BIOL W3006: Physiology, Fall 2000

Topic 4: Calcium balance

Assignment :  Bones in space

Goal of this assignment:

• read an original research article
• use this article to review what you've learned about calcium  homeostasis
• gain insight into design of scientific experiments, specifically, the choice of which parameter to measure
• read a scientific review
• gain insight into critique of scientific research

Articles:

S.M. Smith, et al., Calcium metabolism before, during, and after a 3-mo spaceflight:  kinetic and biochemical changes  American Journal of Physiology, Vol. 277, Issue 1, R1-R10, July 1999

R.T. Turner, What do we know about the effects of spaceflight on bone? Journal of Applied Physiology, Vol. 89, Issue 2, 840-847, August 2000

Assignment:
1. Read the article by Smith, et al.   The scientists wanted to understand why bone density changes during space flight, but they didn't simply measure the density of bones.  Why did they measure all these other variables?    What did they hope to learn from this? 

• Make a list of the variables that the scientists chose to study, and explain why they chose to study each of these variables.  Or, you could list the aspects of calcium/bone metabolism that they wanted information on, and then mention which variable they measured to get that information.  You could do this by looking at the handout on Calcium Balance, and consider each step where calcium and bone metabolism might be affected, and then mention the variables that were studied.  For example, : 
  • Calcium into body
  • Calcium leaving body
    • urine
    • feces
  • Calcium into bone
  • Calcium removed from bone
  • etc.
• This part should be 1-2 pages, maximum.

2. Read the review article by Turner. 

• Write a brief summary of this review article, 1 page maximum.   This means that you have to read the article, and decide which information is most important to include in the summary.  To give you some sense of how to write this, pretend that you are in a congressional hearing, which is trying to decide whether to cut off funding for this sort of research.    Senator Fleece gets up and complains about all those scientists, always asking for more money, when there has already been more than enough research on bone physiology in space.  You are trying to explain to him the limitations of the results that have been found so far.  Summarize what you think are the most important reasons why the currently available research results can't answer all the questions posed about bone metabolism in space.

Write for an audience of other students in this class, not for professional scientists.  That means that you should translate what you've read into everyday English, not simply parrot the technical jargon you read.  For example, if you read an article stating "We assisted them to regain their ambulatory capacity", you should "translate" this into "They helped the patients learn to walk again."    

 

• To write this article, Turner had to critically review the published research in this field.   In a future assignment, I'll ask you to critically review some published research articles.  What ideas can you get from this article regarding how to review scientific studies?  Make a list of questions that you might want to address in critiquing an article. You should phrase these in terms of general questions you would ask about any kind of article, not in terms of the specific studies of bone or calcium or space biology. 

For example, one problem that Turner finds is "Only small numbers of immature animals have been flown at one time..."  Considering this critique, you might list the following questions to ask about research articles in general:

• How many individuals were studied? 
• Were the individuals in the experiment the same (with regard to age, maturity) as the individuals in the population that the scientists were really interested in?

You should be able to come up with at least 1/2 page of such questions.  Just list the general questions you think of based on his article, don't list the particular phrase in the article that gave you this idea.

 

3. You are expected to work on this assignment in groups of 3.  In other words, you should meet with the other students to decide what to write, not just work on this individually, and then staple your work together.  You should each email me a list of the people in your group, other than yourself, and what percent of the work they each contributed.  If all three of you contributed equally, then you would list 2 other names, and 50% each.  I will calculate a grade for the assignment turned in by each group, and then give each member in the group a "corrected" grade, based on their contribution to the assignment.