Thermodynamic Witchcraft

Story time, everybody!

So, right now I’m on a field research team working on the prairies of Colorado. Also right now, the temperature out where the deer and antelope play is stuck in the nineties. Needless to say, I bring a lot of water to work. But since I do not want my water to warm up too quickly and start tasting like old bath water, I freeze it overnight. This is very nice, but I can’t drink completely frozen water. Solid ice is just about useless when you’re thirsty. It needs to melt. Luckily, water (and everything else) has free energy. Free energy (represented by G) is a component of the total energy of a system that can do work at constant pressure. The system is the object or react in question and by work I don’t mean that free energy has a desk job or something. In physics, work is the displacement of an object by a given force. Push a book across your table/desk/park bench with wifi and you can say that you are doing work on that book. This also means you are transferring energy to the book, causing it to move. It’s like witchcraft. Minus the hoods and black goats.

Such evil things.

ANYWAY, if free energy changes, the system/my water bottle is undergoing some kind of reaction. If the change in energy is negative, that is, energy is exiting the system, then we say that the reaction is exergonic. Such reactions are also called spontaneous because they produce product under a given set of conditions and without any work until a reaction reaches equilibrium. However, when the change in energy is positive, energy is entering the system and we say that the reaction is endergonic. It is also non-spontaneous because the reaction won’t proceed toward product production without work being done. So where is my water bottle in all this? It is sitting in the hot Ford Explorer, and given those conditions it doesn’t have to do any work in order to melt. The bum.

Exergonic and endergonic reactions do not necessarily involve things heating up or cooling down. Explosions are a great example of exergonic reactions and they involve (quite a lot of) heat, but protein synthesis is an excellent biological example of an endergonic reaction that does not involve a drastic temperature change.

Now if you’ll excuse me, I’m going to go set up another exergonic reaction in my glass.

Cheers!

Sources

Hoffman, Kurt. “Work and Power.” Physics. Whitman College. Walla Walla, WA. 2011. Lecture.

Sholders, Aaron. “Thermodynamics.” Biochemistry. Colorado State University. Fort Collins, CO. Jan 2013. Lecture.

 

EDIT: Got my endergonic/exergonics confused with regard to ice melting. Fixed now!

Kidding Around Part 2

Back to goat guts.

 

Once a goat has masticated a mouthful (preferably grass and NOT my hair), it travels down the esophagus into the forestomach. The forestomach consists of the first three compartments of the entire stomach, the rumen, the reticulum and the omasum. At this point the food is less food and more of a wet mass. Scientists call it a bolus, but in ruminants it tends to be called cud. As in the stuff they regurgitate to chew on. Anyway, the rumen and reticulum are quite large, most of the anaerobic bacterial fermentation occurs here, besides some absorption of simple molecules and nutrients. Furthermore, food can loop from rumen, to reticulum back to the mouth a couple times before it is digested enough to move on to the omasum. Non-food items (like my hair) will make this trip a quite a few times, assuming the goat does not eventually give up (unlikely) or realize that this particular bite is not terribly appetizing (hella unlikely). Anyway, this loop of repeated mastication, fermentation and absorption greatly increases the efficiency of digestion. If you’ve ever wondered why it’s harder for humans to be herbivores, among other things, our omnivore digestive tract is a LOT less efficient at tackling an exclusively plant-based diet. Our digestive tract is more like that of a carnivore, particularly in terms of length (proteins are much easier to digest so carnivore digestive tracts and relatively short).

Again, back to the goat guts. When the bolus/cud has been chewed for the last time, it heads straight for the omasum. Here water and more nutrients are absorbed via the omasum’s highly folded surface. Oh, and get this: the omasum SORTS shit. Seriously. Big stuff that needs more ruminating will get chucked back (and possibly up-chucked) for more digesting. Anything not turned back continues on to the abomasum. The abomasum secretes acids to digest proteins and rumen microbes (remember the NPCs? They need to stay put or they’ll cause an infection) before the bolus moves on to the intestine as gooey chyme. Nummers. If the digesting goat in question is a kid, the abomasum will also secrete rennin (cheese, anyone?) to clot casein (milk protein) for better digestion.

With the high appetizing chyme now safely in the intestine, I think most of you get the rest: highly folded small intestine continues to absorb water and nutrients, chyme gets denser as it is moved via peristaltic waves (muscles squeezing it down the line) to the large intestine for compression and eventual expulsion. Probably right when the goat’s yard has just been swept.

You guys are lucky you’re so cute.

 

 

Source

Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.

Photo credit, me.

Kidding Around

OK, so goats.

I love goats. Not just itty kiddies, but grown ones too. Not sure why, they’re not usually terribly cuddly. Although if you scritch that spot on their backs, right between the hind legs they just go weak in the knees and it’s adorable.

Anyway, in high school I volunteered at the local zoo’s (Woodland Park Zoo) “Family Farm” which featured goats and other farm animals that are part of the summer petting zoo. Besides tidying their stables, etc., we were responsible for keeping the goats and sheep social in the winter so that when summer came they did not flip any shits over small children trying to pet them. Or at least in one goat’s case, make sure he continued to ignore/avoid everything (he was not actually in contact area at all, but we continued to dream).

So we got used to the goaty quirks, like chewing on our hair and coats. You would also notice them stand still, not moving then suddenly belch softly and start chewing, mouth abruptly full. If you think they just regurgitated something to continue chewing on it…you are exactly right. Goats are herbivores, and considering the low nutritional value of plants, and the high difficulty in digesting large quantities of plant fibers, they possess a stomach with four compartments with which they tackle their dinners. The biggest contribution to digestion in goats comes from bacteria. Bacteria actually aid in fermentation of ingesta (ingested food/miscelani). Though periodically the goats need to regurgitate things that require more chewing.

That’s just a little introduction, but I will continue tomorrow.

Source

Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.

Photo credit, me.