Digestive System Anatomy.pdf

Anatomy of Digestive System Digestive System Digestive tract is continuous tube that begins at the mouth and ends at the anus Measures approximately 30 feet long in the average adult Functions - Digestion of food into nutrients - Absorption of nutrients into the bloodstream - Elimination of solid wa...

Anatomy of Digestive System Digestive System Digestive tract is continuous tube that begins at the mouth and ends at the anus Measures approximately 30 feet long in the average adult Functions - Digestion of food into nutrients - Absorption of nutrients into the bloodstream - Elimination of solid wastes Digestive System: Mouth Salivary Glands Three pairs of glands that open into the oral cavity and produce saliva Parotid Sublingual Submandibular The sensory organs such as the nose and eyes send a message to the brain, the brain sends the message to the salivary glands, and they secrete the chemicals to begin the digestive process Digestive System: Mouth/Tongue Muscle covered with a mucous membrane Root, the tip, and the central body Covered with taste buds and raised elevations called papillae Digestive System: Teeth Used for mastication Food particles mix with saliva to form a bolus to swallow Muscular constrictions move the bolus through the oropharynx and into the esophagus while blocking the opening to the larynx and preventing the food from entering the airway. Esophagus Food is moved down the esophagus toward the stomach by peristalsis (wavelike muscular contractions called peristalsis) At the distal portion of the esophagus is the lower esophageal sphincter (LES) – a muscle that permits the passage of food Stomach Muscular, expandable organ, the upper portion called the fundus and the lower portion called the antrum Hydrochloric acid and other gastric juices convert the food to a semiliquid state called chyme Chyme passes through the pyloric sphincter valve at the bottom of the stomach, into the duodenum Small Bowel SI is about 21 feet long and 1” diameter, extending from the pyloric sphincter valve to the large intestine The duodenum is the foot-long section just beyond the stomach; the jejunum is the next 8 feet, and the ileum is the remaining 12 feet. Liver The liver’s primary contribution to digestion is the production of bile or gall which drains into the duodenum, and some is stored in the gallbladder It travels through the hepatic ducts, which merge together Bile is involved emulsification helps digest fats The liver also stores iron and the fat-soluble vitamins A, D, E, and K. Gallbladder Bile stored in the gallbladder becomes more concentrated, increasing its potency and intensifying its effect When chyme containing fat leaves the stomach, the gallbladder contracts and discharges bile through the cystic duct and common bile duct and into the duodenum of the small intestine Pancreas Secretes pancreatic juice into the duodenum via the pancreatic duct which merges with the common bile duct Pancreatic juice contains digestive enzymes and bicarbonate ions Jejunum and Ilium Are lined with hair-like protrusions calIed villi Villi slow the passage of food, and allow food particles to be captured in among them so that that capillaries inside the villi can absorb the nutrients Villus capillaries collect amino acids (proteins) and glucose (simple sugars) Villus lacteals collect absorbed fatty acids. Large Intestine Absorb the remaining water and nutrients from indigestible food matter, store unusable food matter (wastes), and then eliminate the wastes from the body The large intestine is only about 4-5 feet in length, and 2 ½ inches in diameter Cecum, the ascending/transverse/ descending/and sigmoid colon sections Rectum and Anus The rectum is where feces are stored until they leave the digestive system, through the anus as a bowel movement Rectal walls expand with waste material and then , receptors from the nervous system stimulate the desire to defecate For defecation we consciously relax the external anal sphincter muscle to expel the waste through the anus