Hot answers tagged

16

Overview. This is a very interesting question. The ideas behind this have been around for a while and the methods are covered in great detail elsewhere. The overall answer to the hypothetical question is rather surprising. There may be actually potential benefits to perpetual liquid ventilation for people with disease. Trials so far have not found side ...


14

Short answer This is a difficult question to answer. As far as I am aware, asphyxiation results in excitotoxicity, which causes unconsciousness, brain damage and eventually, death. Background Asphyxia is a condition of the body that occurs from severely inadequate oxygen supply, or because of excessive carbon dioxide in the body (First Aid and CPR ...


12

There are two uses of the term respiration: physiological respiration and cellular respiration Physiological respiration involves the intake of outside oxygen and its distribution to the tissues of the body. Breathing is a part of physiological respiration and functions to bring oxygen into the lungs and expel carbon dioxide. Cellular respiration is a ...


10

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 ...


10

Breathing is a part of respiration but respiration is not a part of breathing. Breathing is a process through which oxygen is taken into the body for use in respiration. This involves physical movement to take oxygen (into the lungs) and also chemical action (haemoglobin-carries oxygen from lungs to blood and carbon dioxide from blood to lungs). But ...


8

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 ...


8

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 ...


8

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 ...


8

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 ...


8

The simple answer to your question is that in the absence of oxygen the electron transport chain stops. (It can't go backwards, that would generate oxygen.) However your assumption that it stops at the last step is incorrect, all the cytochromes are converted to their reduced form, and there is feedback that diverts the NADH elsewhere. The situation is ...


6

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 ...


6

According to the abstract from this paper, the intragastric LD50 of $\Delta^9THC$ (tetrahydrocannabinol) in sesame oil using Fischer rats was 1270 mg/kg. Assuming rats and humans are identical (they're not), for an average-sized adult human weighing 70 kg (~155 lb.), the median lethal dose would be 88.9 grams, or about 3.1 oz. Keep in mind that's 3.1 oz. of ...


5

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 ...


5

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 ...


5

An addition to previous answers plus some clarification The term respiration originally meant breathing i.e inhaling and exhaling (See here). It was believed that it is the oxygen and in turn the act of breathing is what lets an organism survive. After substantial research it had been found that, in individual cells it is the ATP production by ...


5

if a person is both (1) hyperventilating and (2) has a low blood pH then this is a case of metabolic acidosis... in metabolic acidosis the patient compensates by breathing heavy... why? because hydrogen ions are captured by bicarbonate (the conjugate base of carbonic acid) which is then exhaled as carbon dioxide... metabolic acidosis is not caused by ...


4

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 ...


4

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 ...


4

Bicarbonate is not carbon dioxide. In acidic conditions, bicarbonate will be protonated to form carbonic acid which in turn decomposes into carbon dioxide and water. The overall result is the removal of a proton (ie increase in pH) and formation of carbon dioxide (which accounts for the rapid breathing). The idea behind giving bicarbonate is that it will ...


4

Pyruvate transfers an acetyl group to coenzyme A. The acetyl group from acetyl co-A is the molecule that provides the 2 carbon atoms that get added to oxaloacetate to form citrate, and as you said, citrate starts the cycle over again. Without coenzyme A, pyruvate cannot transfer the acetyl group to oxaloacetate to form citrate so without coenzyme A/acetyl ...


3

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 ...


3

Nitrogen is much less reactive than oxygen. Indeed, if I haven't totally forgotten my long-ago chemistry courses, most chemical reactions involving N2 are energy-consuming. Thus you get nitrogen compounds produced by lightning, in auto engines, and other places where there's a lot of energy to spare. Oxygen reactions, OTOH, are energy-producing. You ...


3

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 ...


3

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


3

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 ...


3

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 ...


3

To my limited knowledge, I believe respiration is the chemical process of the body converting glucose and oxygen into energy, whereas breathing is the physical process of inhaling oxygen and exhaling carbon dioxide. Breathing is somewhat like an "external" respiration.


3

Not all plants have their stomata closed during the night. A notable exception are Crassulacean acid metabolism(CAM) plants that keep their stomata closed during the day and open it during the night. This is a common evolutionary strategy with Xerophytes. There are also 2 other types of metabolic pathways namely C3 and C4. As a consequence we get what is ...


3

Nice question. Now a perfect answer should include all the regulatory steps involved in this transition (a lot) and all the places where a change of metabolic fluxes occur. But, the question can be answered in essence at least, by a very simple model. Assume that no other regulations act except direct enzymatic feedback inhibition. This means that ...



Only top voted, non community-wiki answers of a minimum length are eligible