Warm Up What does digestion mean? What does absorption mean in regards to the digestive system? How long are your intestines?
Functions of the Digestive System 3 main processes Digestion –the mechanical and chemical breakdown of foods for use by the bodys cells. Absorption –the passage of digested food from the digestive tract into the cardiovascular system. Elimination –The expulsion of undigested cardiovascular food or body wastes.
Digestion involves both mechanical and chemical processes. Mechanical –Chewing –Mashing –Breaking food into smaller pieces Chemical –Digestive juices that breakdown food into simpler substances
The nervous system and the cardiovascular system play major roles in digestion. The nervous system triggers the digestive system process to begin at the smell or sight of food. After food has been broken down- nutrients- such as carbohydrates, proteins, fats, vitamins and minerals- are absorbed by the body.
Structures of the Digestive System The process of digestion begins in the mouth. Teeth –Break down food into smaller pieces. –Mastication: process of chewing Salivary Glands –Produce the first digestive juices –Saliva contains an enzyme that begins to break down the starches and sugars in food. –Lubricates food and makes it easy to swallow
Tongue –forms chewed food into easy to swallow size –As you swallow Muscles force food to pharynx, or throat. The uvula, a small flap of muscle tissue closes off opening to nasal passages. Epiglottis, the flap of tissue covering the throat, closes the opening to the trachea (windpipe).
The Esophagus When food is swallowed, it enters the esophagus. 10 inch long muscular tube that connects the pharynx with the stomach. Food is moved through the esophagus, stomach, and intestines through a process called peristalsis – a series of involuntary muscle contractions that move food through the digestive tract.
The Stomach A hollow, saclike organ enclosed in a flexible muscular wall that allows your stomach to expand when you eat. 3 Tasks of Digestion #1: Mixing food with gastric juices: secretions from the stomach lining that contain hydrochloric acid and pepsin, and enzyme that digests protein. #2: Storing swallowed food and liquid #3: Moving food into the small intestine. –Food is converted into chyme: a creamy, fluid mixtureof food and gastric juices
Pancreas –Produces enzyme that break down carbs, fats, and proteins in foods. Liver –Produces another digestive juice: BILE A yellow-green, bitter fluid important in the breakdown and absorption of fats. Gallbladder –Stores the Bile in between meals. –Released at mealtime into the intestines.
Large and Small Intestine Small Intestine 20-24 feet in length Broken into 3 parts –Duodenum, jejunum & ileum The inner wall contains millions of finger-projections called villi, which are lined with capillaries. The capillaries absorb and carry nutrients throughout the body. Large Intestine Undigested parts of food pass into the colon, or large intestine. 2.5 inches in width and 5-6 feet in length. Main function is to absorb water, vitamins, and salts, and the eliminate waste.
The body produces waste in the form of solids, gases and liquids. Solid waste is eliminated through the large intestine. Bacteria live in the large intestine to convert undigested food into feces, which is then excreted out of the body. The skin excretes some waste through the pores. Liquid waste is filtered through the urinary system.
Assignment: Page 446 - Q#1-5- AYR Color the digestive diagram on the back of the crossword puzzle.