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Bio102

Laboratory 6

Blood PressureECG (EKG)

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Objectives for Today’s Lab• Blood Pressure

– Become familiar with determining pulse rate

– Become familiar with taking a blood pressure reading and with using a sphygmomanometer (<- can you spell this? )

– Correlate the effects of various experimental conditions on pulse and blood pressure

• ECG– Acquire a better understanding of the theory behind the ECG

– Record and analyze an ECG

– Computers set up in lab

– You will conduct a one-lead ECG on a lab partner

– Identify the components (waves, intevals) of a normal ECG

– Describe the phases of the cardiac cycle represented by each wave form on the ECG

– Calculate heart rate from an ECG

– Identify the beginning and end of the PR, QRS, and QT intervals

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Location of Pressure Points

Temporal artery

External Carotid artery

Facial artery

Brachial artery

Radial artery

Femoral artery

Popliteal artery

Posterior tibial arteryDorsalis pedis artery

Pulse =

# beats/30 sec X 2

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Pulse in Lab Today

• Use the radial artery of your partner, and use your index finger

• Note the characteristics of the pulse– Regular, irregular– Strong, weak

• Count number of pulses in 30 sec. and multiply by 2 to get the pulse rate

• Do this sitting down, standing up, and after exercise

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Heart Sounds

Lubb (S1)• first heart sound • occurs during ventricular contraction• A-V valves closing

Dupp (S2)• second heart sound• occurs during ventricular relaxation• semilunar valves closing

♥

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Heart Sounds

Listening to the heart (auscultation) is done using a stethoscope (can you spell this?)

Because sounds must pass through several layers of tissue, sounds are not heard directly above their point of origin

S1 = “Lubb” (1 looks like L)

S2 = “Dupp” (2 curved like D)

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Heart Sounds

Auscultate over the left sternal border about the level of the 3rd or 4th rib

Find the point where you can hear the sounds the best, and use that

Remember: lubb-dupp <pause> lubb-dupp <pause> …

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Auscultatory Method of Determining Blood Pressure

Use an average bp from two different readings from both arms.

Do this standing up, sitting down, and after exercise

Korotkoff sounds…

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For the BP portion of today’s today…

• If you need a bit of background and haven’t read it already, take a look at the first few pages of today’s handout

• Also see Marieb’s Lab Manual, pp. 501-508

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Great Book on Cardiovascular Physiology

Excellent reference for cardiovascular physiology

Author: R. E. Klabunde

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A GREAT Book on ECGs

This is you after reading the book…confident and no longer intimidated by ECGs!!

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Electrocardiogram

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Time

Mil

livo

lts

PR Interval: 0.12 – 0.20 sec

QT Interval: 0.20 – 0.40 sec

QRS Interval: < 0.10 sec

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The Bipolar Limb Leads

We will be using only Lead II today, so the right arm will be negative, and the foot will be considered positive

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The Electrocardiogram

A wave of the ECG will be positive (up) when the positive wave is moving toward the positive electrode

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Electrocardiogram and Heart Events

Recall that the left foot electrode is POSITIVE, so when the wave of depolarization is moving toward the left foot, we get a positive (up) deflection on the ECG

Right Arm(-)

Left Foot (+)

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Electrocardiogram and Heart Events

Right Arm (-)

Left Foot(+)

Remember that the T-wave represents repolarization of the ventricles.

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ECG Animation…

NYU ECG tutorial site…

This is available on Links to Explore for Lab 6

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The Paper Chart ECG

0.2 sec0.04 sec

Small boxes are usually 1 mm on each side

Ten mm high represents 1 mV

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The Paper ECG Chart

How long is the PR interval on this strip? The QT interval?

(See Marieb’s Lab Manual pg. 461-462 for further explanation of these)

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Calculating the Heart Rate

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Calculation of Heart Rate

As shown in the sample ECG below, you will calculate your heart rate by measuring the time between 5-8 beats of your heart (4 beats shown below).

Then, to determine your heart rate from that, use the following proportion:Beats measured (beats) * 60 seconds / Total time measured (sec) = Heart rate (bpm)

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For the ECG portion of today’s lab…

• If you haven’t read it already and need a bit of background, see Marieb’s Laboratory Manual pp. 461-464

• Run the ECGs for each member of your group by following the Procedure in your handout– Follow the instructions for the PowerLab ECG module in your handout

• Be sure electrode placement is correct

• Input the correct bioamp settings to reduce interference

• Be sure to record values you measure on the EGG on the computer while you have them on the screen, and then transfer them to the ECG strip after you print it

• Print each person’s ECG and directly on the printed ECG

– Show calculations for the heart rate

– Mark the PR, QRS, and QT intervals on hard copy with their times (that you recorded when they were on the screen)

– Indicate the P, QRS, and T waves and what they mean

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What you should do in lab today…

• After EACH member of your group has an ECG recorded, be sure to SAVE the ECG into a file until the lab is over (just in case)– Select File | Save As (to prevent overwriting

someone else’s file with your data)– Enter a file name using your first and last name

with no spaces as the file name, e.g., SueCidal). – File is saved to the Desktop, so when you retrieve

it later to analyze the data , LOOK ON THE DESKTOP!

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Next Lab…

• Lab 7 - Microcirculation– We will be examining the circulation in arterioles,

capillaries, and venules• In a goldfish tail (a real one; not the cracker)• Examining the effect of various substances/factors on

circulation

– See the handout online