49

Proteases are enzymes in your digestive system that help break down food, acting like molecular-sized scissors that cut up proteins. Proteases have clefts, or subpockets, into which proteins fit, where the substrate (protein) gets cut. Infectious or pathogenic prions are resistant to proteases, because of their three-dimensional conformation, or shape, ...


47

Sugars in 100% natural fruit juices are chemically the same as in whole fruits. They mainly include glucose, fructose and sucrose: Apple nutrition data (expand the carbohydrate section) Apple juice nutrition data Sugars in whole fruits are "incorporated" into the fruit, which means the digestive system first needs to physically decompose the fruit and then ...


27

Birds may indeed digest seeds under conditions of rest. It has been postulated that almost all current knowledge on mechanisms of internal seed dispersal has been obtained from experiments with resting animals. A study with the mallard Anas platyrhynchos (common wild duck), claimed to be quantitatively one of the most important seed dispersing animals in ...


24

I'm almost certain that your question is based on the press that Patricia J Yang's research is receiving (e.g., here and here). Yang and her co-authors examined the structure and mechanics of some dead wombats to investigate this question further. They found that varying degrees of pressure in the latter portion of the wombat's intestines (in conjunction ...


10

Yes, they do. For a look at survival of Lactobacillus and other bacterial species after multiple freeze/thaw cycles, check out Harrison 1955 (below). The awesome hand-drawn graphs show that many bacteria survive after being frozen for 11 weeks. There's also a figure on the following page showing that many bacteria also survive after multiple freeze-thaw ...


10

apparently walking helps in the movement of food into the stomach and improves digestion. Also helps in decreasing blood sugar after meals, which decreases cardiovascular risk and potential signal diabetes by helping muscles absorb glucose in the blood. Here is the link to a study done comparing the results of walking after food and after a drink. Also a ...


10

First, there are two different isomers of the lactic acid, the L(+)- and the D(-)-form. Both differ in the position of the OH-group in the molecule: Both turn polarized light in different ways, the D(-) to the left and the L(+) to the right. The physiological form of lactic acid for the human body is the L(+) form, which is taken up in the gut and then ...


9

The answer really depends on what aspect of the urine and feces one is considering. On the atomic level, no, urine and feces are composed entirely of atoms taken from our environment. As one would expect, as there is no "Humanium" on the periodic table. In fact, all the atoms in urine and feces were originally created by stars. On the molecular level, yes. ...


9

The main reason for the color of our stool (or feces) is the presence of bilirubin, a breakdown product of the hemoglobin. The amount of it causes different variations from yellow to dark brown. When the passage time of the food in the intestine and the amount of bilirubin is constant, the color changes very little. Illnesses like diarrhea, which cause a ...


9

On a more serious note than my comment, and as a supplement to theforestecologist's answer, it's worth pointing out that a cube with rounded corners and edges has larger surface area to volume ratio than a spherical dropping, making it more efficient for the reabsorbtion of moisture, which would be an evolutionary advantage in a place where water is in short ...


8

After we have eaten... the maximum blood supply is transferred towards the digestive system so that digestion is done, and therefore the brain to does not get adequate blood supply. Am I right about this? This is a very, very common myth, but it is a myth. Because blood flow and oxygen delivery to the brain is critical for survival, cerebral circulation is ...


7

According to Crispim et al 2011, caloric intake late at night is correlated negatively with sleep quality: We conclude that food intake during the nocturnal period is correlated with negative effects on the sleep quality of healthy individuals. Indeed, food intake near the sleeping period (dinner and late night snack) was negatively associated with sleep ...


7

Your question does not have a clear answer yet, as stated in Metabolic regulation: a human perspective / Keith N. Frayn. – 3rd ed (2010) on page 39. There is still debate about how fatty acids cross cell membranes. On that page they claim that a simple diffusion transport is possible through a 'flip-flop' mechanism, where the fatty acid inserts itself in ...


7

Drinking the juice without the fruit can easily lead to over-consumption. It is after all harder to eat four apples than drinking 500ml apple juice. As the liver breaks the fructose through lipogenesis it creates fat and can cause non-alcoholic fatty liver and obesity. Since sugar (fructose/glucose/sucrose et al.) can be absorbed already through the mucus ...


7

In short, sugars are absorbed quicker than proteins and fats because they pass through the stomach quicker and their digestion is simpler. Sugar can be absorbed through the mouth mucosa when applied as a sublingual gel, as discussed here on Biology SE: Is sugar absorbed into the bloodstream through the walls of the mouth?, but probably in much smaller ...


6

The part of the corn kernel that is visible in human feces is the outer coat of bran called the pericarp (see this image). This is a common structure in cereal grains like corn and wheat. However, the bulk of the corn kernal is starchy endosperm, which is readily digestible by humans and provides carbohydrates and vitamins A and C. The non-digestible (by ...


6

The answer to questions like this is just a guess (Primarily Opinion Based), and I've voted to close. But some food for thought too long for a comment: As it is really beneficial for all organisms... Why do you think that cellulase is so very beneficial to mammals? Animals did have cellulase (some ancient invertebrates still do, like sea squirts, abalone;...


6

A moderate amount of water while eating will not dilute digestion ...according to Michael F. Picco, M.D. and the Mayo Clinic: There's no concern that water will dilute the digestive juices or interfere with digestion. In fact, drinking water during or after a meal actually aids digestion. Water and other liquids help break down food so that your ...


5

This is not a problem, since the gall bladder "only" stores bile, but the production itself happens in the liver. There are some cases described which can get problems digesting very fatty food, but for most people this is not a problem. Additionally eating low-fat food in the first few weeks after the removal is recommended. See here for some more details. ...


5

Lactic acid has been found to act as a fuel for the muscles. Refer to: http://www.nytimes.com/2006/05/16/health/nutrition/16run.html?_r=0 Most athletes consider lactic acid their enemy, and think that training helps eliminate the metabolic waste product from their muscles so the muscles will function longer and harder. But UC Berkeley physiologist George ...


5

Whatever the diet, the food intake contains macronutrients: carbohydrate, fat and protein. When they are metabolised all of these molecules will end up, for the most part, as carbon dioxide, water, and ammonia, unless they are incorporated into components of the body. These waste products are, of course, lost via breathing, and via the urine. That's where ...


5

The digestive system of a horse is by no means small: They have 15 to 21 m (50 to 70 ft) of small intestine, with a capacity of 38 to 45 L. They have a 1.2 m (4 ft) long caecum that holds 26 to 30 L. They have 3.0 to 3.7 m (10 to 12 ft) of colon, capacity up to 76 L. (Figures sourced from Equine Anatomy (Wikipedia)) Certainly horse stomachs are ...


5

Here's a simple cross-section of the stomach (from here): The stomach accomplishes much of its function by mechanically breaking down the swallowed food particles and mixing them with acid and enzymes into a sort of slurry. To do this, there are three major layers of muscle surround the stomach - from the outside, the longitudinal layer, the circular layer, ...


5

Although I'm having a hard time finding a source that provides specific information on fluoride in toothpaste, this review explains that fluoride is most readily absorbed through intestinal epithelia and that fluoride absorption through other tissues, such as oral epithelia, depends strongly on other chemical properties of fluoride-containing compounds: ...


4

Your question supposes a very linear version of the flow of stomach contents of: 1->2->mouth->3->4 In reality, it is not so linear. Firstly some background: The rumen and reticulum form the first two parts of the four, and are in fact a single chamber/organ (collectively known as the reticulorumen). They have different wall structures, and perform initial ...


4

Well it depends what you mean by helping digestion. This answer in skeptics may shade some light: a walk after my lunch [is] a healthy habit that helps with digestion. Walking may be a healthy habit but it does not specifically assist digestion. Digestion is a process which takes place in resting conditions. Exercise is characterised by a shift in ...


4

This is not a yes / no question. Many tortoise eat plants (veggies and fruits) while some turtles eat fish too. Snakes are basically predators and do not dwell on plants neither do most of the lizards. I think if a reptile is capable of digesting plant food in general, then it should be able to digest preprocessed grains as well. Edit: As for whole intact ...


4

Bananas seem to contain lots of dietary fiber that help move consumed food through the intestines (popular article) thereby promoting digestion. Whether one should eat bananas before or after dinner is probably a debatable subject (Yahoo forum).


4

The answer probably varies for different nutrients. An informal article by ConsumerLab.com indicates that many vitamins are better absorbed from natural sources, but a few are actually more readily absorbed from supplements. Looking at Vitamin C specifically, a 2013 review article by Carr and Vissers concluded as follows (emphasis mine): Overall, a ...


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