Class 11 Biology (India)
he human stomach is a marvel, capable of storing up to four liters of food and playing a crucial role in digestion. This process involves receiving a bolus of food, churning it, and breaking it down through hydrolysis, resulting in a product called chyme. The stomach's anatomy, including parietal cells, chief cells, and mucus cells, facilitates this complex process. Created by Raja Narayan.
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- what happens in our stomach when we feel hungry?(27 votes)
- It is a common misconception that when your stomach growls it is only due to no food being present in our stomachs. It can happen at anytime :)
As the muscles of your digestive system push food through the digestion process, the food gets broken down to be used by your body. In addition to the food and liquids that move through your digestive system, gas and air bubbles also get into the mixture. It is these pockets of gas and air that make the sounds you know as stomach growling.
They’re not as loud when you have food in your stomach, because the food absorbs some of the sound. When your stomach is empty, though, these sounds are much more noticeable. That’s probably why we associate stomach growling with being hungry. A couple hours after you eat, your stomach sends signals to your brain to get your digestive system muscles working again.
FYI: There is a scientific word for this, its called: borborygmi after the Greek word borborygmus .(46 votes)
- What happens when we feel "stomach aches"? Is it due to a discomfort in our stomachs?(11 votes)
- "Stomach ache" is a very general term. Your stomach can hurt due to ulcers, or due to cancer, or due to an infection, or due to a chemical burn from excess acid. I'm sure there can be other reasons, but understand that it is a very broad term.
Stomach aches may also be confused with aches in the nearby region not associated with the stomach. For example, intestinal discomfort may be confused by some as stomach discomfort, since part of the intestines is in such close proximity to the stomach.(12 votes)
- Why not mention enteroendocrine G cells, which secrete the main hormone gastrin? Also needed to mention that parietal cells secrete intrinsic factor on top of HCl since intrinsic factor is the crucial role of the stomach (if I remember correctly, we can live without all it's other functions, but we need the vitamin B12 from the intrinsic factor!).(9 votes)
- At5:45, how does the stomach 'know' when its the right time to release the food into the duodenum?(6 votes)
- The stomach (along with the rest of the GI) would have rhythmic contractions called peristalsis. This wave of contraction would push the food from the stomach into the the small intestine through the pyloric sphincter. However once at bit of food has passed the sphincter closes and the rest of the food is smashed into the closed sphincter (helping to produce chyme!).
This would happen all of the time, so the stomach wouldn't specifically identify each piece passing through but would just use contraction waves.(5 votes)
- What about intrinsic factor produced by parietal cells in the stomach which aids in digestion of vit b 12?(3 votes)
- This answer is probably two years late, but it might be useful to others who has the same question. As you said, Intrinsic Factor is produced by the parietal cells which also produce HCl, the parietal cells are found in the Corpus & Fundus regions of the stomach.
Intrinsic factor is necessary because without it we can't absorb B12-vitamins in our small intestine, more precise in the ileum region of our small intestine. B12 is essential in the formation of Erythrocytes (Red Blood Cells), so without intrinsic factor and in extension B12-vitamins we can get pernicious anemia.
If i forgot anything please feel free to correct me.(6 votes)
- Is there any information on the hepatic portal circulation?(3 votes)
- Search more on the internet. Basics: blood from the intestines ( with nutriments that you absorb) doesn't go directly to the heart (veins -because you collect something from an organ and send it to the heart) it passes first through the liver first( portal vein composed of the superior, inferior mesenteric vein and the splenic vein) so it can get detoxified and then the detoxyfied blood gets out of the liver through the hepatic vein that gous into the inferior vena cava and so on.(4 votes)
- Is there any video on anatomy of stomach ?(1 vote)
If your talking about MCAT. Go to organ systems. Then scroll all the way down to the gastrointestinal system section :)(7 votes)
- why protein digestive enzymes do not digest the wall of the digestive system?(2 votes)
- Mucous cells in the wall of the stomach produce a substance called mucin. This chemical moistens and protects the stomach cells from the hydrochloric acid and pepsin used to digest large polymers.
Hope this helped!(4 votes)
- The video mentioned that ulcers can be caused by HCl/the lack of mucus -- I thought the bacteria Helicobacter pylori were (mainly) responsible for ulcers? (Or do the bacteria do something that messes with the mucus?)(3 votes)
- While naming the stomach what happen to mentioning the different parts ? The body the fundus the pylorus any others(3 votes)
Voiceover: Did you know that the human stomach can store up to four liters of food at any time? That's about as much as two Coke bottles, insane! So, in this video we're going to see how our stomach helps us process food it just received, from the oral cavity and the esophagus. So, why don't we take a look just at the stomach here and I will zoom in on it, so that we can talk exclusively about what this guy is up to. The stomach is primarily responsible for three steps. First of all, it is going to receive a bolus of food from the esophagus above. This bolus is just food that has been turned into a sphere, that can now be processed. Then the stomach can do two things here to help process the food even more. The first thing the stomach does, is that it churns this bolus or it churns the food. The muscular walls of the stomach here allow it to compress down and break up this food even more. In addition, there's also a certain degree of hydrolysis. Hydrolysis, or enzyme assisted degradation, or breakdown of this bolus and we will talk about the enzyme that's responsible for this process in a moment. And then finally after we do all these things, we receive a product that is called chyme. Chyme is just a mixture of whatever the bolus has been broken up to, including the gastric enzymes and juices that we've used. And then, the food is going to actually just stay here for a little bit, because the stomach also stores food. It will store the food, until it's an appropriate time for the chyme to be squirted into the duodenum, or the first part of the small intestine to be processed. And that's why we can store up to two to four liters of food, at any given time. Now, what about the anatomy of the stomach here? How do we release these enzymes and breakdown this bolus? Let's take a look at a little bit of gastric anatomy right about there, and see how it's responsible for the breakdown of food here. We can imagine that the stomach is lined with all these infoldings. These infoldings of the gastric wall, that help to increase the surface area and in doing so there's actually a layer of cells that sit around here. This layer of cells actually secretes a lot of the components of the gastric juice we're going to see, and it is nicely ripe with a ton important components. And the main thing to remember in the stomach is that there are three types of cells that are involved here. The first type I am going to talk about are called parietal cells, parietal cells. And the main thing that is released from parietal cells is hydrochloric acid. Hydrochloric acid, it is a very acidic or very corrosive acid that's actually more acidic than battery acid. In addition to parietal cells we also have chief cells, chief cells. These guys secrete an enzyme called pepsinogen, pepsinogen. And this is the inactive form of the enzyme. Pepsinogen is not active, in fact, in order for hydrolysis to occur we need an enzyme that's call pepsin. How is pepsin made? Well, we're going to need pepsinogen to make it, but the pepsinogen and whenever you see "gen", at the end of the name, that means that it is almost there. It just needs to be processed. In order to turn pepsinogen in to pepsin, we need hydrochloric acid which will break down this protein to turn it in to this active form, that can then be used for hydrolysis. Now, what would happen if we just had a bunch of pepsin, or a bunch of hydrochloric acid present in the stomach all the time? What do you think would happen to the stomach? It would probably eat itself alive, isn't that right? I mean you've got your cell membrane that definitely has a considerable amount of protein that should be present there. And in addition you've got this really corrosive acidic substance, that can eat through your stomach. And that's actually how you have gastric ulcers, but not all of us have gastric ulcers. What do we also have in our gastric pits right here, that help us prevent gastric ulcers from occurring in the first place? Well, the third type of cell we have sitting in here are actually called mucus cells, mucus cells. And just like the name suggest, mucus cells release what's called mucin and this is a coating that will sit around the stomach to make sure that things like pepsin, or hydrochloric acid don't degrade the stomach. Without mucus cells we would eat ourselves alive. So, as a review, the three things a stomach will do for us is that it will churn with its very muscular walls to help break down the bolus, in a very physical activity. Also, there's an enzymatic or chemical process that occurs here, where we used pepsin to degrade food. Now, pepsin itself only degrades one type of nutrient and that's it protein. This will break peptide bonds or the bond that connects amino acids to one another, to degrade your protein macromolecules. So, that's the only type of nutrient that's broken down in your stomach. Once we hydrolyze a significant amount of the protein we're going to produce chyme, that is stored in the stomach until it's the right time for it to be released into the next part of your GI tract called the duodenum. The first part of the small intestine, and that's how your stomach works.