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Chapter 18 The function of the digestive system is to supply the body with energy. This is done by processing food. Food is processed in your body in four stages ____________________, ____________________, ____________________, and ____________________ .
____________________ is the process that breaks down food into small molecules so that they can be absorbed and moved into the blood and then into the cell through the cell membrane. There are two types: 1. ____________________ digestion takes place when food is chewed, mixed, and churned. 2. ____________________ digestion occurs when chemical reactions occur that break down large molecules of food into smaller ones. · ____________________ are special protein that speed up a chemical reaction. They are not changed themselves. Many reactions would not occur without enzymes, and humans could not live without them. o ____________________ is an enzyme that is produced near the mouth. It breaks down complex carbohydrates, such as starch, into a simpler one sugar. o ____________________ is found in the stomach and breaks down proteins into less complex ones. These are broken into amino acids in the small intestine. ____________________ is located on the back side of the stomach and releases enzymes into the small intestine. Some of these continue to break sugar into glucose sugar. Others work on proteins. Without enzymes, the chemical reactions of your body would not happen. In fact, you would not exist. ORGANS OF THE DIGESTIVE SYSTEM The digestive tract and the accessory organs are two parts of your digestive system. · ____________________ organs are the tongue, teeth, salivary glands, liver, gallbladder, and pancreas. o Food doesnt pass though the accessory organs. o Liver, gallbladder, and pancreas produce or store enzymes and chemicals that help break down food as it passes through the digestive tract. · The ____________________ organs of your digestive tract are mouth, esophagus, stomach, small intestine, large intestine, rectum and anus. o ____________________ § Mechanical and chemical digestion begin in your mouth. § Digestion begins with a watery substance called saliva. § Saliva is produced by three sets of glands near your mouth. § It contains mucus and an enzyme that aids in the breakdown of starch into sugar. § It is swallowed and passes into your esophagus and ingestion is complete · There are four different types of teeth. Each with its specialized job. The diet of an organism determines the type of teeth in the mouth. o _____________- chop and cut o _____________- rip and tear o _____________- grind o _____________- grind · There are three types of diets o _____________- eat meat only o _____________- eat meat and plants o _____________- eat plants only o ____________________ § It covers the opening to the windpipe to prevent food from entering the windpipe. o ____________________ § It is a muscular tube about ____________________ cm long. § It takes about 4s to 10s for food to move down the esophagus to the stomach. § No digestion takes place here. The waves of muscle contractions, called ____________________, move food through the entire digestive tract. o ____________________ § It is a muscular bag. § Mechanical and chemical digestion takes place in the stomach. · Mechanically food is mixed in the stomach by peristalsis · Chemically, food is mixed with enzymes and strong digestive solutions, such as hydrochloric acid solution, to help break it down. · Specialized cells in the walls of the stomach release about 2 Liters of ____________________ acid solution each day. o This solution works with the enzyme pepsin to digest protein. o It destroys bacteria that are present in the food. o The stomach also produces mucus to protect the stomach from the strong acid solution § Food moves through your stomach in 2 hours to 4 hours and is changed into a thin, watery liquid called ____________________. § ____________________ moves out of your stomach and into your small intestine. o ____________________ § It is small in diameter, but it measures ____________________ m in length. § Most digestion takes place in you ____________________ (the first part of your small intestine). § A greenish fluid from the liver, called ___________________, is added in the duodenum. · ____________________ breaks up the large fat particles, similar to the way detergent breaks up grease. § Chemical digestion of carbohydrates, proteins, and fats occurs when a digestive solution from the pancreas is mixed in. § Bicarbonate ions help neutralize the stomach acid. § Your pancreas also makes ____________________, a hormone that allows glucose to pass from the bloodstream into your cells. § Absorption of food takes place in the small intestine. § The wall has many ridges and folds that are covered with fingerlike projections called ____________________. From here, blood transports the nutrients to all cells of you body. Peristalsis continues to force the remaining undigested and unabsorbed materials slowly into the large intestine. o ____________________ § The main job of the large intestine is to absorb ________________ from the undigested mass. § The chyme might stay there for as long as _________________ days. § Muscles in the ____________________, which is the last section of the large intestine, and the anus control the release of semisolid wastes from the body in the form of ____________________.
BACTERIA ARE IMPORTANT Bacteria live in many of the organs of your digestive tract including your ____________________ and ____________________. Some of these bacteria live in a relationship that is beneficial to the bacteria and to your body. Bacteria make vitamins you need---vitamin ___________and two __________ vitamins. · Vitamin ___________ is needed for blood blotting. · The two ___________ vitamins, niacin and thiamine, are important for your nervous system and for other body functions. The breakdown of intestinal materials by bacteria produces gas. |