Gastrointestinal System Physiology PDF

Gastrointestinal System Physiology Digestive System organs and reflexes  Thedigestive system is a complex tube closed by the mouth at one end and the anus at the other. Food enters through the mouth, travels through the esophagus; it crosses the stomach, small intestines (duedenum, jejunum...

Gastrointestinal System Physiology Digestive System organs and reflexes  Thedigestive system is a complex tube closed by the mouth at one end and the anus at the other. Food enters through the mouth, travels through the esophagus; it crosses the stomach, small intestines (duedenum, jejunum and ileum), large intestines (ascending, transverse, descending colon) and rectum; then it goes out through the anus. Gastrointestinal = Gastrointestinal System Its main task is the ABSORPTION of nutrients. In order to maximize the absorption of nutrients, various substances are secreted from the salivary glands, stomach, liver, gall bladder and pancreas, added to foods, and these substances are transformed into simpler complex molecules. This translation event, called DIGESTION, is also affected by enzymes.  ÜSTÖZEFAGUS SFİNKTERİ ALTÖZEFAGUS SFİNKTERİ PİLORSFİNKTERİ İLEOÇEKAL SFİKTER ANALSFİNKTERLER  Peristaltic contractions and relaxations in the digestive system allow it to move from one section to another. During this transmission, some substances are STORED, and undigested foods are REMOVED. General function of the digestive system; It is to process the foods eaten into molecules and then transfer them to the inner environment of the body with salt and water. These substances are then distributed into the cells by the circulatory system.  Most foods are added to the gastrointestinal tract such as protein and polysaccharides. It enters as coarse particles containing macromolecules. For these foods to be absorbed, they must first be dissolved in water and broken down into small molecules (Small nutrients such as vitamins and minerals do not need to be broken down).  This breakdown process is called DIGESTION and is achieved by the action of HCL (hydrochloric acid) in the stomach, bile and various digestive enzymes released from the liver by the bile and exocrine glands. Each of these substances is released into the gastrointestinal tract by the event called SECRETION. In addition, some digestive enzymes settle in the intestinal epithelial membranes. Molecules formed by digestion and water and small nutrients that do not need to be digested enter the blood or lymph from the lumen of the gastrointestinal tract. This is called ABSORPTION.  While digestion, secretion and absorption occur, the smooth muscle cells of the gastrointestinal tract contract. These contractions mix the nutrient content with the various secretions and push this content from the mouth to the anus. These contractions are cal ed MOTILITY of the gastrointestinal tract. The kidneys are responsible for removing most of the waste products from the body. The material called feces leaves the system at the end of the gastrointestinal tract. Stool consists of bacteria and material that has not been digested and absorbed. This represents the REMOVE event. THE DIGESTIVECHANNEL PROVIDES ELECTROLYTES,WATERAND FOODTOTHEBODYCONTINUOUSLY… 1. Movement of food in the digestive tract 2. Secretion of digestive secretions and digestion of food 3. Absorption of digestive products, water and various electrolytes 4.Excretion of undigested, non- absorbable substances 5. All these functions need to be controlled by local, nervous and hormonal mechanisms.  The Layers that Make up the Digestion System The digestive tract is made up of many layers. From inside to outside mucosa, submucosa, muscularis externa, serosa. 1- Mucosa: It is the innermost layer that is in direct contact with the content in the lumen. 2- Submucosa: Although it is a thicker layer, it is a soft connective tissue layer consisting of collagen and elastin. The neural network (plexus) ** is in this layer.Especially there is the neural Meissner plexus which is responsible for the control of the secretions of the gland structures in the gastrointestinal system.  THE LAYERS THAT MAKE UP THE DIGESTIVE SYSTEM 3- Muscularis externa:There is the Auberch (myenteric) plexus responsible for the peristaltic and segmentalmovements of the gastrointestinal system. When the inner circular muscles contract, the lumen. narrows. When the longitudinal muscles located on the outside contract, it shortens the size of the digestive canal and enables the materials in the canal to be advanced. 4- Serosa: It is a connective tissue layer with blood vessels, nerves and lymphatics  TWO TYPES OF CONTRACTION ARE SEEN IN THE DIGESTIVE SYSTEM. 1. Peristaltic 2. Mixing (progressive) (segmentation motion contractions) movement: Stretchingof the wall is It is the contractions of stimulated by the circular muscle groups contents of the lumen. that occur at regular intervals throughout the intestine. The resulting reflex After the relaxation of the causes contraction in contracted parts in these the part behind the contractions, the non- passage in the lumen contracted parts in and relaxation in the between contract after a front. while. In this way, the As a result, the passage contact of food with the is advanced. mucosal surface is increased by moving the intestinal passage back and forth.  Although the ENS functions independently from the CNS, the CNS has an important role in the coordination of various functions of the ESS. In addition, theintestines also have their own nervous system(Enteric nervous system) * E NS coordinates with the autonomic nervous system and is intertwined with gastrointestinal activities. * In general, digestive system activities are outside of our consciousness and we cannot control. In the digestive system, only the mouth, throat, upper esophageal sphincter and anus are under conscious control. That is, only the beginning and the end of the system can be controlled consciously. ENS activity is modulated by the sympathetic and parasympathetic nervous system. Although ENS is regulated by these external (extrinsic) nerve inputs, it can work on its own through intrinsic regulation and sensory reflexes. Extrinsic regulation: Parasympathetic inervation: The main mediator (neurotransmitter) that provides parasympathetic control is acetylcholine. The parasympathetic nervous system of the intestine is primarily supplied by the vagus nerve. The nerve vagus forms plexus-like structures as it emerges from its nuclei in the brain and descends through the esophagus. From here, it passes into the diaphragm as two branches, giving branches to the stomach, small intestine and colon.  In this way, parasympathetic fibers exit directly from the brain and extend between the circular and longitudinal muscle fibers in the intestine and into the submucosa. Sympathetic Inervationon: Noradrenaline * is the most important neurotransmitter of the sympathetic nervous system. Sympathetic nerves emerge from the spinal cord of the medulla. From here it ends in the (intramural) plexus between the circular and longitudinal muscles.  Intrinsic regulation: There is a system that makes plexuses in various regions between the bowel layers. The ENS consists of short neurons and intermediate neurons that are located entirely within the gastrointestinal wall, including neuron bodies. The human digestive system is surrounded by a hundred million nerve cells. These nerves are in connection with each other. ENS contains sensory, motor fibers and neurons that provide integrity. An important part of the regulation of gastrointestinal movements is in the ENS. Therefore, the intestine ascribes the small brain to the ENS. In some functions of the stomach and intestine, ENS is more important. Some isolated parts of the stomach and intestine can affect the peristaltic contractions of the gastrointestinal system.  “SECOND BRAIN” The latest research shows that the digestive system and spiritual processes are more closely interconnected than previously thought. When a scientist takes a piece of the gut and examines it with a simple microscope, he discovers that there is a two-layered network of nerve cells in the wall of the gut. It is observed that this network is thin and hidden between two muscle layers. The intestines are the control center of the digestive system, not only analyzing gross values such as the composition of nutrients, salt ratio and water amount, but also controlling the delicate balance of sympathetic and parasympathetic nerves, stimulating hormones and protective secretions, as well as nutrient absorption and defecation mechanism.  “Second brain”*** The intestines are the body's largest organ and 70% of the defense cells are located here. Most of the processes in the gut work completely independently FROM the first brain. When poison enters the body,the second brain in the gut “senses” the danger first and sends danger signals to the first brain in the head, because the brain in the head must be ready at the time of danger, the person must be aware of the state of his stomach and act according to the plan, react in the form of vomiting, cramps and diarrhea..  Serotonin is a chemicalthat acts as a neurotransmitter and can be produced by the human body. It is an indispensable moleculeforour psychological balance. Serotonin is found in the central nervous system and intestines. 80-90% of the serotonin in the body is found in the digestive system. This is because the only function of serotonin is not to affect psychology, but also to control bowel movements.  “Second brain” British doctors opened the stomach of a drugged dog in their laboratory in London and expelled a moving intestinal node. This piece of gut, still associated with the dog, showed uniform behavior. When the scientists applied pressure on the part they removed, the intestinal knuckle was contracting in waves. During this movement, they saw that the bowel continued in an inward direction, always from mouth to the anus. He called this phenomenon the "Law of the Intestines". This phenomenon is also called the "peristaltic reflex". This is a vital function for the digestive system.  The enteric nervous system basically consists of 2 plexuses *: Myenteric or Auerbach plexus located between longitidunal and circular muscle layers * Submucosal or meissner plexus is located in the submucosa. While the myenteric plexus mainly controls gastrointestinal motions, the submucosal plexus mainly controls gastrointestinal secretions and local blood flow. Hormones regulation: In addition to neurotransmitters, hormones * also regulate and control the digestive system. Depending on the distance between the hormone secreting cell and the target cell, these hormones are divided into 3: 1. E ndocrine: They are released into the circulation and can affect all parts of the organism with blood. 2. Paracrine: They can only affect cells in the immediate vicinity. 3. Neurocrine: Since they are synthesized by neurons, they are transmitted through the neuron to the cell they will affect. G astrointestinal Hormones: Most of the functions of the digestive system are regulated by hormones made by the digestive tract itself. Gastrin Cholecystokinin Secretin Enterogastrin ▶The stomach is the first place where food is collected after passing through the mouth. The nervous system and the endocrine system work together for the functioning of the stomach. The nerve that regulates the functioning of the stomach is the vagus nerve, and the hormone is the gastrin hormone. ▶With the hormone gastrin, the stomach glands produce secretions necessary for digestion. As a result of these secretions, the pH of the stomach becomes very acidic. The production of mucus, pepsinogen, and HCl is controlled by the gastrin hormone. ▶The small intestine is where all types of food are last digested. The small intestine also directly affects digestion with the hormones it produces. Small intestine hormones are produced in the duodenum part of the small intestine. When the acidic food mixture from the stomach passes into the duodenum, three hormones are secreted from the duodenum. ▶Secretory hormone ▶Cholecystokinin hormone ▶ Enterogastrin hormoneof the gastrin hormone.  ▶The function of the secretin hormone releases bicarbonate ions  from the pancreas. When bicarbonate ions are given to the small  intestine, the smallintestine becomes basic. Secterin hormone  also increases bile secretion in the liver. As you can see, the  secretin hormone affects the small intestine by stimulating the pancreas.  ▶Cholecystokinin hormone (CCK) also stimulates the pancreas to  produce digestive enzymes. These enzymes carry out digestion in  the small intestine. In addition, bile empties into the bile duct with the action of cholecystokinin hormone.  ▶Enterogastrin hormone stops gastric secretion when food leaves  the stomach. In this way, stomach activity decreases, and the  stomach is protected from self-digestion. It functions as the opposite  MOUTH The upper half of the gastrointestinal tract (mouth, esophagus and stomach) plays the lowest role in nutrient absorption. They participate in the transport and preparation of nutrients to be absorbed in the small intestine. This preparation involves mechanically breaking down nutrients into smaller pieces to increase the surface area. The mouth is the part where food enters the body. The mouth contains teeth, tongue and salivary glands.  Tooth: Helps in cutting, shredding, dril ing and grinding food and crushing. Tongue: Tongue, which is a powerful muscle, detects the good and bad taste of food, while it enables the food to mix with saliva and break down by the teeth. It helps to deliver moist and chewed food to the pharynx to aid in swal owing In addition, the tongue contains taste buds.  Salivary glands: There are 3 pairs of large salivary glands in the mouth. Parotid: in front of and below the ear Submandibular; below the lower end of the mandible Sublingual; at the floor of the mouth under the tongue These glandsinitiate chemical digestion in the mouth, They form saliva or saliva, All the glands discharge their contents into the oral cavity. In saliva, salts, proteins, antibodies tampons and digestive enzyme amylase are found. Amylase initiates carbohydrate digestion.  CHEWING It breaks the donut into small pieces, mixes it with saliva, softens it and makes it ready to swallow. Chewing is provided by the coordination of many muscles by the chewing center in the central nervous system.  ESOPHAGUS The swallowing process is a coordinated process involving many structures. Swallowing is initiated largely voluntarily but once started it becomes involuntary. The esophagus carries food from the pharynx to the stomach. It also produces digestive secretion called mucus. The sphincter located at the upper end of the esophagus prevents air passage. The sphincter located at the lower end of the esophagus prevents the passage of stomach contents into the esophagus. The larynx is the respiratory tract. The tongue grabs the food and pushes it into the throat. A special structure in the throat allows the larynx to close during the swallowing process. ANAL SFİNKTERLER  SWALLOWING Sending food to the stomach is an active event. It takes 5-10 seconds for the bite to reach the stomach. During the swal owing process, the mouth closes and the tongue pushes the bite towards the soft palate, while the soft palate is pul ed up and back, thus preventing the bite from escaping into the nasal cavity. During swal owing, breathing is stopped, and it slides over the epiglottis to close the glottis airway. (Epiglottis is located on the upper floor of the glottis opening.) As swallowing begins, the glottis moves up and down the epiglottis. The bite is delivered to the stomach by peristaltic movements. The swallowing center in the brain stem receives sensory impulses from the palate, pharynx, and esophagus. Since the upper third of the pharynx and esophagus are made of striated muscle, it is stimulated by the fibers of the somatic nervous system. The lower two-thirds of the esophagus is made of smooth muscle.  SWALLOWING The pharynx provides respiration as well as swallowing. For a few seconds during the swallowing process, the pharynx acts as the pathway through which food passes. Cessation of breathing due to swallowing is especially important. Swallowing takes place in 3 stages ***; 1. Voluntary stage; It initiates the swallowing process. 2. Pharynx stage; It develops involuntarily and the nutrient is transferred from the pharynx to the esophagus. provides the passage. 3. Esophageal stage; It is an involuntary phase. It carries out the transport of nutrients from the pharynx to the stomach.  SWALLOWING 1. Voluntary stage; It takes 5-10 seconds for the bite to reach the stomach. During the swallowing process, the mouth closes and the tongue bite voluntarily pushes towards the soft palate, while the soft palate goes up and With the backward pressure, it compresses the food between the tongue and the palate and pushes it backwards to the pharynx. After that, swallowing has become automatic and usually cannot be stopped.  SWALLOWING 2. Pharynx stage; When food is pushed into the pharynx, it stimulates the swallowing receptor sites on the tonsils. These impulses travel to the brainstem, causing a series of automatic muscle contractions to begin. The soft palate is pulled upward to cover theposterior end of the nostrils, thus preventing food from entering the nasal cavities. The pharynx becomes a curved structure and forms a slit through which food can pass into the posterior pharynx. This slit acts selectively, allowing sufficient chewed food to pass easily, while preventing the passage of large items. Since this phase is completed in less than 1 second, any major The passage of a substance from the pharynx tothe esophagus is prevented.  SWALLOWING 3. The larynx is pulled up and forward (through the neck muscles). By closing the epiglottis larynx opening /top, the food prevents it from passing. 4. The upward movement of the larynx also pulls up the initial part of the esophagus and expands it. 5. With the relaxation of the part called the sphincter, food easily passes from the posterior pharynx to the upper esophagus. 6. This sphincter prevents air from going to the esophagus during breathing between swallows. If we summarize the pharynx stage of swallowing: The trachea closes. The esophagus opens. Peristaltic movement originating from the pharynx forces the bite to pass into the upper esophagus. All these processes take less than 2 seconds.  SWALLOWING 3. Esophageal stage; The main task of the esophagus is to deliver food from the pharynx to the stomach. There are 2 types of peristaltic movements; 1. primary peristalsis and 2. secondary peristalsis Primary peristalsis; it is simply the continuation of the peristaltic wave that starts in the pharynx and spreads to the esophagus. This wave passes al the way from the pharynx to the stomach in 8-10 seconds. If the primary peristaltic wave cannot send al the food entering the esophagus to the stomach, secondary peristaltic waves develop and these waves continue until al the food is emptied into the stomach.  One-third of the pharynx and esophagus has striated muscle structure. The muscle structure of the2/3 lower part of the esophagus is a smooth muscle.  COMPENSATORY RELAXATION OF THE STOMACH Relaxation of the lower esophageal sphincter allows the bite to pass into the stomach. Auerbach's plexus is congenital in the disease called achalasia Since the lower esophageal sphincter cannot relax, these patients have difficulty in swallowing. The lower esophageal sphincter helps prevent stomach contents from leaking into the esophagus (reflux). Another mechanism that prevents refluxis the esophagus to the stomach. It is a cap-like mechanism located just below the diaphragm before it reaches. Otherwise, stomach acid would pass into the esophagus every time we walk, cough or breathe deeply.  STOMACH 1.Storing large amounts of nutrients in the duodenum until they can be processed, 2. Mixing these foods with gastric secretions until they become semi- liquid called chyme, 3. It is the slow discharge of food from the stomach to the small intestine in order to provide sufficient time for digestion and absorption in the small intestine.  STOMACH The stomach is the organ where food is stored, mixed and digested. Foods are stored in the stomach (1-1.5 liters) until ready to be given to the small intestine and the stomach can expand to 4 liters when necessary. The digestive juices of the stomach are secreted by the stomach glands. These secretions immediately meet the stored food. If there is food in the stomach, weak peristaltic constricting waves start from the body part of the stomach towards the antrum every 15-20 seconds. And it becomes severe. When it intensifies, it creates powerful peristaltic constricting waves that force the content to advance towards the pylorus. These waves confuse the stomach contents.  STOMACH Most of the contents of the antrum are sprayed back into the body of the stomach. Since the opening of the pylorus is small (pieces larger than 7 mm) milliliter of antrum content passes into the duodenum. CHYMUS: It is the form that food passes into the intestine after mixing with gastric secretion (semi- liquid, semi- creamy).  STOMACH Inaddition to peristaltic contractions, there is another type of contraction called hunger contractions. They occur when the stomach has been empty for a few hours or more. Hunger spasms are much stronger in young and healthy people. When blood sugar drops, it also increases.  EMPTYING THE STOMACH Opening at the lower end of the stomach is pylorus. Gastric emptying occurs when the pyloric sphincter relaxes. It pushes some into the duodenum. Although the pyloric sphincter contracts, it often opens enough to allow water and other fluids to be easily discharged from the stomach. The contraction prevents the passage of nutrient particles until they mix into the chyme and become almost liquid. The degree of pyloric contraction can be increased or decreased by the effect of neural signals from both the stomach and duodenum.  REGULATION OF STOMACH EMPTYING The speed of gastric emptying is mostly caused by the signals in the duodenum. * It is desirable that the rate of discharge of chymus into the duodenum not greater than the rate of digestion and absorption in the small intestine. A hormone called Gastrin is secreted from the stomach. Gastrin causes the secretion of highly acidic gastric fluid from the stomach glands. It has the effect of increasing the activity of the pylorus pump. It stimulates gastric emptying.  In the Control of the Emptying of the Stomach; 1.The degree of filling of the stomach, 2.It is controlled by the stimulating effect of gastrin. The most important control comes from the duodenum; 1.When there is too much chyme in the small intestine, 2.When chymus is very acidic, contains too muchunprocessed protein or fat, it slows ejaculation.  STOMACH Gastric emptying occurs when the pyloric sphincter relaxes. Pieces larger than 7 mm cannot pass through the pylorus. Gastric emptying is adjusted according to the capacity of the small intestine to digest and absorb food. While the passage of food containing excess fat from the stomach to the small intestine is slower, it is easily digested. Light food consisting of carbohydrates passes to the small intestine faster and becomes more difficult to digest.  STOMACH FLUID The stomach secretes about 1.5 liters of fluid daily. These liquids are, Hydrochloric acid (HCl) Mucus, Pepsinogen (the precursor of the pepsin enzyme), Intirinsic factor, Lipase (small amount) Tears or damage to the mucus layer can lead to stomach ulcers.  HCl is required for the activation of pepsinogen (pepsin). *** Pepsins are neutral pH inactivated. Pepsinogen provides protein digestion. intrinsic factor provides the absorption of B12 from the ileum. Mucous protects the mucosa from the effects of HCl.  STOMACH LIQUID The secretion of gastric juice is controlled in 3 stages; 1.Cephalic phase; The sight, smell or taste of food initiates its secretion. 2.Gastric (stomach) phase; Secretion in response to stomach filling with food 3.Intestinal phase; It is an inhibitory component that prevents excessive gastric fluid secretion. It starts with the passage of food into the small intestine.  SMALLINTESTINE After the chymus stays in the stomach for 1-3 hours, it enters the sma l intestine. Sma l bowel movements can also be divided into two as confounding and progressive contractions. Chymus is prope led by peristaltic waves through the sma l intestine. These waves can occur in every part of the sma l intestine. They are weak waves. Chymus’s movement is also very slow. Peristaltic activity of the sma l intestine increases greatly after eating. In addition to the neural impulses that af ect the peristalsis of the sma l intestine, many hormonal factors also play a role. Gastrin, insulin, serotonin... They increase intestinal motility. Secretin, glucagon... suppresses fine intestinal motility.  SMALLINTESTINE Although peristalsis in the small intestine is normally very weak, irritation of the intestinal mucosa causes strong and rapid peristalsis as in severe cases of diarrhea due to infection. Strong peristaltic contractions travel a long way through the small intestine within minutes, draining the contents of the small intestine into the colon, thereby relieving the small intestine from irritating chyme or excessive strain.  SECTIONS OF THE SMALL INTESTINE  Duodenum: It is the C -shaped starting part of the small intestine, Approximately 25 cm long, The remaining part of digestion is completed by mixing enzymes from the pancreas and gall bladder with chyme.  Jejenum: It is about 1 meter long. It contains many folds (plica) and villi. It has digestive and absorption functions.  Ileum: It is about 2 meters Most of the absorption occurs.  The primary task of the ileocecal valve is to prevent the backflow of contents from the colon into the small intestine. Just in front of the ileocecal valve is a muscle sheath called the ileocecal sphincter. Apart from increasing peristalsis immediately after a meal, normally there is a slight contraction and the contents of the ileum It provides slow discharge into the cecum. Resistance to discharge in the ileocecal valve chymus ileum It prolongs the residence time in it and thus facilitates absorption. The degree of contraction of the ileocecal sphincter is also controlled by reflexes originating from the cecum. THE FUNCTIONS OF SMALL INTESTINE The main task of the small intestine is digestion and absorption. Digestion and absorption occurs through the action of smooth muscles in the intestinal wall and the chemical action of enzymes. Some of the enzymes are secreted from the pancreas.  VILLI-MICROVILLI The protrusions in the small intestines are called villi. These increase the absorption surface. Villi also have additional protrusions called microvilli.  Mucosal and submucosal glands in the intestinalwall secrete intestinal secretions and enzymes. With this secretion and enzyme, protein and fats help carbohydrate digestion. In Intestinal secretion (fluid); Salt, Mucus, small intestinal enzymes, and small intestine hormones are found.  Enterokinases: The pancreatic enzyme converts trypsinogen into its active state, trypsin. Trypsinogen Enzyme: It is secreted passively by the pancreas as it digests proteins. Enzyme activation is provided by the enterokinase enzyme secreted by the sma l intestine – Trypsinogen (passive) === enterokinase enzyme ===> Trypsin (active). Disaccharides: Sucrase, maltase and lactase (carbohydrate digestion is complete) Aminopeptidases: They help protein digestion. HORMONES OF SMALL INTESTINE Secretin: increases pancreatic and liver secretions. It stimulates pancreatic and hepatic secretion and inhibits gastric acid secretion. Cholecystokinin: stimulates the production and release of pancreatic enzymes, bile secretion from the gallbladder. ABSORPTION Carbohydrate, proteinand lipid, electrolytes, vitamins and aquatic products are absorbed by the smal intestine. Carbohydrates are easily absorbed as monosaccharide (glucose). After proteins are broken down into structural amino acids, they are absorbed. The absorption of lipids is a little different and difficult. Lipids arrive in the smal intestine as large droplets of triglyceride insoluble in water. Pancreatic lipase + Bile secretion Triglycerides are packaged in droplets cal ed chylomicrons in the intestinal cel and delivered to the lymph and blood circulation. ABOUT 5-10 LITERS OF WATER EACH DAY ENTER THE SMALL INTESTINE AND REABSORB IT. MOST OF THIS WATER COMES FROM THE DUODENUM.  LARGE INTESTINE When the chyme leaves the small intestine, digestion is complete, and the chyme enters the large intestine. The large intestine allows the absorption of water and salts from the liquid chyme.  THE PARTS OF LARGE INTESTINE Cecum Ascending colon Transverse colon Descending colon Sigmoid colon Rectum 1. Anal canal 2.Anus  THEFUNCTIONSOFLARGEINTESTINE Absorbation; Some of the remaining water, salts and vitamins are absorbed from the large intestine. Bacterial activity: Thereare beneficial Bacteria involved in the synthesis of Vit K12 and B12 in the large intestine. These live or dead bacteria constitute 20-25% of the weight of dry faeces. These bacteria also generate intestinal gases. Fecal formation; The final product of the digestive system is feces. Approximately 150 g of faeces are excreted from the body per day (100 g of water is 50 g of solid matter) In addition to water and bacteria, faeces contain oil, nitrogen, bile pigments, and indigestible foods.  PANCREAS *, GALLBLADDER * AND LIVER* They act as auxiliary organs for the intestines by providing specialized secretions for the digestion of carbohydrates, proteins and lipids in the pancreas, gal bladder and liver and smal intestine. Digestive enzymes secreted from pancreas are; Pancreatic lipase, Pancreatic amylase, Pancreatic proteolytic enzymes (trypsinogen, chymotrypsinogen, procarboxypeptidase)  LIVER* The liver is the largest secreting organ in the body. It consists of hepatic cells. To the liver; hepatic artery and hepatic portal vein enter, hepatic vein and bile duct exit. The hepatic artery carries oxygenated blood and brings 20% of the blood to the liver, The hepatic portal vein carries venous blood from the gastrointestinal system to the liver, bringing 80% of the blood coming to the liver. There are nutrients absorbed from the intestines. The hepatic vein carries blood from the liver to the inferior vena cava. The bile ducts, on the other hand, carry the bile synthesized in the liver to the small intestine by combining with the channel coming from the gall bladder.  THEFUNCTIONSOFLIVER Making the nutrients we take available to the body, To send beneficial molecules from the digestive system to other cells through the blood, To send useless molecules to the kidneys (The useless molecules sent to the kidneys leave our body as urea by filtering with the help of kidneys. To regulate fat, protein and sugar metabolism, Adjusting the body's temperature, Making water and vitamins that the body needs, etc. THE FUNCTIONSOF LIVER Metabolic regulation; Detection and adjustment of amino acid, carbohydrate and lipid levels from the portal vein. Converting excess amino acids to urea, Storage of vitamins and minerals, Metabolization of drugs, poisons and chemicals (detoxification), Storage of carbohydrates, vitamins, fats, amino acids, Bile synthesis and secretion  GALL BLADDER The gall bladder stores and concentrates the bile coming from the liver until it is needed for digestion. Contraction of the gallbladder drains bile in the bladder. Bile is essential for fat digestion. Thank you