Human Digestive System Quiz

Digestive System Overview

• The digestive system, also known as the gastrointestinal tract (GI tract) or alimentary canal, is approximately 30 feet long, extending from the mouth to the anus.
• This system's functions include physical breakdown of food, chemical digestion into nutrients (fats, carbohydrates, proteins), nutrient absorption, and waste elimination.

Functions of the Digestive System

• Physical digestion (mechanical digestion): Breaks food down into smaller pieces through chewing and churning
• Chemical digestion: Enzymes break down food molecules (fats, carbohydrates, and proteins) into absorbable nutrients.
• Absorption: Absorbs nutrients into the bloodstream.
• Elimination: Removes waste products.

Structures of the Digestive System

• Mouth (oral cavity): Where food enters the digestive system. The hard palate and soft palate form the roof of the mouth. The tongue assists in mixing food with saliva, and taste buds in papillae on the tongue detect tastes. The uvula prevents food from entering the nasal cavity during swallowing. Teeth aid in mechanical digestion through mastication (chewing)
• Salivary glands: Parotid, sublingual, and submandibular glands produce saliva to moisten the mouth and begin the breakdown of carbohydrates.
• Pharynx (throat): A muscular tube connecting the mouth to the esophagus, serving as a passageway for food.
• Esophagus: A hollow tube connecting the pharynx to the stomach. Peristalsis, rhythmic muscle contractions, moves food to the stomach.
• Stomach: A muscular sac that stores food and allows time for digestion. Hydrochloric acid and enzymes continue food breakdown. The cardiac sphincter controls food passage from the esophagus, and the pyloric sphincter controls food passage to the small intestine.
• Small intestine: Divided into three segments: duodenum, jejunum, and ileum. Most nutrient absorption occurs here. Digested food enters the bloodstream.
• Pancreas: Located behind the stomach. It serves as both an exocrine and endocrine gland. Exocrine function releases enzymes to aid chemical digestion; endocrine function produces insulin to control blood sugar levels.
• Liver: Located in the upper right quadrant beneath the diaphragm. Produces bile, processes nutrients, detoxifies harmful substances, and manufactures essential blood proteins.
• Gallbladder: A small organ on the inferior surface of the liver. Stores and concentrates bile, releasing it to aid in the digestion of fatty foods.
• Large intestine (colon): Approx 2" in diameter. Absorbs water, forms & stores feces, chyme is the state of food when it enters here, and water balance is reabsorbed here. Sections include the cecum, appendix, rectum, and anus.
• Teeth & Gingiva: Teeth aid in mechanical (physical) digestion (chewing), Gums (gingiva) protect teeth. Deciduous (baby) teeth (20) are replaced by permanent teeth (32)

Common Digestive System Disorders

• Cholecystitis: Inflammation of the gallbladder.
• Cholelithiasis: Gallstones.
• Cholecystectomy: Surgical removal of the gallbladder.
• Constipation: Infrequent bowel movements.
• Cirrhosis: Chronic disease of the liver where normal tissue is replaced with fibrous tissue, often due to excessive alcohol consumption.
• Gastroenteritis/Diarrhea: Inflammation of the stomach and intestinal lining, often caused by a virus; symptoms include vomiting and diarrhea.
• Gastroesophageal Reflux Disease (GERD): Acid reflux from the stomach to the esophagus.
• Hiatal hernia: The upper part of the stomach pushes through an opening in the diaphragm.
• Hepatitis: Inflammation of the liver, often caused by a virus.
• Irritable Bowel Syndrome (IBS): Affects the colon, symptoms include cramping, gas, abdominal pain, diarrhea, or constipation.
• Peptic Ulcers: Open sores or lesions in the lining of the stomach or duodenum, often caused by H. pylori bacteria.

Electrolytes and Vitamins

• Sodium is absorbed actively in the large intestine.
• Potassium absorption or secretion depends on body levels.
• Vitamins K and B are produced by bacteria in the large intestine.