In this video, we're going to briefly talk about gastric juice as a chemical defense that can help prevent microbial growth by lowering the pH. And so, gastric juice is really just going to be a complex mixture of many different substances that includes hydrochloric acid or HCl, as well as several different types of enzymes, for example, lysozyme and mucus, all in the stomach. And so, this highly acidic solution is going to lower the pH of the stomach, which is therefore going to kill most of the bacteria that are ingested. And it will also inactivate most toxins as well. And so, it does serve as a first line of defense, a chemical means of protecting us.
And so, if we take a look at this image down below on the left-hand side, notice we're showing you our map of the first line of defense, specifically the chemical barriers, and we're focusing in on the gastric juices here. And so, gastric juice, again, is going to be a complex mixture found in our stomachs, as you can see here. And so, we can label this gastric juice. And what you'll notice is that the pH is going to be very, very acidic. And so, notice here it says the pH is about 2.5. And so, notice through this little cartoon here that these microbes are not most microbes are not capable of surviving in these acidic conditions. And so it is so acidic here, and notice this one saying is, it burns. And so, it's just showing you here that many microbes are not capable of surviving those acidic environments within, the gastric juice within our stomach.
And so, this here concludes our brief lesson on gastric juice as a chemical defense mechanism, and we'll be able to apply some of these concepts that we've learned as we move forward in our course, and then we'll get to talk a little bit more about some other chemical defenses. So, I'll see you all in our next video.