Biology 450 - Animal Physiology Lab Fall 2004

Writing a Physiology Lab Report

Your write-up for Bio 450 should be a clear and concise report of the purpose of the experiments you did, the way in which they were performed, the resulting data, and your conclusions based on these data.  In other words, your report should read like a scientific research article.

In most cases, these reports should be 6-8 pages long, not including the title page or any full-page figures.  You should always turn in what used to be called a typed report, not a hand-written one, and proofread to eliminate spelling and grammatical errors (yada, yada, yada).

Your report should include the following:

Title page

The title page of the report should include only the title of the lab report, your name and your partners’ names, and your lab section (Tuesday P.M., Thursday A.M. or Thursday P.M.).


Your introduction should include basic background information relevant to the experiments you did. (Note that not everything we covered in a particular subject area is necessarily relevant to a particular set of experiments.) This background information needs to be referenced from a reputable source - generally not my lectures, but instead a physiology textbook or article.  Do not use direct quotations from your source.  Instead, put the information in your own words and cite the source of your information in parentheses, like this:

The rate of shortening of a muscle tends to decrease as the load placed on the muscle increases (Germann and Stanfield 2004, pp. 226-234).

Your introduction should also include a description of the goals or purpose of the experiments, and the specific hypotheses or questions being addressed.  A sample introduction for a different experiment is available.

Page numbers should be used beginning with this section.

Material and methods

This section describes what you used and what you did to perform your experiment(s), in moderate but not excruciating detail.  It should be written in the past tense, and should reflect the procedures you actually used and the experiments you actually carried out rather than simply what the lab handout says.

The important equipment you used should be included in your description, with electronic devices and software specified by model number or name and version, respectively. This specification is important so that the reader has complete information about how your results were obtained. For example, you may consider the Acme Tune-rrific 700 Position Transducer & Slide Whistle to be a perfectly reliable piece of equipment, but your reader may have a different opinion.

When discussing procedures, you can assume that the reader has some general knowledge of and experience with the type of work you are describing. Therefore your descriptions can be more concise than the instructions supplied to you to carry out the lab.  Try to distill the important steps and variables from all the details. Keep in mind that the particulars of the equipment, software, etc. will probably differ from one person's lab to the next, so avoid providing step-by-step instructions that may well be irrelevant. For example, instead of writing

In Scope, we opened the Stimulator window and.set Mode to Pulse, the delay to zero, duration to 10 ms, and the voltage range to 10 V. Stimulus amplitude was set to 10 V and the Stimulator window was closed. We then tested the muscle preparation by clicking the “Start” button on Scope’s main window to apply a twitch stimulus.

you could state simply

Stimulus length was set to 10 ms. We initially tested the muscle preparation by applying a single 10V stimulus.

Similarly, you could write "we generated a train of 10 ms duration, 1.5 V stimuli at 10 Hz for 500 ms,” rather than describing exactly the steps involved in getting Scope to produce such a stimulus train. 


Here is where you present the data you collected from each experiment.  Like the other three sections in the body of your paper, this section needs to be in narrative (i.e. paragraph) form, rather than just a list of numeric results. The narrative can include written descriptions of what you observed during your work as well as more quantitative types of results.  Some data may most appropriately be presented in the form of a table or graph (see below), although you may also want to describe any general trend or pattern seen in these data.  If you use a table or graph, it should be referenced at an appropriate point in the body of your text.  For example

Muscle shortening velocity generally decreased with increasing load (Figure 2).

In cases where large number of individual data values were recorded, it may be useful to report summary statistics (means, ranges, etc.) in addition to (or in some cases in place of) those individual values.


This is the section where you interpret or explain your results.  At least part of your discussion should relate back to the ideas, questions or hypotheses presented in the Introduction.  For example, were you able to answer the questions you posed?  Were your hypotheses accepted or rejected?  Were your data in accord with your predictions?  You may also wish to point out any problems you may have had, or any ways in which the experiments could be improved.  If other (or “typical”) data are available, you can compare your results to these. You may also have been left with unanswered questions, and you might want to propose other experiments that might be done to further examine the system you investigated.


A table is a collection of values (typically experimental results) arranged in a column-and-row format. Each table should be given a number and a title. For example

Table 1. Effects of stimulus voltage on isometric force production.


A figure is a graph, drawing, photograph, etc. Each figure should be given a number and title. When creating a graph, be sure to label each axis and provide a legend when more than one data series is present. (On the other hand, if only a single data series is plotted, a legend is typically unnecessary.)


List the sources you cited in your report, in alphabetical order by the first author’s last name.  For each source you should also include the page numbers containing the information you cited, if not included in the citation itself.  The format is:

Germann, W.J. and Stanfield, C.L.  2004.  Principles of Human Physiology. 2nd edition.  Benjamin Cummings, San Francisco.  Pp. 226-234.

Note that in scientific writing direct quotations from sources are quite rare – so don’t plan on using them in your report!

An important point:

Do not plagiarize when writing this report.  This means you should not copy the work of either another student, a book author, or anyone else.  Note that simply rearranging or changing a few words is not sufficient to make the work your own.  You should be able to read and understand someone else’s ideas, or talk over your results and conclusions with your lab partners, but then write your report in your own words.