what happens to the food and water that we ingest every single day that's exactly what we're going to be talking about today in this video focusing on the ait's version 7 portion of the exam for human anatomy and physiology more specifically the gastrointestinal system let's get started so when it comes to the human digestive system we're going to explore the proficiency of Performing four essential functions we have ingestion digestion absorption and elimination starting with ingestion it's simply the intake of food as we move into digestion this involves the breakdown of large biomolecules recall that we have four major biomolecules that we discussed in our previous ait's videos these particular biomolecules are going to be broken down into their respective building blocks through mechanical and chemical means next as we move into absorption this is where those nutrients are going to be taken up by the body this process is crucial because it allows nutrients to be delivered to the cells supporting their survival and function through cooperation with other bodily systems and then lastly we have elimination which deals with the expulsion of substances that were not digested clearing waste from our bodies so let's break these down even further so in humans ingestion begins when food enters our mouth if you think about it even the thought of food can actually make our mouth release saliva so when that food is brought into our mouth this this is when that digestion process begins and that is when the saliva that contains enzymes are going to start to break down those biomolecules using things like salivary Amala which starts to break down carbohydrates this enzymatic breakdown is known as chemical digestion alongside this we have mechanical digestion which occurs in our mouth mechanical digestion is the physical breakdown of food primarily accompanied by our teeth and they ultimately end up grinding that food into smaller pieces saliva is going to play a multi-functional and underappreciated role when it comes to chemical digestion not only does it contain digestive enzymes but it also includes buffers that are going to neutralize that acidity found inside of our mouth helping to protect our teeth against tooth decay additionally a lack of sufficient saliva is a condition known as dry mouth and this can also pose serious health risk when it comes to our Dental Health saliva not only AIDS in our digestion of food but it also lubricates it making it easier for your tongue to mold that food into a small ball known as a Bolis this Bolis of food is then going to be swallowed as it travels down our esophagus an ingenious feature when it comes to our body is known as the epiglottis and this epig glotus is going to act as a protective flap that's going to cover our wind pipes so that we don't have any food going down the wrong hole this is crucial because the trachea and the esophagus are located very very close to one another and this prevents that food from entering the cha essentially avoiding us from choking on our food the process of parsis is then going to take place and what's Happening Here is there's a WAV likee muscle contraction of our smooth muscles in the esophagus efficiently moving that bolus further downward as it heads towards our stomach so when we talk about the adult stomach the adult stomach actually has a capacity to hold approximately 2 lers of both food and liquid this environment is highly acidic facilitating chemical digestion through the stomach's gastric juices this includes our hydrochloric acid HCL and enzymes like pepsin that helps us break down proteins additionally mechanical digestion is also going to take place as a stomach is going to churn its muscles to help churn all of that contents found within it thoroughly mixing them with those gastric juices this process of that churning of the food is going to make it into a semi- liquid mixture known as Kim there's a couple of sphinges you're really going to need to be made aware of when it comes to the aits and that is our lower esophagal sphincter and our pyloric sphincter when it comes to our lower esophageal sphincter it is positioned at the junction where our esophagus ultimately meets our stomach this sphincter primary function is to open and allow food and liquids to enter the stomach and then close it tightly to prevent any of that acidic contents from the stomach reflexing back into our sof us this ultimately helps prevent things like heartburn and gastrosoph reflex disease also known as gird on the other end of our stomach we have our pyloric sphincter and this valve is located between our stomach and our small intestine also known as the start of our dadum its main function is to control the passage of partially digested food into our small intestine this sphincter also helps prevent any backflow of intestinal contents into the stomach so let's move on to our small intestine this is the point when digestion ends and absorption Begins the duum junam and ilium are the three contigous sections when it comes to our small intestine each of them playing a unique role when it comes to digestion and absorption these sections ultimately work together to ensure that nutrients are effectively absorbed into the body so we're going to start with our danum and this is ultimately the first and shortest segment of our small intestine it immediately follows our stomach its primary role is is the chemical digestion of Kim facilitated by enzymes from the pancreas as well as bile from the liver the Dum is crucial when it comes to the fats proteins and carbohydrates that need to be broken down it also absorbs iron and other minerals in this specific location and then next up we have the junim which is the middle section of our small intestines and it's primarily responsible for the absorption of nutrients the walls of her gunum are lined with these kind of villi they these little small finger-like projections that increase the surface area for absorption here most of the carbohydrates and proteins are going to be absorbed into the bloodstream and then last up we have our ilium which is the final segment of our small intestine and it's primarily responsible when it comes to absorbing vitamin B12 bile salts and whatever products of digestion were not absorbed by the junim the ilium is also going to play a crucial role when it comes to absorbing fat soluble vitamins like a d e and K an easy way I like to remember the order of the small intestines is digestive juices intake digestive stands for our duum juices stands for our junim and intake completes it with our Ilan signifying the completion of nutrient absorption next up we have the large intestine and this is an essential part of our digestive tract as it's comprised of several key segments we have our ascending colon our transverse colon and our descending colon starting with our ascending colon this is the first segment of our large intestine and it's located on the right side of our abdomen it begins at the seeum just below that ilocal valve and it receives digested material from the small intestine the primary function of the ascending colon is to absorb water and salt from the remaining digested material this absorption is going to help solidify that waste into a more formed stool next up we have our transverse colon and this is the longest most mobile part of our large intestine the transverse colon stretches across our abdomen from the right to the left it acts as the storage site for the remains of our digested food that was not previously absorbed in the small intestine in this segment further absorption of water and salts continue gradually turning that digestive material into a thicker more solid form as It prepares to enter our descending colon and then last up you guess it we have our descending colon which is located on the left side of our body the desent and colon carries the increasingly Solid Waste downwards towards our rectum it continues that process of water and mineral absorption further consolidating that waste before it's eventually expelled from the body this segment plays a crucial role in storing the feces until defecation and it's integral part of the body's waste management and excretion system the biggest key takeaway I want you to remember when it comes to large intestines is it's the primary site for water absorption it's the most prevalent place where this takes place an easy way to remember this is ascending absorbs transverse transports and descending drives down this demonic ultimately helps encapsulate the primary functions of each segment ascending absorbs water and minerals are absorbed here transverse transports it acts as a conduit while continuing that absorption and descending drives down moves that Solid Waste further down before it gets eliminated then lastly we reach the concluding phase of our digestive system known as elimination and the rectum marks that final segment of our large intestine where feces are stored until they're ultimately expelled from the anus so throughout this talk we've noted organs such as the gallbladder liver and pancreas because they contribute digestive juices to that digestion process process though they're referred to as accessory organs their roles are far from secondary the liver is the largest internal organ not only does it perform various functions outside of digestion but within the digestive system it is crucial for the metabolism of carbohydrates and proteins it also produces bile which is essential for the breakdown of lipids and the gallbladder acts as a storage facility for the bile that the liver produces releasing it when it's needed for the process of digestion meanwhile the pancreas produces pancreatic juices that contain vital digestive enzymes that help neutralize that acidic kind playing a critical role when it comes to the digestive process and lastly we're going to talk about key players when it comes to hormones as well as enzymes that we're going to find in our digestive system these are a few that are going to be crucial for you to know when it comes to the aits first up we have gastrin and gastrin is found in the G cells within our stomach lining their primary function is to help with stimulating gastric glands to secrete pepsinogen it's a precursor for pepsin like we talked about before and hydrochloric acid which is going to Aid in the digestion of proteins it's ultimately going to be released when we eat foods that are high in proteins next up we have Cho cinin which are going to be found in the eye cells of our mucous Linings within our dadum and our gunum its primary function is to digest fats as well as proteins it's going to stimulate that gall bladder to release and contract all of that stored bile that it has into the intestines cck also prompts the pancreas to secrete its digestive enzymes which are necessary for breaking down proteins carbohydrates and the fats that you find in K next up we have secretin which are found in the S cells of our duum Secret's primary role is to regulate the pH balance in the duum by inhibiting gastric acid secretions from the stomach and stimulating the production of bicarbonate from our pancreas bicarbonate is going to help neutralize that acidic time that enters that small intestine from the stomach next up we have insulin and insulin is found in the beta cells of our pancreas insulin plays a crucial role when it comes to glucose metabolism it's going to facilitate the uptake of glucose by the cell C thus lowering our blood sugar levels insulin is also going to stimulate the liver and our muscle cells to store glucose as glycogen and it promotes the synthesis of fats in our atopos tissue then we have glucagon which is found in the alpha cells of our pancreas glucagon is going to do the complete opposite of what insulin does and it's going to work to raise our blood glucose levels it does this by stimulating the liver to break down that store glycogen into glucose and then that glucose is going to be released into our bloodstream this hormone is essential for maintaining fuel balance and is especially active between meals and during exercise and then last up we have our bile which is produced by our liver and ultimately stored in our gallbladder bile itself does not break down substances but It ultimately emulsifies fats making them more accessible to the digestive enzymes that digest lipids this action is crucial for the efficient digestion and absorption of fatty substances in the small intestine I hope that this video is helpful in understanding what you need to know when it comes to the gastrointestinal system for the aits as always if you have any questions make sure that you leave them down below I love answering your questions head over to nurse Chun store.com there's a ton of additional resources in her to help you Ace those ait's exams and as always I'm going to catch you in the next video bye y