Major structures involved

STRUCTURES  MAIN ORGANS  Mouth  Pharynx  Esophagus  Stomach  Small Intestine  DUODENUM  JEJUNUM  ILEUM  Large Intestine/Colon  ASCENDING COLON  TRANSVERSE COLON  DESCENDING COLON  SIGMOID COLON  RECTUM  ANAL CANAL  ACCESSORY ORGANS  TEETH & TONGUE  SALIVARY GLANDS  PAROTID  SUBMANDIBULAR  SUBLINGUAL  LIVER  GALLBLADDER  PANCREAS  APPENDIX

Mouth/Oral Cavity  Chemical digestion of carbohydrates:  Salivary glands secrete salivary amylase  Mechanical digestion of food into a bolus: Teeth and tongue

Deglutition

Pharynx (and upper esophageal sphincter)  Passes food to esophagus  Upper Esophageal Sphincter  During swallowing  Upper esophageal sphincter opens  Allows food, liquids to pass  Reduces backflow of food, liquids from the esophagus into the pharynx.

Esophagus and Lower esophageal sphincter  Esophagus: Muscular walls (longitudinal and circular) causes peristalsis  Cardiac/Lower Esophageal Sphincter- prevents backflow of acidic food contents

Stomach and Pyloric Sphincter  Mechanical digestion of food into chyme: 3 layers of muscle (longitudinal, circular, oblique)  Chemical digestion of proteins  Pepsin  When empty, lining lies in folds called rugae  Peristalsis drives Peristalsis movement of materials

Peristalsis in stomach

Small Intestine: Duodenum, Jejunum, Ileum  Mech/Chem Digestion  Absorption of Nutrients  Circular folds:  Plicae (plica, s)  Folds covered with:  Villi (villus, s)  Fingerlike projections  Covered w/ microvilli  Nutrient absorption takes place in capillaries of villi o Plicae/Villi  SA, which  nutrient absorption

Absorption of nutrients in the SI: Villi & Microvilli

Duodenum  Bile from liver/gallbladder emulsifies fat (breaks it into smaller droplets)—mech dig.  Lipase from pancreas released here Other pancreatic enzymes : Proteases (protein) Amylase (carbohydrates)

Small Intestine, cont’d  Secrete intestinal enzymes:  Peptidases (peptides  amino acids)  Sucrase, lactase, maltase (disaccharides  monosacharides)

Ileocecal valve  Regulates flow of materials between ileum (SI) and cecum (LI)  Plicae of the small intestine & large intestine, appendix

Large Intestine (all these words!!!)  Cecum (and appendix)  Ascending colon  Transverse colon  Descending colon  Sigmoid colon  Rectum   Anal Canal

Large Intestine  Water Absorption/Stool Formation  Transit time  Too fast  diarrhea (too much water in stool)  Too slow  constipation (too little water in stool)  Vitamins B & K Production  Result from bacteria feeding on undigested material

Peritoneum  Visceral Peritoneum: surrounds digestive tract  Parietal Peritoneum: lines abdominal cavity  Extensions:  Greater Omentum: hangs down from lower edge of stomach/transverse colon over intestines (“lace apron”)  Mesentery: connects intestines/ anchors intestines to posterior abdominal wall

Rectum  Stores feces prior to elimination  Anal sphincter regulates movement through anal canal  Under voluntary control  Learned during “potty training”