Good evening all,
As I scan the science news each week, I very often encounter science news reports that are worth sending to you. Some of them are timely matches to our course content, some of them are just plain interesting, and still others are just too important to ignore. This one may fall into the last category.
There is an epidemic of the 'Wuhan coronovirus' in China. And, infected individuals are known to have traveled to a large number of places outside of China, such that infections are now being detected in other countries, including here in the U.S. Worldwide, many thousands are known to be infected, and the number of deaths attributed to this virus, while still low, is rising.
This is a new virus, not seen previously in humans. As viruses go, this one is not especially lethal. But, like may other viruses, it appears to be able to spread reasonable easily from person to person. And, persons infected with the virus can be asymptomatic (e.g., show no outward signs of illness) for some time, allowing them to come into contact with others before they are aware of the need to limit their exposure to others.
Is there a vaccine? No, it is not possible to create a vaccine to a new virus in such short time.
From where has this virus come? It has been suggested to have originated in reptiles (possible snakes), and then made the jump to human hosts. This is not completely novel, as other viruses which cause human disease (such as the HIV virus, or those causing 'swine flu' or 'avian flu') also originated in animals.
Why are humans at risk from these new viruses? Because we have no prior exposure, our medical community has no ready defenses (such as vaccines). Because this virus may be appearing in humans for the first time, our immune systems have not evolved any natural defenses, either.
Should you panic? In short, no. Many more people die because of the seasonal flu virus each year than are likely to suffer death from this one.
What should you do: Most importantly, pay attention to the news, stay informed, and be cognizant of anyone in your circle of interaction who may recently have traveled from an area in China experiencing an outbreak. Only if cases are detected in our community will specific calls to action be issued.
So, if the lethality of the virus is low, and the risk of infection is low, why should you care? It's worth paying attention because this is just the latest in a series of 'new' viruses that have emerged (most in the Asia or the Middle East, including SARS and MERS) that, while of relatively little consequence here, are severely problematic there. Imagine entire cities on lock-down, quarantine. Imagine all of the work, school, and travel that has been disrupted. And, remember, there is still much we do not know about this virus, of its origins, its ability to mutate, and spread.
Ask yourself: what if it happened here? Would our U.S. health agencies be ready and able to combat the emergence of a new virus? Many feel that the answer is 'no'... The best individual defense is information, and awareness - that is why I am sending this along today.
I will occasionally pass along articles of this type during the semester. My purpose in doing so is to help you to become more aware of current physiology and health topics, and also to help you assess how you obtain your science and health news.
Those of us working in science obtain our scientific news, quite often, directly from the original sources: the people conducting the studies and reporting the results. They publish their findings in science journals, or present them at conferences.
Most people do not obtain their science news directly, but hear news via secondary sources, such as news releases from scientific organizations, or as science news stories from the major news outlets. These secondary reports often are then carried by tertiary outlets (smaller/other reporting sources).
Along the way from source to audience, science news is normally distilled (a lot) - much of the detail is excluded or simplified, and the reports often are boiled-down to singular take-home messages, which may, or may not, be good representations of the original work.
When you browse the links that I will forward, or when you access science and health news on your own, I'd encourage you to delve a little bit deeper into them, to read more than just the summaries, and to follow links back to original sources when possible. I'd also encourage you to think a little about the translation of news from source to consumer, and the reputability of the news outlets that you use.
None of these news links that I send you will be represented on our course exams, but I do hope that the material in them makes its way into our physiology conversations. I'm sending this link to both my BIOL 240 lecture and lab sections, so my apologies if you receive this message twice.
This first link is from the New York Times, which provides one of the best (e.g., best funded and most reliable) secondary sources of science and health news. They do limit access to only a handful of free articles each month, so I will use them sparingly.
Have a great rest of the weekend -
Good morning all,
As we remain on-schedule, we will not meet in-person for lecture on Friday (15 Nov). I'd like instead to offer you several pieces of recent science news:
We have considered issues surrounding vaping several times this terms, most recently the alarming and poorly-understood severe respiratory distress that has developed in otherwise healthy individuals who vape. After several months of investigation, our CDC (Centers for Disease Control and Prevention) have released a report that appears to identify the likely cause of his distress syndrome: vitamin E acetate, and oily compound used as a additive in some vaping products.
Vitamin E and its derivatives are lipophilic (fat soluble), which allows them to interact with cell membranes more easily than most biological compounds (which are hydrophilic, or lipophobic). Multiple samples of lung tissue from persons afflicted with vaping-associated respiratory distress have revealed this compound adhering to the lung surface. If you remember our discussions on lung structure/function, we described the exchange surface between the alveoli and the capillaries of the lungs as being as thin as possible (essentially, two single-cell layers of epithelium), to allow as much gas diffusion across them as possible. Now, imagine that same surface covered with a sticky, oily residue - it's easy to see that gas exchange could be severely impaired.
There may be other substances contributing to this distress syndrome, and not all experts are convinced that vitamin E acetate is the culprit. But, the evidence is accumulating, and it appears likely to be the primary cause of the cases investigated so far.
If you do vape, check your products - do they list this as an additive? Can you select other materials that do not?
Juul, one of the largest companies producing vaping products, recently agreed to stop making some kinds of flavored vaping products, as they and others in the industry were being accused of improper marketing toward minors:
One young person with vaping-associated respiratory distress recently was forced to undergo a double lung transplant:
Vaping seems like a habit to be avoided at all costs, in my view. Our lung tissue is simply not designed to handle contact with things other than atmospheric gases. In a few years, we may look back at this as a trend that appeared, and briefly flourished, before its significant health implications were well-understood. I suspect that regulations around vaping will get tighter and tighter, and the available evidence suggests that our public health would be best served by limiting access to vaping materials and more carefully regulating their contents.
Have a great rest of the week - see you on Monday for Chapter 22 (DNA Biology and Technology).
Good morning everyone,
Last week I sent you a news report about the prospect of "sugar taxes", extra monetary tax levied against sweetened drinks as a way to reduce their consumption and to (hopefully) induce some improved health in the persons who might normally consume too much sugar in their diets.
The article that I sent you last week considered some of the potential benefits, and potential difficulties, of implementing such taxes. It also described the limited amount of data available thus far, suggesting that it is still too early to know whether these kinds of taxes lead to health improvements.
In this news this week is report of a newly-released study on this very topic. Here, researchers followed the health of a focal group of 200+ people at the University of California-San Fransisco medical school, where a full ban on the sale of sweetened drinks has been in effect. Researchers report improvements in several subject health measures, including reduced waist size, less belly fat, and improved response to insulin. They suggest that these changes were directly a function of reduced sugary drink consumption in these subjects.
Note that this study described subjects under a workplace ban on the sale of sweetened drinks, not those under a "sugar tax". Here, subjects could purchases sweetened drinks elsewhere, or bring them from home, but could not purchase them at their workplace. This is likely to have a larger effect on consumption than a sugar tax itself, but it does suggest that the benefits of lowering the consumption of sweetened drinks is a very worthwhile goal. The available data suggests that most of us consume too much refined sugar (in some form), which suggests that most of us would benefit by reducing our sugar intake. As we have seen many times during the term, our health depends heavily on the choices we make.
Hope that you are enjoying the weekend - see you tomorrow.
Good evening all,
As I noted in lecture on Wednesday, we remain on-schedule with out lecture chapters, and do not have a chapter scheduled for tomorrow (Friday 25 Oct). So, I would like once again to propose that we do not meet in person for lecture tomorrow, and ask instead that you consider the reading that I am forwarding here.
In our last lecture on the endocrine system, we noted the central role of the pancreas and its hormones in the regulation of blood glucose ("blood sugar") levels. When levels of blood glucose rise (such as when we are absorbing digested sugars into our bloodstream after a meal), the hormone insulin is released by the pancreas. Insulin causes our cells (especially liver and muscle cells) to uptake glucose - that is, to take glucose out of the bloodstream and move it into cells by means of membrane transporters. This allows cells to have glucose available for fuel, and also allows cells to store the excess glucose for later use.
On the flip side, when our blood glucose levels decline (such as when we are several hours past a meal and done absorbing nutrients), other cells in the pancreas release the hormone glucagon, which causes our cells (especially liver and muscle cells) to release some of their stored glucose. Together, the use of the two hormones allows us to maintain a relatively even profile of blood glucose levels.
As we discussed yesterday, when blood sugar levels are not well-controlled, diabetes may result. The primary symptom of diabetes is high (and poorly controlled) blood glucose levels. This causes a number of immediate effects, such as excess urination, thirst, and excessive fat metabolism. Over the long term, high levels of blood glucose are very damaging to our tissues, particularly through scarring of the inner lining of our blood vessels. This can lead to the failure of organs with extensive capillary beds (such as the retina of the eye, and the kidney), and has negative effects on circulation in general, especially in the lower periphery. Persons with uncontrolled blood sugar often suffer poor wound healing (especially of the feet), which can lead to infections and, in some cases, require amputation.
In lecture, we distinguished the two general types of diabetes as well. "Type I" diabetes occurs when our own immune system causes the destruction of the insulin-producing cells of the pancreas. This is classified as an auto-immune disorder, as the disease stems from a problem with the immune system. Type I diabetes is often called "juvenile diabetes", because it is typically first diagnosed in one's youth. It can be treated (usually successfully) with injections of insulin - daily, often multiple times. Insulin pumps can also be used - these are small, battery powered pumps that infuse gradual, small amounts of insulin into a catheter. They are expensive and require maintenance, but are effective solutions for many.
"Type II", or "adult onset diabetes" is more challenging. It tends to appear in people with a combination of risk factors: obesity, poor diet, little exercise. Over time, the cells of their body gradually become resistant to insulin, and stop responding to it. Their pancreas produces normal amounts of insulin, but it is ineffective - blood glucose remains elevated, cells become starved for sugar fuels, and metabolize other fuels (mostly fats). Tissue damage accumulates because of the persistently elevated blood glucose levels. Additional insulin (injections) can help somewhat, but the most effective treatment is improvements in diet and exercise. Some people can almost completely reverse their condition through these lifestyle changes, and nearly everyone can benefit at least somewhat from them.
There is a lot of biology associated with diabetes: its causes, effects, and treatments. There also is a lot of sociology to it as well. Diabetes strikes populations very unevenly, and impacts populations of relatively poorer socioeconomic levels most severely. This is believed to be due to a number of factors, including reduced access to high-quality food, more-restrictive employment and familial responsibilities that limit time to exercise, and less access to good information about health. It has also been suggested that food corporations specifically target these populations with advertising and vendors for "fast food", including soft drinks ("soda", or "pop", depending upon where you were raised).
As a food, soda is of very low quality. It is mostly water, but the other primary ingredients are sugar, and often caffeine. It is also quite acidic, and has quite damaging effects on our teeth. So, why do we buy/drink it? We do so at least in part of because of very successful, and very prominent, advertising, which has allowed some soda companies to develop enough clout that they can contractually deliver soda to schools, hospitals, corporations, and even cities.
Think back to your middle- and high-school education: did soda vending machines exist in your school? Were fountain drinks available over the counter in the cafeteria? For most of us, the answer to these questions is "yes". Do you buy bulk quantities of soda? Do you see others around you who do? Again, for most of us, the answers here are "yes" as well.
In recent years, public health experts have recognized the dangers of over-consumption of soda, and more importantly, the danger of exposure to it in our youth. Too often, adolescents develop a "soda habit", and maintain it into adulthood. This, in combination with other lifestyle choices, has led to skyrocketing rates of juvenile obesity. Even more alarming, "adult onset" diabetes is now diagnosed in adolescents at alarming rates.
So what can be done? Well, the debate rages, because to eliminate soda from communities and diets is not really an option. Soda companies are large, and powerful, and they have an avid user base that wants their products. This is a situation similar to that faced years ago with the tobacco industry: large and powerful corporations, well-paid lobbies, a desirous user base, and mounting evidence of the dangerous health effects of the product. Here, too, numerous solutions were discussed and tried. One of the remedies that seemed to be most effective was to implement larger and larger taxes on tobacco, to the point at which fewer people were willing, or able, to financially support their tobacco habit.
Because of the success of this strategy to reduce tobacco usage, we now live in an era of the "soda tax". The idea here is the same: if a popular consumer product is legal, but unhealthy, tax it in order to reduce the number of people using it, and/or the amounts that they use. This remains a controversial idea. Why should companies producing a legal, desirable product be punished? Is this ethical? Does this not also punish the people that work for them, and their suppliers, accountants, and all of the other people who work in associated jobs? Does this also punish consumers of relatively lower income unfairly, because they would be the ones least likely to be able to afford a price increase?
With soda, too, the application of a tax is more complicated. Tobacco and alcohol are relatively uniform in how they are packaged and purchased, but sugary drinks exist across the spectrum (from soda, to sweetened milk, to orange juice and yogurt). Wait -- aren't milk, orange juice, and yogurt good for us? Well, yes, but less so if they have a lot of added sugar. Should they be taxed less than soda, because they are relatively more healthy? What about sugary cereals and granola bars? What about foods with artificial sweeteners? The lines are less clear in this current health debate.
The news report I am forwarding describes a recent assessment of the effectiveness of "sugar taxes". Dozens of other countries, and multiple large cities in this country, have imposed this tax. They have existed for a relatively short time, so there is much yet to be learned about them. They do appear to cause a drop in soda consumption, but whether that translates into improved health of the population is still to be determined. Not surprisingly, the soda companies have responded aggressively, with a variety of tactics. This battle is far from settled.
The next time you are at the grocery store, ask yourself if you are planning to put soda into your cart. And, look around: how many people do? It's common to see people pushing shopping carts with 6-packs of bottled soda (often multiple of them) draped over the edges of the cart. This behavior didn't exist 10 years ago! Have the bottles changed to make this more convenient? Or are we buying more? Our fast food restaurants and convenience stores offer *enormous* fountain drinks - 30, 40, even 50 ounces at a time! Does anyone rally need that much soda at once?
On this, and all of our topics, stay informed. Healthy habits require good information, and wise choices. There is plenty of information available on the health aspects of soda and its social implications. Be wise shoppers and consumers!
And, have a great weekend. See you on Monday for Chapter 17.
Good morning all,
During our recent EMG lab, we considered muscle structure/function, and how muscle strength can be improved through enlargement of muscle fibers. We also noted that testosterone can support the development of larger muscles in both men and women. In the news this week is a report confirming that testosterone improves muscle and athletic performance in women, along with news of a strict limit on testosterone in female athletes being imposed by a track-and-field regulatory body.
Testosterone is a potent steroid hormone, produced in abundance by the male gonads (the testes). Testosterone is also found in women. The female gonads (ovaries) do not produce testosterone directly, but do produce several estrogens, which can be converted to testosterone by enzymes (especially in the brain). Both sexes also produce other androgens (male-typical hormones) in the adrenal glands, which also can be converted into testosterone.
So, we tend to think of testosterone as a 'male hormone', but the reality is not so simple. Both women and men have circulating testosterone, although men typically have levels that are 10-30x higher that those found in women. But, here too, our simplistic and convenient categorizations are not always reflected in reality.
While men typically have much more testosterone in circulation than do women, the range of variation in each gender is large. What of women who produce unusually large amounts of testosterone? Will that give them a muscular and a competitive advantage in sporting events? The anecdotal and the experimental evidence say that it will.
It is convenient to think of all persons as being purely binary in terms of their sex, such that all aspects of their sexual make-up (genetic sex, physical sex, physiological sex, gender identity) align to be either purely female or purely male, but the reality is, as always, more complicated. Persons of differential sexual development may not be perfectly aligned in all of their sexual characteristics, causing them to have characteristics which are not purely 100% typical of one gender or another. Apart from the social and physical challenges this poses, how such individuals can be evaluated in regulated sporting events recently has come into question. The most notable case has been that of the South African athlete Caster Semenya, a multi-medal winning foot race champion who has repeatedly been sanctioned because her testosterone levels are higher than the thresholds set for female athletes.
And what of athletes that are making a gender transition? Their testosterone levels are highly variable, and may fall within the male-typical or the female-typical range. Should they be barred from, or limited in, participation in sporting events?
These are important issues, beyond sporting regulation. Most aspects of society long have been male-biased, and it is becoming increasingly apparent that we suffer because of this. In science, it has become very clear that work done largely on male physiology serve females poorly. For decades, the standard experimental models for human physiology have been male mice and rats. Only one gender was used in order to reduce experimental variability. We long have known of differences in the female and male reproductive systems, but we never really appreciated how their influences translate into other systems (including the muscular system). But, now we are learning how surprisingly different male and female physiology outside of reproductive systems can be. And, the fact that this recent study of testosterone supplements in women was one of the first of its kind suggests that we have a lot of catching-up to do:
There is much to be learned about differences in female and male physiology and their implications for our health and well-being, and our scientific community is finally waking up to this fact. How the sporting community deals with the complexities of our physiology is of relatively little importance, perhaps. But the issue of equality in general, in science, health, and society, is one that recent generations have failed to properly address. May your generation be more open, more mindful, and more egalitarian.
Have a great weekend -
Good afternoon all,
Now that our second exam is completed, we will spend a bit of time discussing the nervous and endocrine systems as we start into the 3rd unit of our course. These are the two primary regulatory systems in the body, which makes their place in our homeostatic control very important. Accordingly then, when these systems are dysregulated or hijacked, the problems that arise can be very severe.
We do not have a chapter assigned for tomorrow (Friday 18 Oct), so I would like to give you some supplemental reading, instead. You can review this material on your own, so we will not have to meet in person on Friday (tomorrow).
In lecture yesterday, we outlined the cellular basis of the nervous system, and the method by which neurons communicate with each other and their targets at synapses. Synapses are points of communication between cells, but are not actual points of physical contact between cells. The communication is achieved not by direct cell-to-cell transfer of materials, but rather through neurotransmitters, chemical signals that are released from the 'signaling' cell, drift across the synapse space, and bind to receptors on the 'receiving' cell.
If you think back to early in the term about our discussions of how cells can communicate with each other, you will picture that these neurotransmitters can have effects on their target cells by binding to receptors on the cells, and causing some change: perhaps ion channels open or close, ions move in or out of the cell (or stop flowing), or some enzyme is activated that changes the metabolism of the target cell. These changes might have the effect of stimulating the target cell (causing it to perform more of its cellular function), or inhibiting it.
As I pointed out in lecture yesterday, synapses also are the place where most of our drugs (both legal and illegal) influence nervous system function. Our drugs may change the amount of neurotransmitter that is released, or cause it to stay in the synapse for a longer or shorter time. Some drugs block neurotransmitters from binding to their receptors, or artificially activate the receptors even when no neurotransmitter is present. These all are potentially very powerful effects on synaptic function, and thus brain function. If the effects of medications are targeted to specific neural systems (sensory, motor, motivation, reward, or other), they can drastically alter our behavior and our capabilities.
When we quickly reviewed some some common drugs and their effects at the end of lecture yesterday, I noted that heroin is among our most dangerous drugs, for its ability to cause very high levels of dependence (users can't bear to be without the drug) and tolerance (users need successively larger doses to feel the same effect). Heroin is one of the opioid drugs, a class of drugs long known for their ability to relieve pain and provide pleasure/euphoria. This class of drugs includes morphine, long used clinically for pain relief.
Historically, heroin was derived from natural (plant) sources, and humans have been cultivating and using opioids for thousands of years. Poppy plants have long been grown for their opium sap, which can be consumed as-is, or refined into more-potent forms. With the advent of global travel, poppies grown in Afghanistan can produce opium sap, which can be refined into heroin and trafficked for thousands of miles. This wave of heroin across the planet initiated the opioid crisis, decades ago.
More recently, pharmaceutical advances have led to the development of many other opioids: hydrocodone, oxycodone, fentanyl, and others. They are so effective at providing pain relief that they have been heavily marketed, and heavily prescribed. Black-market sourcing and illegal use of synthetic opioids now far outstrips that of heroin, as the pharmaceuticals are typically cheaper, easier to obtain, and preferred by users because they are, in many cases, more potent. Fentanyl, for example, is estimated to be 20x as potent as heroin. Other synthetic opioids may be as much as 500x as potent.
Prescription and illegal use of opioids now has reached a crisis point in our country. One cannot listen to the news without hearing of opioid uses and deaths (even here at IUP). Opioids do target the pleasure and pain centers of the brain, but they also serve as a general depressant of respiratory function. As users become dependent upon and more tolerant of these drugs, they acquire and use them in higher amounts. This puts them more and more at risk of respiratory failure: their brains simply stop signaling enough breathing. This is especially problematic when users consume illegal drugs, for their contents may not be well-regulated. Far too often, users overdose on drugs which are more concentrated, or in higher doses, than expected.
And so, for your reading on this topic, I'm offering here below a link not to a recent news story, but rather to a more comprehensive news report that was issued last Fall. It describes some of the biology and the neuroscience of opioid addiction, but also presents a variety of personal perspectives from addicted individuals. In many ways, addiction can be considered to be a disease, and the viewpoints and anecdotes describing addiction are both powerful and scary.
This article also includes links to a few other resources on the topic of opioid addiction.
But let us add to this discussion some good news: Because the action of opioids is relatively well-understood, pharmaceutical advances have made available a very effective antidote to opioid overdose. Commonly referred to by its product name (Narcan), naloxone is a substance that binds to opioid receptors, in place of the opioids themselves. But, naloxone does not activate the receptor in the same way as do the opioids; rather, it blocks the receptor from being activated by the opioids.
Naloxone is remarkably effective, and many first responders and emergency personnel now carry it. They find themselves using more frequently than they would like, but there is no doubt that it has saved thousands of lives.
Naloxone is so important in the fight against opioid abuse that the Pennsylvania Department of Health has issued a standing order that allows public citizens to obtain it, if they believe that having Narcan might help them prevent an opioid overdose. If you think that having it would benefit you or those around you, I'd encourage you to consider obtaining it. You can start at the PA Department of Health web site, especially the text pertaining to ACT 139, which described how private citizens might obtain naloxone, through a standing prescription order:
There also are opioid resources available here at IUP, through IUP's Center for Health and Well-Being:
I can help you navigate these resources, if you like.
I hope that these materials help to put our discussions of brain structure/function and synapses into some context. I'd be happy to provide more material on these topics, if anyone is interested.
Have a great weekend - see you on Monday.
Nobel Prize for Medicine jointly awarded to William Kaelin Jr, Sir Peter Ratcliffe and Gregg Semenza - CNN
Good morning all,
In recent weeks we have considered the role of the circulatory and respiratory systems in collecting and delivering oxygen to our tissues, and just last week I sent you a long article about altitude-induced hypoxia and the physiological challenges that it stimulates. We've also discussed the kidney hormone EPO, and its role in stimulating the production of RBCs.
Fresh on the heels of those discussions and reading, this week's science news included the awarding of this year's Nobel Prize in Medicine, to a group of three researchers who study this very phenomenon, the physiological responses to oxygen. Their work is crucial to an understanding of how cells adapt to changing oxygen levels.
Nobel Prizes in science fields are awarded to researchers who have long, established careers and who have made discoveries that defined their fields. This year's winners are no exception - these scientists are well-established and highly respected. And, not surprisingly, they are still active. They also are likely to follow another tradition in that they most likely will use the award not to enrich themselves personally, but to support the work of their research groups. It's a great example of the selflessness that drives much of science: exploration and discovery for the greater good.
There are plenty of other news stories on these awards, including
Breakthroughs in science normally come after long, hard work, built from many small steps of progress - and informed by many failed experiments, a lot of trial-and-error, and requiring much patience. One prize winner (of years past) said that 'if I have seen further than others, it is only because I have stood on the shoulders of those who came before me'. They say that 'no man is an island', and in science that is certainly true - modern science is a highly collaborative venture, and today's advances are built upon the progress of earlier investigators.
When you contribute to a project, no matter how small or insignificant your part may seem, it's important to remember that it adds to our collective knowledge and capability. Who knows? Future Nobel Prizes may depend on you!
Have a great weekend -
Good morning everyone,
In the recent science news are articles related to several of the topics we have considered recently - this is a nice confirmation that our course topics are 'up-to-date'!
Early in the term we considered the behavior of parasitic wasps, that stun prey and then oviposit eggs within them so that their larvae have a ready food supply during early growth. In the news this week is description of a different kind of parasitic wasp, one which parasitizes other wasps.
Here, the form of parasitism is less direct, in that the parasite deposits its eggs into the same plant gall that its host occupies. The parasite larvae then can attack the host, and in doing so, they accomplish a form of behavioral and physiological 'hypermanipulation'. Not only do they use the host tissues for their own nourishment, but they actually trigger a malformed version of the hosts normal escape behavior, which ensures that the host itself doesn't escape the gall but which provides the parasite an escape route.
The degree to which parasites manipulate their hosts can be extraordinary. We are used to thinking that parasites can make use of host tissues, but examples like this reveal more complicated interactions, with some parasites hijacking host behavior as well. There are plenty of examples, such as these:
All are good reminders that host behavior, as well as host tissues, can be exploited by parasites.
Even more recently, I sent you some information about humans who have developed some ability to perform echolocation. Just this week came a report on this topic, suggesting real, functional remapping of the brain's visual cortex to support this new capability:
At some level, neural plasticity is responsible for all that we can learn, but to have whole-scale re-functioning of a part of the brain from one sense to another is very impressive.
Have a good weekend -
Good evening all,
As we remain caught-up on our lecture schedule, we do not need to meet in person on Friday (04 Oct) for lecture. Instead, I'd like to you to consider a recent science news article that bears on our lecture material.
In recent weeks, we have considered the properties of our blood, its red blood cells and hemoglobin, as well as the ways in which the circulatory and respiratory systems interact to deliver oxygen to our tissues. We've also described how erythropoietin (EPO, a hormone released from the kidneys in response to low blood oxygen levels) can stimulate the production of more RBCs.
The article I am sending you considers these same phenomena in a human population that lives (but not thrives) in perhaps the highest-elevation city in the world, La Rinconada, Peru. La Rinconada sits at an elevation of 5,100 m (more than 16,500 ft) above sea level, and has a regular population of >50,000 at this very high altitude, there to work in gold mines.
The air at this elevation contains only half as much oxygen as the air at sea level. Persons not accustomed to living at high altitude can become very ill (sometimes fatally) at elevations above 9,000 ft. To give you an idea of how high in the Andes this city is, consider that 'mountain climbing' here is the US is typically considered to be very technical above 12,000 ft in elevation, and not for amateurs. At La Rinconada, people may spend their entire lives above 16,000 ft in elevation.
The physiological challenges of life at this altitude are many and severe. The low oxygen levels stimulate extremely high levels of RBCs and hemoglobin, as much as 3x those considered to be normal. This, in turn, causes blood viscosity to rise dramatically, which causes abnormally high blood pressures. These elevated blood pressures place extra strain on the heart, causing it to enlarge, often dramatically. Despite these adjustments, many suffer from chronic hypoxia, termed 'chronic mountain sickness', or CMS. Blue-ish skin, fatigue, and low endurance all are common symptoms of CMS, and all stem from low levels of blood oxygen.
Curiously, populations long adapted to life at high altitudes (including some populations in these South American Andes mountains, and others in the Himalayas of Southern Asia) seem to have evolved at least some protections against chronic hypoxia and the challenges it poses. This suggests that there may be genetic tools that can be put to use in helping others who suffer from hypoxia not because of altitude, but because of diseases related to cardiac or respiratory function.
This article describes one team of physiologists and their efforts to assess human physiology and health at this altitude. Their initial focus was on CMS and body responses to it, but they quickly became caught-up in the socio-economic plight of the people there - life is brutal for the residents of this city, and the researchers felt, in many ways, helpless to help them. They certainly could not improve the economic status of the town's residents, nor could they offer a cure for CMS. There, as in many parts of the world (including our own country), the working class are too easily exploited, too easily marginalized. Lack of access to basic health care is often one of the first signs of a population that is short of options and resources. When that combines with dangerous forms of employment for the un- or under-educated, health issues rise and life expectancy falls.
There is a companion podcast for this article as well:
As you review these materials, I'd like you to think about the basic physiological mechanisms at play: how low blood oxygen levels can stimulate RBC responses, and, in turn, how these can contribute to blood pressure, which itself can trigger responses (remember ANF, when blood pressure rises?). Keeping ourselves in homeostatic conditions is complex even under typical environmental conditions; life under extreme conditions only amplifies the challenge.
I hope that you enjoy this article, and I hope that you enjoy the Homecoming weekend. Please be safe, and I will see you on Monday.
Good morning all,
The results of our vaping survey are in!
We had 93 responses in total.
Almost exactly 2/3 (61/93) respondents said that they do not vape.
Almost exactly 1/3 (32/93) respondents reported that they did vape at least one per week.
Those respondents who did not vape rated its danger as 8.1 out of 10.
Those who do vape rated its pleasurability as 6/10, and its danger as 7.3/10.
(interesting that users ranked the pleasurability lower than the danger, isn't it?)
Those who vape do so an average of 12x per week (range:1-100 times per week).
17/31 (42%) of those who vape do check the source/ingredients, while the majority (17/31, 55%) do not.
The vaping materials used (and the number of people who reported using them) are
don't know 1
These findings reflect much of what is reported in the recent news:
- vaping is very popular among college-age students
- additives or alternatives to tobacco are prominently used
- users pay relatively little attention to the ingredients or sourcing of vaping products.
These are dangerous trends! That one can directly and intentionally infuse nicotine is especially worrisome, as is the fact that users do not know with great confidence the source or identify of the other compounds that are inhaling. Our lungs are designed for exposure to atmospheric gases only - introducing any other compounds is potentially quite risky.
We will continue to discuss this topic, and I will continue to pass along more information. Education and effort are the keys to behavioral change - with any luck, we can increase awareness of the dangers of vaping and reduce its prevalence. The numbers of vaping-associated cases of severe respiratory distress and mortality continue to climb - please be aware of the dangers, and use that knowledge to make good choices about your health.