Final Review and Assessment of Profile and Nutritional Health – FSM 159 Nutrition - 30 points After you have completed your IProfile analysis and your personal iProfile questions - you must now review

Chapter 3 Digestion: From Meals to Molecules The Organization of Life • Begins with atoms that form molecules, which are then organized into cells to form tissues, organs, and whole organisms. o Atom : the smallest unit of an element that retain s the properties of the element. o Molecule : group of two or more atoms of the same or different elements bonded together. o Cell: the smallest unit of life. o Tissue : made up of cells that are similar in structure and function. ▪ Types of tissue: muscle, nerve, ep ithelial, and connective. o Organ: structure composed of more than one tissue that performs a specialized function. o Organ system: 11 organ systems interact to perform all the functions necessary for life. ▪ An organ may be part of more than one organ system. • Major organ systems of the human body: integumentary system, muscular system, skeletal system, lymphatic system, respiratory system, digestive system, nervous system, endocrine system, circulatory system, urinary system, and reproductive system. The Digestive System • Digestion: the process by which food is broken down into components small enough to be absorbed into the body. • Absorption: the process of taking substances from the gastrointestinal tract into the interior of the body. o Feces: body waste, including unabsorbed food residue, bacteria, mucus, and dead cells. Eliminated from the gastrointestinal tract. Organs of the Digestive System • Gastrointestinal tract: hollow tube, about 30 feet long. o Also called: gut, GI tract, alimentary canal or digesti ve tract. • Organs include: mouth, pharynx, esophagus, stomach, small intestine and large intestine • Transit time: time it takes food to travel the length of the GI tract: healthy adult 24 -72 hours. o Dependent on the composition of the diet, level of physical activity, emotional state, health status and use of medications. • Accessory organs: salivary glands, liver, gall bladder and pancreas. Digestive System Secretions • Muc us: viscous fluid secreted by glands in the digestive tracts and other parts of the body. o Lubricates, moistens, and protects cells from harsh environments. • Enzymes: protein molecules that accelerate the rate of specific chemical reactions without themselves being changed. • Hormone: chemical messengers that are produced in one location in t he body, released into the blood, and travel to other locations, where they elicit responses. • The digestive enzyme, Amylase , breaks down large carbohydrate molecules, like those in bread, into smaller ones. Amylases have no effect on fat, whereas enzymes called lipases digest fat and have no effect on carbohydrate. Digestion and Absorption of Nutrients The Mouth • Chemical and mechanical digestion begins in the mouth. • Saliva: moistens food. o Salivary amylase: enzyme which begins the chemical digestion of foods . ▪ Helps protect against tooth decay. • Chewing: mechanical breakdown of food. The Pharynx • Responsible for swallowing. o Bolus: chewed food mixed with saliva. o Epiglottis: connective tissue that covers the opening to the lungs during swallowing. • Also part of the respiratory system. The Esophagus • Connects the pharynx with the stomach. • Peristalsis: coordinated muscular contractions that move material through the GI tract. • Sphincter: muscle that encircles the tube of the digestive tract and acts as a valve. The Stomach • Temporary storage place for food. • Chyme: semiliquid food mass produced when a food bolus mixes with highly acidic stomach secretions. • Chemical digestion occurs. o Gastric juice: hydrochloric acid and pepsin. • Little absorption occurs. • Regulation of stomach activity: regulated by signals from nerves and hormones. o Signals originate from the brain, stomach and the small intestine. o Large meal takes longer than a liquid meal. o Solids take longer than liquids. o Nutriti onal composition: ▪ Carbohydrates leave quickly. ▪ Fiber and protein take longer. ▪ High fat meal stays in the stomach the longest. The Small Intestine • Narrow tube about 20 feet long. • Main site for the chemical digestion of food. • Primary site for absorption of water, vitamins, minerals, and the products of carbohydrate, fat and protein digestion. • Secretions that aid digestion: o Pancreas secretes pancreatic juice: contains bicarbonate. ▪ Neutralizes the acid in the chy me. ▪ Makes the environment of the small intestine neutral or slightly basic. o Pancreatic amylase: enzyme that continues the breakdown of starch and sugars. o Pancreatic proteases: enzymes that breakdown protein to shorter chain amino acids. o Lipases: fat digesting enzymes. o Gall bladder stores and secretes bile made by the liver . ▪ Aids in fat digestion and absorption. • Absorption o Diffusion: movement of substances from an area of high concentration to an area of lower concentration. o Simple diffusion: material moves freely across the cell membrane. o Osmosis: unassisted diffusion of water across the cell membrane. o Facilitated diffusion: a ca rrier molecule is needed for a substance to cross the cell membrane. o Active transport: requires energy and a carrier molecule. ▪ Can transport material from an area of lower concentration to one of higher concentration. The Large Intestine • About 5 feet long. • Divided into the colon, and the rectum. • Water and some vitamins a nd minerals can be absorbed in the colon. • Peristalsis occurs slowly. Fecal material may spend 24 hours or more in the colon. • Intestinal microbiota : beneficial bacteria o Breakdown unabsorbed portions of food. o This breakdown may produce gas, which causes fla tulence. • Rectum: temporarily stores unabsorbed material until it is evacuated through the anus as feces. Digestion in Health and Disease The Digestive System and Disease Prevention • Intestinal Microbiota: o Most of the 100 trillion microorganisms in the gut are found in the colon o Established in infancy and early childhood o A healthy microbiota resists change under physiological stress and supports health o Right mix is needed for optimal GI function, maintenance of immune function, and overall health • Intestinal Microbiota Functions: o Act on unabsorbed food and substances secreted by GI tract to produce nutrients used by the bacteria and can affect human health o Helps maintain mucosal layer lining the intestine ▪ Serves as a ba rrier ▪ Modulates inflammation in the gut ▪ Prevents growth of disease causing bacteria o Assists in maturation of immune system • Unhealthy Microbiota: Less diverse , u nable to maintain balance between beneficial and harmful bacteria, b een implicated in develop ment of intestinal diseases o Chrohn’s disease , Obesity , Type 2 diabetes , Colon cancer , Heart disease • Effect of Diet on Microbiota : determines the food available to the microorganisms in the gut and therefore what bacteria grow there. • What a Scientist Sees: Bacteria on the Menu o Prebiotic: a substance that passes undigested into the colon and stimulates the growth and/or activity of c ertain types of bacteria. o Probiotic: live bacteria that, when consumed, live temporarily in the colon and confer health benefits on the host. • Mucosa of the GI tract contains tissue that is part of the immune system. o Antigen: foreign substance. Stimulates an immune response when introduced to the body. o Phagocytes: type of white blood cell; part of the body’s defense. o Lymphocytes: specific type of white blood cell. • Food Allergies: o Food allergies affect 5% adults and 8% children in U.S. Even a tiny amount can cause anaphylaxis and can be fatal. o Antibodies: proteins released by a type of lymphocyte; interact with and deactivate specific antigens. o Allergen: a substance causing an immune reaction. ▪ An allergic reaction occurs when the immune system produ ces antibodies to a substance. ▪ Common food allergens: peanuts, tree nuts, milk, eggs, fish, shellfish, soy, and wheat. Manufacturers must clearly state on the label any of the 8 major allergens. • Celiac disease: a protein gluten, found in wheat, barley and rye, triggers an immune system response that damages or destroys the villi of the small intestine. o Causes: abdominal pain, diarrhea and fatigue. o Can lead to: malnutrition, weight loss, anemia, osteoporosis, intestinal cancer, and other chronic ailments. o Also called: gluten intolerance, celiac sprue, non -tropical sprue, gluten sensitive enteropathy. o Diagnosed by a blood test or intestinal biopsy; inherited condition (1% of the population) . o Treatment: Eliminate all products made with wheat, barley, or rye DEBATE: Should You Be Gluten -Free? • Gluten -free diets are essential for people with gluten -related disorders, but a gluten - free diet has also been promoted for weight loss and to treat a host of other ailments.

Should you be gluten free? Digestive System Problems and Discomforts • Heartburn and gastroesophageal reflux: when the acidic contents of the stomach leak back into the esophagus. Produces a burning sensation in the chest or throat. • GERD: gastroesophageal reflux disease: a chronic condition in which acidic stomach contents leak into the esophagus, causing pan and damaging the esophagus. o If left on treated can lead to bleeding, ulcers and cancer. o To avoid discomforts: limit amounts and types of foods consumed; eat small meals; consume beverages between rather than with meals; avoid fatty and fried foods, chocolate, peppermint, and caffeinated beverages; remain upright after eating; wear loose clothing; avoid smoking and alcohol; lose weight. • Peptic Ulcers: open sores in the lining of the stomach, esophagus, or small intestine. o Causes: GERD; misuse of medications such as aspirin or nonsteroidal anti - inflammatory drugs; infection with the bacterium Helicobacter pylori (H. pylori) . ▪ H. pylori can be treated with antibiotics. • Gallstones: clumps of solid material that accumulates in either the gallbladder or the bile duct. o They can cause pain when the gallbladder contracts in response to fat in the intestine. o Treatment: removal of the gallbladder. • Diarrhea and constipation: common discomforts related to problems in the intestines. o Diarrhea: frequent water y stools. ▪ Can be caused by: bacterial or viral i nfections; irritants that inflame the lining of the GI tract; the passage of undigested food into the large intestine; medications; and chronic intestinal diseases. ▪ Causes loss of fluids and minerals. ▪ Can be life threatening if lasting for more than a day or two. o Constipation: hard, dry stools that are difficult to pass. ▪ Occurs when the water content of the stool is too low. ▪ Causes: low intake of water or lack of fiber; lack of exercise; weakening of the muscles of the large intestine; and a variety of med ications. ▪ Prevention: drinking plenty of fluids; consuming a high fiber diet; and getting plenty of exercise. What Should I Eat? For Digestive Health • Reduce your risk of adverse reactions. o Read food labels to avoid foods that you are allergic to. o Chew each bit thoroughly to maximize digestion and avoid choking. o Don’t talk with food in your mouth. o Learn the Heimlich maneuver: You could save a life. • Reduce the chances of heartburn. o Eat enough to satisfy your hunger but not so much that you are stuffed. o Wa it 10 minutes between your first and second courses to see how full you feel. o Stay upright after you eat – don’t flop on the couch in front of the television. • Avoid constipation by consuming enough fiber and fluid. o Choose whole -grain cereals such as oatmea l or raisin bran. o Double your servings of vegetables at dinner. o Eat two pieces of fruit with your lunch. o Choose whole -grain bread. o Have one or two beverages with or before each meal. Thinking It Through: Case Study on How Changes in the Digestive System Affect Health (Answers: Appendix L ) • Medications and their effect on saliva production. • Ill-fitting dentures. • Dietary fiber increased. • Treatment for colon cancer. • Gallstones. • Deficiency of pancreatic enzymes. • Gastric banding surgery. Delivering Nutrients and Eliminating Wastes The Cardiovascular System • Delivery of digested and absorbed nutrients to the cells. • Capillaries: small, thin -walled blood vessels through which blood and the body’s cells exchange gases and nutrients. • Lacteals: lymph vessels in the villi of the small intestine that pick up particles containing the products of fat digestion. o Part of the lymphatic system. • Heart and blood vessels: the heart is the workhorse of the cardiovascular system. o Vei ns: blood vessels that transport blood and dissolved substances toward the heart. ▪ Venules: the smallest veins. o Arteries: blood vessels that transport blood and dissolved substances away from the heart. ▪ Arterioles: the smallest blood arteries. • Blood flow at rest: 25% of blood goes to the digestive system; 20% to skeletal muscles; and the rest to the heart, kidneys, brain, skin and other organs. o Changes when eating or exercising. • Blood flow during exercise: 70% directed to skeletal muscles during stren uous exercise. Delivering Nutrients to the Liver • Liver acts as a gatekeeper between the body and substances absorbed from the intestine. o Some nutrients are stored in the liver, some are changed into different forms, and others are allowed to pass through unchanged. • Hepatic portal vein: carries molecules from the intestine to the liver. • The liver determines whether nutrients are stored or delivered immediately to the cells. • The liver is important in the synthesis and breakdown of amino acids, proteins and lipids. • The liver contains enzyme systems that protect the body from toxins absorbed in the GI tract. The Lymphatic System • An important component of the immune system. • Absorbs fat -soluble nutrients such as cholesterol, fatty acids, and fat -soluble vitamins • Removes fluids from tissues to prevent swelling • Contains immune cells to fight infection Elimination of Wastes • Gastrointestinal tract: material not absorbed from the gut is eliminated as feces. • Lungs: carbon dioxide and some water. • Skin: water, minerals and some nitrogen containing material. • Kidneys: primary site for the excretion of metabolic wastes. Overview of Metabolism • Metabolism: chemical reactions that break down molecules to provide energy and those that synthesize l arge molecules • Metabolic pathways: actions of metabolism • Mitochondria: cell organs that responsible for breaking down molecules to release energy. Releasing Energy • Cellular respiration: occurs in the mitochondria. The breakdown of glucose, fatty acids and amino acids in the presence of oxygen to produce carbon dioxide and water and release energy. • Adenosine triphosphate (ATP): a high -energy molecule that the body uses to power activities. Synthesizing New Molecules • Glucose molecules are used to synthesize the glycogen and, in some cases, fatty acids. • Fatty acids are used to make body fat, cell membranes, and regulatory molecules. • Amino acids are used to synthesize the various proteins that the body needs, and when necessary, to make glucose. Exce ss amino acids can also be converted to fatty acids and stored as body fat.