Digestive system

Digestive system

1. D IGESTIVE SYSTEM By Mr. V inayak R. B odhankar M. Pharm. (QA) 1 20-06-2021

2. H UMAN DIGESTIVE SYSTEM Major organs Mouth Esophagus Stomach S mall intestine L arge intestine. Acessory organs : Liver Gall bladder Pancreas. The process of reducing food into smaller molecules that can be absorbed into the body . Digestive system consists of 2 major parts . 2 20-06-2021

3. pH: 7 The first part of the digestive system . T he entry point of food. Structures in the mouth that aids digestion Teeth – cut, tear, crush and grind food. Salivary glands – produce and secrete saliva into the oral cavity . S aliva M oistens the food . C ontains enzymes ( ptyalin or salivary amylase ) begins digestion of starch into smaller polysaccharides . Function: Mechanical digestion. I ncreasing surface area for faster chemical digestion. THE M OUTH 3 20-06-2021

4. THE E SOPHAGUS A tube connecting the mouth to the stomach R unning through the Thoracic cavity. Location: lies behind windpipe (Trachea). The trachea has as an epiglottis , preventing food from entering the windpipe, moving the food to the esophagus while swallowing. Food travels down the esophagus, through a series of involuntary rhythmic contractions (wave-like) called peristalsis . Function : The lining of the esophagus secretes mucus which lubricat e & support the movement of food. 4 20-06-2021

5. ESOPHAGEAL SPHINCTER: B olus reaches the stomach must pass through a muscular ringed valve called the esophageal sphincter (Cardiac Sphincter). Function: P revent stomach acids from back flowing into the esophagus. 5 20-06-2021

6. S T OMACH J-shaped muscular sac . Has inner folds ( rugae ) Increasing surface area of the stomach . Function: Stomach performs mechanical digestion HOW : By churning the bolus and mixing it with the gastric juices secreted by the lining of the stomach. GASTRIC JUICES HCl, salts, enzymes, water and mucus HCL helps break down of food and kills bacteria that came along with the food. The bolus is now called Chyme. 6 20-06-2021

7. ENZYMES IN STOMACH: Acidic environment HCl secretion K ill any microbes that are found in the bolus, C reating a pH of 2. Mucus prevents the stomach from digesting itself. Pepsin secretion R esponsible for initiating the breakdown of proteins ( in)food . H ydrolyzes proteins to yield polypeptides . 7 20-06-2021

8. PYLORIC SPHINCTER C hyme moves from the stomach to the small intestine. It passes through a muscular ringed sphincter called the pyloric sphincter. Why stomach does not digest itself ? First the stomach only secretes small amounts of gastric juices until food is present. Second the secretion of mucus coats that lining the stomach, protecting it from the gastric juices. The third mechanism is the digestive enzyme pepsin is secreted in an inactive protein called pepsinogen. Pepsinogen is converted to pepsin in the increased presence of hydrochloric acid (pH 1). 3 Protective Mechanism 8 20-06-2021

9. SMALL INTESTINE R esponsible for the complete digestion of all macromolecules and the absorption of their component molecules E.g . G lucose Glycerol fatty acids amino acids nucleotides The S mall intestine is made up of three parts D uodenum Jejunum ileum 9 20-06-2021

10. 1.DUOD E N U M The first part is the duodenum , u-shaped organ. approximately 30 cm in length. This area completes most of the digestion processes. Enzymes are secreted into the duodenum form the pancreas and the gall bladder. The duodenum is lined by folds of tissue called villi . The villi are covered by fine brush-like microvilli . These folds increase the surface area of the small intestine increase the rate of absorption. 10 20-06-2021

11. 2 . J E J U N UM The jejunum is approximately 2.5 m long. Although some digestion is completed here, it has more villi and microvilli; its role is absorption o f nutrients. 3 . Ileum The ileum , is approximately 3m long. H as fewer villi and microvilli than the other two parts. Although absorption also occurs here, it is responsible for pushing the waste materials into the large intestine. 11 20-06-2021

12. FUNCTIONS OF THE SMALL INTESTINE 90% of the digestion and absorption of food occurs . O ther 10% taking place in the stomach and large intestine. The main function of the small intestine is absorption of nutrients and minerals from food . DIGESTION OF PROTEINS Proteins , peptides and amino acids are acted upon by enzymes such as trypsin and chymotrypsin, secreted by the pancreas. This breaks them down to smaller peptides . DIGESTION OF LIPIDS Enzymes, like lipases secreted from the pancreas, act on fats and lipids in diet. lipase can break them into the smaller parts that can enter the intestinal villi for absorption. DIGESTION OF CARBOHYDRATES Carbohydrates are broken down to simple sugars and monosaccharides like glucose. Pancreatic amylase breaks down some carbohydrates to oligosaccharides as well. Some carbohydrates and fibers pass undigested to the large intestine where they may, depending on their type, be broken-down by intestinal bacteria. 12 20-06-2021

13. ABSORPTION IN THE SMALL INTESTINES T he nutrients are absorbed by the inner walls of the small intestine into the blood stream. The nutrients are absorbed by processes of simple/passive diffusion, facilitated diffusion , primary active transport, or secondary active transport 13 Other absorbed substances in the small intestines include : 1.Water 80% is absorbed by the small intestine 10% by the large intestine remaining 10% excreted in the faeces. 2.Electrolytes 3.Vitamins and minerals 20-06-2021

14. LARGE INTESTINE The large intestine is composed of several very distinctive parts: Cecum : Colon :. The colon consists of four parts: Ascending colon Transverse colon Descending colon Sigmoid colon Rectum 14 20-06-2021

15. C ECUM F irst section of your large intestine looks like a pouch, two inches long. ROLE T aking in digested liquid from the ileum(small intestine ) & passes it on to the colon. COLON M ajor section of the large intestine Function: T he principal place for water reabsorption, A bsorbs salts when needed. Components: The colon consists of 4 parts: Ascending colon Transverse colon Descending colon Sigmoid colon 15 20-06-2021

16. COMPONENTS OF COLON Ascending colon: 1st portion of the colon pushes any undigested debris up from the cecum just under the right lower end of the liver. Transverse colon : 2nd portion of the colon Food traveling from left to right just under your stomach. Descending colon: 3 rd portion of colon pushes its contents from down to the lower left side of your abdomen Sigmoid colon: final S-shaped length of the colon, empties into the rectum. 16 20-06-2021

17. R E C TUM The final section M easures from 1 to 1.6 inches (or 2.5 to 4 cm). Leftover waste collects there expanding the rectum , e mptied through anus . 17 20-06-2021

18. FUNCTION OF LARGE INTESTINE 1. Absorb Water One of the primary functions is to absorb water prepare the waste as a solid stool that will be expelled from the body. 2. Absorb Vitamin beneficial bacteria role in breaking down undigested sugars and fibers into fatty acids. produce many vitamins, of which are Vitamin K and Biotin that are absorbed back into the body. 3. Reduce Acidity The fatty acids cause acidic environment. The LI produces alkaline solutions . R educe the acidity and balance the pH in the LI . 4 . Protect from Infections The mucous lining of the large intestine acts as a protective layer , prevents harmful bacteria from being reabsorbed into the body . 18 20-06-2021

19. THE ACCESSORY ORGANS: S upport the digestive system BUT are not part of the digestive tract . These organs secrete fluids into the digestive tract, and are connect by ducts. The accessory organs include : liver gall bladder pancreas. 19 20-06-2021

20. 1.LI VER L argest of these organs mass of about 1.5 kg. liver produces bile B ile : greenish yellow pigment made up bile pigments and bile salts I t breaksdown old red blood cells. 20 20-06-2021

21. 2.GALL BLADDER A storage sac. The bile is secreted into it . The bile is stored here. HOW IT WORKS F ood containing fat enters the digestive tract . S alts are secreted into the small intestine to digest fats. The bile emulsifies fats in partly digested food , thereby assisting their absorption . 21 20-06-2021

22. 3.PANCREAS The pancreas secretes a number of different enzymes into the small intestine Role is to digest carbohydrates lipids & proteins completely. It also secretes bicarbonate ions . Role : N eutralize the HCl from the stomach change the pH of the small intestine to a pH of 8 . The pancreas will secrete about 1.0 L. of pancreatic fluids per day . 22 20-06-2021

23. Ingestion of food Secretion of fluids and digestive enzymes Mixing and movement of food and wastes through the body Digestion of food into smaller pieces Absorption of nutrients Excretion of wastes PRIMARY PROCESSES OF DIGESTIVE SYSTEM 23 20-06-2021

24. INGESTION Intake of food Responsible organ: M outh S tomach-storage of food to be digested SECRETION Digestive system secretes 7 liters of fluids/day . Saliva – moistens dry food and contains digestive amylase . Mucus – serves as protective barrier and lubricant inside GI tract . Hydrochloric acid – helps digest food chemically and protects body . Enzymes – disassemble large macromolecules like proteins, carbohydrates, and lipids into smaller components . Bile – used to emulsify large masses of lipids into tiny globules for easy digestion . 24 20-06-2021

25. MIXING AND MOVEMENT 3 main process to mix and move Swallowing Peristalsis Segmentation – occurs only in small intestine DIGESTION Is the process of turning large pieces of food into its chemical component. ABSORPTION Responsible organs: S tomach S mall intestine L arge intestine 25 20-06-2021

26. EXCRETION The final function of the digestive system is the excretion of waste in a process known as defecation. Defecation removes indigestible substances from the body so that they do not accumulate inside the gut. 26 20-06-2021

27. GI Disorders 27 Diarrhoea Presence of non-absorbable substances in the intestine Peptic ulcer An inflammatory disorder causing deep erosion of stomach or duodenal mecosa by HCl and Pepsin Ulcerative colitis A disease that causes inflammation and sores in the lining of the large intestine. Crohn’s disease A disease that causes inflammation in the small intestine, but it may affect any part of the GI tract Gastric Cancer Adenocarcinoma Colorectal cancer 20-06-2021