Digestion and stomach movements

[Gurumanickam]

As the food enters stomach the digestion is continued in it.

 

Then the partly suggested food (chyme) is moved to duodenum for further digestion.

 

As different types of food may take different duration for digestion, how and when the chyme is pushed to duodenum?

 

Do they move en masse in a single instance or they move as and when a portion of chyme is ready to be moved, ie now a little, later some more like that?

 

I would like to know when the stomach will be empty of all chyme.

[Acme]

According to Wikipedia page on stomach:

... Chyme slowly passes through the pyloric sphincter and into the duodenum of the small intestine, where the extraction of nutrients begins. Depending on the quantity and contents of the meal, the stomach will digest the food into chyme anywhere between forty minutes and a few hours. ...

The amount of time required to reduce food to chime likely depends on the amount and type of food consumed, so the total time from eating to an empty stomach will also vary.

[Gurumanickam]

My question is do the chyme evacuate once completely, or is it (the evacuation) happening portion by portion?

 

For instance one may have eaten fruits and cereals. The fruit may have suggested quickly than the cereals. As the fruit portion is digested quickly do they evacuate to duodenumm immediately or will they wait for the cereal portion also to complete the digestion and move to duodenumm both together?

[Acme]

My question is do the chyme evacuate once completely, or is it (the evacuation) happening portion by portion?

 

For instance one may have eaten fruits and cereals. The fruit may have suggested quickly than the cereals. As the fruit portion is digested quickly do they evacuate to duodenumm immediately or will they wait for the cereal portion also to complete the digestion and move to duodenumm both together?

I suspect once completely as I see no mechanism whereby the foods once mixed could differentiate.

[StringJunky]

According to Wikipedia page on stomach:

 

The amount of time required to reduce food to chime likely depends on the amount and type of food consumed, so the total time from eating to an empty stomach will also vary.

I haven't found anything that supports the idea of different foods being treated differently in terms of time apart from water which is evacuated pretty quickly. Probably stiffness of the food is the main factor for how long it stays in the stomach i.e. stiff mixing food takes longer.

Edited July 8, 2017 by StringJunky

[Acme]

I haven't found anything that supports the idea of different foods being treated differently in terms of time apart from water which is evacuated pretty quickly. Probably stiffness of the food is the main factor for how long it stays in the stomach i.e. stiff mixing food takes longer.

I had to go looking, but it seems there is a difference that's not dependent on the stiffness/texture. For example, this source says dairy stays in the stomach longer than fish. (Not the strong kind of reference I prefer, but it's a start.)

 

Digestion Time of Various Food

DIGESTION TIME OF VARIOUS FOODS: (The time spent in the stomach before emptying)

 

...

Dairy: Skim milk, cottage or low fat pot cheese or ricotta - approx. 90 min. digestion time whole milk cottage cheese - 120 min. digestion whole milk hard cheese - 4 to 5 hours digestion time.

...

Animal proteins: Egg yolk - 30 min. digestion time Whole egg - 45 min. Fish - cod, scrod, flounder, sole seafood - 30 min. digestion time Fish - salmon, salmon trout, herring, (more fatty fish) - 45 min. to 60 digestion time Chicken - 11/2 to 2 hours digestion time (without skin) Turkey - 2 to 2 1/4 hours digestion time (without skin) Beef, lamb - 3 to 4 hours digestion time Pork - 41/2 to 5 hours.

Addendum:

 

My question is do the chyme evacuate once completely, or is it (the evacuation) happening portion by portion?

 

For instance one may have eaten fruits and cereals. The fruit may have suggested quickly than the cereals. As the fruit portion is digested quickly do they evacuate to duodenumm immediately or will they wait for the cereal portion also to complete the digestion and move to duodenumm both together?

 

 

I suspect once completely as I see no mechanism whereby the foods once mixed could differentiate.

 

So I found a more credible source -Stomach @ InnerBody- contradicting my supposition. They say:

After the stomach has been filled with food from a meal, it stores the food for about 1-2 hours. During this time, the stomach continues the digestive process that began in the mouth and allows the intestines, pancreas, gallbladder, and liver to prepare to complete the digestive process.

 

At the inferior end of the stomach, the pyloric sphincter controls the movement of food into the intestines. The pyloric sphincter is normally closed to keep food and stomach secretions within the stomach. Once chyme is ready to leave the stomach, the pyloric sphincter opens to allow a small amount of chyme to pass into the duodenum. This process, known as gastric emptying, slowly repeats over the 1-2 hours that food is stored in the stomach. The slow rate of gastric emptying helps to spread out the volume of chyme being released from the stomach and maximizes the digestion and absorption of nutrients in the intestines.

There is no suggestion however that the chyme is differentiated by foodtype, i.e. it is a mixture of all types consumed.

Edited July 8, 2017 by Acme

[Function]

Of course, your stomach will keep on working and will continue pumping food into the duodenum and, by extension, the jejunum. However, not all at once: this might result in gastric dumping syndrome, in which persons have "shock-lik" symptoms. Look it up.

[StringJunky]

I had to go looking, but it seems there is a difference that's not dependent on the stiffness/texture. For example, this source says dairy stays in the stomach longer than fish. (Not the strong kind of reference I prefer, but it's a start.)

 

Digestion Time of Various Food

 

Addendum:

 

 

So I found a more credible source -Stomach @ InnerBody- contradicting my supposition. They say:

 

There is no suggestion however that the chyme is differentiated by foodtype, i.e. it is a mixture of all types consumed.

Yes, i meant evidence-based material which not easy to find. The way I'm looking at it is, how does the stomach sense what is in it? i can't see it having chemical sensors for specific food types to determine how long it should churn for and it's lined with mucus to protect itself from the acid which would probably mask any sensors that might be there anyway.

[Acme]

Yes, i meant evidence-based material which not easy to find. The way I'm looking at it is, how does the stomach sense what is in it? i can't see it having chemical sensors for specific food types to determine how long it should churn for and it's lined with mucus to protect itself from the acid which would probably mask any sensors that might be there anyway.

Good question. Clearly there is some sort of signaling going on. Guess we have more researching to do...

Here's something from Wiki again that seems germane:

Control of secretion and motility

 

The movement and the flow of chemicals into the stomach are controlled by both the autonomic nervous system and by the various digestive system hormones:

 

Gastrin The hormone gastrin causes an increase in the secretion of HCl from the parietal cells, and pepsinogen from chief cells in the stomach. It also causes increased motility in the stomach. Gastrin is released by G cells in the stomach in response to distension of the antrum, and digestive products (especially large quantities of incompletely digested proteins). It is inhibited by a pH normally less than 4 (high acid), as well as the hormone somatostatin.

Cholecystokinin Cholecystokinin (CCK) has most effect on the gall bladder, causing gall bladder contractions, but it also decreases gastric emptying and increases release of pancreatic juice which is alkaline and neutralizes the chyme. CCK is synthesized by I-cells in the mucosal epithelium of the small intestine.

Secretin In a different and rare manner, secretin, produced in the small intestine, has most effects on the pancreas, but will also diminish acid secretion in the stomach.

Gastric inhibitory peptide Gastric inhibitory peptide (GIP) decreases both gastric acid release and motility.

Enteroglucagon Enteroglucagon decreases both gastric acid and motility.

 

Other than gastrin, these hormones all act to turn off the stomach action. This is in response to food products in the liver and gall bladder, which have not yet been absorbed. The stomach needs to push food into the small intestine only when the intestine is not busy. While the intestine is full and still digesting food, the stomach acts as storage for food.

...

[StringJunky]

Good question. Clearly there is some sort of signaling going on. Guess we have more researching to do...

Here's something from Wiki again that seems germane:

 

That's very interesting. I never considered that other organs further down might influence the action of the stomach. Thinking about it, some amino acids, glucose or other product from the enzymatic action might pass through the stomach lining into the bloodstream and that would tell the body how to respond wrt to the churning time.

Edited July 8, 2017 by StringJunky