Pharmacy Lecture (GIT Physiology) PDF

GIT Physiology Dr. M. Abdelmohsen Assistant Professor of Physiology MBBCh, MSc, DMSc, DHPE Faculty of Pharmacy 2024-2025  Objectives ❖ At the end of this lecture, the 2nd year student sho...

GIT Physiology Dr. M. Abdelmohsen Assistant Professor of Physiology MBBCh, MSc, DMSc, DHPE Faculty of Pharmacy 2024-2025  Objectives ❖ At the end of this lecture, the 2nd year student should be able to: Discuss the functions of the liver. Describe the functions of gall bladder & pancreas. Explain the pathophysiology & types of peptic ulcer.  Digestive System "GIT“ ❑ Functions of the mouth: 1. Ingestion: receive food. 2. Prepare food for digestion. 3. Begin the digestion of starch. ❑ Function of saliva: 1. Saliva moistens the food and facilitates the processes of chewing, or mastication, and swallowing, or deglutition. 2. Helps keep the teeth and mouth clean and reduce bacterial growth. 3. Converting starch to sugar by its salivary amylase enzyme.  Digestive System "GIT“ ❑ Functions of the stomach: 1) Grinding food and mixing it with digestive juices. 2) Serving as a storage pouch and digestive organ. 3) Gastric juice contains hydrochloric acid (HCL) which softens the connective tissue in meat and destroys foreign organisms and pepsin enzyme which digests protein and activated by HCL. 4) Push the semi-liquid mixture of gastric juice and food (chyme) to the small intestine through the pylorus. ❑ Functions of small intestine: 1) Secreted Large amounts of mucus protect the small intestine from the strongly acid chyme entering from the stomach. 2) Secreted enzymes digest proteins and carbohydrates. 3) Secreted liver and pancreas juices complete most of the digestive process. 4) Most absorption of digested food: (millions of villi and smaller microvilli to increase the surface area for absorption of nutrients). ❑ Functions of large intestine: 1) Elimination of any undigested material 2) Reabsorption of most of the water secreted to prevent dehydration. 3) Ileocecal valve prevents food from traveling backward into the small intestine. 4) Rectum serves as a temporary storage area for indigestible or unabsorbable food residue (feces). 5) Bacteria that normally live in the colon act on it to produce vitamins K and B. Unfortunately, systemic antibiotic therapy may destroy these bacteria. ❑ Functions of the liver: 1) Storage of glucose in the form of glycogen (glycogenesis). 2) Conversion of glycogen to glucose when needed (glycogenolysis). 3) Formation of plasma proteins: albumin, globulins, and clotting factors. 4) Synthesis of urea, a waste product of protein metabolism. 5) Modification of fats, to be used more efficiently by body cells. 6) Manufacture of bile: bile salts act like a detergent to emulsify fat for digestion and aids in fat absorption from the small intestine. 7) Destruction of old RBCs. 8) Detoxification (removal of the poisons) of harmful substances. 9) Storage of some vitamins and iron. ❑ Functions of gall bladder: 1) Storage pouch for bile. 2) The gallbladder contracts, squeezing bile through the cystic duct then into the common bile duct to the duodenum when chyme enters it. ❑ Functions of the pancreas: 1) Its enzymes digest fats, proteins, carbohydrates, and nucleic acids. 2) Its secreted alkaline fluid neutralizes the chyme for protection 3) Endocrine gland, producing hormones e.g., insulin and glucagon that regulate sugar metabolism.  Mechanisms of absorption 1) Salts (sodium salts): actively transported through the intestinal mucosa. 2) Water follows by osmosis. 3) Glucose: facilitated diffusion and sodium glucose co- transport. 4) Amino acids: Facilitated diffusion. 5) Fats: enter the lymphatic vessels or lacteals found in intestinal villi by means of chylomicrons (lipoprotein- transport vehicles). This process needs presence of bile salts.  Digestive Juice Enzyme Digested Substance Resulting Products Saliva Amylase Starch (Polysaccharide) Maltose (disaccharide) Gastric Juice Pepsin + HCL Proteins Partially digested proteins Pancreatic Juice Trypsin Proteins Peptides (Partially digested) Lipase Fats emulsified by bile Fatty acids, and glycerol Amylase Starch Maltose Intestinal Juice Peptidases Peptides Amino acids Sucrase Sucrose (Cane sugar) Glucose and fructose Lactase Lactase (Milk sugar) Glucose and galactose Maltase Maltase (Malt sugar) Glucose ❖ Peptic ulcer: ▪ It is categorized into 2: gastric and duodenal peptic ulcer diseases (PUD). ▪ Duodenal ulcers are 5 - 10 times more common than gastric ulcer. ▪ Gastric ulcers affect the old age group with peak incidence in the 50 – 60 years. ▪ Both types of ulcer affect men 3 - 4 times compared to women. ▪ Peptic ulcers can occur in any area of GI tract exposed to acid-pepsin secretions. Predisposing factors: 1) Increased level of acid and pepsin production by neural stimulation (stress ulcer). 2) Failure of mucosal barrier to resist the destructive action of enzymes & acids. ❖ Peptic ulcer: ❑ Conditions affect mucosal barrier integrity: 1) Diseased mucosal membrane is unable to secrete sufficient mucus. 2) Reflux of bile from intestine to stomach. 3) Drugs are recognized as a “barrier- breaker” e.g., aspirin and alcohol. 4) Anxiety and stress inhibit the glands (Brunner’s gland) that produce mucus. 5) Helicobacter pylori inhibits the mucus secreting epithelial cells of stomach and duodenum and digest the protective mucus secreting membranes. ❑ Clinical Manifestations and complications of PUD: 1) Uncomplicated PUD: discomfort and pain in the epigastrium. 2) Complicated PUD: a) Hemorrhage: GI-bleeding e.g., Hematemesis b) Obstruction: vomiting of undigested food. c) Perforation: peritonitis or perforated pancreas. ❑ Treatment: 1) Proton pump inhibitors (PPIs) e.g., Omeprazole: 4-8 weeks : reducing acid & preventing damage 2) Treatment of helicobacter pylori: PPIs, amoxicillin, and clarithromycin twice daily. 3) Prophylactic: To reduce your risk of developing a peptic ulcer: a) Avoid tobacco products. b) Avoid alcohol. c) Decrease aspirin and/or NSAIDs. d) Consuming foods that have been cooked thoroughly.  Thank You Faculty of Pharmacy 2024-2025