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Questions tagged [digestive-system]

Organs that play a role in digestion and/or absorption of nutrients: breaking down of food into smaller components that can be absorbed and used as for sources of energy, cellular/tissue building blocks, or cofactors for vital biochemical reactions.

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How does saliva help us to absorb the nutrients we need? [on hold]

How does saliva (or a different chemical in the digestive system) help us absorb the nutrients we need?
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1answer
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Do sharks fart?

My son is 5 and I'm encouraging him to be curious and ask questions of the world around him. He asked if sharks fart and how does it smell? He feels that it would smell of fish and be disgusting. He ...
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Does pepsin enzyme digest other enzymes like other pepsin molecules

Pepsin digests proteins, as we know, but can it digest other enzymes that are actually made up of proteins, like digesting other pepsin molecules?
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Could a mammal convert ingested dissolved CO2 to usable energy?

I'm trying to find out if it's possible that a mammal could orally ingest dissolved CO2 and convert it to energy for body heat, organ function, etc. Unfortunately, most of the scientific sources I've ...
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Is countercurrent exchange system used in lungs or intestines?

Here is a question from the book My Max Score SAT Biology E/M Subject Test: Which of the following uses a countercurrent exchange system? I. Gills II. Kidneys III. Intestines IV. Lungs ...
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Location of lipid absorption

I've looked-up in many textbooks about the location of fat absorption in the GIT and I've never found out the information. We know that the biliary salts form micelles in the proximal part and that ...
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Muscle layers of pharynx and gi tract

Why does pharynx have an internal longitudinal muscle layer and external circular muscle layer, while oesophagus and the rest of gastrointestinal tract have inner circular and outer longitudinal ...
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11 views

Human digestion of chitin

According to the source below, humans can digest chitin. https://www.ncbi.nlm.nih.gov/pubmed/17587796 Is there a limit to how much a human can effectively digest this substance?
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Can the human gut work with other type of gut bacteria?

I was wondering if the human body would be capable of functioning with, say, cellulolytic bacteria in their gut (instead of or in addition of their current bacteria), like that of ruminants and if ...
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1answer
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Do cows chew in a preferential chirality?

One of the enduring myths in molecular physics, when talking about chirality as pertains the existence of enantiomers and the differences between them, is that the way cows chew is also chiral, i.e. ...
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1answer
41 views

Epidermal layer and muscle wall of colon?

First of all,I wanted to ask that whether epidermis is present in colon ? And if yes than how is muscle wall present with respect to epidermis. Can anyone give me a pic that has both the epidermis and ...
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1answer
35 views

Nonpancreatic digestion of tryglicerides

In an answer about coconut oil I can read the digestion of coconut oil does not involve in the Pancreatic digestive enzyme system In both primary and secondary school I have learned that fat needs ...
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1answer
423 views

How exactly is casein digested?

I mean it seems first step is rennin or pepsin digestion in stomach - then what happens with remaining peptides? I am interested in the whole process from casein to amino acids. Is there brush border ...
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Can gut flora affect what we can eat and what we cannot?

Back many years ago, I've read a mushroom guidebook, which I don't have anymore. I was unable to find the name of a particular mushroom. The book comprises listing of edible and poisonous mushroom ...
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What can pass through the abdominal wall?

As I understand it, most substances need help to pass through the walls of the intestines. For example, in hepatic recirculation (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781307/) bile salts are ...
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1answer
100 views

Why does enteral carbohydrate yield higher energy than parenteral?

The following is written in a well-known textbook of surgery: Each gram of enteric carbohydrate provides 4.0 kilocalories (kcal) of energy. Parenterally administered carbohydrates (eg, ...
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Sensitivity Along Digestive Tract [closed]

Suppose you swallowed a little capsule with a blunt poker which had some impulse of force applied every few seconds. What would be the sensitivity ordering (of lips, mouth, throat, esophagus, stomach,...
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Do humans produce rennin?

At school, we've been taught that human infants produce rennin/chymosin (which aids in the digestion of milk). More specifically, it is the peptic cells in the stomach which secrete prorennin, the ...
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1answer
415 views

Can Fluoride be absorbed into the blood from within the mouth without swallowing?

I'm having a discussion with somebody regarding Fluoride usage. I told him that even if he doesn't like the idea of ingesting it, brushing and spitting it out will do you no harm. He then said this: ...
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1answer
100 views

Why do humans cook animal meat

Why do humans "need" to cook animal meat? It seems there's an aspect of safety to it: are other animals (eg, house cats, dogs) not vulnerable to the same diseases we get from modern food processing ...
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1answer
373 views

Which cells produce HCl produced in stomach? Don't these cells get destroyed by HCl?

Which cells produce HCl produced in the stomach? Or is HCl produced due to the translation of proteins. Don't these cells get destroyed by HCl?
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1answer
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Bicarbonate concentration in saliva

From the picture it can be seen that Bicarbonate is secreted into lumen of duct of salivary glands by exchanging Cl- ions. So if flow rate of saliva is increased then its obvious that less Cl- is ...
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1answer
1k views

In which organs is water that we drink absorbed into the blood?

From biology classes I remember that water from food we eat is mostly 'sucked in' (absorbed into blood) in the colon. I guess the same is true for water we drink. But if I eat something, it will reach ...
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1answer
370 views

How are micelles formed from the byproducts of emulsification in fat digestion?

It is known that fat droplets are made into emulsion droplets via the addition of bile salts. It is then said that the emulsion droplets are made into micelles through some sort of lipase, which can ...
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1answer
603 views

Does the pyloric sphincter contract after ingesting only liquid?

At university, I was told by one of my fellow students that the reason why eating before going on an alcohol laden night out was a good idea, was because the pyloric sphincter contracted once food was ...
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2answers
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Does posture matter while drinking water?

I have heard a lot of people (where I am from, India) say that one must drink water sitting, not standing. Recently, I also came across a video that said the same thing (link). The reason given is ...
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2answers
264 views

Betaine HCl stomach pH

It seems betaine HCL is often recommended for those suffering from "low stomach acid" -- which, as I understand, is having too high stomach pH for proper digestion (especially for proteolysis via ...
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1answer
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What inactivates pepsin in infants?

In infants, rennin helps in digestion of milk. Pepsin is also present in their stomach. Why do infants need rennin for milk digestion, at the first place? Why does pepsin not act on the milk ...
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1answer
405 views

What happens to the enzymes produced by the digestive system?

Our digestive system produces a lot of enzymes and they help to catabolize the food, and after completing their work are they excreted out or as they are also made up of proteins are they catabolized ...
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1answer
52 views

Why are there not effective pharmaceutical treatments to prevent weight gain?

Hunger is caused by signals from the brain, so is there a way to suppress the signal of hunger in the same way we suppress the signal of pain with painkillers? If people felt less hungry, they would ...
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Eating possibly spoiled food in the fasted state - is it considered protective against the potential harm?

It is a known fact that the acidic environment in the stomach serves several purposes, such as providing suitable conditions for primary chemical digestion of food molecules and protection from ...
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1answer
97 views

How is chewing gum processed?

There is the common belief that Chewing gum takes 7 years to digest But is this actually true? Does it really stick to your intestines for 7 years, or is it processed like all foods, except it isn'...
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1answer
224 views

Why does a stomach come before the gizzard in birds?

Since the gizzard is for mechanical digestion, shouldn't that happen before the stomach digests the food with acids? (to make the morsels smaller)
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1answer
43 views

How does horse extract the energy to needs from a relatively small digestive system?

Recently I saw Inside nature's gaints episode on horse, and was fascinated about its internal organisation. And my question is that they have a very large lungs to accommodate, but a relatively ...
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1answer
230 views

Absorption of pentoses in intestine

Why pentoses are absorbed by facilitated diffusion in intestine? Wouldn't it be futile because , when the pentose concentration is lower in intestine, the pentoses would diffuse back to the intestinal ...
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1answer
365 views

Movement in microvilli

My textbook( COMPREHENSIVE TEXTBOOK OF PHYSIOLOGY VOL-1 by GK PAL) says: Microfilaments project into microvilli present on the epithelial surface such as on the intestinal mucosa, and extend up to ...
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3answers
448 views

How would a herbivore's digestive tract differ from a human's? [closed]

How would a herbivore's digestive tract differ from a human's? What are parts (organs, tissues, etc.) or enzymes that can't be found in one but is in the other? Also, is it correct to say that a ...
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1answer
315 views

What are the sites of nutrient digestion and absorption in the human GI tract? [closed]

Where does nutrient digestion and then absorption take place for different nutrients along the alimentary tract?
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1answer
344 views

How are nutrients absorbed by a pitcher plant?

I've read that pitcher plants thrive in nitrogen-poor soil, which is solved by dissolving insects and absorbing nitrogen that way. I have a few plants, and when a pitcher start to rot, I cut it off ...
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1answer
66 views

What are the obstacles to “refitting” the human body's metabolism?

As a layman, I understand the problem of rising obesity like this: In the old times, humans could never get enough food, thus they would eat whatever they could get. This "program" is encoded in our ...
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1answer
331 views

Shape of feces in herbivores

Why do some herbivores like sheep, cow, and others excrete feces in a pellet (or biscuit or other) shape, while other species including humans do not do so? What is the reason for such an adaptation ...
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3answers
102 views

Special bacteria in infants

This question is similar to a previous question, but is not the same. I was told, you are born with a bacteria in your digestive track that are made by the body. Can a body in development create it'...
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What percentage of human excrement is toxic if ingested?

I have been considering food production, waste management and 3D food printing, particularly during space exploration. This led me to wonder if human excrement could be processed into raw materials ...
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1answer
1k views

Is there a link between digestion and nightmares?

A common belief is that eating too much before going to sleep can cause to have nightmares. In fact, I often experience it: I systematically have nightmares after eating too much in the evening. ...
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1answer
543 views

What are the consequences of drinking water with food?

Does drinking water with a meal release lesser energy/glucose into the blood stream due to a diluted digestive mixture ? For simplification : If a person eats 100 grams of cooked jasmine rice with no ...
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1answer
471 views

Product of reaction between HCl and bile [closed]

In the mammalian digestive system HCl is the main acid and bile is the main alkali. What is the product of the reaction between these two chemicals?
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42 views

Is it safe to feed an adult fire salamander with slime maggots? [closed]

As a reminder, maggots feed of a flesh, while fire salamander consumes his prey alive, without killing it. Can it happen that the maggot will start eating the salamander from the inside?
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1answer
327 views

How does the human stomach handle a mix of digested and undigested food?

As I understand it, the stomach digests the bolus into chyme and then passes the latter on to the small intestine. This process takes between 40 minutes and a few hours. However, what happens when ...
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1answer
43 views

Do I have to chew for digestion to kick in?

Liquid nutrient-rich products (such as Soylent) are consumed without chewing. But if I have to chew to initiate digestion, are those nutrients really "processed"?
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1answer
82 views

Is there a difference in how Gas is produced which determines if it becomes a burp or flatulence?

I know that some gases are heavier than air and in the case of a gas leak it's best to escape to higher ground, while some gases are lighter than air such as Helium. However unlike Helium I haven't ...