Digestive System Two Key Functions Digestion breaking down

Digestive System �Two Key Functions: �Digestion - breaking down food into smaller molecules (nutrients). �Absorbing these nutrients into the bloodstream

TYPES OF DIGESTION MECHANICAL CHEMICAL

Digestive System �Parts � Mouth � Pharynx � Esophagus � Stomach � small intestine � Liver � Gallbladder � Pancreas � large intestine � Rectum

Mouth �Mechanical Digestion �Tongue and teeth work together to break down food mechanically �Chemical Digestion �Amylase - enzyme in saliva that breaks the carbohydrates � Starch Simple Sugars

Esophagus � No digestion � Food is directed from mouth to stomach using peristalsis �Epiglottis – flap of cartilage Ensures food travels to esophagus and not wind pipe (larynx)

Stomach � Large muscular sac that continues digestion � Acidic p. H – 2 -3 on the p. H scale � Cardiac sphincter – circular muscle that keeps food in stomach � Mechanical Digestion �Peristalsis � Chemical Digestion – protein digestion begins here �HCL and Pepsin - pepsin (enzyme) and hydrochloric acid begins protein digestion. HCL changes inactive enzyme, pepsinogen active pepsin �Chyme - mixture of stomach fluids and food produced in the stomach by contracting stomach muscles

STOMACH

REVERSE PERISTALSIS

Small Intestine � Digestion is completed and nutrients are absorbed here. � Small in diameter, not in length (> 6 m) � Chemical Digestion completed here. � Digestion �Intestinal Enzymes Pancreatic amylases – starch Peptidases (trypsin, chymotrypsin) – proteins amino acids Nucleases – nucleic acids nucleotides Lipases – break down fat � Nutrient Absorption – Villi (villus-singular) – millions of fingerlike projections (latter portion of small intestine) �Increase surface area

Villi and the Small Intestive

Liver �Liver - large organ just above the stomach that produces bile, a fluid loaded with lipids and salts �Produces bile that digests fat �Sends bile to gallbladder for storage

Gallbladder and Pancreas � Gallbladder � Stores bile � Cholesterol Deposits (gallstones) � Pancreas � Secretes peptidases – protein digestive enzymes

Large Intestine or Colon �large intestine � No digestion � 2 major functions �Egestion – removal of undigested waste Rectum – stores feces for release Anus – Releases feces �Reabsorption Water is absorbed

Digestive Disorders � Belching / Burping � swallowed air, eat fast, improperly fitted dentures, & chewing gum � Intestinal gas � foods rich in fiber, starches, & sugar � beans, dairy, some vegetables � bacteria in the GI � fat substitutes � GERD - gastroesophageal reflux disease � painful, persistent heartburn (acid in esophagus) � cause: hiatal hernia, cigarette smoking, alcohol, overweight, pregnancy, chocolate, citrus, spicy or fried foods, large high-fat meal 14

DIGESTIVE PROBLEMS/DISORDERS

Digestive Disorders �Peptic ulcers � areas of GI eroded by HCL & pepsin �Helicobacter pylori – bacteria contributes to production of gastric & duodenal ulcers �Food allergy � hypersensitivity reaction of immune system �Food intolerance � GI gas, pain, diarrhea, or constipation 16

Digestive Disorders �Celiac disease (celiac sprue) � genetic disorder � inability to absorb gluten - protein in wheat, rye, & barley � Immune cells damage the small intestine � leads to poor nutrient absorption � requires a diet lacking wheat, rye, & barley � early diagnosis avoids delayed growth & malnutrition �Crohn’s disease � inflammatory bowel can affect any area of the GI tract � possible immune system reaction to a virus or bacteria � diarrhea, abdominal pain, rectal bleeding � weight loss, fever, anemia � children can experience delayed growth 17

Digestive Disorders �Ulcerative colitis � chronic disease of the colon � inflammation & ulceration of inner most lining � possible immune response to a virus or bacteria � symptoms are similar to Crohn’s disease � not caused by food � patients may avoid foods that cause discomfort �Diarrhea � frequent passage of loose, watery stools � Infection, stress, food intolerances � reactions to medications, or bowel disorders � can lead to severe dehydration � more dangerous for children & the elderly 18

Digestive Disorders �Constipation � infrequent hard, small, difficult to pass stools � prevention includes fiber-rich foods & regular exercise �Irritable bowel syndrome (IBS) � interferes with normal colon function � abdominal cramps & bloating � diarrhea or constipation � stress, caffeine, large meals, chocolate, alcohol, dairy, wheat � more common in women � treatment includes stress management, high fiber diet, fluids, avoiding offending foods 19

A blast from the past