Question | Answer |
Gastrointestinal Tract (Digestive Organs) | Oral cavity, Pharynx, Esophagus, Stomach, Small intestine, Large intestine, Anus. |
Accessory Digestive Organs | Parotid salivary gland, Teeth, Tongue, Sublingual salivary gland, Submandibular salivary gland, Liver, Gallbladder, Pancreas. |
Digestive Functions | Ingestion, Mechanical digestion, Chemical digestion, Propulsion, Secretion, Absorption, Elimination of waste. |
Ingestion | Taking food into mouth. |
Mechanical digestion | Physical breakdown. Mastication=chewing. Segmentation=mixing & churning in small intestine. |
Chemical digestion | Molecules broken down by enzymes. |
Propulsion | Peristalsis: muscular contraction that moves food through GI tract. |
Secretion | Production & release of bile, enzymes, etc. |
Absorption | Nutrient transport into blood/lymph vessels |
Peristalsis | Form of propulsion. Involves the contraction & relaxation of the smooth muscle in the alimentary canal (AKA digestive/GI tract). It does not break up the food. |
Segmentation | Local contractions of smooth muscle. Involved with mechanical digestion. Mixes food with digestive juices. |
Histology | Mucosa, Submucosa, Muscularis, Serosa |
Mucosa | Epithelial lining closest to lumen. Secretion and absorption. Ex. Esophageal mucosa is stratified squamous. Touches food/feces. |
Submucosa | Vascularized and innervated. |
Muscularis | Inner circular and outer longitudinal layers of muscle. Segmentation and peristalsis. 2 layers of smooth muscle squishes in all directions. |
Serosa | Visceral peritoneum. |
Oral cavity | Structures: cheeks, hard palate, palatal rugae, labia, labial frenulum, vestibule. Lips consist of non keratinized stratified squamous epithelium. Initial location of mechanical & chemical digestion. |
Salivary Glands | Parotid gland & duct-25-30% of saliva production. Sublingual-3-5%. Submandibular-60-70%. Autonomic innervation. Produce 1.5L saliva/day. |
Saliva | Wets and binds food, cleans teeth, kills harmful microorganisms, dissolves food chemicals, enzymes begin digestion of starch. |
Tooth Structure | Gingiva (travels around root). Alveoli-sockets in the mandible & maxilla. Periodontal ilgaments. Root. Enamel-hardest substance in body, form cusps. Cementum-covers the root. Dentin-bulk. Pulp-contains blood vessels & nerves. |
Deciduous Teeth | 20 primary teeth. Fall out and are replaced. 8 incisors, 4 canines, 8 molars. |
Permanent Teeth | 32. 8 incisors, 4 canines, 8 premolars (bicuspids), 12 molars. |
Pharynx | Part of respiratory & digestive systems. passageway for food, fluid, and air. |
Swallowing | Stage 1 is voluntary. All of other stages are involuntary. |
Esophagus | Muscular tube. Propels food to stomach (peristalsis). Esophageal hiatus-opening in diaphragm. Inferior esophageal or cardiac sphincter-circular muscle where esophagus and stomach meet. |
Reflux Esophagitis | AKA Heartburn. Acidic stomach contents regurgitate into the esophagus. Risk factors: obesity, smoking, types or quantity of food, bulimia. Symptoms: ab pain, difficulty swallowing, increased belching, bleeding. |
Stomach-upper left quadrant | Mucosa is simple columnar epithelium. Functions: storage of food, mechanical digestion-churn w/ gastric juice, chemical digestion-initiate protein digestion, LIMITED ABSORPTION: only meds & alcohol. |
Stomach structures | Cardiac sphincter (AKA lower esophageal sphincter). Cardia. Fundus. Body-majority. Greater curvature. Lesser curvature. Gastric rugae. Pyloric region. Pyloric sphincter. Label! |
Histology of the stomach wall | Stomach mucosa is simple columnar containing 5 different cell types. |
1. Surface Mucous Cells | Mucin secretion to protect stomach lining. |
2. Mucous Neck Cells | Acidic mucin secretion to maintain acidic conditions. |
3. Parietal Cells | Hydrochloric acid secretion. Gastric intrinsic factor secretion: GIF binds to B12 assisting in B12 absorption. Hyposecretion leads to pernicious anemia. |
4. Chief Cells | Secretion of pepsinogen, an inactive enzyme: Acid activates pepsinogen into pepsin. Pepsin digests proteins. |
5. Enteroendocrine Cells | Hormone secretion |
Peptic Ulcer | Erosion of stomach or duodenal mucosa. May be caused by ibuprofen & asprin use. Majority of cases associated with bacterium HELICOBACTER PYLORI. Perforating=eroded through entire wall. Emergency. Treatments: Antibiotics, neutralizing acid-Tums/Rolaids. |