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 we’re going to talk about how our stomach helps us process food it just received from the oral cavity and the esophagus, the stomach is primarily responsible for three steps, first of all it’s going to receive a bolus of food from the esophagus, this bolus is just food that’s been turned into a sphere that can now be processed then the stomach can do two things here, to help process the food, 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’ll 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’s 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’ll 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 litres of food at any given time. Now what about the anatomy of the stomach here, how do we release these enzymes and break down this bolus, let’s take a look at a little bit of gastric anatomy right about there so we know how it’s responsible for the breakdown of food, we can imagine that the stomach is lined with all these in foldings, these in foldings of the gastric wall that helped 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’s nicely ripe with a ton of 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 we are going to talk about are called parietal cells, parietal cells and the main thing that’s released from parietal cells is hydro chloric acid, hydrochloric acid is a very acidic or a 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 pepsin and this is the inactive form of the enzyme pepsinogen, it is not active in fact in order for hydrolysis to occur we need an enzyme that’s called pepsin. How is pepsin made? well we’re going to need pepsinogen to make it but the pepsinogen and whenever you see Jin G en at the end of the name, that means that it’s almost there, it’s just needs to be processed, in order to turn pepsinogen into pepsin we need hydrochloric acid which will break down this protein to turn it into 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 we also have in our gastric pits right here that help us prevent gastric ulcers from occurring in the first place.