Everyone, in this video, we're going to talk about our introduction to lipid digestion. Here, we're going to say that Triacylglycerols, which we abbreviate as TAGs, are the most abundant dietary lipids and are a rich source of energy. Now, unlike glucose, which only produces 2 Acetyl CoA molecules, when it comes to TAGs, we can make a lot of CoA molecules per TAG. And we're going to say here when it comes to TAGs, they're mechanically digested in the mouth and the stomach, but they're biochemically digested in the small intestine. Now, here we're going to say we have A, B, and C when it comes to lipid digestion. We're going to say A deals with grinding in the mouth and churning of the stomach converts lipids into these small droplets which we call globules. And, when we look at this overview of this image that would happen here. We have our fatty acid, we have our fats here, Mechanical digestion, we're chewing it, we're using our mouths, our stomach helps to mechanically break it down, and we're going to have our fat globules here. Then we're going to say emulsification by bile turns these globules themselves into micelles. Now here we're going to say that bile itself, it contains our bile salts as well as emulsifying agents, which will help to change these globules into these micelles. And, this is going to increase their surface area and solubility. So, we have our fats which are mechanically broken down in digestion here in our image, that helps to change these globules into our micelles eventually. So here we have our fatty globules, they undergo emulsification through the use of bile and its bile salts. And remember, bile themselves they contain phospholipids as well as these bile salts which will help to emulsify our globules into these micelles. Emulsification is B here, and then we’re going to say, emulsification helps to change these globules into our fat micelles. And then when we get to C, we have our pancreatic lipases, which would be here. They partially hydrolyze fats or TAGs to monoacylglycerols and fatty acids. So, basically, we’re severing these connections here, these ester linkages within our TAGs to eventually get to our monoacylglycerols right here. And if we look at the image, this represents a hydrolysis product. We’ve severed some ester linkages so that only one remains when it came to our original fat. Alright. So this gives us a good overview when it comes to lipid digestion.
Intro to Lipid Digestion - Online Tutor, Practice Problems & Exam Prep
Created using AIIntro to Lipid Digestion Concept 1
Video transcript
Intro to Lipid Digestion Example 1
Video transcript
Here in this example question, it asks which of the following statements is correct about the role of bile in lipid digestion? So, remember, when we talked about bile, we said it contained phospholipids as well as bile acids or salts, which help to emulsify or solubilize our globules into micelles. So, from that description, which of the following statements most matches up with that idea?
So here, bile contains bile acids that provide an acidic medium for lipid digestion. Now, remember, they're helping to solubilize or emulsify our globules into micelles. Bile enzymes make lipids hydrophilic by oxidation, never referred to this in terms of bile. Bile salts and lecithin in the bile emulsify lipids as a preparation for the subsequent hydrolysis. Yes. Remember, in step b of our lipid digestion, we're talking about biles. This is in preparation till we get to step c, where we have our pancreatic lipases getting involved to help create our hydrolysis products. So this would be true. Bile contains lipases that hydrolyze lipids to fatty acids and glycerol. No. That's not what is occurring there. We're changing our tags into monoacylglycerols. We're severing some ester linkages to get our hydrolysis product. So this would not be true. So the only statement here that is true would have to be option c.
Which of the following statements is incorrect about lipid digestion?
Emulsification of fat globules by bile increases their surface area.
Triacylglycerols are partially hydrolyzed in the stomach before they enter the small intestine.
Triacylglycerols in the small intestine are partially hydrolyzed by pancreatic lipases.
Mechanical digestion of lipids takes place inside the mouth and the stomach.
