Wikipedia:Reference desk/Archives/Science/2017 January 31

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January 31

Which parts of one's brain can trick one into thinking that one is thirsty and/or fatigued/exhausted even though one isn't?

Which parts of one's brain can trick one into thinking that one is thirsty and/or fatigued/exhausted even though one isn't actually thirsty/fatigued? Futurist110 (talk) 04:54, 31 January 2017 (UTC)

The question isn't worded very well, because if "thirsty" means "desiring fluids" and fatigued means "desiring rest" then no trickery is possible -- thinking you are thirsty means that you desire fluids and therefore actually are thirsty. So let's refine the question into something more meaningful: which parts of the brain can give rise to a desire to drink when the body does not actually need fluids, or a desire for rest when the body does not actually need rest? The first answer is the cerebral cortex, because that is where complex cognitive interpretation of sensory inputs takes place, and errors in interpretation can give rise to dysfunctional desires. (As a concrete example, there have been cases of marathon runners dying from drinking too much water. They were actually salt-deprived and started feeling bad because of it. They interpreted the malaise as thirst and responded by drinking water, causing them to be even more salt-deprived, therefore felt even worse, therefore drank more water, etc.) It is also possible for disorders in subcortical structures to give rise to dysfunctional desires, but the structures in question are specific to the type of desire. (For example dysfunctions in parts of the hypothalamus can give rise to a desire for food in people whose bodies don't really need any.) Looie496 (talk) 16:30, 31 January 2017 (UTC)

Great answer, and I happen to know that you're an expert in neuroscience, so I believe you. But if we wanted to read more on the topic, where should we go? I found this [1] article that discusses "dysfunction of the thirst regulatory mechanism", but it's not exactly easy reading for the general public, and it's also behind a paywall. So if you or anyone else has more suitable accessible references, I'd appreciate it! SemanticMantis (talk) 17:15, 31 January 2017 (UTC)

I learned the Parasympathetic_nervous_system is responsible for all that and more. Im far away from real medical profession and knownledge tho. --Kharon (talk) 22:39, 31 January 2017 (UTC)

See also excessive thirst. --47.138.163.230 (talk) 03:52, 2 February 2017 (UTC)

Use of definite article "the" before names of biological features

In Secretin#Discovery, it is written as "It was known that the pancreas secreted digestive juices in response to the passage of food (chyme) through the pyloric sphincter into the duodenum."

Notice use of "the" before pancreas, pyloric sphincter and duodenum. Notice omission of use of "the" before digestive juices.

In Human_digestive_system#Salivary_glands, it is written that "The largest of these are the parotid glands – their secretion is mainly serous. The next pair are underneath the jaw, the submandibular glands, these produce both serous fluid and mucus. The serous fluid is produced by serous glands in these salivary glands which also produce lingual lipase. They produce about 70% of the oral cavity saliva. The third pair are the sublingual glands located underneath the tongue and their secretion is mainly mucous with a small percentage of saliva."

Notice use of "the" before parotid glands in the first sentences, and before sublingual glands and tongue in the fifth sentence. Notice omission of "the" before serous in first sentence, serous fluid and mucus in second sentence, serous glands and lingual lipase in third sentence.

This kind of arbitrary use of definite article is confusing. Is there any rule on this? --IEditEncyclopedia (talk) 05:15, 31 January 2017 (UTC)

This is more of a linguistic question than a scientific one, but it is standard to refer to an anatomical feature in terms of an ideal one in a perfect, theoretical body. That it what the use of the definite article implies. —Μετάknowledge^{discuss/deeds} 06:35, 31 January 2017 (UTC)

The use of "the" when speaking of a substance like saliva or blood tend to suggest all of it. Consider the difference between "I drank water" and "I drank the water" - the second one suggests that you didn't leave any for the next person. So you say "the pancreas" because it is a single organ, but not "the digestive juices" as the pancreas does not secrete all of them, just some of them. Also, bear in mind that "serous" and "mucous" (rather than "mucus") are adjectives, not nouns. Wymspen (talk) 09:36, 31 January 2017 (UTC)

Definite articles can also be used to indicate specificity; I drank water does not specify which water. I drank the water specifies which water has been drunk, specifically some specific water that was previously established by context. The distinction here, however, is the difference between a discrete object and an uncountable substance. Mass nouns don't take the definite article unless one is trying to make some specific statement about it. Discrete objects do. So "I put gasoline in the car" is the analogy here "I put gasoline in car" is poor grammar regardless, and "I put the gasoline in the car" means you are clarifying the word "gasoline" to indicate amount or specificity. It's the same with "saliva" and "the pancreas" here. --Jayron32 16:30, 31 January 2017 (UTC)

The English definite article is a bit mysterious - the Russians never figure it out, even after they have mastered the rest of the language. In biology and other science it has sort of an implication of total generality, perhaps at the expense of fact - "the ductus arteriosis is obliterated shortly after birth" (unless it isn't), for example. Many researchers obtain results in "the" mouse, and then get griefed on whether it was a male mouse or a female mouse, what kind of chow it was eating (which has amazing effects on the results), etc. There is a certain lingering aftertaste of Platonic Form to it all. Wnt (talk) 21:49, 2 February 2017 (UTC)

Medicine school duration in French is indeed 9 years?

I saw this information but it doesn't make sense for me, especially according to what I've read on the article medical school on Wikipedia. In addition it's totally different from most other countries of Europe that they have 6 year program93.126.88.30 (talk) 21:02, 31 January 2017 (UTC)

Speculation here, but I'm guessing that the 9 years includes what we in the US would call a combined undergraduate and medical degree program. Your link says that in the first two years the students study humanities, social sciences, law, foreign languages, and computer science in addition to medical things. Loraof (talk) 22:00, 31 January 2017 (UTC)

The content at the link provided (which needs some copy-editing, and probably should be taken with a grain of salt in case something was lost in translation) breaks down the program into three "cycles".

• Cycle one (two years) appears to correspond roughly to a two-year undergraduate program tailored to subsequent medical study.
• Cycle two (four years) looks a lot like a typical four-year M.D. program.
• Cycle three (three years or more, depending on specialization) appears to be the usual sort of residency program.

If I had to guess, I'd suggest that the confusion about the duration of the program arises because this site is counting the time spent in residency in its total. TenOfAllTrades(talk) 00:47, 1 February 2017 (UTC)

If you think about it, to become a doctor in medicine, 9 years is not very different from a French doctorate, which is 8 years (4 years for "Maitrise", 1 year for the "DEA" (research preparation year), then 3 years for a PhD). --Lgriot (talk) 10:56, 1 February 2017 (UTC)

That information is a bit outdated, French higher education completed its switch to the license-master-doctorate (3-2-3) system in 2006, see fr:Réforme_Licence-Master-Doctorat. (You still have "research masters" where the second year looks a lot like a DEA). Tigraan^{Click here to contact me} 11:50, 2 February 2017 (UTC)