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
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)
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”