What makes blood smell metallic?

Swedish researchers asked that exact same question. Odorants, molecules that dissolve in air and find their way into our nasal mucus membranes to interact with our olfactory receptors, must be volatile. So, first, they extracted volatile compounds from mammalian blood. Then they separated and analyzed them for their chemical composition using gas chromatography-mass spectrometry.

(Guess Chem class is good for something!)

Next, to determine which chemical is responsible for “blood smell” they tested each extract with human subjects. Turns out just one compound smells like blood: trans-4, 5-epoxy-(E)-2-decenal. Say that five times fast!

Finally, to make sure this compound could attract large, dangerous predators (to answer questions about animal behavior and olfaction, not to weaponize it…I hope), they compared the responses of wild dogs and tigers to blood, blood odorant, a fruity odorant, and a control solvent by soaking wooden blocks in the substances. Turns out dogs and tigers love blood odorant as much as the real thing.

Tigers don’t know it’s not blood!

Reflective Blog

Why Reflective Writing?
Reflective writing might not be something you’re used to, especially in a science class, but many students who are willing to give it a try find it helpful. The primary purpose of reflective writing is to critically examine what you have taken away from an experience. This is important in the classroom context because it allows you to identify what you do and (just as importantly) do not understand.

Additionally, reflective writing builds critical thinking skills, writing proficiency, and improves retention of information — all useful skills for a life or health science professional!

What Makes Writing Reflective?
Reflective writing involves thinking about an experience, evaluating what happened, how it affected you, and then putting that learning experience into words. The process of reflective writing involves introspection and critical self-examination (things that do not come naturally to all of us).

Here are some guidelines to help you get started. The guidelines are not meant to be a check list, but rather a framework to guide your introspection and help you write a quality reflection (to gain the benefits listed above). You may expand upon my guidelines to personalize your reflection writing style.

Your blog post should be a reflection on your learning over the last week. A good reflection should summarize what happened and describe how it affected you, what you will take away from the experience, and what you’ll do next.

Start with outlining what you knew going into the week. Then describe what your reading covered. Did the information in the reading match or conflict with your prior understanding? What was difficult to understand? Were you confident in your discussion question answers? Did what you learn raise new questions?

Next, describe what was discussed in class. How did participating (actively or passively) affect your learning? Did class help improve your understanding? Why do you think that was? Did the discussion raise new questions?

Finally, how have your experiences in biology this week changed you? How do you think you’ll use this knowledge in class or in the future? What will you do to answer questions you might still have? How does what you learned this week relate to what you learned previously? How will you resolve conflicting ideas?

Introspection tends to come naturally to introverts, but for those of you who are more extroverted and find reflective writing challenging (or boring), you might try having a reflective discussion with another student in the class. “Interview” each other using the questions presented in the guidelines section above. Take notes, then write out what you discussed.

If you are having trouble getting started, try stream of consciousness writing. Start with a summary of the material discussed, then write whatever you feel next. Keep writing until you come up with answers to some of the questions above. Go back and review what you wrote. Then revise it to meet the guidelines above.