The Introduction should briefly state
the rationale for your experiments and clearly state the hypothesis.
For example, if you were testing the effect of pH on a system, you could
start by mentioning the importance of pH in physiology and stating a few
things that it is known to affect. This leads naturally to your curiousity
about how it would affect the system you are looking at. You may
also want to discuss how and why it might have an affect. What steps
in the normal process will hydrogen ions most likely interfere with?
Your introduction should have a clear logical flow of thoughts that explains
why you are testing this particular hypothesis.
Once you have made it clear why your topic
is a reasonable one to study, state exactly what you plan to test (ie.
state your hypothesis). The hypothesis should make it clear what
variables you intend to study. For example, it is not sufficient
to say "we will test the effect of pH on nerves"; you must be clear
what that effect will be. You could say "we hypothesize that low
pH will slow nerve conduction velocity (or change refractory period, threshold...)".
A good hypothesis is never vague.
The Methods should describe what you did in a way that will allow another specialist to analyze the validity of your results. In other words, describe what techniques you used, but don't step through every detail of routine measurements. Other specialists will not need to know how to hook up an EKG, for instance. You should, however, describe any conditions that would affect the measurements. This includes relevant details about the subjects, all the controls that were used, and special modifications or simplifications of standard technique. Typical questions you may answer in this section are: How long was the treatment applied, what doses were used, how long did you record data etc...
The Results should include a written
description of your findings and one or two figures or tables. Describe
what effect the treatments had (or didn't have). Point out any general
trends. Note any observations that may be relevant to interpreting
the results. At this point you should not make any conclusions, just
describe what you found. The written part of results should describe
them in the same way you would summarize them verbally to a colleague.
In other words, don't just list facts, describe what happened.
For the data presentation, don't describe
the response of each individual subject; summarize the data to spot
general trends. Calculate averages and standard deviations for each
set of experimental conditions, if applicable. Graphs and tables
are a good way of summarizing your data. Tables should give averages,
rather than listing every individual data point. Raw data is difficult
for a reader to sort through; it is your job to do the analysis.
You may use simple statistical tests such as chi-square and T-tests where
applicable (although I do not require this). For graphs, make sure
that your graphics are meaningful and help clarify any patterns that may
exist. One or two graphs should be sufficient. If you have
more, you probably haven't summarized your data enough.
The Discussion should analyze and comment on your results. Did the results support your hypothesis? Comment on the strength of your evidence. Was there a clear trend or a weak one? Were there specific conditions or sources of error that weaken your conclusions? Don't just say human error or experimental error, these just cast vague aspersions on your ability. Only mention specific things that introduce error. Also discuss alternative explanations for your results. What else could have given the results you see? Finally, discuss the next logical steps that one could take if they intended to verify or build on your work (or refute alternative explanations). The discussion section discusses the results, it should not bring up any new data that is not found in the results.
If you refer to outside sources, you must have a References Cited section. Any information you get from texts or papers should be cited. Any information that would not be common knowledge for the average physiologist should be cited (ie. anything we don't learn in class). I don't expect you to use outside sources, but some groups find it useful.
I have one final comment with regards to writing a paper as a group. Usually, groups assign each person one or two sections to write. The best way to make this work is to meet as a group after collecting the data and analyze it together. Decide what your conclusions are, and what the main points of the paper should be. Decide on roughly how you want to present the data and talk about the analysis. Then each person can write their section. Once you have all the sections written, you should meet again to go over the final product. I have seen several groups who did not meet the final time. They often end up getting a lower grade than they should have, because they didn't check up on each other's work. If someone in your group does a poor job on their section, it looks just as bad for you as for them. Remember that you all get the same grade, so you should each want to make sure you are happy with the final product before you turn it in. I suppose this doesn't sound entirely fair, but this is the way that projects are done in the real world.