The Science of Saliva
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What is the main topic discussed in this episode?
Show me the science with Professor Luke O'Neill. News Talk Original Podcast.
Hello, Luke O'Neill here, and welcome to Show Me The Science, my weekly podcast when I pick sometimes wacky stuff or stuff I'm reading about, and I hope you enjoy it. And thanks for the emails. And this one is a request, and I have a few requests lined up. All right, I've got a fair few. Actually, I'm trying to pick ones I know something about. But this one's easy for me because it's the science of saliva.
What is the episode's focus and who requested the topic?
Now, Sarah and Kerry sent me a lovely email saying she's enjoying the podcast and asked for this topic. It does sound a bit strange, doesn't it, that there will be specifically a podcast on saliva. And the question is, why did Sarah ask for it? But I'm very happy to take the request, Sarah. It's a great topic, actually. It's a great one if you're a biochemist or an immunologist, because saliva is very important in both areas. Because saliva, even though it seems like something rather gooey and uninteresting, is really interesting from a biochemical point of view, from an immune point of view. There's all kinds of interesting things in saliva. And without it, you couldn't digest your food. Your mouth wouldn't defend itself against infections, for example.
So it's a really interesting thing. And of course, early in the field of biochemistry, it was easy to study because you could get someone to spit. And then you could use biochemical analyses to figure out what was in saliva. And then they discover all these interesting things. Now, obviously, you don't need to be a genius to realize it's mainly water. It's 99% H2O, and it's made by special glands in your mouth, under your tongue, the submandibular gland, for example, the parotid gland. These are structures that make the saliva, basically. And there are differences between them, actually. One of them, the submandibular one, makes mucus. Now, saliva also has these sticky proteins in it, so it gets a bit sticky called mucus.
And that gives it this kind of consistency and certain properties that make it very fluid and a lubricant. And that's another one of the functions I'll come on to. But those glands make the stuff that ends up in the saliva. But as I say, it's 99% water. Now, here's some interesting facts. Now, if you have any kids, you can tell them this because they love quirky facts. You know, you make about a litre a day. Isn't that remarkable? So every day your mouth makes a litre of saliva. That's like a bottle. a litre of Coke, imagine that sort of amount. It's incredible, you know. And over your lifetime, someone has done a calculation, you will fill a swimming pool with your saliva, which is another strange fact, I suppose.
So we do make an awful lot of it during the day, and that tells us something very important, that it must have a very important function, obviously, enough. Now, sometimes the mucus gets a bit thick. Some diseases like COPD, saliva gets especially thick in cystic fibrosis as well. So we do see saliva as a kind of a diagnostic factor for certain diseases if its properties change. And that's to do with this mucus substance that's in it as well. So people have looked at it as a special sort of fluid to look at different diseases, which I will come back to. Now, function number one is to lubricate your mouth. Now, why do you want to lubricate your mouth? Well, obviously you eat food and the food goes into your mouth and you begin then to swallow it and that needs lubrication.
If your mouth was dry and there are certain situations where you can't make enough, which I'll come on to as well, it's very difficult to digest food. Secondly, there's important enzymes. And again, enzymes is the bread and butter for biochemistry. And saliva has an enzyme called amylase and that digests starch. Carbohydrates in your diet, the digestion process begins in the mouth and the amylase breaks up starch. Now, starch, remember, is the big carbohydrate in vegetables. Secondly, there are lipases and lipases break down fats or lipids. And of course, most enzymes end in A's and lipase means, or lipase is to break down lipids, we say lipase strategy.
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Chapters
5 chapters
1
What is the main topic discussed in this episode?
0:00–0:28
2
What is the episode's focus and who requested the topic?
0:28–5:01
3
How is saliva produced and what are the main glands involved?
5:01–7:23
4
How much saliva do humans make and why does that matter?
7:23–10:30
5
What are saliva's roles in digestion and oral health?
10:30–13:49