Biology 5: Chapter 9: Check your progress

2. Discuss what could occur if each of the accessory organs of digestion did not function properly.

a nonfunctioning pancreas would not make pancreatic juices to aid in digestion, nor insulin, which would disrupt glucose metabolism; a nonfunctioning living would not procude bile to emulsify fats and could not filter the blood effectively; if the gallbladder was not functioning, bile would not be stored and released properly.

2. Discuss why carbohydrates and fats might be the cause of the obesity epidemic today.

carbohydrates and fats store lots of energy, they are consumed in excess, and with a sedentary lifestyle are not burned off with exercise but instead stored as fat.

9.6. 1. Briefly describe and give an example of each class of nutrients.

carbohydrates are simple or complex sugar units used as energy sources. they include products made from refined grains, beans peas, nuts, fruits, and whole-grain products. proteins are long chains of amino acids the body breaks to make other proteins. they are found in meats, eggs, and milk. lipids are cholesterol or fats and oils that contain either saturated or unsaturated fatty acid chains used for energy storage. olive oils contains high levels of monounsaturated fat. minerals are elements needed either in larger quantities (calcium, phosphorus) or trace quantities (zinc, iron). vitamins are other organic compounds the body cannot synthesize, like vitamins A,D,E, and K

9.5. 1. Describe the parts of the large intestine provide the function for each.

cecum and colon: absorb water and vitamins. rectum: form feces. anal canal: defecation.

3. Describe how constipation and diarrhea are related to the large intestine.

if the large intestine is irritated by infection or is subject to nervous stimulation, not enough water is absorbed and diarrhea results. if feces are retained, if the person is dehydrated, or id the person does not eat enough fiber, constipation can result.

3. Summarize the differences in how carbohydrates, proteins, and fats are digested and absorbed by the small intestine.

in the small intestine, carbohydrates are hydrolyzed to glucose, and proteins are broken down to amino acids. the glucose and amino acids are absorbed into the cells of intestinal villi and moved into the bloodstream. fats, after being emulsified by bile, are broken down to glycerol and fatty acids, which diffuses into the cells of the intestinal villi where they combine with proteins producing chylomicrons that then enter lacteals.

2. Describe the processes that occur during the digestive process.

ingestion: the mouth takes in food. digestion: divides food into pieces and hydrolyze food to molecular nutrients. movement: food is passed along from one organ to the next and indigestible remains are expelled. absorption: unit molecules produced by digestion cross the wall of the GI tract and enter the blood for delivery to cells. elimination: removal of indigestible wastes through the anus.

3. Identify the four layers of the GI tract from the lumen outward.

lumen, mucosa, submucosa, muscularis, serosa.

2. Detail how mechanical digestion and chemical digestion occur in the mouth.

mechanical digestion: teeth chew food into pieces convenient for swallowing, and the tongue moves food around the mouth. chemical digestion: salivary amylase begins the process of digesting starch.

9.1. 1. List the digestive organs and accessory structures of the digestive system.

organs: mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus. accessory organs: salivary glands, liver, gallbladder, pancreas

9.4. 1. Name and describe the functions of three main accessory organs that assist with the digestive process.

pancreas: secretes pancreatic juice containing enzymes and buffers into the small intestine, and hormones such as insulin into the blood. liver: filters the blood, removes toxic substances, stores iron and vitamins, functions in sugar homeostasis, regulates blood cholesterol. gallbladder: stores bile.

3. Detail why the regulation of digestive secretions is important to the overall process of digestion. Describe what could occur without regulation.

regulation of digestive secretions is important in order to have the needed secretion at the correct time to digest the particular foods that have been ingested. without regulations, the process of digestion could not occur properly and nutrients would not get into our circulatory system and into our cells.

2. Explain the role of the large intestine in the digestive tract.

the large intestine regulates fluid balance by absorbing water, absorbs vitamins made by intestinal flora, and forma feces to remove indigestible waste.

9.2. 1. Describe the role of the mouth, pharynx, and esophagus in digestion.

the mouth, pharynx, and esophagus compose the upper portion of the GI tract. the mouth receives food and beings the processes of mechanical and chemical digestion. the mouth leads to the pharynx, which is a space in the back of the throat that opens into both the esophagus and trachea. the esophagus, which is posterior to the trachea, connects the pharynx to the stomach.

2. Detail the functions of the small intestine and how the walls of the small intestine is modified to perform these functions.

the small intestine completes digestion using enzymes that digest all types of food and absorbs the product of the digestive process its wall contains villi that have an outer layer of columnar epithelial cells, each containing thousand of microvilli that increase the surface area for absorption.

3. Explain what ordinarily prevents food from entering the nose or trachea when you swallow.

the soft palate moves back to close off the nasal passages, and the trachea moves up under the epiglottis to cover the glottis. this prevents nasal obstructions and choking.

9.3. 1. Describe the functions of the stomach and how the wall of the stomach is modified to perform these functions.

the stomach stores food, mechanically breaks it down, initiates the digestion of protein, and controls the movement of chyme into the small intestine. the mucosa has millions of gastric pits, which lead into gastric glands that produce gastric juice. the muscularis contains circular, longitudinal layers and also an oblique layer that better allows the stomach to stretch and contract to mechanically break down food.

3. Explain the difference between a vitamin and mineral.

vitamins are organic molecules that cannot be synthesized by the body, whereas minerals are chemical elements needed in various amounts by the body.