesbehigh or low in oxygen?
Lab Topic 22:YertebrateAnatomy II: The Circulatory and RespiratorySystems 595
Results
Tiace the pathway of blood from the umbilical vein to the umbilical artery
by filling in the blanks in the next paragraph.
Blood from the umbilical vein passesthrough the liver and into the
which carriesblood into the heart, specificallyinto the chamber called the
In one circuit of blood flow, blood goesfrom
this chamber into the right ventricle and out the
(presentonly in fetal cirbranch from this vessel,the
culation), carriesmost of this blood into the dorsal aorta. The dorsal aorta
passesthrough the body, giving off branchesto all organsof the body Two
Iarge branches located near the tail lead into the umbilical cord and are
called the
An alternateroute carriesblood from the right atrium through a fetal hole
into the heart chamber, the
From this chamber,blood next goesinto the left ventricle and out the
called the
Branchesof this vessellead to the head.
Discussion
I.
What is the advantageof the circuit of fetalblood flow through the ductus arteriosus?
2. What is the advantageof fetal blood flow through the foramen ovale?
E X E R C I S E2 2 . 6
Details of the Respiratory System
You have previously located severalof the major structuresof the respiratory system(Exercise22.1). Direct your attention againto the neck region
of the pig and complete the study of the respiratorysystem.
Procedure
1. Identify again the larynx and the trachea (Figure 22.8).
2. Follow the tracheacaudally to the pJeuralcavitieshousing the lungs. The
tracheabranchesinto bronchi (sing., bronchus), which lead into the
lobes of the lungs (Color Plate 62).It will be necessaryto push aside
blood vesselsto seethis. Tahecarenot to destroythesevessels.
r
596
LabTopic22: ve.teb.at.AnutomyII: The circulutorya.rdRespiratory
Systems
Teaseapart lung tissuesto observethat the larger bronchi branch into
smaller and smaller bronchi. when the tubei are abour l-2 mm rn
diameter, they arecalled bronchioles. Bronchiorescontinue to branch
and ultrmatelylead to microscopicalveoli (not visible with the unaided
eye),thin-walled,blind-ending sacsthar are coveredwith capillanes.
It is here that the exchangeof oxygen and carbon dioxide takesplace
betweenthe blood and the atmosphere.
Identify the epitheliallining of the pleural cavity How would this epithelium be named?
5.
complerethis lab topic, rerurn your pig to its plastic bag.
{fter_yo-u
that
your labels are intact and that your "u-., lab ,oom, arr-d
-Cl"9k
lab day are legible.Add preservingsolurion and securelyclosethe bag.
Results
List, in order, the structures,tubes, and cellurarbarriers through which air
passesasit travelsfrom outside the body to the circulatory syslem of a pig,
a teffestrial vertebrate.
Discussion
1. In terrestrialvertebrates,what is the advantageof having the surfaces
for oxygenand carbondioxide exchangeembeddeddeepin lung tissue?
2. The capillariesthat lie in closecontactwith alveoli arebranchesof what
blood vessel?
3. The confluenceof thesecapillariesforms what blood vessel?
+. compare blood composition in adult circulation with referencero oxygen and carbon dioxide betweencapillariesapproachingalveoli and
capillariesleaving alveoli.
22:Yertebrate
II; The Circu
Lobes ol
lung
Figure 22.8.
The respiratorysystemof the fetarpig. Air passes
througha succession
of
smallerandmorenumeroustubes:the larynx,trachea,bronchi,bronchioles,
andultimately,microscopicalveoli(seeenlargedarea).
-r-=t
598 Lab T
22:YertebrateAnatom II: The
Circulatoryand
5'
Review the coelomrc cavities,
the organs contained within
them, and
the associaredcoelomic -"-t.u.r.,
8y.ornpt"ti ngTable 22-.1.
Table22.I
Cavities,
Organs,
andCoelomicMembranes
of theMammalian
B ody
Thoracic
Abdominal
(peritoneal)
Applying your Ituowledge
l ' The appearance
of lung tissuediffersin an adult
and a fetalpig. predict
differencesin appearance
and explainthem.
Using materialsprovided in the lab,
your rexr, Ilbrarymarerials,or your
pfevio.,l knowledge,answerthe
followrnglrertion, relaredto the
effects
ol smokingon thestructureand funcdo.,
oJtrr. rru,.ur, ,"rp""*"1,y".-.
a' Describechangesin the celrs
and dssuesof the rungsand describe
the
concomitanteffectson function.
Lab Topic 22: VertebrateAna
II: The Circu
b. Describethe effectsand syrnptomsof each of the following diseases
linked to cigarerresmoking.
Disease
Effects and Symptoms
Chronic bronchitis
Emphysema
Lung cancer
c. what effectsdoessmoking during pregnancyhave on the fetus?
3. The tracheais composedof rings of cartilage,while the nearby esophagusis composedof muscleand lackscartilage.How arethesesiructural
differencesrelated to the functions of eachi
References
American Lung Association. All About smohinglon-line] www.guesswhat.com/ske_l.htm,1998.
Marieb,ElaineN. HumanAnatomyandphysiology,4th
ed. Menlo park, cA:
Benjamin/Cummings, 1998.
"what
You Need to Know about cancer." ScientficAmeicdn, special Issue.
September1996.