
Digestive System Azami PHD
Digestive System Anatomy • Digestive tract • Alimentary tract or canal • GI tract • Accessory organs • Primarily glands • Regions • Mouth or oral cavity • Pharynx • Esophagus • Stomach • Small intestine • Large intestine • Anus
Oral Cavity • Mouth or oral cavity • Vestibule: Space between lips or cheeks and alveolar processes • Oral cavity proper • Lips (labia) and cheeks • Palate: Oral cavity roof • Hard and soft • Palatine tonsils • Tongue: Involved in speech, taste, mastication, swallowing
Salivary Glands • Produce saliva • Prevents bacterial infection • Lubrication • Contains salivary amylase • Breaks down Starch • Three pairs • Parotid: Largest • Submandibular • Sublingual: Smallest
Teeth • Two sets • Primary, deciduous, milk: Childhood • Permanent or secondary: Adult (32) • Types • Incisors, canine, premolar and molars
Pharynx Nasopharynx Oropharynx: Transmits food Laryngopharynx: Transmits food Esophagus Transports food from pharynx to stomach Passes through esophageal hiatus (opening) of diaphragm and ends at stomach Pharynx and Esophagus
(Swallowing) • Three phases • Voluntary • Pharyngeal • Reflex • Esophageal • Reflex
Nervous regulation Involves enteric nervous system Types of neurons: sensory, motor, interneurons Coordinates peristalsis and regulates local reflexes Chemical regulation Production of hormones Production of paracrine chemicals Digestive System Regulation
Peritoneum • Peritoneum • Visceral: Covers organs • Parietal: Covers interior surface of body wall • Retroperitoneal: Behind peritoneum as kidneys, pancreas, duodenum Retroperitoneal
Mesenteries • Routes which vessels and nerves pass from body wall to organs
Mesenteries • Mesenteries • Routes which vessels and nerves pass from body wall to organs
Stomach Anatomy • Openings • Gastroesophageal: To esophagus • Pyloric: To duodenum • Regions • Cardiac • Fundus • Body • Pyloric
Stomach Histology: • Layers • Serosa or visceral peritoneum: Outermost • Muscularis: Three layers • Outer longitudinal • Middle circular • Inner oblique • Submucosa • Mucosa
Stomach Histology • Rugae: Folds in stomach when empty • Gastric pits: Openings for gastric glands • Contain cells
Small Intestine anatomy and Histology • Site of greatest amount of digestion and absorption • Divisions • Duodenum • Jejunum • Ileum: Peyer’s patches or lymph nodules • Modifications • Circular folds or plicaecirculares, villi, microvilli • Cells of mucosa • Absorptive, goblet, granular, endocrine
Small Intestine Secretions • Mucus • Protects against digestive enzymes and stomach acids • Digestive enzymes • Disaccharidases: Break down disaccharides to monosaccharides • Peptidases: Hydrolyze peptide bonds • Nucleases: Break down nucleic acids • Duodenal glands • Stimulated by vagusnerve, secretinsecretinincreases water and bicarbonate secretion from duodenal (Brunner's) glands