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Your digestive system has three main functions
The Digestive System
• digestion
• absorption
• elimination
Mouth• Mastication: teeth tear,
crush, and grind your food. An enzyme in saliva begins to break down starches in your food.
• The pharynx is the junction between the digestive tract and the respiratory system.
• A flap of tissue called the epiglottis seals off the trachea, or windpipe, preventing food and liquid from entering your lungs.
• After passing through the pharynx, the food enters the esophagus, a muscular tube that connects the pharynx to the stomach
Esophagus
• Waves of muscle contractions, called peristalsis, push food through the rest of the digestive system.
Pharynx
Epiglottis
Mouth
Salivary gland
LiverEsophagus
Stomach
Pancreas
Small intestine
Large intestine
Rectum
Gallbladder
• From the esophagus, food passes through a valve and into the stomach, a muscular pouch located in the abdomen.
Stomach
• Mechanical digestion occurs as three layers of muscle produce a churning motion.
• Pepsin: breaks down the proteins• Hydrochloric acid: kills bacteria
• Peristalsis moves the food, which is now a thick liquid called chyme (kym), into the small intestine.
• The small intestine is where most chemical digestion and absorption of nutrients takes place. It’s about 22 feet long.
Small Intestine
• Liver The role of the liver is to produce bile. Bile is a substance that physically breaks up large fat droplets that clump together.
• Gallbladder Bile flows from the liver into the gallbladder, the organ that stores bile.
• Pancreas The pancreas secretes enzymes into the small intestine that complete the breakdown of carbohydrates, proteins, and fats.
• The lining of the small intestine is covered with millions of tiny fingerlike projections called villi.
• The large intestine is about 5 feet long and 3 inches wide.
The Large Intestine
• As the material moves through the large intestine, most of the remaining water is absorbed into the blood.
• Collects waste from the small intestine and gets rid of it
Rectum• A short, muscular tube that
forms the lowest portion of the large intestine and connects it to the anus.
• Feces collects here until pressure on the rectal walls cause nerve impulses which send messages to the voluntary muscles in the anus to relax, permitting expulsion.
• Healthy eating habits and regular exercise are important for keeping your digestive system healthy.
Avoiding Digestive Disorders
• Consume plenty of fiber.
• Avoid fatty foods.
• Eat moderately.
• Plan meals for a time when you can relax.
• Drink water.
• Get regular exercise.