Name
Human Physiology Lab Manual
Biology 219
Daniel Clemens, Ph.D.
Fall 2014
Human Physiology Lab Manual
TABLE OF CONTENTS
Exercise 1
Scientific Measurement and Data ............................................................ 1
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Introduction
The exercises in this manual are designed to reinforce the concepts covered in physiology
lecture and to provide hands-on experience performing physiological measurements and
lab procedures. The labs are not simple “cookbook” exercises, but require that you think
about what you are doing and understand how your observations in the lab are connected
to the underlying principles of physiology.
In order to maximize your success in the lab, it is important that you come prepared to
each lab session by reading the assigned exercise and reviewing the pertinent topics in
your textbook before you come to lab. If you have questions about any of the procedures
or concepts, please ask your instructor before proceeding with the exercise.
Your instructor will review the lab safety and hygiene procedures during the first class
meeting (see pages iii-iv). Prior to each exercise, be sure you understand how to operate
the laboratory equipment to be used and be aware of potential hazards such as sharp
objects, electric current, or hazardous materials. Take good care of the lab instruments
and equipment, and leave the lab as clean or cleaner than you found it.
Finally, make the most of your time in the lab: be curious, engage your mind, and be an
active participant in all the lab exercises.
Acknowledgements
Some of the exercises in this lab manual were modified from Stuart Ira Fox, A Laboratory
Guide to Human Physiology, 13th edition, and from Elaine Marieb, Human Anatomy &
Physiology Laboratory Manual, 6th edition. Dr. Bonnie Moore developed the procedures
for the Concentration and Dilution exercises and contributed to the Spirometry and
Urinalysis exercises. Dr. Alysia Thomas contributed material for the Membrane Potential
exercise, ECG lab (diving reflex), and Acid-Base exercise. We would also like to thank
Dr. Susan Wilson at Santa Rosa Junior College for the use of material from her Human
Physiology Laboratory Manual, 2002 edition.
Microscopy images and photographs of anatomical models in this manual were created by
the author and are the property of Napa Valley College. Sources of other images and
diagrams are cited where applicable.
This manual was developed solely for the use of the students and instructors of Human
Physiology (Biology 219) at Napa Valley College. It is not intended to be sold or
distributed to the public. Any mistakes or omissions in this lab manual are the
responsibility of the author and the NVC Biology Department. Please let us know of any
errors or suggestions for improvements so that we can correct them in future editions.
Dr. Dan Clemens
August 2014
ii
Laboratory Safety Rules
Your participation in this laboratory requires that you follow safe laboratory practices. You are
required to adhere to the safety guidelines listed below, as well as any other safety procedures
given by your instructor or the instructor(s) in charge of the course. You will be asked to sign a
form certifying that you were informed of the safety guidelines and emergency procedures for
this laboratory. Violations of these rules are grounds for expulsion from the laboratory.
Note: You have the right to ask questions regarding your safety in this laboratory, either directly
or anonymously, without fear of reprisal.
 Locate emergency shower and eyewash station. Locate the fire extinguisher and fire alarm.
 The Material Safety Data Sheets (MSDS) contain information on all known health hazards of
the chemicals used in this course. In addition, there is information concerning the cleanup of
spills and the accidental exposure to the chemical (e.g. skin contact or inhalation). You are
advised to inspect the contents of the MSDS binder located in the Instructional Assistant’s office.
 Dispose of all broken glassware, needles and scalpel blades (sharps) in the specially marked
receptacle. Never place any of those items in the trash can.
 Dispose of all animal material in plastic bags.
 Exercise care in working with surgical instruments. Notify you instructor immediately if you
receive any type of injury in the laboratory no matter how slight.
 Never pipette fluids by mouth. Pipetters will be available for your use. Check odors
cautiously. Never taste a chemical.
 Do not drink water from the taps in the laboratory.
 Shoes must be worn in the laboratory. Do not wear open-toed shoes or sandals.
 We suggest that you do not wear loose long sleeves, and wear a lab coat. If you have long hair,
we suggest that you tie it back so that it cannot fall into your work.
 Children and pets are not allowed in the laboratory.
 College regulations prohibit eating or drinking at laboratory tables. If you wish to bring
food/drink to lab, it must be stored in a designated “clean” area and eaten outside the lab.
 Wash hands before and after working in the lab. Wear gloves as needed.
 Turn off the Bunsen burner when you are not using it.
 If any hazardous reagents are spilled, notify your instructor at once.
Before obtaining any reagents, carefully read the labels on the bottles twice. Many chemicals
have similar names. Never return unused chemicals to the original dispensing bottle.
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 Follow the instructor’s directions for disposal of chemicals. When no specific directions are
given, dispose of non-hazardous, water-soluble substances in the sink, and put insoluble materials
such as filter paper in the wastebasket.
 Perform only the experiment assigned; do not experiment on your own. No unauthorized
experiments are allowed.
 Every chemical in a laboratory must be properly labeled. Many chemicals have similar names
and you should read the name twice. If a chemical is a solution, the concentration will also
appear on the label. Solution concentration is commonly described by molarity (e.g., 6M HCl) or
by percent concentration (e.g., 0.9% NaCl).
 Use the proper instrument (eye-dropper, scoopula, etc.) to remove reagents from bottles. Do
not cross contaminate reagents by using the same scoopula for 2 different reagents. E.g. don’t
use the mustard knife in the mayonnaise jar.
 All biohazardous materials are to be disposed of in the special biohazard receptacle.
 All biohazardous spills are to be reported to the instructor or to the instructional assistant and
are to be cleaned up using disinfectant and disposed of properly.
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Exercise 1. Scientific Measurement and Data
This exercise covers basic principles of scientific measurement and data analysis,
including units of measurement, conversion between different units, and graphing of
scientific data.
Materials
calculators
rulers with metric units
graph paper
Introduction
In the physiology laboratory, you will be measuring and analyzing many different types
of scientific data from your lab experiments. Scientific measurement is an essential part
of physiology. To understand the function of the human body, we must not only describe
biological processes, but also quantify the physical and chemical variables that affect
body function. It is important, therefore, to develop the skills needed to make accurate
measurements and to become familiar with methods of scientific data analysis.
First, some definitions (from Merriam-Webster’s Online dictionary, 2009):
data - factual information (as measurements or statistics) used as a basis for reasoning,
discussion, or calculation.*
variable - a quantity that may assume any one of a set of values.
unit - a determinate quantity (as of length, time, heat, or value) adopted as a standard
of measurement.
* the word data is plural when referring to a set of measured values as in “the data are conclusive.”
Most physiological data are numerical values of biological variables such as body
temperature or concentration of a substance in the blood. As a rule, physical variables
must have specific units associated with them. A measurement value without a unit is
meaningless (with a few exceptions, such as pH and specific gravity). Some units are
simple, such as length in meters (m) or time in seconds (s); other units are compound,
such as concentration in grams per deciliter (g/dL) or heart rate in beats per minute
(beats/min). A familiar example from chemistry is the unit of molarity (M) which stands
for moles per liter.
As a physiology student, you will need to become familiar with commonly used units of
physiological variables and be able to perform basic mathematical operations with
physiological quantities, including standard conversions between different units. In
addition, you will need to become familiar with common methods of graphing data and
be able to interpret graphed data.
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In this exercise, you will:




review the metric system
make standard conversions between different units
perform basic mathematical operations with ratios and proportions
calculate average values and graph a physiological data set
The Metric System
Scientists usually use the metric system to quantify physical and biological variables.
The metric system uses units that are based on the decimal system and are related to each
other by some power of ten, which greatly simplifies calculations and conversions. The
modern system of metric units is referred to as the International System of Units (SI).
Physiologists use the SI system for most measurements, but some non-SI units are still in
common use. Table 1.1 gives examples of units that are commonly used in physiology.
Table 1.1. Units Commonly Used in Physiology
Variable
Units
length (distance, height, diameter, etc.)
mass (weight)
time
volume
temperature
concentration
pressure
flow
transport rate
frequency
electrical potential
energy
m, cm, mm, m
kg, g, mg, g
s, min, h, day
L, mL, L
C
mM, mEq/L, g/L, g/dL, mg/mL, mOsm
mm Hg, cm H2O, kPa
L/min, mL/min
g/min, mmole/min
cycles/s (Hz), beats/min (bpm), breaths/min
mV
kcal, kJ
The symbol for an SI unit often contains a prefix indicating the power of ten. Table 1.2
lists the SI unit prefixes that are most commonly used in physiology.
Table 1.2. Selected SI Unit Prefixes and Symbols
Prefix
Symbol
Multiplication Factor
mega
kilo
deci
centi
milli
micro
nano
pico
M
k
d
c
m

n
p
1,000,000 (106)
1,000 (103)
0.1 (10-1)
0.01 (10-2)
0.001 (10-3)
0.000001 (10-6)
0.000000001 (10-9)
0.000000000001 (10-12)
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Unit Conversion
To convert between metric units with different prefixes, first determine the multiplication
factor (power of ten) between the old and new units (see Table 1.2). Write the
conversion formula as: 1 (old units) = x (new units), where x is the conversion factor.
Then, multiply the old value by this factor to convert to the new units.
For example, to convert from cm to mm, first write the appropriate conversion formula:
1 cm = 10 mm. Then, multiply the measurement in cm by 10 (the conversion factor) to
convert it to mm. To convert from mL to L, write the conversion formula: 1 mL =
0.001 L, then multiply the volume in mL by 0.001 to convert to L.
Since we are working with powers of ten (a built-in advantage of the metric system), you
can also do these conversions simply by moving the decimal point the appropriate number
of places, that is, one place for each power of 10, but be sure to move it in the proper
direction! A rule of thumb is that a smaller unit will have a larger numerical value (move
the decimal point to the right) and a larger unit will have a smaller numerical value (move
the decimal point to the left).
The line below may help you to visualize this:
I
k
I
I
I
unit
I
d
I
c
I
m
I
I
I

I
I
I
n
Each tick mark represents one decimal place to move when converting between unit
prefixes; “unit” refers to the base unit with no prefix (such as g or L). In the examples
above, to convert from cm to mm (larger to smaller unit), move one decimal place to the
right (1.0 cm = 10 mm). To convert from mL to L (smaller to larger unit), move three
decimal places to the left (1.0 mL = 0.001 L).
While the metric system is the standard for science and medicine, the “English system”
of measurement is still commonly used in the United States. Table 1.3 shows some
conversion factors between units in the metric system and English system.
Table 1.3. Equivalence Between Metric Units and English Units
Metric (SI) Unit
Length
English Equivalent
English Unit
1 meter = 39.37 inches
1 meter = 3.28 feet
1 km = 0.62 mile
Metric Equivalent
1 inch = 2.54 cm
1 foot = 0.305 meter
1 mile = 1.61 km
Mass (weight)
1 gram = 0.035 ounces
1 kg = 2.2 pounds
1 ounce = 28.3 grams
1 pound = 0.454 kg
Time
1 minute = 60 s
1 hour = 3600 s
Volume
1 liter = 1.057 quarts
1 liter = 33.8 ounces
1 quart = 0.946 liter = 946 mL
1 fluid ounce = 29.56 mL
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Temperature
To convert between Celsius and Fahrenheit scales, use the following formulas:
C = (F – 32) / 1.8
F = (1.8 x C) + 32
Dimensional Analysis
Dimensional analysis is a useful method for converting between different units. This is a
problem-solving method that is based on the fact that any number or numerical expression
can be multiplied by one without changing its value. To convert from one unit to a
different unit, multiply the value to be converted by a ratio of the two units that is equal to
one, arranging the ratio so that the old units cancel out. This is demonstrated in the
following examples.
Example 1: Convert 5000 mm into meters.
Step 1 - Write a ratio of the two units that is equal to one (the conversion ratio), so
that the new unit (m) is in the numerator and the old unit (mm) is in the denominator.
1 m = 1000 mm, therefore,
1m
1000 mm
= 1
Step 2 - Multiply the value to be converted by the conversion ratio and do the math.
1m
= 5000 m = 5 m
1000 mm
1000
Notice that the old units (mm) cancel out, leaving the new units we want (m).
5000 mm x
Example 2: Convert 5000 mm into cm.
Step 1 - Set up the conversion ratio:
Step 2 - Do the math:
5000 mm x
1 cm
10 mm
1 cm
= 500 cm
10 mm
Example 3: Convert 150 pounds into kg.
Step 1 - Set up the conversion ratio:
Step 2 - Do the math:
150 lbs x
1 kg
2.2 lbs
1 kg
2.2 lbs
= 68.2 kg
Example 4: Convert 60 miles per hour into meters per second.
This example requires two conversions: from miles to meters and from hours to
seconds. Also notice that we want seconds to be in the denominator (remember that
“per” means “divided by”).
1 hr
1000 m
Step 1 - Set up the conversion ratios: 1.61 km
1 mile
3600 s
1 km
Step 2 - Do the math:
60 miles x 1.61 km x 1000 m x 1 hr = 26.8 m/s
1 hr
3600 s
1 mile
1 km
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Ratios and Proportions
A ratio is a mathematical expression that relates two quantities by division. Many kinds of
scientific data are expressed as ratios. Ratios are often used to compare two quantities (for
example, the number of computer stations to the number of students in Physiology class).
When using ratios to compare quantities, the two quantities must have the same units. One
cannot compare the weights of two animals if the first is expressed in pounds and the
second is in kilograms. Alternatively, ratios can be used to perform conversions between
units (see Dimensional Analysis above), in which case the conversion factor is a ratio of
two values with different units that is equal to one.
The term proportion is sometimes used as a synonym for ratio, but it also has a more
specific meaning in mathematics. A mathematical proportion is an expression of equality
between two ratios, as in:
A = C
B
D
Proportions are often used to solve for an unknown quantity. If three of the quantities are
known, the fourth can be calculated by cross multiplication, i.e., A x D = B x C. For
example, if a muscle contraction is recorded on a chart moving at a speed of 50 mm/s and
the trace covers 5 mm, you can determine the duration of the contraction (x) using a
proportion as follows:
50 mm =
1s
5 mm
x
Cross multiply and solve for x:
50 x = 5,
x = 0.1 s
Average Values
Analysis of scientific data often includes calculation of the arithmetic average or mean
value. The mean is calculated as the sum of the values in a set of numbers divided by the
number of values (n = sample size). In mathematical terms:
X = Σ(x) / n.
Average values are useful for summarizing data and for comparing between groups.
Many scientific studies test whether there is a significant difference in the mean value of
a variable between two groups (say between a treatment group and a control group). This
involves using statistical analysis, which is beyond the scope of this exercise.
Physiological values from an individual are often compared with the population mean or
“normal” value. Normal physiological values will be referred to often during the course;
however, because physiological data are naturally variable, in practice it is more correct
to refer to a normal range of values for a physiological variable. Values that deviate
significantly from the normal range can be important indicators of physiological
dysfunction or disease.
When we collect data from humans in the laboratory, the natural variation that exists is
compounded by the fact that the data will be collected by many different observers with a
wide range of skills. Therefore, we do not expect most of our data to show statistically
significant differences, we will only be noting trends or suggestions of differences.
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Graphs
Scientific data are often plotted in a graph to facilitate presentation and interpretation of
results. Graphs commonly used in the physiology lab include bar graphs, X-Y plots
(scatter plots and line graphs), and time traces.
A bar graph is often used to compare average values of a variable between different
groups; for example, blood cholesterol levels between a control group and a drug-treatment
group. Bar graphs are simple to construct and provide an easy-to-read, visual summary of
the data. In general, you should plot only one variable at a time on a bar graph, with the
variable on the Y axis (height of the bar) and the groups being compared along the X axis.
An X-Y plot is used to show the relationship between two variables. As a rule, the
independent variable is plotted along the X axis and the dependent variable along the
Y axis. The data may be plotted as separate points (a scatter plot) or as a line connecting
points (a line graph). Note that it is not always appropriate to connect the data points
with a line. Use a line graph to plot continuous data from the same individual or
experimental run. Use a scatter plot to graph points from different individuals in a
population or test group. In this case, the points should not be connected with a line, but
a “best-fit” line may be drawn through the data points to show the general trend.
A time trace is a type of X-Y plot that has time along the X axis and a measured variable
along the Y axis (Fig. 1). This is one of the most common kinds of graphs in physiology
For all graphs, it is essential to label your graphs and axes with the correct units. The
names of the variables for the X and Y axes are usually written along the axes (to the left
of the Y axis and below the X axis) with their units in parentheses. In a laboratory report
or scientific paper, a graph is called a figure. Each figure should have a title that includes
the figure number and a short caption that explains what the figure shows. Look through
your textbook to find examples of the three kinds of graphs described above.
Figure 1. Arterial blood pressure of a healthy, resting person.
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Exercise 1. Scientific Data
Questions
Name
1. Why is it important to include the correct units with a numerical value?
2. What is the main advantage of the metric system over the English system of measurement?
3. How are ratios used to convert between different units of measurement?
4. What is the benefit of using a bar graph to present data?
5. What information does an X-Y (scatter) plot provide that the bar graph does not?
6. What are some examples of time traces that are commonly used in physiology?
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Exercise 1 Scientific Data
Problem Set
Name
Part 1
1. Use a small metric ruler to measure the length of the line shown below. Record your
measurement in millimeters and in centimeters.
______________________________
________ mm
________ cm
2. Record your weight in pounds and your height in inches; convert these measurements to
kilograms and centimeters.
weight: ________ lbs = ________ kg
height: _______ inches = _______ cm
3. Compute the following conversions:
242 mg =
g
3450 mL =
L
6.28 kg =
g
25 L =
mL
4 kg =
lbs
10C =
F
0.83 cm =
mm
72 F =
C
4. Solve the following proportions for x:
6/36 = x/48
x = _________
9:72 = x:64
x = _________
24/144 = 18/x
x = _________
x/27 = 17/81
x = _________
5. At rest, the left ventricle of the heart pumps 5,000 mL of blood per minute. Blood flow to the
kidneys is approximately 1,200 mL per minute at rest. Assuming that renal blood flow increases
in proportion to total blood flow, what will be the blood flow to the kidneys if the heart pumps
7,000 mL/min? Show your work!
renal blood flow = ________________
6 An electrocardiogram is recorded on mm-grid chart paper moving at a speed of 25 mm/s. If the
recorded distance between heart beats is 20 mm, what is the subject’s heart rate in beats per minute?
Show your work!
heart rate = ________________
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10
Exercise 1. Scientific Data
Problem Set
Name
Part 2
The following table gives data for birth weight and the time of gestation of babies born to
healthy mothers and to alcoholic mothers.
GROUP A
Babies born to healthy mothers
Birth Weight (kg)
Gestation (Days)
3.60
288
4.48
278
3.23
265
2.85
245
4.12
289
3.89
269
3.23
237
3.32
265
3.04
254
GROUP B
Babies born to alcoholic mothers
Birth Weight (kg)
Gestation (Days)
3.02
267
2.91
234
2.32
200
3.13
278
2.87
190
2.38
243
2.99
210
3.31
287
2.84
199
1. Calculate the average weight and average gestation time of each group of babies.
Group A:
Group B:
average birth weight
____________ kg
average gestation
____________ days
average birth weight
____________ kg
average gestation
____________ days
____________ pounds
____________ pounds
2. On a sheet of graph paper, plot a bar graph that compares the average birth weight between the
two groups and a second bar graph that compares the average gestation time between the groups.
Label the graphs appropriately.
3. On the same or a different sheet of graph paper, plot an X-Y scatter plot of the data (gestation
on the X axis and birth weight on the Y axis). Scale and label the axes appropriately and use
different symbols to distinguish the two groups. Draw a best-fit line (with a straight-edge)
through the data for each group (there should be two lines), and label the lines.
4. What do your graphs show about the effects of alcohol on birth weight and gestation time?
What additional information does the X-Y plot show that the bar graph does not?
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