Vidula

= Week 1: Why does the taste of water change from place to place? =

Ever wonder why the taste of water varies depending on where you are in the world? Also, why does the same water taste different when you leave it out. What about the flavor of hot and cold tap water? (Yup, it's not just the temperature)

Depending on the source (underground, rivers, reservoirs) and location, water encounters different rocks and tends to contain different minerals such as salts like magnesium and calcium or sulfur compounds. Water with high concentrations of these minerals are often referred to as "hard" water, which is commonly found in (mostly privately owned) mineral springs such as the effervescent springs of Vichy, France, which has naturally carbonated or "sparkling" water. The water that we are used to is "soft" water. Neither taste can be defined as superior, as it seems that for most people, preference for water lies in what they are used to. Sometimes, when the mineral concentrations in tap water are too high or low, people can suffer adverse effects. An imbalanced intake of these minerals, as by drinking water with an abnormally high concentration of calcium, can contribute to kidney stones, and one might resort to drinking only mineral water to solve this.

Mineral content is not the only factor in the flavor of water. Chlorine, added in water treatment, can also cause water to taste different. This also helps to explain why water straight from the tap and water from the same tap that has been left out overnight tastes different. When the water is kept out, chlorine evaporates from the water. Also, when water is cooled, part of what contributes to its taste is it's ability to dissolve more oxygen. As the water is left out to cool, however, the water molecules are less condensed and and therefore contain a lower amount of oxygen. Flowing water also tends to have more dissolved oxygen as opposed to stagnant water that has been sitting in the pipes or on your kitchen counter. Lastly, as O2 leaves CO2 reacts with the stagnant water to form carbonic acid, increasing the acidity of your now tepid, low-oxygen drinking water.

Humans have an (perhaps) evolutionary tendency to prefer cold and oxygenated water, due to the tendency of harmful bacteria to proliferate in warm and stagnant water. [|Here is a news clip of what happened in Des Moines, Iowa, when melting ice carried pollutants into the rivers, forcing water treatment plants to use more chlorine in the purification process (February, 2014).] [|This website shows how the flavor of water can be influenced by other factors, anywhere from rusting and bacteria-ridden pipework to dead animals dying on a roof tank.] What this website doesn't mention is the tendency of the flavor to change in the spring and summer due to algal blooms in some areas that use surface water as a source. Although the water is treated, traces of this flavor can survive to the water that you put in your mouth. This water is usually safe to drink, however. If you use a water filtration system or a water softener, those pellets can also influence the flavor of your water.

As demonstrated in class earlier this week there is a very small percentage of water in world that is fresh water, and an even smaller percentage is drinkable. It is important that we keep our water sources clear of chemicals and pollutants. We should also be able to identify whether a change in the flavor of our water is due to a safe and natural change in the environment, a change in the water purification process, and/or a problem that needs to be addressed, such as a plumbing issue. Would you be scared if your drinking water suddenly tasted completely different, like the people of Des Moines earlier this year? Does this connect to any of the everyday experiences you have had with your drinking water?

= Week 2: How do leeches digest blood? =

While we were sampling macro invertebrates, I happened to be at a table with a bin containing two leeches. One was thin sliver of red, and the other a darker hue. I was curious about how an animal can get all its essential nutrients from just blood, which is what motivated me to learn more about them. Plus, leeches are just generally off-p utting and fascinating creatures.



Leeches are annelids, and have 32 internal segments, each with its own knot of nerve cells called a ganglion, all connected to one anterior brain. They can sense variations in light intensity and are sensitive to smell and touch. Most live in freshwater environments, but some species are terrestrial and marine inhabitants as well. They have two suckers, one located anteriorly on the ventral side and one on the posterior end, that can be used to simultaneously suck in blood using muscular contractions along the length of the body. Only 10% of leeches can actually bite into the skin. Medicinal leeches have 3 incisors, as portrayed in the sketch below. Predatory leeches have one proboscis that they can use to spear their target. Some leeches don't have any teeth, simply feeding open wound, small aquatic organisms (invertebrates eaten as a whole), or various forms of detritus. Those that consume blood store it in their crop, where it is slowly digested. They can store about 5 times their weight in blood, becoming engorged until they can barely move. One can be seen at the end of this video: [|"Leech Doctor"] (viewer discretion advised because this guy literally just lets a bunch of leeches suck his blood). Since the blood is slowly digested, a leech can survive from just two feedings in a year.

The intestine of a leech contains enzymes called exopeptidases that work to detach protein monomers from the amino or carboxyl ends of polypeptides within the blood. Leeches lack the endopeptidases (such as Trypsin and Pepsin) that help with the initial break down of proteins in certain other animals. Blood-sucking leeches obtain the rest of what they need from the two symbiotic bacterial species living in their intestines: Aeromonas veronii and Rikenella. These bacteria are passed down from parent to offspring as they form their cocoon. [|Leech Depositing Cocoon]



Though leeches have been used throughout history for various medicinal purposes in places like medieval Europe, (for bloodletting, which was said to release the "bad" blood of someone who was sick), Greece, and India (and even today with some Quack Doctors), those practices have no proven beneficial effects for illness. Leeches are, however, used for practical purposes in medicine today. Below is a video of how medicinal leeches can help after procedures such as appendage grafting where the establishment of circulation is imperative. The anticoagulant, hirudin, produced by leeches that prevents blood clotting, causes blood to flow freely from the wound for anywhere from a few hours to three days. In grafts, doctors are able to reattach arteries but not the smaller and flimsier veins, so blood tends to build up and cause the appendage to inflame. The leech allows this excess blood to flow out. There has been no proof of any kind of anesthetic being found in leeches, though there may be chemicals that with numbing properties in the saliva. Some leech bites hurt and some can be barely noticeable.

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=== Do you agree with the use of leeches in medicine, or is the risk of infection too great? Instances of the spread of disease are not very common, but it is a possibility. Might there be other methods of blood release, such as the isolation or production of synthetic anticoagulants, or should we keep with the natural method? ===

= Week 1: The Effects of a Sedentary Lifestyle on Human Health =



So you remember those hover chair thingies that the obese passengers of the Axiom rode in WALL-E? How accurate exactly is this portrayal of a population of humans that does nothing but sit and drink their food? We can't know exactly what they're eating, but we can presume that they would be able to develop flavorful, healthy food in the future that would give everyone a good balance of nutrients, so it seems that the issue here is indolence alone. Then again, though weight gain may be a major consequence of sitting for long periods of time, there are several other terrible things that you are doing to your body just by sitting for too long. It is estimated that this alone can increase the risk of death from any cause by nearly 50%, which is particularly alarming with the multitude of desk jobs that we have these days.

So many of the problems associated with excessively sitting have to do with disuse. The statement in WALL-E that the ship-goers had lost much of their bone density over the years holds true. The use of bones throughout your life causes them to grow thicker and stronger. It must have been incredibly difficult for the captain to actually get up and fight Auto, the robot co-pilot. Osteoporosis, a disease characterized by fragile bones that are liable to fracture, is becoming more prevalent as technology has played a more major role in our lives. The disuse of our muscles can also cause muscular degeneration, as we strengthen the muscles associated with sitting and lose use of the muscles that we needed to function normally when standing. Many people will start to report back problems and as they are always bending forward, no longer dependent on the natural curvature of the spine.

The risk of Type 2 Diabetes also increases rapidly. Since these unused muscle cells no longer respond as easily to insulin, the pancreas produces more and more insulin in and endless loop. One study even found a measurable decrease in insulin response after just ONE DAY of sitting too long. Experiments were not only performed on mice, but on humans as well. 14 young, fit, and healthy people had a 40% reduction in their insulin's ability after 24 hours of sitting. As an overall result, a variety of harmful substances are no longer easily removed from the blood and levels of good substances, such as High-Density Lipoproteins (HDL or good cholestorol), decrease.

Not only does your physical health take a toll, but your mental health declines as well with prolonged sedentary activity. The use of muscles in stimulating metabolism and brain activity largely decreases when you are moving, and as a result, some of the naturally produced feel-good hormones do not circulate as effectively through the body. This can eventually lead to depression, which I can certainly relate to from those days that I just sat in front of the computer instead of doing anything more rewarding than clicking through videos and watching movies. Even brain function has been shown to slow as we continue to sit for extended periods of time. This can explain why going out for a run or lifting a few weights can make you feel much happier and more awake, with the effective release and uptake of endorphins and serotonin.

[|The Health Hazards of Sitting]



I don't believe that every single human being will become obese as we make technological advances that limit our activity, however. It may become a more evident issue, but health consciousness has become more prioritized in the US today when compared to just a few decades ago, and people will continue to try to exercise and eat healthy foods.

[|Spending on Technology Equals More Obesity, Study Shows]

This problem can also be connected to the topic of sustainability. It is important to have healthy and fit individuals that can produce healthy offspring. Without enough reproductive success in a population, people will just die out, whether on earth or in space. That is, of course, assuming that we won't manage to artificially interfere with the reproductive process with the new technology, externally joining eggs and sperm like in //Brave New World//. In that case, I guess they can eat away with the their individual health being the only thing to worry about.

What do you think? Do you think that WALL-E accurately portrays what may happen to the human race in the future, and to what extent?