Digestive System
Cards (9)
- Digestive systemA continuous tube that begins at the mouth and ends at the anus, also known as the alimentary canal or gastrointestinal tract. It has 3 functions: the digestion of food into nutrients, the absorption of nutrients into the bloodstream, and the elimination of solid wastes.
- Mouth
- Salivary glands (parotid, sublingual, submandibular) secrete saliva to begin the digestive process
- Tongue is a muscle covered with taste buds and papillae that can taste sweet, sour, salt, bitter, and umami
- Teeth are used for chewing food (mastication) and forming a bolus to be swallowed
- EsophagusFood is moved down the esophagus toward the stomach by wavelike muscular contractions called peristalsis. The lower esophageal sphincter permits the passage of food but not the backup of stomach contents.
- Stomach
- A muscular, expandable organ with an upper fundus portion and lower antrum portion
- Hydrochloric acid and gastric juices convert food to a semiliquid state called chyme
- Chyme passes through the pyloric sphincter valve into the small intestine
- Small intestine
- Duodenum is the first foot-long section, followed by the 8-foot jejunum and 12-foot ileum
- Liver produces bile which helps digest fats, and stores iron and fat-soluble vitamins
- Gallbladder stores and concentrates bile
- Pancreas secretes pancreatic juice containing digestive enzymes and bicarbonate ions
- Jejunum and ileum are lined with villi that slow food passage and absorb nutrients
- Large intestine
- Absorbs remaining water and nutrients from indigestible food matter, stores unusable waste, and eliminates waste through the rectum and anus
- Rectum is where feces are stored until expelled through the anus
- Defecation is controlled by consciously relaxing the external anal sphincter muscle
- The digestive system is about 30 feet long in the average adult
- The small intestine is about 21 feet long and 1 inch in diameter
- The large intestine is only about 4-5 feet in length, and 2 1/2 inches in diameter