hi welcome back to educator.com this is the lesson on the digestive system functions of the digestive system include ingestion the act of physically putting food into your mouth that's ingesting mechanical breakdown starts in the mouth that's with the teeth with the tongue when you swallow food your stomach does mechanical digestion that's anytime you're ripping tearing crushing food so that's the physical breakdown digestion itself if we look at like what causes digestion to occur mechanical breakdown does assist with it but on a microscopic level it's the chemical breakdown that that really gets it done that's enzymes acids all those molecules that that physically break down macro molecules larger molecules into the tinier ones that you can absorb into the bloodstream and actually provide your body nourishment secretion throughout parts of your digestive tract all the way up in the mouth with saliva all the way down to the large intestine you are secreting items um glands are are physically releasing substances uh fluids enzymes other molecules into your digestive tract uh to assist with the breakdown and movement of this food through there absorption the opposite of secretion you're physically absorbing uh those n those nourishing molecules those nutrients into your blood stream so that you can stay alive and excretion uh that's releasing waste out the exit hole the elementary Canal is a fancy way of saying your digestive tract or your GI tract gastrointestinal tract so either of these terms or digestive tract is acceptable and we look at this tube from the mouth all the way to the end all of these are connected to each other um some parts of it are little expanded or twisty turny or really long but all of these are in sequence later on I'll cover the accessory organs that are off to the side of the tract like the liver and the pancreas so of course it starts with the mouth you swallow food it goes down the FX right in here and then into the esophagus if it goes down into the larynx tra you have a problem and you could be choking or aspirating and and that's no good um once food and liquids go down the esophagus they enter the stomach from the stomach we go through the small intestine um the longest portion uh percentage wise of the GI tract then the large intestine which is large in terms of width not length uh which is right here most of it is known as the colon and then you get into the rectum and the anus so we're going to start with the oral cavity the mouth the the starting of the uh chemical digestion of food is definitely due to salivary glands um even just seeing food on television or seeing a picture of food smelling food is going to initiate salivation and you have three pairs of salivary glands for a total of six the pared glands are in this region um in in the kind of sides of the cheeks the sublingual that literally means under the tongue um we see those uh some people can lift up their tongue and you can see these little holes and they and they squirt like little hoses those are the sublingual under the tongue salivary glands and then submandibular which are uh deeper uh and Associated more with the mandible there's this mandibular Groove uh that's next to the back of the teeth where um these particular salivary glands are rooted and actually the majority of saliva comes from the submandibular glands and the rest of it from the pared and sublingual so of course salivary glands release Sal so what's in saliva well the vast majority of it is water but what's the other 6% you're looking at enzymes um antibodies even white blood cells on occasion um but the enzymes are really what we're going to focus on amalay salivary amalay is what we would call it is one of the main ones that breaks down larger carbohydrates in the tinier ones like glucose galactose those monosaccharides Lyme is an enzyme that actually helps keep the bacterial populations in your mouth at acceptable levels everyone has bacteria in their mouth uh even you know using a really good mouthwash you're not going to get rid of all of them it's important to have uh some bacteria in your mouth that's that's normal but you don't want them to get out of control um out of control bacteria is going to lead to infections like gingivitis uh tooth decay periodontal disease things like that so lome or sorry I I misspoke lys o zyme uh is an enzyme that helps keep that bacterial population in check your tongue has a lot to do with of course um getting the food swallowed and to help break it down um as you chew your tongue is is a very strong set of muscles uh that work together um and and I mean over time your tongue is so so strong that you can actually end up moving your teeth in the long run if your tongue keeps pushing on them uh yes the teeth have a lot to do with mechanical digestion uh the physical breaking down of food products teeth are not technically bones they're structure is a bit different than the bones of the body I'm going to cover that in the next slide and then last the hard pallet and soft pallet in this particular image uh this this sagittal cross-section straight through here um there's a little bit of German in this image but um here's the hard pallette right here uh that's um a lot of it is actually uh the maxillary bones and the palatin bones and then if you go posterior to there you've got the soft pallet where that that uula hangs that thing that looks like a little punching bag in the back of your mouth um the soft pallette has a lot to do with uh swallowing which we're going to get to in a bit teeth so first we're going to start off with the anatomy of teeth um I'm going to start by by mentioning um Denton and I'm going to erase um one sec this right here because this image says dentine but you actually see the word Dentin much more often so Dentin is a lot of the mass of a tooth and that is not quite on The Superficial level like enamel it's a bit deeper Dentin is similar to Bone but the reason why you wouldn't consider a bone is unlike your skeletal bones there are no cell in Dentin uh there are if you look at any bone of the body there are cells that help um you know regulate what's going on in your bones and help produce additional bone matrix over time but Dentin uh doesn't have cells in it superficial to dtin you have what's called enamel enamel is the hardest biological substance in the human body uh there is nothing else in your body that is harder than this and that's important for protecting the outside of your tooth uh um not just the mechanical wear and tear on teeth but the acidic substances that enter your mouth if it wasn't for the enamel you'd be getting much more of a wearing away of these tissues deeper in the tooth uh over time enamel can wear away uh eating too much acidic food um chewing on things that are way too hard too often can damage your enamel I've actually lost some enamel in my teeth because I tend to grind my teeth in my sleep I don't do it as much as I used to I I wear a mouth guard now but over time uh that's additional wear and tear that you don't want deeper uh to the Dentin is where you get into the pulp layer and the pulp is where you're going to find uh the nerves associated with teeth and blood flow into the tooth so as you can see uh there are um tiny little arteries and veins uh capillaries associated with each tooth and there's also nerves associated with uh the pulp and yes here are the root of the teeth uh depending on what tooth we're looking at the amounts of roots can vary some teeth only have one root some have three or even four roots cementum is a structure that helps keep the tooth anchored in the gum or the gingiva is the other term for the gums uh so if it wasn't for cementum the chances of losing an adult tooth would be uh drastically increased so thank you to uh cementum which is kind of like cementing the tooth in place and yeah here is the bone that the tooth is anchored so that bone is either going to be the mandible or the maxillary bones and yes there are nerves associated with every tooth as well uh the crown is what emerges out from the uh the gum of the tooth and yes when you look at like teeth in in a baby versus teeth in an adult babies get their deciduous teeth also called milk teeth or baby teeth depending on who you talk to deciduous means uh falling out like uh deciduous trees lose their leaves in the fall uh same meaning so yes those baby teeth are supposed to fall out uh they typically start falling out by the time you're seven or eight years old and they can keep falling out in through um you know high school or or um higher grades even uh some adult people still have deciduous teeth that's not that common but you tend to get around 20 deciduous teeth that can vary slightly depending on the person but 20 is about average by the time you're an adult and you've lost all the deciduous teeth and you you've gained your what are supposed to be permanent adult teeth you should have 32 now that number can vary as well because uh I no longer have 32 adult teeth I actually got some of my teeth removed which I'm going to get to in a moment incizors are the ones that are right up front here so four in sizers um the two big ones here and and the two that are right under them uh in sizers tend to have one root uh and they tend to have that structure that's um kind of Broad and and flat and so when you you know bite on something that you're sticking in your mouth incizors are going to be the first to make contact typically cuspids also known as can9 teeth you have uh a total of four of them if you count top and bottom U they're right on the sides of the incizors my canines not as sharp as they used to be because like I told you about grinding my teeth that that literally wore away the sharpness of my canines and some people's canines are sharper than others these also tend to have one root by cuspids a little further not quite to the MERS but bicuspids um have two cusps uh meaning when you look at the surface of them it looks like they have two points instead of one point like on a canine uh bicuspids can have kind of a double root like this and then molers all the way in the back on the top and bottom the MERS those tend to have uh numerous points they tend to be broader uh more for grinding of plant material and if you compare different animals in the animal kingdom an animal like um let's say a giraffe which eats plant material its whole life you're going to see teeth in its jaw that resemble our molers but they're going to be kind of the whole surface um yes in the very front of a giraffe's mouth you will have teeth that resemble the front of ours but the majority of their teeth are meant for grinding um you know that plant material but then you look at something like a canine a dog it's no coincidence that they're called that because they have much more sharper teeth for tearing flesh because you know they tend to hunt and kill live animals we are meant to be omnivores omnivorous meaning um eating all eating um animal materials and plant materials instead of one or the other and that's why we have that variet as humans we have some sharp teeth and some flatter broader teeth for both kinds of of foods now when I when I said that I don't have um 32 teeth anymore I got all four of my wisdom teeth removed and that's a term for uh teeth in the back some people um don't get all four uh some people are born with with less it's just a genetic factor maybe having something to do with um the development in the womb in utero as well but um my wisdom teeth as they were coming in when I was in uh early High School I was probably about 15 they were impacted meaning as my wisdom teeth were coming in the last of my adult teeth they were pushing against the other teeth so let's say this is um a Moler that was uh not quite in the back and here's the gum line here's the gum line and then and there'd be another tooth over here but the back part the more posterior portion of my jaw had a tooth that wanted to grow in this way like it was pushing on my molers and so the dentist said hey if if we let this continue its path over time they're going to keep pushing on those mullers that are closer to the front and and cause you a lot of pain discomfort and can actually um disrupt the placement of your teeth so they went in and removed all four um so I actually have 28 adult teeth instead of 32 when it comes to swallowing there are four main contributors to the action of of getting food that you've been chewing up and salivating on back into um your fairings and esophagus so the tongue major contributor if you look at what happens in this sequence this sort of sagittal depiction um you could see that this is the tongue here and the tongue as you swallow it tends to brush up on the pallet mostly the hard pallet and push backwards so swallow right now and you'll see what I'm talking about pay attention to what your tongue's doing so I just felt it do that it just kind of brushed back and it makes this action that physically pushes that bunch of food that you've been eating or or the liquid you just put in your mouth back down your fairings the fangio muscles as you swallow you can feel that there are muscles located in here that also tend to move Parts like the soft pallet and the epiglottis so the soft pallet is right back here you can see that it it does move as you push a bol of food backwards the soft pallet kind of kicks up to provide um that clump of food it's it's called a Bolis b o l us to move back the epiglottis also makes an action every time you swallow you can feel your larynx kind of arch up and back the epig glotus this little flap right here closes on top of the glotus and you can see that here if it wasn't for this epig glotus closing this food Bolis could potentially go through the glotus and into the larynx and trachea that would be no good uh you want it to go through that posterior passageway the esophagus uh down into the stomach uh speaking of esophagus L here they label upper esophagal sphincter that's the um kind of muscular Doorway to the top for the esophagus in in British English uh there's an O uh in front of esophagus in American English there isn't um one of the many differences between those two forms of English but uh this is the stepbystep process uh that happens when you swallow a chunk of food and you notice that once that food has gone past the glotus once that swallowing action is over the epiglottis will come back up allowing you to to breathe adequately in and out until you swallow again and the amount of time it takes for food to get all the way down the esophagus into the stomach about 9 seconds it certainly depends uh but that's an average when we look at the esophagus the esophagus here is a hollow muscular tube approximately 25 cm long and at its widest portion about 2 cm wide moves food into the stomach through peristalsis peristalsis in general is a wavelike muscular uh contractions so any any tube that has a muscular lining that needs to move something through it in your body and it's it's usually not conscious voluntary control it's it's sort of an unconscious thing involuntary uh that moves food through or in other cases when we look at the internal female anatomy uh peristalsis happens in the uh Fallopian tubes uh to help move an egg through to eventually meet sperm but this case we're talking about uh moving food from after the swallowing action down into the stomach once you swallow your voluntary control is done right I I can't physically move it faster down my esophagus or physically move it into my stomach uh more quickly it just it happens naturally so that action is called uh peristalsis and there are these wavelike muscular contractions that move food down no absorption happens in the esophagus yes items are secreted um there are um lubricating secretions into the Lumen the the space in the esophagus to help ease food down uh but you do not do absorption of nutrients here uh the first place that that happens is actually in the stomach um and then further down the major layers um in general when we look at the digestive tract there are four major layers uh you see three significant layers here and I'll mention the fourth layer in a moment but the inner layer or deepest layer of the esophagus is the mucosa so think of mucus that's secreting stuff that's in the innermost part so the mucosa layer deepest sub mucosa just superficial to that it's a supporting layer for the mucosa the sub mucosa often times is going to have uh blood flow in there um lymphatic tissue as well which has to do with u protection the immune response and then the muscular layers are superficial to that and without that muscular layer you're not going to get that peristalsis happen to move food and liquids down there's an additional layer when you look at the stomach and and further on down the GI tract it's called the Sosa uh the Sosa is is absent from the esophagus you don't see a significant Sosa there but the adventia that that layer of tissue on The Superficial most part of the esophagus does have connective tissue that anchors it to the dorsal body wall so the esophagus is really close to your back it's it's close to the the spinal column um the vertebrae of your spine uh you want to keep your esophagus anchored you don't want to have it moving around uh within your body you want it stay in put um so in general Sosa in the other parts of the digestive tract allow connection uh of those organs to the organs around them and also provides uh stability for the outer part of the organ so once you have food and liquid uh exiting the esophagus it's going to go into the stomach right here at the top is something called the lower esophageal sphincter it's the lower part of the esophagus and a sphincter is a muscular doorway into the stomach it's not very tight um in some animals it's much tighter I've heard that in horses that sphincter there is very tight and they're unable to vomit um you want it to be tight enough to keep you know the food you're digesting in the stomach but if you've eaten something that is not good for your body or too much of something your body sometimes has a need to expel it and I'll talk more about uh that vomiting reflex in a bit but in general the stomach is a j-shaped organ meant for storage of food temporarily mechanical and chemical breakdown and emptying of Kim into the small intestine K is a mixture of gastric juice produced in the stomach and your partially digested food um a lot of digestion happens in the stomach it can happen further on down as well uh so Kim is exiting the stomach into the small intestine on a daily basis um in terms of mechanical and chemical breakdown remember mechanical is the physical uh movement that that mashes or crushes something the stomach is filled with uh muscles that that churn and your stomach does that without you having to think about it of course a lot of chemical breakdown happens in theom as well uh through gastric secretions and that word gastric always means stomach four layers like I mentioned earlier mucosa most deep layer where that mucus is coming from sub mucosa the supporting layer just superficial to that that's going to have the the blood flow uh and and lymphatic access um and also um nerves going in there uh muscular layers um of course those are connected to nerves because without stimulation of the muscles to track they're not going to move um you actually have um three different orientations of muscles you have um circular muscles longitudinal muscles oblique muscles wrapped around the stomach in in various ways that maximize the ability of it to to churn the Sosa is the outermost layer on the outside the most superficial layer um that's protective and and helping anchor the stomach in place the stomach is slightly to your left um you know people often times touch this part of of their abdominal area they're really touching uh where their abdominal muscles are and where it's mostly small intestine bundled up the stomach is actually super or sorry Superior to that and slightly lateral slightly off to the left your liver is slightly to the right the four regions of the stomach cardia fundus body and pyloris you can see the labels here in this image from gry's Anatomy the cardiac portion has to do with the area of the stomach that's adjacent to that esophageal opening the fundus is the part of the stomach that actually lies just um Superior uh to that opening the body is this area in here that's that's where food tends to rest where Kim is going to be built up um a very acidic mixture of gastric juice and parti digested food and the pyloris is the part of the stomach that leads to uh the pyloric sphincter which is the opening into the small intestine uh one more thing I want to mention before moving on is uh the pyloric sphincter its closing and opening is very important because having food stay in the stomach uh not only is is good for breaking it down further and and making it easier for your small intestine to to break it down and absorb but also um a disorder has been discovered in certain people who tend to become become obese and um the small percentage of the population they have a disorder where their pyloric sphincter is too loose it lets food exit the stomach too quickly you want food to stay in the stomach for a little while because there's a signal that goes to your brain that says hey we've eaten enough we can stop eating for now this this meal is over effectively but if food is exiting the stomach out through the pyloric sphincter too quickly your brain doesn't have time to get that signal and these people tend to eat so an operation that tightens the pyloric sphincter can actually help them better regulate their appetite um so that's an interesting little Discovery pertaining to the pyloric sphincter and the tendency to become obese um I just mentioned this about the lower esophageal sphincter right here um or sorry my bad I mixed it up the lower esophageal sphincter is right there at the bottom of the esophagus and here is the pyloric sphincter my bad py sphincter right here and the lower esophageal sphincter up top is going to be right here that doorway into the stomach and here's the doorway out of the stomach if you look carefully in the um mucosa layer of the stomach on the inside there are these little folds called rug uh these folds increase the surface area within the Lumen or the space of the stomach um just like in other parts of the body where you see increased surface are area more tissue means more absorption more secretion so having all these ruge maximize the ability of the stomach uh to release gastric juice for digestion also as the stomach expands the more food you put in it um the ruge when they stretch out that allows you know greater expansion of the stomach with ease gastric pits are these little holes in in the rug where you're going to get gastric secretions and in those pits you find gastric glands um two main cells a part of these gastric glands parietal cells and chief cells parietal cells have a lot to do with the release of hydrochloric acid into uh the the Lumen of the stomach and and we can call the mixture of this and other things gastric juice the interesting thing about parietal cells is if they if they produced and made hydrochloric acid within the cytoplasm Within um the inside of that cell that parietal cell that hydrochloric acid would be enough to to actually physically damage the parietal cell and break it down so interestingly enough the parietal cells send out the H+ so remember if you took chemistry HCL is made of H+ and cl minus um so this particular cation and this annion together make make hydrochloric acid when they're separated it's really not hydrochloric acid so the prial cells send out the H+ and the chloride ions the CL minus separately and then they join together um once they're getting out of that gastric pit and and then together in the stomach that hydrochloric acid has a lot to do with with digestion and keeping the acidity of the stomach High amazingly um there's an an alkaline buffer alkaline meaning meaning basic the opposite acidic that keeps the stomach from digesting itself so that buffer is good for the stomach uh not wearing away over time and then when we look at Chief cells Chief cells secrete a substance known as pepsinogen and then the pepsinogen is broken down into pepsin because of the high acidity of the hydrochloric acid uh pepsin is an important part of gastric juice for digesting uh proteins um getting them broken up into little bits of amino acids that are eventually going to be absorbed primarily by the small intestine the stomach does some absorption of course uh but the main absorber doing the majority of the absorption for the digestive tract is the small intestine um gastrin is is one of those hormones that um has a lot to do with the the functionality of the stomach gin is a hormone that you actually didn't you didn't read a lot about or hear a lot about in older Anatomy textbooks um when I when I took Anatomy early on in in my education I didn't hear about this gin uh hormone but there's more and more research these days into what this does this is a hormone released by the stomach that tells the brain hey uh we're we're we're hungry or we're not the more gin that's released the more the brain feels oh we're hungry we need to eat once food enters the stomach and the stomach has expanded enough the amount of gin is reduced and then you don't feel as hungry after the stomach is the small intestine it plays a key role in digestion and absorption uh so there is further breakdown that happens here uh but a lot of absorption going on as well the small intestine amazingly uh if you were to stretch it out ends up being about 18 feet long um sometimes 20 feet long in the average person and and that is longer than the tallest person who ever lived times two so that that's that's amazing to think about that there's that much intestine uh bundled up right here and and there's connected tissues keeping it kind of uh tied to itself in that little bundle there are three main segments of the small intestine the dadum the junam and the ilum and this is in order from this part being adjacent to the stomach to this part being adjacent to the large intestine once again peristalsis the muscular lining in the small intestine is going to help move uh that kimme from the stomach all the way through that 18 ft uh length eventually into the the large intestine four layers as before so those four layers of the stomach the mucosa sub mucosa muscular layer and Sosa you would find those in the small intestine as well we're going to focus on the the mucosa and what that lining looks like if you were to take a cross-section through the tube of your small intestine and look down it like you were looking down a barrel you would see these little finger-like projections called villy and here's the Lumen that's the space right in there but each of these is a villis and villy uh is plural so villis and then the all these are villy look like little finger-like projections and then when you zoom into one of them so here's one of those villy if we zoomed into the surface of one single villis there are little tiny microvilli on each of the cells of this epithelium so here's a layer of epithelium that goes all the way around the border and this just further increases the surface area uh I've heard that the surface area in all of your small intestine if you were to once again like I mentioned with the lungs in the previous lesson if you were to open up all of all of that surface area and lay it out flat like you were tiling a floor it would be close to the square footage of a comfortable four bedroom home that's amazing to think about that that's all in your small intestines so each of these uh villy have Micro villy that further increase the ability to um break down chemically uh the the Kim the the digested food that's coming in and to absorb it effectively into each of these villy in each of the villy and and you know micro Vil are on the border you're going to have blood flow of course blood flow coming into here that's how you get it into your bloodstream the nutrients enter the bloodstream and then are delivered to all the cells and you're also going to have something called aacal so this green projection this Lac teal uh enables your lymph ftic system the immune system to have access to these Villi and that's important in case something traveling through your digestive tract is harmful to you a potential harm in terms of it containing bacteria or viruses so this lacal um is another way that your body can defend yourself from foreign particles or pathogens that have entered your digestive tract when you get to the end of the small intestine uh and and later on I'll come back to how bile factors into to the small intestine in terms of breaking down fats but when you get to the very end of the uh the small intestine ilum you reach the uh the the appendix so you can see from this graay anatomy diagram here's the illium this is the end of the small intestine here's the entrance into the uh the colon or or the large intestine and right here something called the vermiform process or verm form appendix vermiform means wormlike and it does kind of look like a little worm the appendix is a small wormlike sack located near the opening into the colon large intestine and it's a vestigal structure um if you took biology you know that a vestigal structure is kind of like a remnant of some part from an ancestor that is reduced in size and it's of less importance and sometimes it's completely useless there are different theories about how useful the appendix is um the the best theory I've heard is that we still have this left over from one of our ancestors from millions of years ago uh if you look back at uh the anthropological record um you know if you were to ask a paleoanthropologist somebody who specializes in the fossils of human ancestors they'll tell you that some of the ancestors dating back millions of years ago did not eat cooked meat they they ate of course vegetation but they also ate animal tissue without cooking it and you're introducing um a lot more bacteria into your body by not cooking uh animal meat they think that this particular sack was a bit larger in those ancestors and that was conducive or or helpful to the process of digesting that raw meat and over time when our ancestors finally started cooking meat um that changes the the the proteins in terms of like breaking down some of that stuff prior to uh putting it in your body prior to ingesting it and that heat also kills off a lot of the bacteria so we think that the size of this has gradually been reduced over millions of years and maybe one day in our descendants it could be gone it's hard to say how long it will take for that to happen but the interesting thing is that when you do get it removed because of an infection U many doctors will caution the person and saying hey now that we've REM removed your appendix it's a good idea that you don't uh eat sushi right away or or or be careful with um introducing uh raw animal tissues because you're a little bit more sensitive when you're missing your appendix now that might hit people differently uh depending on who the person is but an appendicitis is an infection of the appendix too much bacteria inside of there can cause it to swell uh and and get inflamed the point where it it it pops it bursts and that could kill a person an appendectomy is the removal of the appendix and since it's vestigal since it's is typically not needed um there's there's no harm in removing the appendix the large intestine begins right here and it kind of loops around where the small intestine is located right in the middle here it includes the seeum which is this initial part right here and then the colon segments it's for the reabsorption of water um it really makes uh your feces your waste solid and hey that's why I say here formation of solid feces is the primary function because when you get diarrhea um that means that your your large intestine is not doing the job it should be doing of sucking water out of the Lumen and making feces solid diarrhea is excessively watery feces it's uncomfortable you don't feel good um and that's usually because some bacteria or virus is inhibiting your large intestines ability to do its job um beyond that other nutrients are absorbed in the large intestine so it's not just um absorbing water out of it uh some nutrients are absorbed in the large intestine but far less than in the stomach and the small intestine the four regions are the ascending colon so since this is rising up on the right side of your body ascending transverse it goes across horizontally uh right under where uh the liver is and and the the stomach the descending colon right here it descends it it physically moves down and as you you move through these segments more and more water has been sucked out of it at least that's what's supposed to happen to the point where when you get to the sigmoid colon kind of this s-shaped curve by the time you get to the rectum uh where feces is stored hopefully it's its solid fees ready for um excretion so the rectum and anus the rectum is that last 15 cm of the digestive tract right in here here's that sigmoid colon and it's for storage of feces um storage of feces in terms of evolution dates back to um having a planned um intentional disposal of your feces in certain areas to to mark your territory and also um you don't want to be constantly letting go of waste because a predator who's trying to hunt you will better be able to uh to track you so the the timed elimination and control of when feces is released dates back to that um so the storage of feces happens in rectum and eventually you get down to the anus that that um muscular doorway uh where feces um is is expelled through so yes the anus exit AES happens there there's two anal sphincters two sets of muscular doorways the internal anal sphincter a little bit um deeper in terms of being internal in your body is involuntary you have no conscious control over it so as the rectum fills up you're going to get a loosening or relaxing of that internal anal sphincter in response to the crowding of feces in this area because once it gets too full time to let it go you do have control over your external anal sphincter uh so when someone is you know actively you know trying to hold in feces they are Contracting the external anal sphincter and the relaxing of that is going to obviously let um feces through hemorrhoids happen when there's too much irrit ation of uh the blood vessels that are around the rectum in the anal region and that causes dilation or swelling of those blood vessels and as hard feces move past them or as they're pushed past uh forcefully it causes bleeding so these uh these enlarged blood vessels bleeding um not very comfortable not very healthy in the long run the way that you can minimize U the occurrence of hemorrhoids and bleeding in that region um get a lot of fiber in your diet fiber helps keep your feces uh a little softer um really hard feces tend to happen uh when you don't eat as much plant products when you don't eat eat as much fire fiber rather and and the meat content of your diet a little too high that leads to really hard uh feces which rub on these walls much more also drinking more water is going to help and not pushing when you're on the toilet uh pushing on the toilet uh is going to irritate at the walls of this part of the digestive tract make it more likely that you're going to develop hemorrhoids and that that bleeding will happen oh by the way hemorrhoids can be removed surgically uh but that's typically not done unless uh they're really really severe uh if you do have hemorrhoids see a doctor uh they will test to make sure that that's all it is that that it's just hemorrhoids because um blood in your stool in in your feal matter in the toilet uh could be a sign of colon cancer so uh definitely get that checked out um they'll do a colonoscopy which is where they actually move a a camera up through the large intestine to see if there are um growths polyps and and they'll take tissue samples of them to see if they are cancerous so now that we've covered the digestive tract the GI tract or Elementary Canal we're going to talk about the accessory organs uh that are kind of off to the side but are very important in digestion the liver is one of them the gallbladder tucked right underneath it this little green sack and the pancreas kind of hidden in this image because it's a little bit behind the stomach a little bit behind the large intestine but there it is right there that that yellow organ so the liver this is the first slide on the liver it is the largest visceral or internal body organ the largest one would be the skin uh but a significant sized uh organ slightly off to the right side of the Superior part of your abdominal cavity to two loes here's one the larger one is on the right and this one a little bit more centrally located they are separated by the fala form ligament it's it's like a white band in between the two deep dark reddish portions of the liver uh one of the reasons the liver is such a a deep dark red organ is the high amount of blood flow lots of blood flow the liver all throughout the day if you take all the blood out of a liver and look at uh that organ from a dead body it still has a a reddish purplish tone but um when it's in a living being very red as an organ uh about 25% of your blood at any given moment could be um in the liver hepatocytes are liver cells that word Hep hepato always pertains to the liver and they're located within lobules if you take a cross-section of the liver uh and look at what's in it um with a microscope there are these little um round regions called um lobules and then in there you have hepatocytes you have lots of blood vessels you have lymphatic tissue um in these little clusters and that's how the liver is arrange microscopically the major functions of the liver it's no coincidence it's called the liver without it you're not going to live uh it has many many functions carbohydrate lipid and amino acid metabolism so it assists with the breaking down uh of all of these macro molecules all these different organic molecules that you eat on a daily basis and it also has to do with the storage of um glycogen so your your glucose levels in the bloodstream have a lot to do with the action of your liver glycogen is a large uh polysaccharide it's like analogous to to um starch in plants so starch is how plants typically store sugars we store it as glycogen and if you haven't eaten in a long time or maybe you you gone for a long run your blood sugar levels might be low so your liver is stimulated to break down glycogen in individual little glucoses that are sent into the bloodstream you also do store some glycogen in your muscles but there's a lot of it in your liver uh you also do store um lipids uh over time um one way that you can get uh too much lipid storage in your liver is um abuse of alcohol uh over time can lead to developing a fat fty liver the liver will actually get enlarged and take on a a whitish appearance because of excess lipid storage and in the long run that enlarge liver could eventually um get really bad and lead to curosis which I'm going to get to in a bit uh waste product removal uh the removal of waste from your bloodstream happens significantly in the liver um bile production bile uh which I'll talk about more in a bit with the gallbladder has to do with the emulsification of fats uh breaking down fats into tinier bits that make it easier for enzymes to break them down and absorb them vitamin storage um a b k B12 uh these vitamins are stored in the liver um yes you need to consume those in your diet uh that that's a matter of keeping yourself healthy if you don't get enough in your diet you're going to be releasing them out of the liver um to supplement uh your cells with those particular vitamins breakdown of drugs alcohol drugs whether legal or illegal your liver is breaking them down um the reason why some medications that are prescribed need to be taken once a day or four times a day it has to do with the speed at which the liver uh breaks down the drug uh my dad worked for a company a pharmaceutical company that figured out if if they just added a certain um molecular component to the drug they had already made it would slow down the liver's ability uh to get rid of it to to physically break it down and and eliminate it um through waste in the body uh so yeah just adding that little molecular component made it so that you only had to give one injection of this drug um you know per week instead of once a day or multiple times a day uh so the liver has its own pace with how it breaks down alcohol with how it breaks down drugs and that has a lot to do with genetic factors and tolerance of the drug over time um more on the liver phagocytosis and antigen presentation so this is uh part of your liver's ability to assist with your immune system um phagocytosis not just of um foreign bodies that are coming into um the liver through the blood flow in the liver but also swallowing up red blood cells that are damaged the phagocytosis or eating of red blood cells and breaking them down and your liver assists with presenting antigens um the U usually protein components on the surface of foreign Invaders or pathogens to assist with your immune systems ability to kill those things synthesis of plasma proteins so yes blood cells are made typically in the bone marrow but a lot of the proteins that end up in the fluid of your blood uh produced in the liver removal of hormones so hormones are released from all different endocrine glands throughout the body but your liver has a lot to do with uh taking in excess adrenaline um insulin and removal of those hormones from the body when they're no longer needed removal of antibodies antibodies um are supposed to be in your in your bloodstream at certain uh times and then other times they're removed and antibodies allow white blood cells to um adequately and efficiently attack foreign Invaders so antibodies the amazing thing is when your liver takes them in to remove them from your bloodstream your liver can break down the antibodies into individual amino acids uh because antibodies are made of protein and then your liver can reuse those amino acids to make other proteins for instance plasma proteins so they can recycle those little bits like I mentioned earlier the removal of red blood cells very important um the the the breakdown of those red blood cells is going to lead to the formation of U Billy Rubin um which has been discussed in another lesson that I went over and then the removal storage of toxins um stuff in your bloodstream that that doesn't belong there toxic substances your liver is going to be able to remove that one example is um hydrogen peroxide there's so many things your liver can remove but um uh hydrogen peroxide is broken down by an enzyme called catalase and the liver of every living being not just humans contains Catal catalase the enzyme that breaks down H2O2 next the gallbladder gallbladder stores bile so the liver produces bile and then sends it to the gallbladder um and that is located just inferior to the liver so here is an inferior view from underneath the liver you can see that there are these hepatic veins remember hepatic means of the liver uh these veins that are helping to take blood from the liver to go back to the heart um and here's the inferior vnea that's the major vein that's going back to uh the right atrium the common hepatic duct is what's going to take bile from the liver to the gallbladder and then the common bile duck connects the gallbladder to the duodenum or the dadum dadum is uh that first part of the small intestine which you're going to get a better view of when I show you the pancreas slide um if it wasn't for that common bile duct you wouldn't be getting bile into the small intestine and that bile um is made from from a lot of different sources one of the sources is cholesterol um it contains a variety of things like bile salts and the the bile in general like I said earlier emulsifies fats so the emulsification of fats is a fancy term for um breaking down lipids into smaller bits that make it easier for enzymes to to further break them down into tiny chemical bits uh for absorption into the small intestine so that bile helps break down fats big time and you're going to get a lot of bile in the deinum you you produce something like a liter of bile per day on average and that bile can creep up into the stomach because the the dadum is right next to it and bile can also be found further down the line um in the uh the small intestine um bile can also be uh reabsorbed uh from the intestines and it can actually go back to the liver uh and can be recycled throughout the day uh some people do get their gallbladder removed I'm going to talk more about gall stones the reason why you don't need a gallbladder is as long as the common hepatic duct is still connected through the bile duct that takes it to the the the deinum you do not need that temporary holding sack uh for the bile so I I know people who who've had their gallbladder removed but their liver is still producing it and still sending it down into the small intestine the pancreas this is an endocrine organ it has a lot to do with hormones but it also is a definite part of the digestive system it lies posterior just behind the stomach in between the duodenum and the spleen uh which is a lymphatic organ part of your immune system it's about 15 cm long it's pinkish gray and it's got a body and a tail so here's the body of the pancreas the tail is kind of that tapered uh part that's that's closer to the left side of your body but you can see hey here's the dadum the beginning of the small intestine your spleen would be uh right over here it produces digestive enzymes and buffers uh so here are some examples of the enzymes uh that are produced and sent out through the pancreatic duct you could see that uh this connects to the duodenum just like uh the bile duct connects to the duodenum pancreatic Alpha amalay this is very similar to salivary amalay in your saliva this helps break down sugars pancreatic lipase named after the fact that it helps break down fats nucleases are enzymes that break down DNA and RNA because when you're consuming plants or animal products they have DNA and RNA too and the proteolytic enzymes also known as proteases that's that's one of the main kinds of these enzymes uh they help uh break down proteins so some digestive conditions and disorders uh gastritis is an irritation or affection infection of the stomach um it is curable antibiotics can can help with that of course ulcers uh ulcers it doesn't just happen in the stomach they can happen in in various parts of the digestive tract it's a wearing away of the lining it can be very painful and there can be even some internal bleeding there was this myth years ago that stress caused ulcers stress can lower the effectiveness of your immune system and that can make an ulcer more likely to happen but it's not the direct cause uh there actually is a kind of bacterium that's been linked to the the causing of ulcers um and it's a pylori um um pylori is in the name um I'll I'll post later on about the specific name of it but um there is a kind of bacterium that that is is the root of causing ulcers and antibiotics can get rid of it um gallstones oh it's H pylori H I just remembered it H pylori that causes ulcers uh gallstones if there is a um inability of getting um bile salts out of the gallbladder and into the small intestine effectively you get this backup and the buildup of uh the bile salts leads to the formation of stone this is a gallbladder that's been taken out of a person's body you can see they're literally Stones um hard deposits that's caused this backup so this person is still able to get vile out of their liver to the small intestine but this needed to be removed um the the backup um and inability of bile to to go from the liver to the small intestine can be a problem uh Cher is um an infection that causes massive diarrhea and massive fluid loss this in the past killed much more people many more people because um you know the discovery of antibiotics and and getting rid of the bacteria that can cause chalaa um has saved many lives but chalera if untreated can dehydrate a person so much that it kills them hepatitis is an infection of the liver hepatitis A B C D or E uh a is the least harmful type typically uh but um hepatitis in general infections of the liver can be deadly uh because the liver is is an organ that's very important jaundice the inability of the liver um to regulate the amount of Billy Rubin in the bloodstream uh can lead to jaundice so when this Billy ruin molecule is is throughout the body way too much the buildup of it in the skin and even in the eyes causes this yellowish kind of appearance and you could see from this particular image this guy his scaras are even yellow um the whites of his eyes um and yeah depending on your skin tone that the yellowness or yellowish of the skin is going to be more apparent um I found that um my aunt who's who's a nurse um in a neonatal unit in a hospital she said that babies who have jaundice right after they're born they found that if they put um heat lamps on them um that actually can help uh get rid of jaundice um fairly quickly actually so jaundice uh is something that is curable but the yellow the yellowness not very pleasant therosis is liver disease that's um a liver that has been damaged over time uh by too many toxins uh drug abuse alcohol abuse over time causes therosis uh if you don't get a liver transplant therosis is deadly constipation uh is having feces that is just way too solid and too rough and and that backup and and solid balls of of feal matter causes a backup and it's hard to physically push it out like I mentioned earlier with hemorrhoids getting uh more fiber more plant material in your diet whole grains more water in your diet and lessening the amount of uh meat intake can actually help a lot with constipation diarrhea like I mentioned with the large intestine before is um a virus or iium that has in inhibited your large intestines ability to reabsorb water and that excess water in your feal matter is going to cause diarrhea lactose intolerance there are genetic links to lactose intolerance uh where the amount of lactase the the enzyme that breaks down lactose in dairy products is just not as high in certain people as it is in others I have no problem digesting lactose I can eat a lot of cheese or ice cream and I feel fine don't notice any negative effects when I go to the bathroom uh but some people do some people it just takes um a little bit of cheese ice cream or milk and and then they have that um uncomfortable um sensation in their GI tra and then they notice a trouble on the toilet with that um there are medications that can assist your body's ability to break down lactose there are pills that you can take um to help with lactose intolerance and then gingivitis the gum disease known as gingivitis is uh a gum infection the gingiva is a technical term for your gums so not brushing your teeth adequately not flossing can lead to gingivitis periodontal disease is another example of um a disease that's going to impact your teeth and and you're more likely to lose your teeth if if that's untreated um brushing your teeth twice a day and and using floss is going to minimize the chances of getting gingivitis you don't want to get that it's going to going to give you typically really bad breath a very um unattractive appearance in terms of your oral health and this is actually from what I've heard the most common bacterial infection on planet Earth uh because if you look at populations around the globe uh various people are not keeping their mouth as clean as they could uh they may not have access to a toothbrush or toothpaste or dental care so gingivitis a very common mouth infection and very common bacterial infection in general thanks for watching educator.com