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A similar question was already answered at How do Gram + bacteria use a proton gradient for F-type ATPase? . In those answers, there is a general belief that Gram negative bacteria do not have much control over their intermembrane space pH, because their outer membranes have many porins, such as OmpC, which allows free passage both ways for protons and other ...


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Assuming the jar is airtight-- I think your oxygen consumption rate may be too high and that 40$\mu l$ per hour$^1$ might be closer but since it's a high figure anyway we can use it. 40 $\mu l$ per minute would be about 2400 $\mu l $/hr. A 12-ounce jar is about 0.355 liters. At sea level, air contains about 20% oxygen so the volume of oxygen in the jar is ...


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According to Wikipedia "In a healthy, young adult, tidal volume is approximately 500 ml per inspiration..." (tidal volume is the volume inspired/expired) Using this figure, together with values for gas composition also taken from Wikipedia, I estimate that in each breath we take in 18 mg O2 (1.1 mmol) and we release 36 mg of CO2 (1.2 mmol) plus 20 ...


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This article quotes a professor of respiratory physiology that says "dogs are built to pant just right. The mechanics of their lungs and chest set a precise rate for panting that minimizes the amount of work while maximizing cooling power." They also don't breathe fully when panting, so they can still cool themselves without increasing gas exchange. This is ...


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The glycogen in the liver begins providing blood glucose. Muscle glycogen is used as fuel by the muscles, fat cells (adipose tissue) release fatty acids to manufacture ketone bodies in the liver and to be used by the brain as fuel, and body proteins are converted to glucose. In short, the body's metabolism shifts to catabolic reactions. If this continues ...


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I'm taking this question at face value. Yes, fish have gills, but we also have a respiratory surface in our lungs so why couldn't we 'breathe' water and extract the oxygen (since extraction is a simple matter of diffusion from the content of the lungs into the blood). Apparently we use 550 L of pure O2 per day. This works out as approximately 400 g. The ...


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This is more about basic physics than biology. When you hold your breath, you normally take in one last long breath and keep it in as long as possible, Your lungs are therefore already full of gas (remember that the oxygen used by our lungs is only ~22% of the total volume of air you inhale). Therefore, when you release that breath and want to take in a new ...


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I'd argue that we do "breathe" all those gases. Air that we inhale (at sea level) is about 78% N$_2$, 20.9% O$_2$, 1% argon, and smaller percentages of CO$_2$, neon, methane, etc. So all those gases are going into the lungs with every breath in. We take up oxygen preferentially because we have hemoglobin to bind O$_2$. When hemoglobin binds the oxygen, it ...


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Inhalation and exhalation happen sequentially as Herman stated in the comments. Yes, your general understanding of inhalation is correct. After the air gets into the lungs, the oxygen is diffused into the capillaries covering the alveoli. The now oxygenated blood travels back to the heart to be circulated throughout the body. As this blood enters ...


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Yes, they are mostly exhaled. The carbon, hydrogen and oxygen that the fats are made of recombine to become $CO_2$ and $H_2 O$ and are exhaled. It's the same overall chemical reaction as if the fats / carbohydrates were burnt, except it's by a different pathway, and the energy produced goes (mostly) towards driving other chemical reactions rather than ...


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For a start, in addition to the International Space Station (ISS), also look at gas mixtures used in scuba diving and breathing gases.


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This shows the major biological transformations of carbon in any system (not just lakes). On the Left Side: $GPP$ (Gross Primary Production) is the total amount of $C$ from atmospheric $CO_2$† that is reduced into organic molecules during the calvin cycle of photosynthesis. This is the process performed by photosynthetic organisms like green ...


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The switch from glucose to ketone bodies as the principal blood metabolite accompanies starvation. This prioritizes the heart, which preferentially uses ketone bodies as a fuel (update; actually it's fatty acids, but they're metabolically similar.) This de-prioritizes the brain, which preferentially uses glucose. [edit] I was asked for a source. This is ...


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Since the question is about risk specific to e-cigarette as opposed to classic cigarettes, what's left is the potential harm from the chemicals in refill-fluids (apart from nicotine): polyethylene glycol, glycerol, alcohol, linalol, flavours. You can find cytotoxicity experiments (e.g. http://www.sciencedirect.com/science/article/pii/S0890623812002833), that ...


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This image is a bit misleading since both ways seem to be the reversion of each other, but in fact they are not (although the same metabolites are used). Reaction A takes only place in gluconeogenesis which makes glucose from other metabolites (coming from the metabolism of fatty acids for example) and this pathway is only active when there is an abundance ...


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Would I be correct in saying that the Bohr effect is ONLY related to the concentration of [H+] in the tissues. I would say no. Because oxygen binding affinity is inversely related to both [1]: high $[H^+]$ concentration and $CO_2$ increase (which is can be a consequence of the first) $CO_2$ is involved in the Bohr effect: The biological ...


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In a strict sense, I think you are correct that [H$^+$] contributes directly to the Bohr effect. A paper by Perutz et al. (1980) identified at least two amino acid residues in hemoglobin that account for the Bohr effect by interacting directly with H$^+$. CO$_2$ is not directly involved. Further, the Bohr effect (and the Root effect) are defined in terms of ...


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Particulates can accumulate in the aveolae in the lungs. This leads to inflammation and tissue damage and scarring. This reduces the available surface area for gas transfer. Low level exposure over long periods is harmful. Asbestos workers are well known to get sick, but miners can get black lung or silicosis from inhaling mining dust, and farmers can get ...


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Well, The paper published in Nature 2003: Despite two decades of progress in understanding the role of LGs and their contents in epidermal barrier function, almost nothing is known about the mechanisms responsible for the assembly of these unique organelles.source: http://www.nature.com/jid/journal/v120/n4/full/5601763a.html Since then the word ...


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Animals use oxygen as a chemical energy source because oxygen gas can react with many other compounds to form oxides, which releases energy and happen spontaneously. Both carbon and nitrogen can be made to react with oxygen, but otherwise they are pretty inert. So of all the gasses in the air present at over a fraction of a percent, oxygen is the only ...


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Good question. If you inhale on top of inhaled air this is more work. There is more dead air, air which is not as useful due to the lower concentration gradient. And we breathe more to exhale carbon dioxide than we require oxygen. Low oxygen levels only push us to breathe when oxygen levels are a good deal lower, however tiny changes in carbon dioxide ...


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I am not sure, if any comparisions have been made with other plant leaves, but unless these contain some pharmacologic active substances, I doubt that they are smoked widely. There are comparisions between normal smoking and the smoking of marijuana and the short version is: Both are harmful. It depends on the temperature at which they are burned, how they ...


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(at an epidemiological scale) WHO on tobacco more than one billion smokers worldwide... Tobacco kills nearly 6 million people each year. WHO on indoor air pollution Around 3 billion people still cook and heat their homes using solid fuels in open fires and leaky stoves. About 2.7 billion burn biomass (wood, animal dung, crop waste) and a ...


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Not knowing the physiology or the literature, I can say based on personal observations that dogs, even when extremely hot or exhausted, mix in a routine of deep inhales and exhales to their panting. Perhaps this prevents unwanted side effects of their cooling mechanisms.



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