Digestion+HW+ZW

Chapter 8 Digestive System

8.1 Overview of Digestion 1. Describe in you words the processes that occur in the digestive system (ingestion, digestion, movement, absorption, elimination) • Ingestion: taking in food through the mouth • Digestion: can be mechanical or chemical. Mechanical digestion occurs when food is divided into pieces that can be acted on by digestive enzymes. It occurs mainly in mouth and stomach. Chemical digestion begins in the mouth and is not completed until the food gets to the small intestine. • Movement: of GI tracts along the digestive system is very important in order for the tract to fulfill its other functions. • Absorption: occurs as unit molecules produced by digestion cross the wall of the GI tract and enter the cells lining the tract. From there, the nutrients enter the blood for delivery to the cells. • Elimination: Molecules that cannot be digested need to be eliminated from the body. The removal of indigestible wastes through the anus, in the form of feces, is defecation.

8.2 First Part of the Digestive Tract 1. Describe the MECHANICAL and CHEMICAL digestion that occurs in the mouth. Mechanical digestion occurs when food is divided into pieces that can be acted on by digestive enzymes. It occurs mainly in mouth and stomach. Chemical digestion begins in the mouth and is not completed until the food gets to the small intestine.

2. What is heartburn? It occurs due to acid reflux, when some of the stomach’s contents escape into the esophagus.

3. What is a dental cavity? (What causes it?) In essence it is decay on the tooth. It is caused when bacteria in the mouth metabolizes sugar and gives off acids, which erode the teeth.

8.3 Stomachs and Small Intestine 1. What are the functions of the stomach and how is the wall of the stomach modified to perform these functions? The stomach stores food, initiates the digestion of protein, and controls the movement of chyme into the small intestine. 2. What are the functions of the small intestine and how is the wall of the small intestine modified to perform these functions? The small intestine absorbs nutrients. The mucosa is filled with folds to absorb food.

3. What is lactose intolerance? What causes it and what are the symptoms? Lactose intolerance is when someone doesn't have lactase, the enzyme that digests lactose. Symptoms include diarrhea, gas, and bloating after dairy intake.

8.4 Three accessory organs. 1. What are the three main accessory organs and how do they assist the digestive process? The pancreas releases enzymes to digest food and secrete insulin. The liver filters blood waste products. It also serves as a storage unit for vitamins A, D, E, K and B12 filtered from blood.

2. What is a gallstone? Hardened liquid in the gallbladder

3. What is hepatitis? Hepatitis is when the liver inflames

4. What is cirrhosis? Cirrhosis occurs when the liver becomes fatty and liver tissue is replaced by inactive fibrous tissue

8.5 Large Intestine 1. What is the function of the large intestine? It absorbs water and vitamins

2. Briefly describe the disorders of the large intestine: diarrhea, constipation, diverticulosis, hemorrhoids, IBS, IBD, polyps, cancer.

• Diarrhea is caused by dehydration • Constipation is caused from hard feces • Hemorrhoids come from frequent constipation