Transcript Digestive
Digestion Digestion Prepares food for cellular intake Nutrients must be small enough to be absorbed Nutrients broken down by mechanical and chemical means Occurs in digestive tract Food moved by peristalsis The Mouth to the Small Intestine Digestion begins in mouth Mastication breaks up food Tongue and palate mix in saliva Moistened food passed: • Into pharynx → through esophagus →into stomach Churning of stomach further breaks down food by: Mixing with enzyme pepsin and HCl The Mouth to the Small Intestine (con’t) Partially digested food passes through pylorus into duodenum Digestion completed after passing through other parts of small intestine (jejunum and ileum) Digested nutrients absorbed into circulation Accessory Organs Accessory Organs Liver Gallbladder Secretes bile to break down fats Bile stored here until needed Pancreas Produces mixture of digestive enzymes The Large Intestine Undigested food, water, digestive juices Begins with cecum Colon twists and turns: Ascending colon Transverse colon Descending colon Water reabsorbed, feces formed Waste material passes into sigmoid colon Waste stored in rectum; eliminated through anus Clinical Aspects of Digestion Gastrointestinal tract Infection Can be caused by variety of organisms Ulcers Lesion of skin or mucous membrane Marked by inflammation or tissue damage Can be diagnosed by: • Endoscopy • Barium study (Radiography with contrast medium) Cancer Colon and rectum most likely affected area Risk factors: Diet low in fiber, high in fat Heredity Chronic inflammation of colon (colitis) Polyps often become cancerous Symptom: bleeding into intestine Cancer (con’t) Internal observations performed with endoscopes Treatment may require surgical removal of portion of GI tract May create a stoma for waste elimination Surgery is called –ostomy, with root named for involved organ (e.g. colostomy) Obstructions Hernia Pyloric stenosis Protrusion of organ through abnormal opening Opening between stomach and small intestine too narrow Intussusception Slipping of part of intestine into part below Obstructions (con’t) Volvulus Ileus Intestinal twisting Intestinal obstruction caused by lack of peristalsis Hemorrhoids Varicose veins in rectum Appendicitis Results from infection of appendix Surgery required to: Avoid rupture Prevent peritonitis Inflammatory Bowel Disease Crohn disease Chronic inflammation of intestinal wall segments, usually ileum May causes: • Pain • Diarrhea • Abscess • Formation of fistula Ulcerative colitis Continuous inflammation of colon lining, usually rectum Hepatitis Inflammation of the liver More than six types of viral infections Hepatitis A • Spread by fecal-oral contamination Hepatitis B • Spread by blood and other body fluids Vaccines available for Hepatitis A and B Cirrhosis Chronic liver disease mainly caused by excess consumption of alcohol Characterized by: Hepatomegaly Edema Ascites Jaundice As it progresses: Splenomegaly Internal bleeding Brain damage Gallstones Cholecystitis Cholelithiasis Presence of stones in gallbladder Usually associated with cholecystitis Diagnosed by: Inflammation of gallbladder Ultrasonography Radiography Endoscopic retrograde cholangiopancreatography Treatment may involve: Drugs to dissolve stones Cholecystectomy Pancreatitis Inflammation of pancreas May result from: Alcohol abuse Drug toxicity Bile obstruction Infections Other causes Disease often subsides with only treatment of symptoms