Solved by a verified expert:OVERVIEW OF LAB
Homeostasis, the
ability to maintain a stable internal environment, is a major characteristic of
living organisms. In this exercise, we will examine some homeostatic
mechanisms. The exercise examines adjustments in the cardiovascular system of
human subjects.
HUMAN CARDIOVASCULAR
PHYSIOLOGY
In order to maintain
homeostasis cells must exchange nutrients and wastes with the external
environment. In single celled organisms acquisition of nutrients and removal of
wastes occurs directly across the cell membrane. However, the cells of complex
organisms are isolated from the external environment and normal cell
homeostasis must be maintained by coordinated function of specialized organ
systems. In mammals, the cardiovascular system functions to allow exchange
between cells and the external environment by transporting blood throughout the
different tissues of the body. For example, blood is delivered to the lungs
where oxygen is provided from the external environment and delivered to cells.
Conversely, CO2generated by cells is released into the blood and transported to
the lungs for elimination into the external environment. Other wastes are
transported by the cardiovascular system to the kidneys and liver to enable
excretion from the body. Nutrients from the diet are picked up from the
digestive system by the cardiovascular system and distributed to cells for
storage and use. The cardiovascular system also functions in the delivery of
chemical signals within the body which enables coordination of function between
different organ systems.
Blood flows throughout the
body as a result of a pressure difference generated by the pumping of the
muscular heart. The mammalian heart consists of 2 atria or receiving chambers
and two ventricles or pumping chambers. At rest, the heart normally beats 70-75
times per minute. The cardiac cycleincludes the electrical, mechanical
and valvular events that occur during one heartbeat. Diastoleis the
period of the cardiac cycle during which the ventricles are relaxing, and systole
is the period during which the ventricles are contracting.
During systole blood is pumped from the heart into arteries which
branch extensively and terminate in arterioles which actively change in
diameter to regulate blood flow to different regions of the body. Blood flows
from arterioles into thin-walled capillaries which are adapted for exchange of
nutrients and waste. Blood is returned from capillaries to the heart by
compliant veins. Delivery of blood by the cardiovascular system may be varied
physiologically by varying function of either the heart or blood vessels.
The objectives of this lab
are: 1) to become familiar with some of the measurements that are used to
assess human cardiovascular function including auscultation of heart sounds,
palpation of the peripheral pulse and indirect measurement of blood pressures;
2) to examine the relationship between body mass index and fitness using
cardiovascular responses to exercise; 3) to determine the homeostatic responses
of blood pressure to exercise.
PALPATION OF SUPERFICIAL
PULSE POINTS
As the heart ejects blood
into the arteries during systole the arteries expand, and because arteries
contain elastic tissue they recoil during diastole. This alternating expansion
and recoil creates an arterial pulsewhich normally equals the heart
rate. In addition to providing a measure of the heart rate, the quality of
the pulse (regularity and strength) also provides important functional
information.
Activity 1:
The pulse may be easily
detected from any superficial artery when the artery is compressed against firm
tissue. Palpate the following superficial pulse points: Common carotid artery:
lateral to the Adams apple in the neck Brachial artery: in the antecubital
fossa (inside the elbow).
Radial artery: inside the
wrist near the thumb.
Pulse rate is recorded in
beats per min. Take your pulse
manually for 20 seconds and multiply it by 3 to calculate beats per minute.
Repeat the measurement to see how reproducible your calculation is. Compare
these numbers to the recordings from the digital sphygmomanometer.
INDIRECT MEASUREMENT OF
BLOOD PRESSURE
Evaluation of arterial blood
pressure is a very useful clinical measurement which provides information
regarding both function of the heart and condition of the blood vessels. The
following pressures are commonly measured or calculated:
Systolic blood pressure: The
maximal pressure in an artery produced during the ejection of blood by the
heart. Normal average resting pressure for young adults: ~120mmHg.
Diastolic Blood Pressure: The
minimal pressure in an artery occurring when the heart is relaxed. Normal
average resting pressure for young adults: ~70mmHg.
Blood pressure may be measured directly via a pressure transducer
attached to a cannula placed in a blood vessel. However, arterial blood
pressure is more commonly measured indirectly by applying a pressure externally
to an artery using a sphygmomanometer and listening to arterial sounds using a
stethoscope or having a digital sensor that can detect these sounds. The basis
of this method is that normal blood flow through an artery is laminar and does
not create a sound. However partial occlusion of a blood vessel creates
intermittent flow and turbulence which can be heard (auscultated) using a
stethoscope. The sounds produced when a cuff is used to apply pressure
externally to an artery were first described by Korotkoff in 1905 and are
referred to as the sounds of Korotkoff. Human blood pressures are most
commonly measured in the brachial artery of the upper arm.
Activity 2:
For the data tables, use the
baseline blood pressure and pulse readings obtained from the digital
sphygmomanometer.
Wait for the digital blood
pressure monitor to power up, push the blue button, and wait until the display
starts blinking “0.” Have the subject seated with his or her arm resting on the
lab bench and make sure they don’t move or talk while the reading is being
taken. Wrap the digital blood pressure cuff around the upper arm with the
sensor directly above the inside of the elbow and secure the cuff. Make sure the valve on the arm cuff is
open (counterclockwise) and squeeze the cuff to make sure all the air from the
previous inflation is out. Turn the valve on the cuff clockwise to close it.
Inflate the cuff to approximately 160-180 mm Hg.
Note: do not leave the cuff
inflated for more than 1 minute.This pressure is above the
normal systolic pressure completely collapsing the artery so that no sounds are
made. Open the valve by turning it counter- clockwise to slowly lower the
pressure in the cuff. Wait until the digital blood pressure meter display stops
blinking and displays the blood pressure and pulse readings.
Activity 3: CARDIOVASCULAR
ADAPTATION TO EXERCISE
During exercise the demand
for blood flow to the heart and exercising muscles increase to several times
the resting demand. People who are more physically fit and conditioned to
exercise may recover homeostatic balance after exercise than those who do not
exercise regularly.
Experimental Exercise:
You should work in pairs to
complete the following experiment. Note: any student with a heart problem or
other issues that make vigorous exercise unwise such as a respiratory infection
or pregnancy should not participate as a subject.
1.Record baseline pulse rate and blood pressure using the digital
sphygmomanometer with the subject seated.
2.Body Mass Indexis
often used as an indicator of obesity. Have the subject calculate their Body
Mass Index (BMI) using the following formula:
BMI = [Weight (in lbs) x 703]
/ [(Height in inches)2]
For example, a person who
weighs 200 pounds and is 6 feet 0 inches tall has a BMI of 27.1.
[200 lbs x 703] / [72 inches x 72 inches] = 27.1
3. The exercise for
ascertaining physical fitness is a protocol known as the Harvard Step Test.
a. Perform the step-test: The subject should stand in upright
posture at a bench of prescribed height of 16 inches (40 cm). The subject will
step up and down on the bench at a rate of 30 steps per minute (all the way up
and down equals one step, which should be completed every 2 seconds) for 5
minutes. The pace should be set by a timer who will call “up-2-3-4,
up-2-3-4 so that each “up-2-3-4” requires 2 seconds. A second
observer must time and monitor the subject to ensure that he or she steps fully
on the bench maintaining an upright posture and that he or she reasonably
maintains the pace.
b. Once the subject completes the full 5 minutes of exercise, he
or she should sit down. The pulse rate and blood pressure should be measured as
soon as possible using the digital sphygmomanometer. Wait a full minute after
the reading has been taken and then take another reading. Repeat 2 more times
for a total of 4 readings, each separated by at least a full minute’s wait.
If the digital
sphygmomanometer gives an error reading: 1. Make sure the cuff is on correctly (follow the instruction on the
cuff to make sure the
sensor is directly above the
brachial artery just above the inside of the elbow). 2. Open the air release valve and make sure all the air has
been evacuated from the cuff
before closing the valve. 3. Re-take the measurement as soon as
possible, this time inflating the cuff to a slightly
higher pressure. Avoid inflating much above 200 mm Hg Calculation
of the Index of Physical Fitness:
fitness index= DURATION OF EXERCISE(INSECONDS)*100 / 2*(SUM OF
THREE PULSE COUNTS DURING RECOVERY)
Data table for individual: pulse rates (beats/min.), BMI &
fitness index values
MEASURMENT
BASELINE
IMMEDIATE
1MIN
2MIN
3MIN
PULSE RATE
60
67
63
62
55
DURATION OF EXERCISE (SEC)
300
FITNESS INDEX
166
BMI
32.28
Data table for individual: Blood Pressure Measurements
MEASUREMENT
BASELINE
IMMEDIATE
1 MIN
2 MIN
3 MIN
SYSTOLIC BP
129
163
154
102
95
DIASTOLIC BP
60
148
130
83
65
CALCULATION:
1.Calculate the linear regression equationfor the best fit
trend line through the data and a graph of this linefor the following
pairs of variables from the overall class data: BMI vs FI, BMI vs. resting
Systolic Blood Pressure, BMI vs. resting Diastolic BP, FI vs. resting Systolic
BP, and FI vs. resting Diastolic BP using the following website:http://www.alcula.com/calculators/statistics/linear-
regression/. Include these equations and graphs in the results section of
your lab report.
2. Use the following website to calcultate the correlation
coefficientfrom the data:http://www.alcula.com/calculators/statistics/correlation-coefficient/
_______________ Correlation coefficient is a statistic that
measures how well 2 variables fit a regression line. If Fitness Index increases
linearly as BMI increases, the correlation coefficient will be close to 1. If
Fitness Index decreases perfectly linearly as BMI increases, the correlation
coefficient will be -1. If there is no trend to the data at all and the points are
randomly distributed, the correlation coefficient will be 0. Record the
Correlation Coefficients for all of the comparisons above and include them in
the results section of your lab report.
3.Much like a t-test, whether
two variables are significantly correlated depends on the sample size as well
as how close the data fit the regression line. A dataset of 7 points with a
correlation coefficient of 0.9 has a highly significant p-value of 0.006,
whereas a dataset of 3 points with a correlation coefficient of 0.9 is not
statistically significant (p-value= 0.29). Use the following website to
determine whether the correlation coefficients from the above comparisons are
statistically significant (use two tailed probability):
http://www.danielsoper.com/statcalc3/calc.aspx?id=44
ASSIGNMENT
Your assignment on this lab
will be to write a full lab manuscriptbased on the class BMI and FI
data. -The Titleshould be less than 20 words and give the reader a good
idea of the subject of the manuscript -The Abstractshould summarize
your introduction, Results, and Conclusions in 150 words or less. It is
something quick for the reader to peruse in order to ascertain if it is worth
their time to read the entire manuscript.
-The Introductionshould
give a brief background on the subject matter and present the hypotheses to be
tested. You should have a hypothesis for each of the 5 comparisons you are
performing to calculate Correlation Coefficient. You should cite the lab
protocol if you use it for background information. An example hypothesis:
“There will be a negative relationship between body mass indexes (BMI)
(independent variable) and fitness indexes (dependent variable) among
individuals.”
-The Materials and Methods
section should allow someone to replicate the experiment exactly, but you
shouldn’t re-write everything in the lab manual. After summarizing how the
experiment was performed, cite this lab manualfor further details
(Bostick et al. 2013). Also be sure to state how the analyses were performed
and cite the web sites used.
-In the Resultssection,
you should present all of your data (data tables from page 6, regression line
equations and graphs, correlation coefficients, and p-values for the
correlation coefficients).
-The Discussionsection
is where you should interpret the meaning of the results. This includes
discussing the significance (or lack thereof) of the p-value for the
correlation coefficent. Clearly state how the results compared to your
predictions (hypotheses). • Describe whether or not the data and statistical
tests support your predictions.
• For any results that don’t
support your predictions, give possible explanations as to why the results
didn’t support your hypothesis; note any flaws in the lab procedure that may
have influenced the results, but also mention biological reasons as to why the
results might differ from what you predict. • Discuss future experiments and
experimental design that could more accurately test the relationship between
physical fitness and obesity.
-Literature Cited
To cite the lab manual, use
the template provided in the assignment for the Fish Lab.
For the websites, cite
according to the following example:
Statistics Calculator: Linear
Regression. 2013. GraphPad Software. 10/6/2014.
10/6/2014 refers to the date
you accessed the website. In general, it’s best to cite research published in
peer-reviewed journals and notto cite web pages, but we’re making an
exception for this course since there isn’t a lot of current research on this
particular type of experiment.
This assignment is to be done
individually; you will submit the assignment to turnitin.com, which will
check for plagiarism. Do not read anyone else’s report or let them read
yours.
Literature Cited
Smith JJ, Kampine JP, Circulatory Physiology, The Essentials(2nd
edition). Baltimore: Williams and Wilkins, 1984. Tharp GD, Experiments in
Physiology(4th edition) Burgess Publishing Company, 1980.
BMI
FI
Resting Systolic
Resting Diastolic
22.9
46.4
126
82
23.7
41.0
125
83
24.7
53.7
125
55
27.4
42.1
123
53
26.6
76.9
118
73
24.3
52.8
110
71
20.1
83.3
110
60
23.9
44.5
110
71
22.0
46.5
101
72
24.2
53.6
120
72
23.6
67.3
121
79
19.4
55.8
118
75
25.0
35.4
119
72
20.8
71.1
117
75
22.9
53.9
141
95
29.8
62.0
141
82
24.4
60.5
138
73
18.9
61.0
108
70
21.8
50.6
115
70
28.3
41.7
110
75
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