physiology
clock | June 7, 2007When I was a kid I swallowed science-fiction by the crates. And I was too young to be very discerning of quality - I liked everything. Good taste developed later, with age. But even at that tender age, there was one book that was so bad that not only did I realized it was bad, it really, really irked me. It was The Ayes of Texas (check the Amazon readers' reviews!), a stupid 1982 Texas-secessionist fairy-tale in which a rich (and of course brilliant and smooth with ladies) conservative Texan, by throwing millions of dollars at scientists, gets all sorts of new gizmos and gadgets which he…
clock | April 11, 2007How did I miss this!?
Knut Schmidt-Nielsen, one of my personal scientific idols, died on January 25th, 2007at the age of 92.
He has re-invented, or perhaps better to say invented, the field of comparative physiology (now often refered to as 'evolutionary physiology'). He wrote the standard textbook in the field - Animal Physiology: Adaptation and Environment, that he updated through several editions, from which generations of biologists (including myself) learned to think of physiological mechanisms as adaptations.
He wrote a definitive book on Scaling, as well as a wonderful autobiography…
voltagegate | April 2, 2007Tomorrow's NOVA is all about cuttlefish!
Kings of Camouflage, eh? It brings me back to freshmen zoology. My prof showed this incredible video of how cuttlefish communicate, both through color changes and signaling. That video was largely responsible for my decision to change my major: from English to biology.
I never found out what the video was, though I would love a copy. Anyone have any ideas?
clock | March 26, 2007Russ noted that someone is using thermography to study thermoregulation in elephants:
Wits University has just completed studies on how elephants cope with high African temperatures and how that influences their behaviour. In African savannahs, elephants are exposed to high environmental heat loads during the day and low ambient temperatures at night and yet these animals are able to cope quite adequately.
Animals that run the risk of losing energy by dissipating heat often deal with this via regional heterothermy, i.e., wading birds have cold legs so there is less of a heat loss when they…
voltagegate | March 23, 2007European researchers at several institutions have found evidence that supports another one of Darwin's speculations: A male roe deer's antlers are representative of the individual's attributes, and thus play a central role in sexual selection.
Jean-Michel Gaillard comments, "Our results provide evidence that antler size of male roe deer mainly reflects their age and body mass, and is more resilient to variation in environmental conditions such as climate, food resources, and density."
"Body mass and age are both reliable descriptors of individual quality in most vertebrates and have been…
voltagegate | March 20, 2007Researchers from the University of Montana are using bee hives as a sort of early warning system for chemicals and pathogens by analyzing the change in frequency of "collective buzzing" when exposed to contaminants:
"We found bees respond within 30 seconds or less to the presence of a toxic chemical," said Research Professor Jerry Bromenshenk. "The military is interested in that for countering terrorism. But the real surprise was that the sounds bees produce can actually tell what chemical is hitting them."
The insects also make different sounds when attacked by honeybee maladies such as…
clock | February 15, 2007This is the last in the 16-post series of BIO101 lecture notes for a speed-course targeted at adults. As always, I welcome corrections and suggestions for improvement (June 17, 2006)...
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Last week we looked at the organ systems involved in regulation and control of body functions: the nervous, sensory, endocrine and circadian systems. This week, we will cover the organ systems that are regulated and controlled. Again, we will use the zebra-and-lion example to emphasize the way all organ systems work in concert to maintain the optimal internal…
clock | February 8, 2007
The penultimate installment of lecture notes in the BIO101 series. Help me make it better - point out errors of fact and suggest improvements:
It is impossible to cover all organ systems in detail over the course of just two lectures. Thus, we will stick only to the basics. Still, I want to emphasize how much organ systems work together, in concert, to maintain the homeostasis (and rheostasis) of the body. I'd also like to emphasize how fuzzy are the boundaries between organ systems - many organs are, both anatomically and functionally, simultaneously parts of two or more organ systems…
clock | February 5, 2007Just quickly for now without commentary:
Totally cool paper in the last Science:
S. Libert, J. Zwiener, X. Chu, W. VanVoorhies, G. Roman, and S.D.Pletcher
Regulation of Drosophila lifespan by olfaction and food-derived odors:
Smell is an ancient sensory system present in organisms from bacteria to humans. In the nematode Caeonorhabditis elegans, gustatory and olfactory neurons regulate aging and longevity. Using the fruit fly, Drosophila melanogaster, we show that exposure to nutrient-derived odorants can modulate lifespan and partially reverse the longevity-extending effects of dietary…
clock | December 15, 2006Teaching circulatory physiology is pretty much the same as teaching fluid physics. It can get a bit tough and boring. But, if it is taught like this, I bet ther would be no students sleeping in the back row and failing the tests....
clock | December 9, 2006PZ probably already knows about this, but I found this discovery of super-reflective skin cells in squid, cuttlefish and octopus quite amazing!
Hanlon's team discovered that the bottom layer of octopus skin, made up of cells called leucophores, is composed of a translucent, colourless, reflecting protein. "Protein reflectors are very odd in the animal kingdom," says Hanlon, who is a zoologist. What's even more odd is just how reflective these proteins are -- they reflect all wavelengths of light that hit at any angle. "This is beautiful broadband reflection," Hanlon told the Materials…
clock | November 27, 2006It's been almost three months since Arunn, in the comments to this post, promised to write a post about the thermoregulatory function of big, flappy elephant ears. Finally, he's gotten to it, and now you can go and read his post. A perfect entry for the next edition of Panta Rei, which needs your entries ASAP.
clock | November 22, 2006Well, it's Thanksgiving tomorrow night so it's time to republish this post from last year, just in time for the ageless debate: does eating turkey meat make you sleepy? Some people say Yes, some people say No, and the debate can escalate into a big fight. The truth is - we do not know.
But for this hypothesis to be true, several things need to happen. In this post I look at the evidence for each of the those several things. Unfortunately, nobody has put all the elements together yet, and certainly not in a human. I am wondering...is there a simple easily-controlled experiment that…
clock | October 14, 2006Giant Insects Might Reign If Only There Was More Oxygen In The Air:
The delicate lady bug in your garden could be frighteningly large if only there was a greater concentration of oxygen in the air, a new study concludes. The study adds support to the theory that some insects were much larger during the late Paleozoic period because they had a much richer oxygen supply.
clock | October 10, 2006I see that I was the only one answering this week's Ask The ScienceBlogger question (so far). Perhaps these two new studies will inspire some of my SciBlings to add their own thoughts:
Everybody Dance: The Energy You Use Won't Shorten Your Life:
The theory that animals die when they've expended their lifetime allotment of energy may be reaching the end of its own life, according to a study presented at The American Physiological Society conference, Comparative Physiology 2006. However, the longitudinal study leaves open a newer form of the theory -- that antioxidants help prolong life by…
clock | October 4, 2006For easy-to-understand quick look at the evolution of vision I have to refer you to these two posts by PZ Myers, this post of mine, and these two posts by Carl Zimmer.
Now, armed with all that knowledge, you will curely appreciate the importance of this new study:
Compound Eyes, Evolutionary Ties:
Biologists at the University of California, San Diego have discovered that the presence of a key protein in the compound eyes of the fruit fly (which glow at center due to a fluorescent protein) allows the formation of distinct light gathering units in each of its 800 unit eyes, an evolutionary…
clock | October 3, 2006No, not (just) that part - your brain. A new study shows that a single dose of Viagra makes symptoms of sleep apnea worse. And sleep deprivation resulting from sleep apnea may be one of the reasons why you may need Viagra in the first place. What a vicious circle! What a conundrum! Sleepdoctor has the goods.
clock | September 24, 2006My sister in law is an artist and is writing a proposal for funding a project. She intends to use red clay to make some figurines. She has heard an old story that the composition of red clay is similar to the composition of the human body and is wondering how much off the mark is that statement. I am pretty sure that at the level of molecules/compounds the difference is huge, but I am not sure how big is the difference if one breaks down the chemical composition down to elements/atoms. I suspect that carbon and hydrogen may be close, but how about nitrogen, oxygen or, even more difficult…