physiology
voltagegate | October 9, 2007Things will be a bit slow on TVG this week. My mother was pulling weeds a bit too hard, fell back and snapped both her radius and ulna in half. The doctors had to bolt and plate the bones, and needless to say, she's out of commission for the next couple of months.
But, mom being mom, she was not going to let little things like broken bones and surgical wounds stop her from spending her vacation in Western PA this week, and I volunteered to help her out around the cabin while she's up here. I'm home briefly to toss up a few reposts of the ecology basics from the beginning of the year (I've…
voltagegate | October 6, 2007I've been on a serious pigment kick lately (reinforced by my little art excursion last night and my review of all of the fall leaf literature), and rhodopsin came to mind, a light absorbing pigment found in animal eyes, archaea and bacteria (often referred to as bacteriorhodopsin in the case of the archaea).
While chlorophyll is capable of absorbing red and blue light from the sun for much of the year (all year for evergreens), bacteriorhodopsin can absorb wavelengths that much of the plant world reflects, from 490 - 550 nm, or the color green (see chart below).
Bacteriorhodopsin is…
voltagegate | October 4, 2007
Heather just finished her self portrait assignment in printmaking, and while others studied pictures of their faces from all angles, she picked up a cell bio text and studied other aspects of self. Her rationale and a few of my thoughts about science and art are below the fold.
I thought her statement was both insightful and poetic:
I am an animal. I am a human. I come from a long branching line of beings, descending in a progression from prehistoric, mammalian, ancestors. Before those ancestral creatures, existed an even longer, and more branched, line of prehistoric plant, and bacterial…
clock | September 28, 2007Yesterday, Chris Clarke wrote a post that I read three times so far, then finally submitted it myself for Reed's consideration for the anthology. Most science bloggers are excellent writers, but rare is the gift that Chris displays in many a post, of weaving many threads into a coherent story that is also gripping and exciting - even when he writes about stuff like respiratory physiology, something that usually puts students to sleep in the classroom. But add a dash of evolution, a cool movie, some dinosaurs, and a personal experience and suddenly the story comes alive for the reader.
This…
clock | September 27, 2007
When teaching human or animal physiology, it is very easy to come up with examples of ubiqutous negative feedback loops. On the other hand, there are very few physiological processes that can serve as examples of positive feedback. These include opening of the ion channels during the action potential, the blood clotting cascade, emptying of the urinary bladder, copulation, breastfeeding and childbirth. The last two (and perhaps the last three!) involve the hormone oxytocin. The childbirth, at least in humans, is a canonical example and the standard story goes roughly like this:
When the…
grrlscientist | September 27, 2007tags: book review, neuroscience, neurobiology, body maps, Sandra Blakeslee, Matthew Blakeslee
As a biologist who reads both widely and deeply about a number of scientific topics, it is very rare when I read a popular book that adds depth and nuance to my understanding of a biological phenomenon, but The Body Has a Mind of Its Own By Sandra Blakeslee and Matthew Blakeslee (NYC: Random House; 2007) is that book. This quiet but well-written book explores the interconnection between the environment, the body and the brain; discusses that the body is more just than a container for the brain and a…
clock | September 24, 2007Sarah Wallace, Matt Ford, ScienceGoGo and Jason Stajich comment on the fungus that gets its energy from radiation. I've heard of Deinococcus radiodurans before, but this is a fungus! Well, if there is an energy source to tap into, even if it is in the middle of Chernobyl, some life form is likely to find a way to do it.
voltagegate | August 31, 2007It's nice when you stumble across some scientific literature that answers a question that's been bugging you. Well, in this case, maybe half of a question.
I've always wondered if there was some connection between an organism's intelligence and its ability to manipulate objects with hands or some analog, and if there would be a way to quantify either attribute effectively. In my mind, cephalopods (squid, octopus) and primates are prime examples of intelligent manipulators, though this connection breaks down as soon as you browse the cetaceans (whales, dolphins).
In my search for literature…
clock | August 28, 2007If we are not there at the moment of birth, how come we can bond with the baby and be good fathers or good adoptive parents? Kate explains. Obligatory Reading of the Day.
Update: Related is this new article by former Scibling David Dobbs: The Hormone That Helps You Read Minds
Update 2: Matt responds to Kate's post.
Update 3: Kate wrote a follow-up: Why help out? The life of an alloparent
terrasig | August 17, 2007The irregular frequency of The Friday Fermentable has been due mostly to my focus on two cases of a (inexpensive) private label wine that has kept my summer drinking variety to a bare minimum. Thankfully, my guest blogger, Erleichda, has often come to the rescue with fabulous descriptions of his group wine dinners.
The focus this time is instead a very interesting research letter published in this week's (16 August 2007) New England Journal of Medicine entitled, "Wine-Induced Anaphylaxis and and Sensitization to Hymenoptera Venom." The full text is currently available freely. Two Spanish…
voltagegate | August 3, 2007Fairy rings are regarded in legends across Europe and North America. In Wales and much of Britain, people thought the rings were leftover from the merriment of fairies. In Ireland they are associated with leprechauns. In Germany, witches gathered around the rings at night. In Scandinavian tales (from which, by the way, Tolkien borrowed heavily), elves danced among the mushrooms in meetings called älvdanser.
In reality, fairy rings are the result of the natural tendency of mycelium (the underground "spreading" portion of the organism) to spread out in a ring shape.
Think of the mycelium like…
clock | July 17, 2007A very interesting new paper was published today in PLoS Biology:
Flight Speeds among Bird Species: Allometric and Phylogenetic Effects by Thomas Alerstam, Mikael Rosen, Johan Backman, Per G. P. Ericson and Olof Hellgren:
Analysing the variation in flight speed among bird species is important in understanding flight. We tested if the cruising speed of different migrating bird species in flapping flight scales with body mass and wing loading according to predictions from aerodynamic theory and to what extent phylogeny provides an additional explanation for variation in speed. Flight speeds…
voltagegate | July 17, 2007Last time we delved into some of the smallest components of spiders and insects, exploring their differences based on deviations in their genetic code through molecular homology.
But there is one particular unifying element to these creatures and their overall make up. They share a series of genes - sequences of DNA that code for an organism's traits - that determine the exact body plan of an arthropod. These genes, called Hox genes,* have become helpful in describing just how evolution by natural selection constructs each different organism from detailed blueprints within our DNA.
More on…
voltagegate | July 16, 2007In the last post of this series, we established that spiders descended from marine arthropods called the eurypterids, distinct and separate from insects, appearing in the fossil record in the late Silurian/early Devonian, about 425 million years ago.
The cladogram we used to analyze the spider's history was based on the organism's morphological characteristics, that is, visible structures like chelicerae and book lungs that can be tied to other organisms that possess the same structures. Limulus (the extant horseshoe crab) has both of these structures and predates the spiders, placing them…
voltagegate | July 11, 2007I started this series of posts almost a year ago, incorporating some basics about taxonomy, evolution, and a little genetics while exploring my fascination with the Chelicerates. I'll be reposting the series, which is included in the Basic Concepts list, this week and next.
Perhaps nothing will spark a lengthy dissertation from an entomologist more quickly than calling a spider a "bug." And lengthy can be well, hours.
Truly, spiders do seem rather buggish; they're creepy, have loads of legs and the thick outer structure (an exoskeleton) that other bugs possess. In short, if it looks like it,…
terrasig | July 8, 2007Have you ever wondered how well-pressurized airlines keep the cabin of the average commercial flight? I have. So, in my gadget days, I once took my altimeter on a flight and learned that on my particular flight the cabin was pressurized to the equivalent of an altitude of 7200 ft (2195 m) above sea level. At the time, I was living at about 8000 ft (2438 m) so I never gave thought to the fact that a prolonged flight might produce symptoms of acute mountain sickness in otherwise unacclimatized individuals predisposed to the disorder.
Now, in research supported by Boeing and published in last…
clock | July 8, 2007What?....
There is a slang phrase in Serbo-Croatian that means "doing nothing; being idle; wasting time", and it is "hladiti jaja", which means "cooling (one's) balls". So, if you see a guy just sitting there, clutching a beer bottle and gazing into the distance, you may ask him "Hey, man, whatcha doin'?" and he may reply " 'ladim jaja", i.e., "I'm coolin' me balls".
Well, this slang phrase, indicating a thermoregulatory behavior, has its origin in the real theromoregulatory physiology. Yes, mammals have to cool their balls. That is why mammalian testes are located outside the body inside…
revere | July 2, 2007Calories are a measure of heat. A small calorie is the amount of heat it takes to raise a gram of water from 3.5 degrees centigrade to 4.5 degrees centigrade. A large Calorie (capital C, also called a kilocalorie) is the amount of heat it takes to raise a kilogram of water (2.2 lbs) from 3.5o C. to 4.5o C. (OK, technically these are 4o calories, so don't write me to complain). The "Calories" we read about in nutrition are large calories. The prototypical male weighs 70 kg. So 70 Calories of heat energy released from food is enough to heat him up one degree centigrade. That's enough to be…
clock | June 29, 2007Modern Brains Have An Ancient Core:
Hormones control growth, metabolism, reproduction and many other important biological processes. In humans, and all other vertebrates, the chemical signals are produced by specialised brain centres such as the hypothalamus and secreted into the blood stream that distributes them around the body.
Researchers from the European Molecular Biology Laboratory [EMBL] now reveal that the hypothalamus and its hormones are not purely vertebrate inventions, but have their evolutionary roots in marine, worm-like ancestors. In this week's issue of the journal Cell they…
clock | June 9, 2007OK, it's been about 20 years since I was last in vet school and I have fogotten most of the stuff I learned there. But I remember a few things.
I clearly remember the Pathology class (and especially the lab!) and the Five Signs (or stages) of Death: pallor mortis (paleness), algor mortis (cooling), rigor mortis (stiffening), livor mortis (blood settling/red patches) and decomposition (rotting). The linked Wikipedia articles are pitifully anthropocentric, though, and there is much more cool stuff to learn when comparing various animals.
The most interesting of the five signs of death is…