Download - Cardiovascular Physiology Lab
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Exercise
ardiovascular Physiology
l bor tory Objectives
On
completion of the activities
in
this exercise, you will be able
to
Locate the auscultation areas for the heart.
• Use a stethoscope
to
listen to the heart
sounds
at the aus-
cultation areas.
• Measure blood pressure at rest,
during
exercise, and
during
the recovery period after exercise.
• Calculate the pulse pressure
and
mean arterial
pressure (MAP).
• Measure the pulse rate at rest ,
during
exercise, and
during
the recovery period after exercise.
Describe the function
of
the cardiac
conducting
system.
Measure and evaluate the electrical activity of the heart (ECG).
aterials
Stethoscopes
Alcohol swabs
Sphygmomanometers
Stopwatch
or
clock with a
se
c
ond
hand
Stationary cycle
• Biopac Student Lab system
T
he
cardiac
cycle refers to the series of events
that
occurs
during one
heartbeat.
During one
cycle, the two atria
will
contract
at the same time.
As
the atria relax, the two
ventricles will
contract
simultaneously. A period
of contraction
in a heart
chamber
is called
systole atrial
systole, ventricular
systole)
,
and
a period
of
relaxation is called
diastole
atrial
diastole,
ventricular
diastole) .
[n clinical use, these
terms
typically refer
to
events in the ventricles, because they are the
larger
and more powerful
chambers that
pump blood into the
grea t arteries.
The events of the cardiac cycle are illustrated and described
in Figure 22.1. During the cycle , changes in blood pressure in-
side the chambers and great arteries cause the heart valves
to
open and close. These events regulate the flow
of
blood through
the heart and into the systemic and pulmonary circuits. During
this laboratory exercise you will investigate some of the physio-
logical
events-heart
valve function, pulse, blood
pressure-that
characterize the cardiac cycle.
You
will also record measurements
of
the electrical activity of the heart (an electrocardiogram or
ECG) and evaluate the results.
(f)
Ventricular diastole-late:
All chambers are relaxed.
Ventricles fill passively.
(e) Ventricular
diastole-
early: .
As
ventricles relax, pressure
in ventricles drops; blood
flows back against cusps of
semilunar valves and forces
them closed. Blood flows
into the relaxed atria.
(a) Atrial
systole
begins:
Atrial contraction forces
a small amount of additional
blood into relaxed ventricles .
(b)
Atrial systole ends;
atrial
diastole
begins
(c) Ventricul ar
systole
first phase: Ventricular
contraction pushes AV
valves closed but does
not create enough pressure
to open semilunar valves.
(d)
Ventricular
systole
second phase: As
ventricular pressure rises
and exceeds pressure in
the arteries, the semilunar
valves open and blood
is ejected.
Figure 22.1 The cardiac cycle.
The illustrated steps describe the
events that occur during one heart-
beat. During each cycle, the atria con-
tract together and the ventricles
contract together.
393
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EXERCISE
TWENTY- TWO
Heart
Sounds
During the cardiac cycle,
when
blood passes from the atria to the
ventricles
and
from the ventricles to the great vessels, the heart
valves open
and
close. The closing of the values produces two dis-
tinctive heart sounds. The sounds can be heard, with the aid of a
stethoscope,
as Iub-dup
vibrations. The cardiac cycle begins
when a small volume of blood
is pumped
into each ventricle dur-
ing atrial systole (Figure
n.la).
The first "lub"
sound is
caused
by vibrations that follow the closing of the atrioventricular AV )
valves (Figure n.2b . This occurs at the end of atrial systole
(Figure n.lb). This point in the cardiac cycle also marks the be-
ginning of ventricular systole (Figure 22.1c), known as isovolu
metric contraction,
when all heart valves are closed. As the
pressure in the ventricles increases, the semilunar valves open
and blood
is pumped
into the great vessels. This
is
the second
phase of ventricular systole (Figure n ld , known as
ventricular
ejection. The closing of the semilunar valves occurs at the begin-
ning of ventricular diastole (Figure n le ) . Vibrations , generated
by the closing of these valves, creates the second "dup" sound
(Figure
n.2b
At
this time, pressure in the ventricles is decreas-
ing and falls below the pressure in the great arteries. At the end of
the cycle, ventricular pressnre falls below the atrial pressure.
As
a
result, the
AV
valves open and passive filling of the ventricles be-
gins. A new cycle begins with the initiation of atrial systole.
CLINICAL
CORRELATION
Incomplete
closure
of the
AV
valves can
cause regurgitation or
backflow of blood into the atria. This can cause an abnormal gur-
gling sound known as a heart murmur.
On
the left side of the
heart, incomplete closure of the biscuspid (mitral) valve is called
a
mitral valve prolapse.
Minor
prolapses are fairly
common
and most people
live
with them and do not experience adverse
effects. However, a major prolapse, possibly caused
by
rupturing
of the
chordae
tendinae
or severe damage to the cusps,
can
nave serious if not life-threatening
consequences.
ACTIVITY 11.1 listening
for Heart Sounds
1.
The best locations to hear heart sounds are the
auscultation areas for the heart
(Figure
n.2a) on
the
anterior thoracic wall. These areas are named after the
heart valve that can best be heard. locate the following
auscultation areas on yourself or your lab partner.
• The
biscupid area
is
located in the left fifth inter-
costal space, where
the apex
of
the
heart
is located . To
find this region, locate the inferior end
of
the sternum
by finger palpation.
From
this point, move
your
finger
approximately
7 em (2.75 in) to the left, where you
120
Valve location
1
Pulmonary
Sounds heardf valve
Semilunar
90
Pressure
(mmHg)
60
30
Sounds heard AV (bicuspid)
Orta
( eft
ventricle
Left
atrium
S,
AV valves
close
AV
valves
open
}
Left
Valve location valve
Valve location
1
Right
Sounds heard f AV (tricuspid)
S2
8
4
i
~ 8 3 . _
8
4
Heart
---A ...'_---lI,
r .
sounds r , r-
"Lub"
"Dup"
(a) (b)
Figure
22
.2 Auscultation
areas
for the heart. a)
Diagram that illustrates the locations
of
the heart valves
(oval areas) and the auscultation areas (circular areas), where heart sounds can best be detected with a stetho
scope.
b)
Graph
sh
owing the relationship
of
the heart sounds with events
in
the cardiac cycle. The two primary
heart sounds, 51and 52 ("Iub-dup"), are caused by the closing of heart valves. Two minor sounds, 53and 54, are
not related to valve
fund
ion and are difficult to hear.
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can feel thefifthintercostalspace
between
the fifth
andsixth ribs.
•
To
locatethe
tricuspid area,
palpatetheinferior
end
of
the
sternum and
place
your
stethoscope
just to
theleft
of
tharpoint.
• The
aortic
semilunar
area is
locatedinthesecondin-
tercostalspace,just to the rightof thesternum.Thesec-
ond
intercostalspacecanbe locatedbyfirstpalpating
thesuperiormarginofthemanubrium.
Fromthismar-
gin,moveyourfingerinferiorlyuntilyoucan feel the
junction
betweenthe
manubrium
andthebodyof the
sternum
.
f
youmoveyourfingerlaterally
to
the right
of
the
sternum,
youcanfeel thecostalcartilageofthesec-
ondrib. Thesecondintercostalspace
is just
inferior
to
thisrib.Place
your
stethoscopein thisspace,
just
lateral
to
thesternum.
• Thepulmonary
semilunar
area is locatedin thesec-
ond
intercostalspace,
just
to theleftofthesternum.
Followthesameprocedurefor locatingtheaorticseml-
lunararea,
but
this time,move to theleftsideofthe
sternum.
WHAT S IN
WOIlD
The term
uscult tion is
derivedfrom the
Latinword
auswlto
whichmeans"tolisten
."
Auscultation
is
an
importantdiagnostictoolused
by
doctorsand
other
healthcare
providers.
t
involveslistening
to
the
sounds
madebyvariousor-
gansinthethoracic
or
abdominalcavities,
such
astheclosing
of
heartvalves.
2. Obtainastethoscopeandsterilize theearpieceswith
an
al-
coholswab.
3. Place the
stethoscope on
thebicuspid areaand listen
lor
theheart
sounds. f
thebackgTOundnoiseis too
highandyouare
experiencing
dirficultyin
detecting
thesounds ,move to a
quieter
area in
the
laboratory
or toanother room.Can you hear
both
heart
sounds
("
lub-dub
")
when
the
stethoscope
is placedover the
biscuspid area? Canyou
hear
one sound better
than
the other?
4.
Listento theheart
sounds
at the
other
auscultationareas.
Howdo the
sounds
compareateacharea? Answerthe
same twoquestionsthat,v e
re
asked forthebiscuspidarea
in thepreviousstep.
an
you hear
an
you hear one
both heart sound better than
sounds?
the other?
• Tricuspid area
• Aortic semilunar area
• Pulmonary
semilunar area
CARDIOVASC ULAR PHYSI OLOG Y
Duringaphysicalexamination,
wh
ydoes the
doctor
listento theheart
sounds
atallfouraus-
cultationareas
7
lood
Pressure
Bloodpressure is theforceexertedbyblood
on
thewallsof blood
vessels .
It
is a function of the
pumping
action ofthe heart and
theresistanceto flowasbloodmovesthrough thebloodvessels.
Bloodflows
throughout
theCirculatorypathways
due
totheex-
istence
of
apressuregradientthat allowsblood
to
movefromar-
eas of high pressure to areas
of
low pressure. Blood flow in
arteriesandveinsbeginswithventricularejection intothegreat
arteries
and
endswithvenous return
to
theatria.
In
thesystemic
circulation ,bloodpressureishighest intheaortadue
to
theforce
of ejection by the left ventricle. Pressure gradually declines
throughout the Circulatory pathway,
and
is close to zero when
bloodentersthe rightatrium.
In large elastic arteries, the blood pressure fluctuates be-
tweenamaximum
and
minimum value,whichcorrespond tothe
cardiac cycle.
For
example,
during
ventricularsystole ,bloodis
ejectedintotheaortafrom theleftventricle.Theforce
of
ejection
causes theelasticwallsofthe aorta to stretch,and the pressure
insidetheaortareachesapeak.This
maximum
pressure
is
called
the
systolic pressure.
During ventricular diastole, the aortic
semilunarvalvecloses ,
and
the elastic fibers in thewall ofthe
aortarecoil to forceblood forward.At this time ,theaorticpres-
suredeclines to a
minimum
level, referred
to
as the diastolic
pressure.
Thus
, bloodpressure in the aorta
is
not
smooth
or
constant,
but
pulsatileinnature. Thischaracteristic is also true
forother elasticarteries,
but
itdiminishesinthesmallerarteries
andarteriolesas the
number
ofelastic fibers inthe vesselwalls
diminishes.Blood, flowingthroughcapillaries
and
veins ,travels
under
relativelylowpressurewith little
or
nofluctuation.
Blood pressure
is
measured in units called millimeters of
mercury
(mm
Hg).Ifthepressureinabloodvessel
is
95
mm
Hg,
itmeansthattheforceexertedbythebloodwillcausea
column
of
mercurytorise95 millimeters.When bloodpressureismea-
sured,it is thearterial blood
pressure
inthe systemiccircula-
tion that is recorded. Usually, the
brachial artery
is used
to
measurearterialbloodpressure(Figure22.3),becauseit is atthe
same level as the heart, so the effects
of
gravity are negligible.
Thus,bloodpressuremeasurementstakenfrom thebrachialar-
teryare fairly close to thebloodpressurein theaorta.
Sincethe
pr
essureinarteriesis pulsatile,bothsystolicand di-
astolic pressures are measured.
f
a person's blood pressure
is
120/80
itmeansthalthesystolicpressure
is
120
mm
Hgandthe
diastolicpressureis
80 mm
Hg. Thesystolicpressurerepresents
the force exertedbythe leftventriclewhenit
pumps
bloodinto
theaorta.Thediastolicpressuremeasurestheresistancetoblood
flow inthearteries.
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this by listening to the brachial artery as you squeeze the
culT.
vVhen you hear no sound, compression is complete.
4. Slowly deBate
the
cuff while listening to the brachial
artery with the s tethoscope.
The
cuff can be deBated by
turning the knob
at
the
base
of
the hand bulb. Try to de
!late
the
cuff at a rate
of
2
to
3 mm Hg per second.
5.
As
the cuff pressure slowly decreases, it will eventually be
come less
than
the arterial pressure. At this
point
, the ar
tery is partially
open
and blood will begin to pass
through
(Figure
n.3c .
Because the blood Bow is
turbul
ent at this
time,
thumping sounds
will be heard. These sounds,
known
as
Korotkoff s sounds,
correspond to the systolic
blood pressure. Make a mental note of the pressure read
ing at the time that you begin to hear KorotkolT's so unds.
6. Continue
to
slowly de!late the cuff. As you do so, the
constriction in the artery is reduced
and
blood !low
becomes less
turbulent. As
a
consequence,
the
thumping
sounds will become faint and eventually disappear.
-r he pressure at the time
when
the thumping sounds stop
corresponds
to the diastolic pressure (Figure n.3d .
Make a
mental
note
of
the
pressure
readi
ng
at this time.
7.
Record your partner's blood pressure in Table 22 .1. Calcu
late your partners' pulse pressure and mean arterial pres
sure and record these values in Table n l
8.
With
your lab partner's assistance, repeat steps 2 through
6 to determine your own blood pressur
e.
Record this value
in Table 22.l. Calculate your pulse pressure and mean ar
terial pressure and record these values in Table 22.l.
The pulse pressure is a good diagnostic tool for
predicting the condition of the arteries. For exam
ple,
arteriosclerosis
causes a decrease in the elasticity of arterial
walls
and
an increase in the resistance to blood
!lmv.
Under these
conditions, how ,vould you expect the pulse pressure to change
so that normal blood flow
is
maintained? Explain.
CARDIOVASCCLAR PHYS10LOGY
ACTIVITY 11 3 Examining the
Effect
of
Exercise
on
Blood Pressure
1.
Using the instructions from Activity 22.2, measure
your partner's blood pressure after he or she sits quietly for
2 to 3
minute£. Record these results in Table
n.2.
Form iJ
Hypothesis
Before
you
begin,
predict
what ef
fect,
if
any, a
period of
exercise will
have on blood pres·
sure,
pulse pressure, and
mean
arterial
pressure
(MAP).
a. Effect on
blood
pressure
b. Effect on pulse pressure _
c. Effect on MAP
2.
Have your partner exercise for 10
to
15 minutes on a sta
tionary bicycle . If a bicycle is not available, another form
of exercise, such as
running
in place, can be substiruted.
Ke
ep the sphygmomanometer an d stethoscope in position
during the exercise period.
Warning:
Anyone who
is
ph
ysically
or
medically unable
to
perJorm
physical eXCI c
ise
should
not
participate
in
this
por-
tion oj the laboratory activity
3. At 3-minute intervals during the exe rcise period, and im
mediately aft
er
exercise ends (i5 minutes), measure yo
ur
lab partner's blood pressure. Calculate the pulse pressure
and MAP Record the results in Table 22.2.
4.
Measure your lab partner 's blood pressure 1 minute after
the exercise period. Take additional measurements at
3-minute intervals until the return to resting blood pres
sure. For each measurement , calculate the pulse pressu re
and
MAP Record the results in Table
22.2.
Assess
the
Outcome Did
your actual results
agree
with
the prediction you
made
earlier?
Explain.
Table 22.1 Blood Pressure Readings
Subject Blood pressure mm
Hg)
1. Population
average
*
120/80
2.
3
Pulse pressure mm Hg) Mean arterial pressure mm Hg)
40
93
.3
• Keep in
mind
that
these readings
are on ly average va lu
es.
You should expect variatio n
In
the population.
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EXE RC I
SE n
NT Y-T W O
Table 22_2 Effect
of
Exercise on
Blood
Pressure
Time
Blood pressure (mm Hg Pulse pressure (mm Hg
Mean arterial pressure (mm Hg
1. Preexercise:
At rest
2. Exercise period:
3 minutes
I
6 minutes
9 minutes
12 minutes
15 minutes
3 Postexercise:
1 minute
4 minutes
7 minutes
10 minutes
I
13
minutes
Pulse
Rate
In the systemic Circulation , waves of pressure are initiated
wh en the left ventricle pumps blood into the aorta . Th e pul se
pressure generates these pressure waves. The waves then
travel alon g other elastic arteries whose walls ex pand and re
co
il
at a frequ ency th at corresponds to the heartbeat. Th e
rhythmi
c
exp
ansion a
nd
reco il of the arteri es is
kn
own as th e
pulse . Pulses can b e felt at various lo
cation
s,
such
as th e radial
artery in
th
e wri st
and
th e femoral
art
ery in
th
e thi gh. They
tend to
dimini
sh in smaller arteries
and
are absent in capillar-
ies and veins.
CTIVITY
22 4 Measuring the
Pulse
Rate
Using your index and middle fingers , appl y
li
ght pressure to the
pulse points a t the following lo cati ons.
l . Temporal artery
pulse
on the side of the head in the tem
poral area
2. Carotid artery pulse in the neck , about 1 cm inferome
dial to the angle of th e jaw
3. Radial artery
pulse
on the
ant
erior su rface of the lateral
wrist
4. Popliteal artery pulse in the popliteal fossa, pos terior to
the
kn
ee
1 Vlhile measuring the pulse, you were in
structed to apply light pressure to the various
pulse points. Exerting too much pressure will stimulate the va
gus nerve. How will this affect y
our
pulse measurement?
2.
The average res ting pulse is b etween 70
and 80
beats per
minute
, but there
is
considerable va
ri
ation in the popula
ti
on.
For example,
it
is not
unu
sual for w ell-trained athletes to ha
ve
pulse rates as low as 40
to
50 beats per
minut
e. (The pulse
rates of some world-class marathon runners are 35
to 40
beats
per minute!)
Wh
y do a thletes tend to have slower pulses?
CTIVITY 22 5
xamining the
ffect of xercise
on
Pulse Rate
l. Have yo
ur
lab pa
rtn
er sit quietly for abo
ut
3
minut
es.
Af-
ter this period, tak e his or her resting pulse. The mos t ac
curate measurement would be to count the number of
beats for 1 full minute; how ever, a resting pulse can usu
ally be measured accurately by counting for 15 seco nds
and multiplying by 4. Reco
rd
your results in Table 22.3.
2.
Ha
ve
yo
ur partn
er exercise for 10 to 15
minut
es
on
a s ta
tionary bicycle. If a b icycle is
not
available, s ubstitute an
other form of exercise (running in place or running up
and down stairs) .
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Table 22.3
easuring
Pulse Rates
Subject
Yourself
I
Lab partner
Resting pulse:
Pulse immediately after exercise:
Pulse rate at various times after exercise:
2 minutes:
4 minutes:
6 minutes:
8 minutes:
10 minutes:
12
minutes:
14
minutes:
16
minutes:
Warning
Anyone who
is
physically
or
medically unable
to
peljonn physical exercise should not participate n this por-
tion o the laborat01J activity
3. Immediately after the exercise period , measure
your
lab
panner s pulse by counting beats for lO seconds and mul-
tiplying by 6. Record the results in Table 22.3.
4. Measure
your
panner s pulse every 2 minutes after exer-
cise until she
or
he returns
to
the resting pulse. Record the
results in Table 22.3. How long does it take for the resting
pulse to return?
5.
Repeat steps 1 through 4 for yourself and record the re-
sults in Table 22.3.
1.
After a period of exercise , counting the pulse
for 10 seconds and multiplying by 6 is more ac-
curate than
counting
for a full minute. Explain why.
2. The length of time it rakes for your pulse to recover
to
a rest-
ing level is an indication
of your
physical fitness and cardiovas-
cular efficiency. As a general rule ,
the
shorter the recovery time,
the better your fitness. How do you compare with your lab
partner
and
with
other
members of the class)
CARDIOVASCULAR PHYSIOLOGY
Sinoatrial
(SA)
node
i AV bundle
k ;rlb
Bund e
branches
Purkinje
fiber
Figure 22.4 The cardiac conduction system. Action potentials
are
spon-
taneous
ly
generated
at
the sinoatrial
SA)
node.
The
other components of
the conduction
sy
stem sp r
ead
depolarizing electric impulses along the
atrial
and
ventricular walls, and
thus,
regulate the heart s pumping action.
lectrocardiography
The heart contains a network of specialized cardiac muscle cells,
known
as the
cardiac conduction system
(Figure 22.4) , which
is able to generate and conduct action potentials without neural
or hormonal stimulation. The sinoatrial (SA)
node
is located in
the posterior wall of the right atrium, adjacent to the opening for
the superior vena cava. Cells in the SA node serve as the heart's
pacemaker
by
spontaneously
generating electrical impulses.
These depo larizing impulses spread across the walls of the atria,
resulting in atrial contraction (systole). As the impulse reaches
the atrioventricular (AV) node in the floor of the right atrium,
the atrial muscle cells repolarize and relax. From the
AV
node,
impulses spread along the AV
bundle,
left
and
right bundle
branches, and Purkinje fibers, resulting in ventricular contrac-
tion. In this manner, these waves of electrical impulses cause the
mechanical
pumping
activity of the heart. Faint traces of these
electric impulses spread through the rest
of
the body
and
create
changes in the electrical potential of the skin. These electrical
changes can be detected by electrodes on the skin and recorded
in a procedure known as electrocardiography. From the resulting
electrocardiogram
(ECG)
it is possible to
examine
the heart's
mechanical activity. If a medical condition causes disruptions in
the electrical activity of the heart, these may be reflected in the
ECG
and
useful for diagnosis.
The normal ECG tracing is a flal baseline interrupted by a
series of waves (Figure 22.5). In a single cardiac cycle,
the
P
wave
indicates the depolarization of the atria
just
prior to the
beginning of atrial contraction or systole.
The
QRS
complex
(QRS interval) represents the depolarization
of
the ventricles,
which precedes ventricular systole. The T
wave
results from
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EXERCISE
TWENTY TWO
• t
:
and other
metal objects.Ask
your
partner
tolie
down
and relax.
ingdeeply,
and
after exercise. In each case, itis
important that
the actual recordingbe done while
your
partner is physically
800
msec
1
I'
-I
R R
P R
S T
+0.5
segmen
egment
S
l
I I
0
0
I I
I
I
S T
I I
I I
I
P-R I
I
interval
1 1
0.5
interval:
ORS interval
O T
(ventricles depolarize)
interval
I I I I
b)
Figure 22.5 Components of the
ECG.
Intervals, such
as
the
P-R
interval,
are
measured from the beginning of the fi
rst
wave to the beginning of the
second wave. Segments. such as the SoT segment, are measured from the
end of the first wave to the beginning of the second wave.
ventricular
repolarization,
which
occurs before
ventricular
re-
laxation
or
diastole.
The
waveassociated
with
repolarizationof
the atriaishidden by the much largerQRScomplex.
Inthefollowingactivity,youwill recordtheECGofyour lab
partner under
varying conditions, correlate electrical
and
me-
chanicaleventsof the heart,and observe the changes inheart
rateassociatedwithbody position
and
breathing pattern.
CLINICAL CORRELATION
Variations
in
the
size
and length
of
the various waves and wave
segments
in
an ECG
are useful in detecting abnormalities in the
heart.
For
example,
a higher
than
normal P
wave may
indicate an
enlarged atrium, and an increase in the height
of the R
wave
(part of the
QRS
complex)
suggests
that
the ventricles
are
en
larged.
The
position of
the ST
segment
(Figure
22.5) can identify
the previous occurrence of a heart attack (myocardial infarction).
If the segment
is
above its normal horizontal position, a heart at
tack likely occurred.
CTIVITY 21 6
Using
the
Biopac Student Lab
System to
Measure
and Evaluate
~ ~
the
Electrical Adivity of
the
Heart
Setup and alibration
1.
Instruct your
lab
partner
to removealljewelry,watches ,
Right forearm,
white lead
Figure 22 ,6 Proper electrode placement and connection
for Lead II ECG.
2.
Attachelectrodeleads(SS2L)to
Channel
2
of
theAcquisi-
tionUnitand then turn theunit on.
3. Use Figure22.6asaguide toattachthreeelectrodes to
your labpartner. Placeone electrodeon themedialaspect
ofeach
Leg just
above theankle
and
athirdelectrode
on
the
anterior
wristof therightforearm. Attach thewhite
electrode lead to therightforearm, theredleadtotheleft
ankle,
and
theblackleadto the rightankle.
4. StarttheBiopac
Student
LabSystem,chooseLesson5
(L05-ECG-l), and
clickOK.
When prompted, enter
a
unique filenameand clickOK.
5. Clickon theCalibrate
button
and waitwhilethecom-
puter
adjusts for optimal recording.The calibrationproce-
dure
willautomatically
stop
after8seconds.
6.
If
thereisasmallECGwaveformwitha relativelyflat
baseline,then calibrationwassuccessful. Ifnot ,clickon
theRedo
Calibration button
,check allconnections,
and
repeatstep 5.
Recording Data
Inthisactivity, youwill recordthe ECG from your lab partner
under
fourconditions: lying
down
,aftersitting
up
,whilebreath-
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8/16/2019 Cardiovascular Physiology Lab
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CARDIOVASCU LAR
PHYSIOLOGY
still. Electrical actIvit)' from muscular movements, like that
B.OpdCSludent I ~ b
flJ - TaJ·lOS
recordedinanEMG,can corrupt the ECG signal.
Fie Edit Transform Display lessons Help
1. With your labpartner lyingcomfortably, click
on
the
Recordbutton.
2. Wait20
seconds
and th enclickon theSuspend button.If
thedatadonotappearcorrector havesignificantbaseline
drift, thenclickontheRedobutton and repeatthis
recordingsegment.
3. Instruct yourlabpartner toqUicklysitupright.Immedi
atelyclickon theResumebutton assoon as
he or
she
is
sittingfullyupright. AmarkerlabeledAftersitting
up
will
beautomaticallyins ertedinto the recording.
4.
Recordfor 20seconds and thenclick
on
theSuspend but
ton
.
I f
thedatadonot appearco rrect,thenclickon the
Redo
button
and repeatthis reco rdingsegment.
5. With yourpartner remainingsea ted,clickon theResume
button.AmarkerlabeledDeep
breathing
will beautomat
icallyinsertedintotherecording.
6.
Recordfor 20secondsand thenhave
your
lab
partner
take
five long,slow,deepbreaths.
You
should
insertmarkersat
thebeginningof eachinhaleand at thesubsequent exhale.
Markersare insertedbypressing theEsckey (Mac)
or
F9
key (PC).
7. Clickon theSuspend buttonand inspectthedata.Deep
breathingmaycausesome baselinedrift.As longasit is
not excessive,youdo notneed to redotherecording.If
thedatacia not appear correct,thenclickon theRedobut
ton,checktheelectrodesandcon nections ,andrepeatthis
recordingsegment.
8. Have
your
labpartner perform anexercise,such aspush-
ups ,jumping jacks ,or running in place to raise theheart
rate. The exerciseperiod
should
lastfor
about
3minutes.
Be careful that theelectrode leadsare not pulled loose
and
are
not obstructing
your partner'smovements. If
necessary,youmayremove theleads,but do not remove
theelectrodes.If
you
do
removethe
le
ads,youmust re
connect th emproperlyimmediatel ya fter theexe rcise is
complete.
Waming Anyone who is phys ically or medically unable to
pe
rform phYSical
exercise should
not
participate
in
this
por-
Iion o th e laboratory activity
9. Onceyourlabpartner
is
seated,
imm
ediatelyclickon the
Resume
button
tocapturetheECGwhile heor she is re
coveringfromexercise.
10. Recordfor 60secondsandclickon the
Suspend
button.
Inspectthedata.Somebaselinedriftisnorma
l. As
long as
it is notexcessive,clicktheDone
button
.i f thedatado
not appearcorrect,clicktheRedo
button
,check theelec
trodesandconnections ,and repeatthissegment.
Data
Analysis
1.
Enterth eReviewSavedData
mode
andselecttheappro
priatedata fil eforLesson5, whichends in-LOS.
E l ~ ~ i l c £ ] ~ D D ~ [ J [ i l l J ~ ~ [ E [ f j J
m
I max I 0.13342mV [TI I none
CG
1.50
1.00
>
5
0.00
-0.50
2716.70 2903.70 31 00.70 3292.70
3484.70
rnliSecondS
Figure22.7 Measuringamplitude
of
the Pwave.
Amplitude
is
mea
su
r
ed by
computingthedifference
in
values between the
last and
firstpoin
ts
of
th
eselected
area
2. Setthreechannelmeasurementboxesas follows:
Ch 2deltaT
Ch2delta
Ch 2
BPM
3. Measure theduration andamplitudeofvariouscompo
nentsofanECG.Thedurationiscalculatedusingthe
delta T measurement.Thismeasurem entcomputes the
differencein timebetween theending andbeginning
pointsof theareaselectedbytheI-beam cursor tool.The
amplitude(mV)ofanECG
component iscalculatedusing
the
delta
measurement.
a. Whenyo uusetheI-beamcursor tool toselectthepeak
andadjacentbaselineofanECG component,themea
surementcomputesthedifferenceinvaluesbetweenthe
lasta
nd
firstpointsoftheselectedarea (Figure22.7).
b. Inorder toaccuratelyselect theproper regionsofthe
ECG,youwillneed tousethemagnifyingglass toolto
zoominonthedesiredheartcycl es. Then ,ifnecessa
ry,
from the
Display
menu,useAutoscale
waveforms
to
scaleandpositiontheECGforoptimalanalysis.
c.
Referto Figure22.5andusetheI-beamcursortoolto
select theappropriateregionsfrom threedifferentcom
pleteheartcycles inSegmentI (atrest ,lyingdown).
Calculatethemean
and recordtheresultsinTable22.4.
tNM wi Do thewavedurations and amplitudes
fall
• h
within normalranges? If anyareabnormal,what
mechanicalor elect ri caleventsareoccurring in theheartat
thistime?
Note Accurately interpreting EeGs
requires significant
training
and practice AIrail ed hea lth care
profeSSional
is best able to
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8/16/2019 Cardiovascular Physiology Lab
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EXERCI E
TWENTY-TWO
Table 22.4 Components
of
the ECG at Rest Segment 1
Component
Normal
range Cycle 1
Duration of P wave delta T 0.06-0
.12
s
Amplitude
of
P wave delta)
0.1-0.3 mV
Duration of PR interval delta
T
0.12-0.20
s
Duration of
PR
segment delta T
0.06-0
.12
s
Duration of QR5 complex delta
T)
0.06-0.10 S
Amplitude of QR5 complex delta)
0.8-1.2 mV
Duration of the
QT
interval delta
T
0.36-0.44
S
Duration of the
5T
segment delta
T
0.12 s
Duration of the T wave delta
T
0.12-0.16 s
Amplitude of the T wave delta)
0.3 mV
- -
Cycle 2 Cycle 1
Mean
determine what abnonnalUies are due
to
/lonnal variation experi-
mental noise and med
ical
cone/itions.
Do
not be alarmed ifyour
ECC is different from those illustrated or from th e nonnal values
in
the tabl e.
4. Measure
the duration delta
T
of the
cardiac cycle. This
measurem
e
nt
reflects
the amount
of time
between
heart
beats.
Th
e
computer can automatically convert
this mea
surement
to beats per
minute
(BPM ) by
dividing
the delta
T value by 60 seconds. BPM will be displayed in the ap
propriate channel measurement
box.
a. In Segment
1, use the
l-b
eam cursor tool to select a
single cardiac cycle from R wave
peak
to R wave peak
(Figure 22.8). Record
the
duration (delta
T and heart
rat e (BPM) in Table 22.5. Repeat for two additional cy
cles
in Segment
1
and
calculate
the mean
.
b. Repeat step (a) for
each of the
remaining three rec
or
d
ing segments and record
your
results in Table 22 .5. In
Segment 3, Deep Breathing, select three cycles that oc
curred during inspirations and then
repeat
on
three cy
cles that occurred
during expirations.
1.
How does
the
heart
rate (BPM)
change dur
ing ea
ch
of the fOllr experimental conditions?
Describe the
ph
ysiological mec
hanisms causing
these changes.
..ta
_
...
...
.. 1
,,1WlII
2J j-oQ
3
__
V )l
..w
I: _
jJ.
u
Figure 22.8
Measuring
beats
per minute.
Heart
rate
is measured by
computing
the
change in time between the last and first points of the se-
lected a
re
a.
2. How does
the duration
(delta T) of
the
cardiac cycle change
during inspiration and expiration?
What
causes
thi s change?
5. Measure changes in the
duration of
ventricular systole and
diastole that. occur
during
exercise.
The
QT interval
is
de
fined as the. period from the Q wave to the e
nd of
the T
wave.
It
corresponds
to
ventricular
systole. Ventricular di
astole, th en , is measured from
the end
of
the
T wave to the
subsequent
R wave.
a. Transfer the
data you
recorded in Table 22.4 for
the
QT interval into the appropriate cells
of
Table 22.6 for
Segment 1.
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8/16/2019 Cardiovascular Physiology Lab
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CARDIOVASC ULAR PHYSIOLOGY
Table 22.5 Changes in eart Rate and Duration
of
Cardiac Cycle
Segment
Measurement
Cardiac cycle Mean
Range
1 2 3
I-Resting lying down Delta T
BPM
2-Sitting
up Delta T
BPM
3-Seated, inspiration Delta T
BPM
3-Seated, expiration
erta
T
BPM
4-After
exercise Delta T
BPM
Table 22 6 Changes in Duration delta T of Ventricular Systole and Diastole
Segment
Measurement
Cardiac
cycle Mean
1 2
3
I-Resting lying down QT interval ventricular systole)
End
of T to subsequent R ventricular diastole)
4-After
exercise QT interval ventricular systole)
End
of T to subsequent R ventricular diastole)
b.
Scroll to the ECC waveform from Segment
1.
Using
How does the
duration
(delta T) of ventricular
the I-beam cursor tool, select the region corresponding
ff WrlNj'j
systole and diastole change from resting to after
to ventricular diastole (from the
end of
T to next
R)
exercise?
and record the delta T measurement. Repeat for two
additional cycles.
c. Scroll to Segment 4, After Exercise,
and
measure the
duration of
ventricular diastole an d systole from three
cardiac cycles. Record the results in Table 22.6 and cal
culate the means.
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8/16/2019 Cardiovascular Physiology Lab
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Name
______________________________________
Exercise Review Sheet
LabSection ____ __________________________
__
ardiovascular
hysiology
Date
______________________________________
1 Describe the physical basis for the first ( lub ) and second
( dup )
heart sounds.
2 Why
is it important for the walls
of
large arteries
to
have an
abundant
supply of elastic
fibers?
3.
What
is
meant
by systolic pressure
and
diastolic pressure?
4
What
is
the pulse pressure? How
is
this value used as a diagnostic tool?
5
Calculate the mean arterial pressure of an individual with a blood pressure of 115170
Questions 6-11: Define the following terms:
6
Cardiac cycle
7
Hypertension
8. Pulse
9
AuscultaLion areas for the
heart
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8/16/2019 Cardiovascular Physiology Lab
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EXERCISE TWENTY TWO
10. Sphygmomanometer
11. Korotkoff s
sounds
12. Identi fy the
components
of the cardiac conduct ion system
and
describe their function .
13.
What
s an electrocardiogram (ECG)? Correlate the various wave patterns on a
normal
ECG with events that occur
during
the cardiac cycle.