Gastrointestinal Tract (PDF)

GASTROINTESTINAL TRACT Diah Ayu Aguspa Dita, S.Kep., Ns., M.Biomed Department of Medical Physiology Faculty of Medicine and Sciences Universitas Bengkulu LEARNING OBJECTIVES After this class, Students should be: Describe about general principles of the alimentary tract – motility, secretion, digestion, absorption, and nervous control Describe about physiology of the alimentary tract – mouth, pharynx and esophagus, stomach, pancreatic and biliary secretions, small intestine, large intestine, Anus OVERVIEW Every cell of the living system needs energy Unicellular organisms: Exists in the sea of nutrients Can satisfy their nutritional need just by Proteins present at the cell membrane MULTICELLULAR ORGANISMS Groups of cells converted to a tissue, to perform specific function Several systems have evolved in vertebrates including humans To provide nutrients to all the systems, The Gastrointestinal tract is accounted for the extraction of nutrients from the food THE FOODS Most of the food we eat are macromolecules, it can not cross the cell membrane easily So, it must be converted to monomers The Gastrointestinal tract makes the food absorbable form by the help of chewing and mixing with various enzymes in the mouth to the small intestine Macromolecules :Food THE FOODS digestive enzymes monomers in small intestine Absorption into blood circulation Think about it! WHAT DOES THE DIGESTIVE SYSTEM DO? First 2 functions you think of What happens when you first smell ayam penyet sambal matah? What does your stomach do? How long is the intestine? Does your GI tract move; or make noise? Does your nervous system control the GI tract? Why do you eat food? GASTROINTESTINAL TRACT Motility Secretion Digestion Absorption Elimination Upper esophageal sphincter STRUCTURE OF GI TRACT Delay of 3 seconds Lower esophageal sphincter Upper gastrointestinal tract Lower gastrointestinal tract Upper esophageal sphincter STRUCTURE OF GI TRACT Lower esophageal sphincter Think about it! STRUCTURE OF GI TRACT Which structures of the GI system are retroperitoneal? Most of the pancreas (except tail) Most of the duodenum (except first segment) Ascending & Descending Colon LAYERS OF GI TRACT LAYERS OF GI TRACT Contraction of longitudinal Secretes a serous fluid à fibers along the length of the Lubricates and prevents tube à shortens the tube friction between the digestive organs and the Contraction of inner circular surrounding viscera fibers decreases the diameter of the lumen à constricting the Provides the digestive tube at the point of contraction tract with its distensibility and Exocrine gland cells à secretion of elasticity digestive juices Endocrine gland cells à secretion of blood-borne GI hormones Houses the gut- associated Epithelial cells specialized for lymphoid tissue (GALT) à absorbing digested nutrients important in defense against disease-causing intestinal bacteria LAYERS OF GI TRACT The individual smooth muscle fibers: 200 - 500 micrometers in length 2 - 10 micrometers in diameter Smooth muscles are arranged in bundles of as many as 1000 parallel fibers The muscle fibers are electrically connected with one another through large numbers of gap junctions Allow low-resistance movement of ions from one muscle cell to the next LAYERS OF GI TRACT Each muscle layer functions as a syncytium When an action potential is elicited anywhere within the muscle mass à it travels in all directions in the muscle The distance that it travels depends on the excitability of the muscle Sometimes it stops after only a few millimeters At other times it travels many centimeters or even the entire length and breadth of the intestinal tract REGULATION OF GI TRACT Neural control Enteric nervous system Autonomic nervous system Hormonal control INTEGRATION OF NEURONAL CONTROL OF GI FUNCTION INTEGRATION OF NEURONAL CONTROL OF GI FUNCTION INTEGRATION OF NEURONAL CONTROL OF GI FUNCTION The enteric nervous system coordinates digestion, secretion, and motility to optimize nutrient absorption. Its activity is modified by information from the CNS and from local chemical and mechanical sensors. ENTERIC/ INTRINSIC NERVOUS SYSTEM Primarily controls motility (length, Controls secretion, intensity, frequency, absorption, velocity of submucosal motility, peristaltic waves) and blood flow Decreases tension of sphincters Neural control of the gut wall, ENTERIC/ INTRINSIC NERVOUS SYSTEM showing the following: the myenteric and submucosal plexuses (black fibers); Controls mainly the extrinsic control of these gastrointestinal plexuses by the sympathetic movements and parasympathetic nervous Elicit local systems (red fibers); reflexes sensory fibers passing from within the the luminal epithelium and gut wall gut wall to the enteric plexuses, then to the prevertebral ganglia of the Controls mainly spinal cord and directly to the gastrointestinal spinal cord and brain stem secretion and (green fibers). local blood flow TYPES OF NEUROTRANSMITTERS SECRETED BY ENTERIC NEURONS 1. Acetylcholine 8. Vasoactive intestinal 2. Norepinephrine polypeptide 3. Adenosine triphosphate 9. Somatostatin 4. Serotonin 10. Leu-enkephalin 5. Dopamine 11. Met-enkephalin 6. Cholecystokinin 12. Bombesin 7. Substance P 13. Neuropeptide Y 14. Nitric oxide GASTROINTESTINAL REFLEXES HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY INCRETINS GIP GLP-1 an “anticipatory” increase in blood insulin in preparation for the glucose and amino acids to be absorbed from the meal Glucagon- Mixed meal Endocrine pancreas Stimulates Like that includes insulin release Peptide-1 carbohydrates (GLP-1) Inhibits or fats in the glucagon release lumen gastric function HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY HORMONAL CONTROL OF GASTROINTESTINAL MOTILITY PARACRINES Secreted into the interstitial fluid diffuse to adjacent cells The site of secretion must be only a short distance from the site of action. Somatostatin Histamine MOUTH MOUTH Functions: Mechanical and chemical digestion of the food Mechanical à Mastication (chewing, cutting and grinding with teeth), mixing with tongue Chemical à secretions some juices The source of the unconditioned reflexes E.g Salivation Control of physical and chemical properties of the food SALIVARY GLANDS The principal glands of salivation are: The parotid glands à 25% secretions of juices The submandibular glands à 70% secretions of juices The sublingual glands à 5% secretions of juices The buccal glands Daily secretion of saliva normally ranges between 800 and 1500 ml Ph between 6.0 and 7.0 COMPOSITION OF SALIVA Saliva contains two major types of protein secretion: Serous secretion Contains ptyalin (an α-amylase) An enzyme for digesting starches Mucus secretion Contains mucin Lubricating and for surface protective purposes COMPOSITION OF SALIVA Saliva contains especially large quantities of K+ and HCO3- Under resting conditions The concentrations of Na+ and Cl− are only about 15 mEq/L The concentration of K+ concentration is about 30 mEq/L Theconcentration of HCO3− concentration is 50 to 70 mEq/L During maximal salivation The formation rate of primary secretion by the acini can increase as much as 20-fold FUNCTIONS OF SALIVA Moistens, cleans, and protects enamel Lubricant aiding in speech, chewing, and swallowing (mucins) Dissolves food à allows for taste Acts as a bonding agent to form bolus Alkaline secretions neutralize regurgitated gastric acid Enzymes (amylase & lipase) begin digestion Immunological: Lysozyme, IgA, and lactoferrin NERVOUS REGULATION OF SALIVARY SECRETION NERVOUS REGULATION OF SALIVARY SECRETION NERVOUS REGULATION OF SALIVARY SECRETION SYMPATHETIC STIMULATION The saliva formed is thicker compared to saliva produced during increased parasympathetic activity The sympathetic nerves originate from the superior cervical ganglia DEFFICIENT SALIVATION XEROSTOMIA?? WHAT? WHY? HOW? DEFFICIENT SALIVATION XEROSTOMIA Xerostomia (salivary flow< 0.2 ml/min) The presence of saliva is vital to the maintenance of healthy hard (teeth) and soft (mucosa) oral tissues. Severe reduction of salivary output results in a rapid deterioration in oral health Patients suffering from dry mouth can experience difficulty with eating, swallowing, speech, the wearing of dentures, trauma to and ulceration of the oral mucosa, taste alteration, poor oral hygiene, a burning sensation of the mucosa, oral infections including Candida and rapidly progressing dental caries After radio therapy, old age and multidrug therapy DEFFICIENT SALIVATION XEROSTOMIA Xerostomia (salivary flow< 0.2 ml/min) The presence of saliva is vital to the maintenance of healthy hard (teeth) and soft (mucosa) oral tissues. Severe reduction of salivary output results in a rapid deterioration in oral health Patients suffering from dry mouth can experience difficulty with eating, swallowing, speech, the wearing of dentures, trauma to and ulceration of the oral mucosa, taste alteration, poor oral hygiene, a burning sensation of the mucosa, oral infections including Candida and rapidly progressing dental caries After radio therapy, old age and multidrug therapy PHARYNX AND ESOPHAGUS PHARYNX AND ESOPHAGUS Swallowing is a complicated mechanism, principally because the pharynx subserves respiration as well as swallowing Swallowing (deglutition) can be divided into the following stages: a voluntary stage initiates the swallowing process When the food is ready for swallowing, it is voluntarily pushed into the pharynx by the tongue. a pharyngeal stage (1 s) involuntary and constitutes passage of food through the pharynx into the esophagus an esophageal stage (6-9 sà food, 2-5 s à fluid) involuntary phase that transports food from the pharynx to the stomach Prevents food from entering the nasal cavity Keeps food from moving into the trachea PHARYNX AND ESOPHAGUS PHARYNX AND ESOPHAGUS Transport food from the pharynx to the stomach by gravity and by peristalsis PHARYNX AND ESOPHAGUS Control of pharyngeal stage à swallowing reflex Reflex initiated when pressure receptors in the walls of the pharynx are stimulated by food or drink forced into the rear of the mouth by the tongue Swallowing center In the medulla and lower pons Afferent nerves à N.V, N.VII, N.IX, N.X Coordination of swallowing with respiration PHARYNX AND ESOPHAGUS The esophagus exhibits two types of peristaltic movements: Primary peristalsis Continuation of the peristaltic wave that begins in the pharynx and spreads into the esophagus during the pharyngeal stage of swallowing Secondary peristalsis Result from distention of the esophagus by the retained food Regulation of esophageal stage initiated by: intrinsic neural circuits in the myenteric nervous system à myenteric and submucosal plexus reflexes à Vagal afferent fibers to the medulla and back again to the esophagus through glossopharyngeal and vagal efferent nerve fibers PHARYNX AND ESOPHAGUS Function of esophageal sphincter: Pharyngoesophageal sphincter (upper) relaxes upon swallowing à high resting tonus Gastroesophageal sphincter (lower) tonically constricted à Circular muscle REGULATION OF ESOPHAGUS The same abdominal pressures as the stomach Prevents the formation of a pressure gradient between the stomach and esophagus that could force the stomach’s contents into the esophagus Multiple mechanisms, including neural and hormonal, regulate gastroesophageal sphincter pressure The musculature of the gastroesophageal sphincter has a tonic pressure It is normally higher than the intragastric pressure (the pressure within the stomach). This high tonic pressure at the gastroesophageal sphincter keeps the sphincter closed. Keeping this sphincter closed is important It prevents gastroesophageal reflux: the movement of substances from the stomach back into the esophagus. DISORDERS OF THE SWALLOWING Dysphagia Achalasia WHAT? WHY? HOW STOMACH STOMACH The motor functions of the stomach: Storage of large quantities of food until the food can be processed in the stomach, duodenum, and lower intestinal tract Mixing of this food with gastric secretions until it forms a semifluid mixture à chyme Slow emptying of the chyme from the stomach into the small intestine at a rate suitable for proper digestion and absorption by the small intestine Gastric motility: Gastric filling Gastric storage Gastric mixing Gastric emptying GASTRIC FILLING When empty à volume of about 50 ml During a meal à volume of about 1 liter (1000 ml) Receptive relaxation Allows the stomach to accommodate the meal with little change in intragastric pressure A plasticity of the smooth muscle layers Nervous action à reduction of vagal tone Hormonal à gastrin GASTRIC STORAGE The basic electrical rhythm (BER) Rhythmic pattern of spontaneous depolarizations Occurs continuously May or may not be accompanied by contraction of the stomach’s circular smooth muscle layer It may be brought to threshold à action potentials à peristaltic waves The peristaltic contractions in the fundus and body are weak Muscle layers are thin The waves reach the antrum à stronger and more vigorous Muscle is thicker GASTRIC MIXING AND EMPTYING Tonic contraction FACTROS REGULATING GASTRIC MOTILITY AND EMPTYING GASTRIC SECRETION BASIC MECHANISM OF HYDROCHLORIC ACID SECRETION The parietal cells secrete an acid solution that contains about 160 mmol/L of hydrochloric acid à isotonic fluids The pH of HCl is about 0.8 à extreme acidity SECRETION AND ACTIVATION OF PEPSINOGEN Secreted by the chief cells Active formed à pepsin Pepsinogen molecule à molecular weight of about 42,500 Pepsin molecule à molecular weight of about 35,000 Pepsin functions as an active proteolytic enzyme in a highly acidic medium (optimum ph, 1.8–3.5) Hydrochloric acid is as necessary as pepsin for protein digestion in the stomach SECRETION OF INTRINSIC FACTOR Secreted by the parietal cells Essential for vitamin B12 absorption in the ileum SECRETION OF MUCUS AND GASTRIN Secreted by the pyloric glands Mucus cells secrete large amount of thin mucus Lubricate food movement Protect the stomach wall from digestion by the gastric enzymes The pyloric glands also secrete the hormone gastrin Role in controlling gastric secretion STIMULATION OF GASTRIC SECRETION Intestinal Stimuli in duodenum –protein Increase + Chief and Increase phase duodenal parietal cells gastric digestive product gastrin secretion INHIBITION OF GASTRIC SECRETION DIGESTION AND ABSORPTION WITHIN STOMACH Digestive processes Carbohydrates à corpus region Protein à antrum Absorptive processes Aspirin ethyl alcohol SMALL INTESTINE MOTILITY OF THE SMALL INTESTINE Mixing contractions (segmentation contractions) The maximum frequency of the segmentation contractions is determined by the basic electrical rhythm (BER) The rhythmical contraction and relaxation of the intestine Propulsive contractions à peristalsis Intestinal peristalsis is distention of the gut Net movement along the small intestine normally averages only 1 cm/min 3 to 5 hours are required for passage of chyme from the pylorus to the ileocecal valve REGULATION IN THE INTESTINAL MOTILITY Neural: Myenteric reflex mechanical stimulation of the duodenum – distention – serotonin Gastroenteric reflex – distention of the stomach – through myenteric plexus Parasympathetic à stimulate sympathetic pars à inhibit Humoral: Acetylcholine + Pilocarpin, physostigmine (inhibitors of cholinesterase) + serotonin + thyroxine + CO2 + SECRETION OF THE SMALL INTESTINE Intestinal epithelium secretes mineral ions such as sodium, chloride, and bicarbonate ions into the lumen and water followed by osmosis. Chloride is the primary ion that determines the magnitude of fluid secretion. Various hormonal, and paracrine signals as well as toxins and bacterial toxins can increase the frequency of these channels and fluid secretion. Water movement into the lumen occurs when the stomach is hypertonic, this then causes osmotic movement of water. SECRETION OF THE SMALL INTESTINE Secretion of mucus by brunner's glands in the duodenum Located in the wall of the first few centimeters of the duodenum Secrete large amounts of alkaline mucus, How? Tactile or irritating stimuli on the duodenal mucosa Vagal stimulation Causes increased brunner gland secretion concurrently with increase in stomach secretion Gastrointestinal hormones, especially secretin Functions: Protect the duodenal wall from digestion by the highly acidic gastric juice emptying from the stomach Neutralizing the hydrochloric acid entering the duodenum from the stomach SECRETION OF THE SMALL INTESTINE SecreEon of intesEnal digesEve juices by the crypts of lieberkühn The surfaces of both the crypts and the villi are covered by an epithelium composed of two types of cells: Goblet cells (moderate number) Secrete mucus à lubricates and protects the intesfnal surfaces Enterocytes in the crypts Secrete large quanffes of water and electrolytes Normally about 1800 ml/day alkaline pH in the range of 7.5 to 8.0 REGULATION OF SMALL INTESTINAL SECRETION Local stimuli Tactile, irritative, chemical (the presence of the chyme, hcl, saccharides...) Neural Parasympathetic à stimulate DIGESTION AND ABSORPTION IN SMALL INTESTINE CARBOHYDRATE DIGESTION DIGESTION AND ABSORPTION IN SMALL INTESTINE CARBOHYDRATE ABSORPTION DIGESTION AND ABSORPTION IN SMALL INTESTINE PROTEIN DIGESTION DIGESTION AND ABSORPTION IN SMALL INTESTINE PROTEIN ABSORPTION DIGESTION AND ABSORPTION IN SMALL INTESTINE FAT DIGESTION AND ABSORPTION DIGESTION AND ABSORPTION IN SMALL INTESTINE ZINC DIGESTION AND ABSORPTION DIGESTION AND ABSORPTION IN SMALL INTESTINE All fluid secreted by the small intestine is absorbed back into the blood. Large volumes of fluid which includes, salivary, gastric, hepatic, pancreatic secretions, and ingested water are simultaneously absorbed from the lumen into the blood. There is a large net absorption of water from the small intestine. Absorption is achieved by the transport of ions mostly sodium from the lumen into the blood with water followed by osmosis. LARGE INTESTINE MOTILITY OF THE LARGE INTESTINE Mixing movements (Haustrations) combined contractions of the circular and longitudinal strips of muscle cause the unstimulated portion of the large intestine reaches peak intensity in about 30 seconds and then disappears during the next 60 seconds During contraction, move slowly in the cecum and ascending colon Propulsive movements (Mass Movements) In cecum to the sigmoid occur only one to three times each day, for about 15 minutes during the first hour after eating breakfast Gastrocolon reflex SECRETIONS IN THE LARGE INTESTINE SecreEon of mucus by non–mucus-secrefng epithelial cells Contains moderate amounts of HCO3− The rate of mucus secrefon is regulated by Direct, tacfle sfmulafon of the epithelial cells lining the large intesfne Local nervous reﬂexes to the mucous cells in the crypts of lieberkühn Parasympathe>c innerva>on from pelvic nerves Funcfons: Protects the intesfnal wall from the great amount of bacterial acfvity that takes place inside the feces Provides a barrier to keep acids formed in the feces from aiacking the intesfnal wall ABSORPTION IN THE LARGE INTESTINE Formation of feces Absorption occurs in The proximal half of the colon (absorbing colon) The distal colon functions principally for feces storage until a propitious time for feces excretion (storage colon) Absorb water and electrolytes and water Abrsob maximum of 5 to 8 liters of fluid and electrolytes each day ABSORPTION IN THE LARGE INTESTINE Composition of the Feces normally are about: three-fourths water one-fourth solid matter, composed of about: 30% dead bacteria, 10% to 20% fat 10% to 20% inorganic matter 2% to 3% protein 30% undigested roughage from the food and dried constituents of digestive juices, such as bile pigment and sloughed epithelial cells. The brown color of feces is caused by stercobilin and urobilin. The odor is caused by products of bacterial action The actual odoriferous products include indole, skatole, mercaptans, and hydrogen sulfide DEFECATION REFLEX Peristaltic waves in the descending Intrinsic reflex mediated by the local colon, sigmoid, and rectum enteric nervous system in the rectal wall Stimulus: distention of the rectal forcing feces toward the anus wall inhibitory signals from the myenteric plexus the internal anal sphincter is relaxed if the external anal sphincter is also consciously, voluntarily relaxed at the same time defecation PANCREAS PANCREATIC ACID SECRETION Pancreatic acini cells Secrete the pancreatic digestive enzymes Carbohydrates digestion à pancreatic amylase Proteins digestion à trypsin, chymotrypsin, and carboxypolypeptidase Fat digestion à pancreatic lipase, cholesterol esterase, phospholipase Pancreatic duct cells Secrete sodium bicarbonate solution Role in neutralizing the acidity of the chyme emptied from the stomach into the duodenum REGULATION OF PANCREATIC SECRETION BILIARY SECRETIONS BILE SECRETION BY THE LIVER Bile secreted by the liver normally between 600 and 1000 ml/day Functions: fat digestion and absorption Emulsify large fat particles of the food into many minute particles, the surface of which can then be attacked by lipase enzymes secreted in pancreatic juice absorption of digested fat end products through the intestinal mucosal membrane excretion of several important waste products from the blood BILE SECRETION BY THE LIVER Normally stored in the gallbladder The maximum volume is only 30 to 60 ml FUNCTION OF BILE SALTS IN FAT DIGESTION AND ABSORPTION The precursor of the bile salts is cholesterol The cholesterol converted àcholic acid or chenodeoxycholic acid + glycineà glycoconjugated bile acids àcholic acid or chenodeoxycholic acid + gtaurine à tauro-conjugated bile acids The salts of these acids, mainly sodium salts FUNCTION OF BILE SALTS IN FAT DIGESTION AND ABSORPTION Fat digestion emulsifying or detergent function of bile salts FUNCTION OF BILE SALTS IN FAT DIGESTION AND ABSORPTION Fat absorption Forming micelles small physical complexes with lipids LIVER SECRETION AND GALL-BLADDER EMPTYING acetylcholine-secre=ng nerve ﬁbers iniVated by faWy foods ENTEROHEPATIC CIRCULATION OF BILE SALTS REGULATION OF FOOD INTAKE Motivation: “hunger“ à subjective feeling Centers: in HYPOTHALAMUS Lateral à feeding (hunger) center (FC) constantly active if stimulated à subject looks for the food à ↑ food intake inhibited by satiety center Ventromedial à satiety center (SC) when stimulated à stop eating Corpus mamillare à coordination of feeding reflexes REGULATION OF FOOD INTAKE Stimuli: Glucostatic cells → monitoring of glycemia (blood glucose) – if ↓ glycemia – FC is stimulated Afferentation from GIT- distention of organs à reflex activation of SC and depression of FC Ambient temperature à cold: enhances eating Blood temperature warm à ↓ food intake Metabolic condition of the body (exhaustion, long-term stress, adaptation) à enhances eating Limbic system (emotions) (+/-) Brain cortex – voluntary influences (+/-) Hormones CONTROL OF WATER BALANCE Control of water intake Mo/va/on à subjec/ve feeling of “thirst“ Center: lateral hypothalamus (next to ncl.paraventricularis) S/muli from: osmo0c receptors: directly in hypothalamus volumoreceptors: low-pressure baroreceptors in RA (type B) periphery: dry mucosa in oral cavity, increase level of angiotensin Control of renal water excre/on s/mula/on of osmo/c receptors and volumoreceptors informa/on into neurohypophysis à ADH- acts at distal tubules and collec/ng ducts → reabsorp/on of water Think about it! WHAT DOES THE DIGESTIVE SYSTEM DO? First 2 functions you think of What happens when you first smell fresh apple pie? What does your stomach do? How long is the intestine? Does your GI tract move; make noise? Does your nervous system control the GI tract? Why do you eat food? 97 WHAT HAPPENS WHEN YOU FIRST SMELL FRESH BREAD? The body gets ready for diges0on: Salivary glands release Serous and mucous ﬂuid Amylase – breaks down carbohydrates Lipase – lipid diges]on Stomach begins to churn (muscles) and acid & enzymes are released Pancreas and gall bladder ac0vate These are controlled by the CNS – the extrinsic nervous system. 98 WHAT HAPPENS WHEN YOU FIRST TASTE AYAM PENYET SAMBAL MATAH? (FOOD IN YOUR MOUTH) Salivary glands release Serous and mucous fluid Digestion begins Amylase – breaks down carbohydrates Lipase for lipid digestion Chewing (mastication) and mixing of food with tongue Stomach muscles contract, acid and enzymes released Pancreas and gall bladder secrete 99 WHAT HAPPENS WHEN YOU SWALLOW THE AYAM PENYET? Tongue helps move food bolus to the oropharynx (mouth) Skeletal muscles in the pharynx move food to esophagus Esophagus = a conduit to stomach muscles contract to allow peristalsis glands secrete to moisten food 100 WHAT HAPPENS TO THE AYAM PENYET IN THE STOMACH? Stomach funcdons: Storage of food Mixing via muscle contracfons Release of H+ & Cl- and pH lowers kills bacteria Degrades foods = chyme Cells release pepsinogen – a zymogen Pepsinogen converted to pepsin in low pH – cleaves proteins Digesfon confnues via Acid and pepsin Amylase, lipase 101 WHAT HAPPENS TO AYAM PENYET (CHYME) IN THE SMALL INTESTINE? Acidic fluids flow into the small intestine: Digestive enzymes and bicarbonate (HCO3-) added from pancreas Liver makes bile for lipid absorption Water added and reabsorbed Digestion accelerates and ph neutralized to ph ~ 7 Absorption of building blocks through enterocytes to the liver via the portal blood system Undigested material remains 102 WHAT HAPPENS TO CHYME IN THE LARGE INTESTINE? Dehydradon of indigesdble material Compacdon of indigesdble material Eliminadon of undigested material 103 REFERENCES Hall, JE and Michael JE. 2021. Guyton and Hall textbook of medical physiology, 14th ed.Elsevier: Philadelphia. Ganong WF. 2010. Review of Medical Physiology, 23th ed. McGraw-Hill Medical: New York. Sherwood L. 2016. Human physiology: from cell to system, 9th ed. Cengange learning: Boston. Silverthorn DU. 2016. Human physiology: an integrated approach, 7th Ed Global Ed. Pearson Education Limited: Harlow. THANK YOU

Gastrointestinal Tract (PDF)

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