Bile Synthesis and Function

hi everyone dr. Mike here in this video I want to talk about bile how it's produced and what it's comprised of [Music] first thing is when you think of bile you need to think of fat digestion and absorption that's the first thing now bile itself is a substance that's made up of a number of different components which I'll talk about in a sec that is produced by the liver and stored and concentrated in the gallbladder now when we eat fatty meals what happens is the fat stimulates a whole downstream cascade that releases hormones that stimulate both the liver and gallbladder to release the bar that's been produced into the small intestines this bile will help break down fats into smaller more manageable manageable pieces for us to then be able to absorb into our lymphatic system than the bloodstream and then be delivered to various aspects of the body and ultimately back to the liver so let's first talk about what is in bile when we look at bile itself bile is comprised 95% so most is water most of all is water then if you look at its components from what I believe to be most important is the bile acids and bile salts I'll talk about the similarities and differences of that in a sec let's go actually going to constitute most of this quick video what else we've got phospholipids we have cholesterol we have bilirubin which is a breakdown product of red blood cells we have proteins and amino acids and we also have ions and the most important ions that you'll find in bile includes sodium potassium chloride and bicarbonate all right let's focus on these bile acids - bile salts or are really important because they are specifically would help us break down fats the term is emulsification and absorb these fats in our small intestines all right in the liver we have cholesterol now this cholesterol can come from the foods that we eat ultimately that food gets broken down in the small intestines gets absorbed in a lymphatic system forms these color microns that ultimately get delivered back to the liver so that's how we can get cholesterol or we can get it from the production of acetyl co a alright they're the two major methods we get cholesterol regardless in the liver cholesterol can be turned into two particular what we call bile acids so now we're talking about bile acids these bile acids are produced through various mechanisms using enzymes which you don't need to talk about and basically if I were to draw cholesterol up right if I were to say that cholesterol looks like this the types of changes we are making to cholesterol to produce these primary bile acids are minor and they look like this [Music] and then the other one looks like this so very minor subtle changes now what we've got is something called colic acid and we've also got is keno deoxy colic acid these are what we call the primary bile acids now what happens with this primary bile acids is this they will move from the liver into the ducts so it goes to the hepatic duct and some of this can be stored now if this is between meals some of this will be stored in the gallbladder and be concentrated all right now what you'll find is all of these components move to the gallbladder from the liver and become concentrated and actually become ten times more concentrated than what like what they are in the liver so that's one important function and they they're stored they until a fatty meal comes through and then it squeezes because of a hormone called cholecystokinin and squeezes the contents out into the small intestines but not all of it is stored there only around about half so we produce around about six seven hundred mils of bile per day and half of it gets stored in that gallbladder but all these ball acids that we're producing a good number of them are going to go into the small intestines and they're going to move their way through the small intestines until they hit near the end of the small intestine so the terminal portion this terminal portion is called the ileum and here in the ileum what we're going to find so let's draw it up we're going to have which one was so we're going Tolec acid and we're going to have Kino deoxycholic acid and what happens is the bacteria present at the terminal portion of the small intestines they further metabolize these bile acids and they turn primary bile acids into the secondary bile acids and they change them just a little bit and so what they end up doing is producing something that may look a little like this for example again subtle changes and what we've now turned into is that taken the cola Kassadin we've turned it into deoxycholic acid and we've taken the Kino deoxycholic acid and turned it into litho colic acid and these are what we term secondary bile acids and what happens is this a very small portion of them will move all the way through into our fecal material a very small portion but what you'll find is most of it actually gets reabsorbed through a blood stream which is termed the portal system the circulation where it goes from the liver through the ducts into the small intestines and back through the portal system this is called the entero hepatic circulation let's write that down inteiro hepatic circulation and you'll find that this deoxycholic acid in the throat colic acid which are secondary bile acids reabsorbed back into the liver now something happens here they these are unconjugated bile acids primary unconjugated bile acids secondary unconjugated bile acids now we want to conjugate something to them this is what happens here back in the liver we can take these secondary bile acids one looks like this the other looks like this and what we do is through a number of enzymatic steps we can give them a hat let's just say this one gets a blue hat and this one gets a green hat we've conjugated something to them in this case it's a hat now what this product is that we've conjugated to them are amino acids so for example the litho colic acid if we give it a taurine amino acid so let's just say this blue hat is a taurine and let's just say this green hat is a glycine what we now have a bile salts bile salts are bile acids with conjugated amino acids on them and the reason why they could bile salts is this the amino acid portion loves water their hydrophilic and the rest of the body is hydrophobic we now have an amphipathic molecule that means a part of it hates water a part of it loves water why is that important because of this these amphipathic molecules and now which we turn bile salts now move back through the ducts some continue to go go to the gallbladder and get concentrated so now in the gallbladder we have water bile acids both salts phospholipids cholesterol bilirubin proteins amino acids and ions it's sitting in accumulating waiting for a facet fatty meal but it also continues into the small intestines where it moves through and what can happen this bacteria can take the hats off and then throw it back in as again deoxycholic acid elliptic Olek acid and this cycle continues and like I said 95% of these bile acids and bile salts go through this in Terra hepatic circulation that means the recycling is the most important part of bile salts and bile acids the liberal only produced 5% and a very minor amount actually gets excreted through our fecal waste right what happens is this as well we've got our stomach right and our stomach's going to have parts of it let's draw this up the stomach is going to connect to this small intestines also known as the duodenum this first part and what happens is we now eat a fatty meal now fatty meals are going to be made up of triglycerides monoglycerides phospholipids cholesterol and it's going to move its way through as it moves its way through the duodenum it stimulates certain cells inteiro endocrine cells to release a hormone called C CK C CK troubles to both the gallbladder and the liver and stimulates them to release bile Collie sister : literally means to contract the gallbladder squeezes it and it squeezes this concentrated bile which has bile acids of both salts into the small intestines where this big bit of fat has moved through now and the important point here is this big bit of fat cannot be broken down because it's so big think of fat or oil in a pan it comes together forms these big globules we need to break it up into manageable pieces how can we do that well these bile salts I will now draw these bowel salts here like this we're gonna have the first one and the second one with their respective hats and what they do is they come along and because one part the body hates water it binds to the fatty part and the other part loves water it's exposed to the outside and so what it does is it starts to break down parts of this fat into smaller more manageable pieces by surrounding it with the hydrophobic portion and then the hydrophilic portion the amino acid is exposed to the liquid environment this is great this is now forming these my seals or Mis seals which then allow for enzymes that come from the pancreas the pancreas is actually sitting in this seat a little area here we've got the pancreas here which creates a whole bunch of digestive enzymes and the pancreas actually connects in as well and the pancreas is going to release all these digestive enzymes into the small intestines molecular scissors called lipases and coli países that start to chop up the fats so that we can then ultimately absorb them into the body and use them this is the importance of bile bile acids and bile salts

Channel: Dr Matt & Dr Mike

Views: 44,354

Rating: 4.9108911 out of 5

Keywords: bile synthesis, bile production, what is bile?, bile composition, cholesterol and bile, bile salts, bile acids

Id: gf-00vAWwLc

Length: 12min 32sec (752 seconds)

Published: Tue Feb 25 2020