NUTR 251 Textbook Notes
NUTR 251 Textbook Notes NUTR 251
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Chapter 1 Food Choices: Preference Habit Ethic heritage and regional cuisines Social interactions Availability, Convenience, Economy Positive and negative association Emotions Values—religious, political, environmental Body weight and image Nutrition and health benefits Cultural competence: having an awareness and acceptance of cultures and the ability to interact effectively with people of diverse cultures Functional foods: foods that have a potentially beneficial effect on health when consumed as part of a varied diet on a regular basis at effective levels Phytochemicals: nonnutrient compounds found in plants Nutrients Body composition: 60% water, 18-21% fat for men 23-26% fat for women, and the rest is carbohydrates, proteins, vitamins, and minerals Minerals: chemical element so atoms are all alike and identity never changes Inorganic nutrients: do not contain carbon (minerals, water) Organic: containing carbon bonds, carbon is an element found in all living things (carbohydrates, lipids, proteins, vitamins) Essential nutrients (indispensible nutrients): nutrients a person must obtain from food because the body cannot make them for itself in sufficient quantity to meet physiological needs Energy yielding nutrients: nutrients that break down to yield energy the body can use (carbs, fats, proteins) o Macronutrients: body requires them in large amounts o Micronutrients: requires only small amounts o Calorie: a measure of heat energy…1000 calories=1 kcalorie 1 kcalorie is the amount of heat necessary to raise the temperature of 1 kg of water 1 degree Celsius o Energy density: a measure of the energy a food provides relative to the weight of the food A gram of carbohydrate yields about 4 kcals A gram of protein yields about 4 kcals A gram of fat yields 9 kcals Denser foods cause weight gain, less dense foods cause weight loss o Energy not used up in the day gets converted into storage o Proteins are found in muscles and skin and help to regulate digestion and metabolism Vitamins: organic, essential nutrients that do not provide energy but facilitate the release of energy from carbs, fats, and proteins o Vulnerable to destruction by heat, light, and chemical agents o Using moderate temperatures for shorter periods of time and small amounts of water to preserve vitamins from vegetables The Science of nutrition Genome: complete set of genetic material in an organism or a cell. The study of genomes is called genomics Nutritional genomics: the science of how nutrients affect the activities of genes and how genes affect the interactions between diet and disease Anecdote: personal account of an experience, is not reliable Blind experiment: an experiment in which the subjects do not know whether they are members of the experimental group or the control group Correlation: the simultaneous increase, decrease, or change in two variables. If A increases as B increases the correlation is positive. IF A increases as B decreases the correlation is negative Double blind experiment: neither the subjects nor the researchers know which subjects are members of the experimental group until after the experiment is over Peer review: a panel of scientist evaluate a research study to ensure the scientific method is followed Randomization: choosing the experimental and control members without bias Replication: repeating the experiment and getting the same results Scientific Method Observation and question Hypothesis and prediction Experiment Results and interpretations o Theory: if hypothesis is supported o New observation and questions if hypothesis is not supported Parts of a Research Article Abstract: brief overview of the article Methodology: defines key terms and describes the study designs, subjects, and procedures Results: report findings and may include tables and figures Discussion: draws conclusions that are supported by the data and reflect the original purpose…usually answers questions and raises more References: reflect investigators knowledge of the subject and should include relevant studies Dietary Reference Intakes (DRI): set of nutrient intake values for healthy people in the US and Canada Estimated Average Requirement (EAR): average daily amount of a nutrient needed to prevent deficiency o Used to set goals for groups, like school children Recommended Dietary Allowance (RDA): average daily amount of a nutrient considered adequate to meet the nutrient needs of practically all healthy people o Used to set goals for individuals Adequate intakes (AI): average daily amount of a nutrient that appears sufficient to maintain a specified criterion. Used as a guide for nutrient intake when an RDA cannot be determined Tolerable Upper Intake Level (UL): maximum daily amount of a nutrient that appears safe for most healthy people and beyond there is an increased risk of adverse health effects Estimated Energy Requirement (EER): average dietary energy intake that maintains energy balance and good health in a person of a given age, gender, weight, height, and level of physical activity Acceptable Macronutrient Distribution Ranges (AMDR): ranges of intakes for the energy nutrients that provide adequate energy and nutrients and reduce the risk of chronic diseases. o 45-65 percent kcalories from carbohydrates o 20-35 percent kcals from fat o 10-35 percent kcals from protein Estimates of adequate energy and nutrient intakes apply to healthy people. Amounts need to be adjusted for those with medical problems Recommendations can only target most of the people Nutrient goals should be met with a variety of foods. Supplements increase risk of toxicity Recommendations apply to average daily intakes Food and Agriculture Organization (FAO) World Health Organization (WHO) Nutrition Assessment Malnutrition: any condition caused by excess or deficient food energy or nutrient intake by an imbalance of nutrients Undernutrition: deficient energy or nutrients Overnutrition: excess energy or nutrients Assessment uses: historical information, anthropometric measurements, physical examinations, laboratory test o Anthropometric: measurement of the physical characteristics of the body such as height and weight o Overt: out in the open and easy to observe Primary Deficiency: a nutrient deficiency cause by inadequate dietary intake of a nutrient Secondary deficiency: a nutrient deficiency cause by something other than inadequate intake such as a disease or drug interaction Subclinical deficiency: a deficiency in the early stages before outward signs appear Covert: hidden symptoms Risk Factor: condition or behavior associated with elevated frequency of a disease but not proved to be casual o Risk factors persist over time o Risk factors cluster…example is an obese person may be physically inactive, have high blood pressure, and high cholesterol o Risk factors that can change are focused on like eating right or quitting smoking Nutrition information and misinformation Academy of Nutrition and Dietetics: professional organization of dieticians in the US Accredited: approved Dietetic technician: a person who has completed a minimum of an associates degree from an accredited university or college and an approved dietetic technician program Dietetic technician registered (DTR): a dietetic technician who has passed a national examination and maintains registration through continuing professional education Dietitian: a person trained in nutrition, food science, and diet planning Diploma mills: entities without valid accreditation that provide worthless degrees Fraudulent: the promotion for financial gain of devices, treatments, services, plans, or products that alter or claim to alter a human condition without proof of safety or effectiveness Public health dietitians: dietitians who specialize in providing nutrition services through organized community efforts Registered dietitian nutritionist (RDN): person who has completed a minimum of a bachelors degree from an accredited university, has completed approved coursework and a supervised practice program, has passed a nation examination, and maintains registration through continuing professional education Registration: listing with a professional organization that requires specific course work, experience, and passing of an examination Chapter 2 Principles and guidelines: Eating pattern: customary intake of foods and beverages over time Adequacy: providing all the essential nutrients, fiber, and energy in amounts sufficient to maintain health Balance: providing foods in proportion to one another and in proportion to the body’s needs Kcalorie control: management of food energy intake nutrient density: a measure of nutrients a food provides relative to the energy it provides. The more nutrients and the fewer kcals, the higher the nutrient density empty kcal foods: foods that contribute energy but lack protein, vitamins, and minerals Nutrient profiling: ranking foods based on their nutrient composition Moderation: providing enough but not too much of a substance Solid fats: fats that are not usually liquid at room temperature. Contain more saturated and trans fats than most oils Added sugars: sugars and other kcaloric sweeteners that are added to foods during processing, preparation, or at the table. Do not include the natural sugars found in fruits and milk products Variety: eating a wide selection of foods within and among the major food groups A healthy diet Emphasizes a variety of fruits, vegetables, whole grains, and low fat milk products includes lean meats, poultry, seafood, legumes, eggs, seeds, and nuts Is low in saturated and trans fats, cholesterol, salt, and added sugars stays within your daily energy needs for you recommended body weight Diet Planning Guides Food group plans: diet planning tools that sort foods into groups based on nutrient content and then specify that people should eat certain amounts of foods from each group o Fruits contribute folate, vitamin A, vitamin C, potassium, and fiber 1 Cup fruit= 1 cup fresh, frozen, canned ½ cup dried fruit 1 cup 100% fruit juice o Vegitables contribute folate, vitamin A, vitamin C, vitamin K, vitamin E, magnesium, potassium, and fiber 1 Cup vegetebals = 1 cup cut up raw or cooked 1 cup cooked legumes 1 cup vegitable juice 2 cups raw leafy greens o Grains contribute folate, niacin, riboflavin, thiamin, iron, magnesium, selenium, and fiber 1 oz grains= 1 slice bread ½ c cooked rice, pasta, cereal 1 oz dry pasta or rice 1 cup ready to eat cereal 3 cup popped popcorn o proteins contribute protein, essential fatty acids, niacin, thiamin, vitamin B6, vitamin B12, iron, magnesium, potassium, and zinc 1 oz protein= 1 oz cooked lean meat, poultry, seafood 1 egg ¼ c cooked legumes or tofu 1 tbs peanut butter ½ oz nuts or seeds o Milk and milk products contribute protein, riboflavin, vitamin B12, calcium, potassium, and when fortified vitamin A and D 1 cup milk or mil product= 1 cup milk, yogurt, fortified soymilk 1 ½ oz natural cheese 2 oz processed cheese o Oils contribute vitamin E and essential fatty acids 1 tsp oil= 1 tsp veg. oil 1 tsp. soft margarine 1 tbs low fat mayo 2 tbs light salad dressing Vegitables sorted into 5 groups o Dark green deliver vitamin B o red and orange provide vitamin A o legumes supply iron, protein, zinc o starchy vegetables contribute carbohydrate energy o other provides more nutrients and add more the same nutrients Legumes: plants of the bean and pea family, with seeds that are rich in protein compared with other plant derived foods. Can be counted as protein group or vegetable group o protein, iron, zinc, fiber, folate, potassium Discrectionary kcals: the kcals remaining in a person’s energy allowance after consuming enough nutrient dense foods to meet all nutrient needs for a day Serving sizes: standardized quantity of a food Portion sizes: the quantity of a food served or eaton at one meal or snack, not a standard amount Healthy eating index: a measure that assesses how well a diet meets the reccomendations of the dietary guidelines for Americans Exchange lists: diet planning tools that organize foods by their proporitons of carbohydrate, fat, and protein. Foods on any single list can be used interchangeably Processed foods: foods that have been treated to change their physical, chemical, microbiological, or sensory properties fortified: the addition to a food of nutrients that were either not origionally present or present in insignificant amounts Refined: process by which the coarse parts of a food are removed Enriched: the addition to a food of specific nutrients to replace losses that occur during processing sot that the food will meet a specified standard Whole grain: a grain that maintains the same relative proportions of starchy endosperm, germ, and bran as the original o Bran: protective coating around kernel of grain rich in nutriets and fiber o endosperm: contains start and proteins o germ: seed that grows into a wheat plant, rich in vitamins and minerals o husk: inedible part of the grain o In early 1940s congress passed legislation requiring that all grain products be enriched with iron, thiamin, riboflavin, niacin, and folate Textured vegitable protein: processed soybean protei used in vegetarian products such as soy burgers Imitation foods: foods that substitute for and resemble another food, but are nutritionally inferior to it with respect to vitamin, mineral, or protein content Food substitutes: foods designed to replace other foods Food Labels Don’t need label if: o foods contributing few nutrients, plain coffee, tea, spices o foods produced by small businesses o foods prepared and sold in the same establishment restaurants are required to post information if have more than 20 locations All packaged foods must list all ingredients in decending order of predominance Daily values: reference values developed by the FDA specifically for use on food labels Percent daily value: the percentage of a daily vale recommendation found in a specified serving of food for key nutrients based on a 2000-kcal diet o Total food energy o Total fat o saturated fat o trans fat o cholesterol o sodium o Total carbohydrate o dietary fiber o sugars o added sugars o proteins o Vitamin D o calcium o Iron o Potassium Nutrient claims: statements that characterize the quantity of a nutrient in a food health claims: statements that characterize the relationship between a nutrient or other substance in a food and a disease or health related condition Structure function claims: statements that characterize the relationship between a nutrient or other substance in a food and its role in the body Free: nutritionally trivial and unlikely to have a physiological consequence High: 20% or more of the daily value for a given nutrient per serving Less: at least 25% less of a given nutrient or kcals than the comparison light: one third fewer kcals than the comparison food/ 50% less of the fat or sodium than the comparision Low: an amount that would allow frequent consumption of a food without exceeding the daily value for the nutrient More: at least 10% more of the daily value for a given nutrient than the comparison organic: at least 95% of the ingredients have been grown and processed accoroding to USDA regulations defining the use of fertilizers, herbicides, insecticides, fungicides, preservatives, and other chemical ingredients Kcal free: fewer than 5 kcals per serving low kcal: 40 kcals or less Reduced kcal: at least 25% fewer kcals per serving than the comparison percent fat free: must meet definition of low fat or fat free and must reflect amount of fat in 100 grams Fat free: less than .5 g of fat per serving low fat: 3 grams or less less fat: 25% less than the comparision low saturated fat: 1 g or less of saturated fat and less than .5g of trans fat cholesterol free: less than 2 mg of cholesterol and 2g or less of saturated fat and trans fat low cholesterol: 20 mg or less of cholesterol and 2 grams or less of saturated fat and trans fat extra lean: less than 5 grams of fat, 2 grams sasturated fat and trans fat combined, 95 mg of cholesterol per serving lean: less than 10g of fat, 4.5 g saturated fat and trans fat combined and 95 cholesterol High fiber: 5 grams or more of fiber per serving low sodium: 140 mg or less per serving very low sodium: 35 mg or less per serving Chapter 3 DIGESTION: the process by which food is broken down into absorbable units Gastrointestinal (GI) tract: digestive tract, extends from mouth, through the esophagus, stomach, small intestine, large intestine, and rectum to the anus. Gallbladder: the organ that stores and concentrates bile. When it receives the signal that fat is present in the duodenum, the gallbladder contracts and squirts bile through the bile duct into the duodenum Lumen: the inner space within the GI tract Sphincter: a circular muscle surrounding, and able to close a body opening. Found at specific points along the GI tract and regulate the flow of food particles Mouth: oral cavity containing the tongue and teeth Teeth crush large pieces of food and mix with saliva and fluids from foods to ease swallowing Fluids help dissolve food so tongue can taste it; only particle in solution can react with taste buds o When stimulated taste buds detect one of the taste sensations: sweet, sour, bitter, salty, and umami (savory flavor associated with monosodium glutamate) o Aroma, appearance, texture, and temperature affect flavor When swallowed it passes through the pharynx o Pharynx: the passageway leading from nose and mouth to the larynx and esophagus, respectively The epiglottis closes off airway to the lungs so you don’t’ choke o Epiglottis: cartilage in the throat that guards the entrance to the trachea and prevents fluid or food form entering it when a person swallows o Trachea: allows air to pass to and from lungs Bolus: a portion of food swallowed at one time Esophagus: the food pipe; the conduit from the mouth to the stomach Esophageal sphincter (cardiac sphincter): a muscle at the upper or lower end of the esophagus During a swallow the upper esophageal sphincter opens and food slides down esophagus which passes through a hole in the diaphragm to the stomach Lower esophageal sphincter at entrance to stomach closes behind bolus so it does not slip back into esophagus Stomach: muscular, elastic, saclike portion of the digestive tract that grinds and churns swallowed food, mixing it with acid and enzymes to form chyme Stomach wall releases juices to bolus and transfers food to its lower portion and grinds it into a semiliquid mass called chyme. Chyme: semiliquified mass of partially digested food expelled by the stomach into the duodenum Bit by bit the stomach releases chyme through pyloric sphincter which opens into the small intestine and closes behind the chyme o Pyloric sphincter (pylorus, or pyloric valve): circular muscle that separates the stomach from the small intestine and regulates the flow of partially digested food into the small intestine. Opens about 3x per minute Small intestine: 10-foot length of small diameter. Secretes enzymes that digest all energy yielding nutrients to smaller nutrient particles; cells of wall absorb nutrients into blood and lymph. Segments are duodenum, jejunum, and ileum Chyme bypasses the opening from common bile duct o Bile duct drips fluids into the small intestine from the gallbladder and pancreas Chyme travels down the small intestine through duodenum, jejunum, and ileum o Duodenum: the top portion of the small intestine o Jejunum: the first 2/5 of the small intestine beyond the duodenum Ileum: the last segment of the small intestine Pancreas: a gland that secretes digestive enzymes and juices into the duodenum. Manufactures enzymes to digest all energy yielding nutrients and releases bicarbonate to neutralize acid chyme that enters the small intestine. Also secretes hormones into the blood that help to maintain glucose homeostasis. o Pancreatic duct: conducts pancreatic juice from the pancreas to the small intestine Large intestine or colon: Absorbs water and minerals; passes waste along with water to the rectum Its segments are the ascending colon, the transverse colon, the descending colon, and the sigmoid colon Ileocecal valve: the sphincter separating the small and large intestines in lower right side of abdomen When entering the colon, the chyme passes another opening, if food slipped into opening it would lead to appendix o Appendix: a narrow blind sac extending from the beginning of the colon that contains bacteria and lymph cells Chyme travels through the large intestine to the rectum while withdrawing water leaving semisolid waste. Rectum and anal canal hold back waste until its time to defecate and then they relax o Rectum: muscular terminal part of the intestine, extending from the sigmoid colon to the anus o Anus: terminal outlet of the GI tract, two sphincters open to allow passage of waste Peristalsis: wavelike muscular contractions of the GI tract that push its contents along GI tract is ringed with circular muscles, surrounded by longitudinal muscles. When rings tighten and long muscles relax the tube is constricted, when the rings relax and the long muscles tighten the tube bulges Waves ripple along GI tract at varying rates and intensities depending on part of GI tract and whether food is present Factors such as stress, medicine, and medical conditions may interfere with contractions Stomach has third layer of diagonal muscles that also contract and relax Segmentation: periodic squeezing or partitioning of the intestine at intervals along its length by its circular muscles Sphincter muscles periodically open and close allowing contents of GI tract of move along at a controlled pace Reflux: a backward flow SECRETIONS OF DIGESTION: from salivary glands, the stomach, the pancreas, the liver, and the small intestine Enzyme: a protein that facilitates a chemical reaction Digestive enzyme: proteins found in digestive juices that act on food substances, causing them to break down into simpler compounds o Catalyst: a compound that facilitates chemical reactions without itself being changed in the process o Hydrolysis: a chemical reaction in which a water molecule is split into two molecules with hydrogen added to one and a hydroxyl group added to the other o –ase: suffix denoting an enzyme. The root of the word identifies the compound the enzyme works on. Carbohydrase: an enzyme that hydrolyzes carbs Lipase: an enzyme that hydrolyzes lipids Protease: an enzyme that hydrolyzes proteins Glands: cells or groups of cells that secrete materials for special uses in the body o Exocrine glands secrete materials out o Endocrine glands secrete materials in Salivary glands: exocrine gland that secretes saliva into the mouth o Saliva: contains water, salts, mucus, and enzymes that initiate the digestion of carbs. It protects the teeth, and linings of mouth esophagus and stomach from substances that might cause damage Gastric glands: exocrine glands in the stomach wall that secrete gastric juice into the stomach o Gastric juice: mixture of water, enzymes, and hydrochloric acid o Hydrochloric acid HCL: acid composed of hydrogen and chloride atoms that is normally produced by the gastric glands pH: unit of measure expressing a substances acidity or alkalinity. The lower the pH the higher the H+ ion concentration and the stronger the acid. A pH above 7 is alkaline, or base (a solution in which OH- ions predominate) o High acidity of stomach prevents bacterial growth and kills most bacteria that enters the body with food Mucus: a thick white slippery substance secreted by cells of the GI lining that protects the cells from exposure to digestive juices, enzymes, and disease causing bacteria Mucus membrane: the lignin of the GI tract with a coat of mucus o Pancreatic juice: exocrine secretion of the pancreas that contains both enzymes for the digestion of carbohydrate, fat, and protein as well as bicarbonate. Juice flows from pancreas into small intestine through the pancreatic duct Bicarbonate: an alkaline compound with the formula HCO3 that is secreted from the pancreas as part of the pancreatic juice (also produced in all cell fluids from the dissociation of carbonic acid to help maintain the body’s acid base balance Bile: an emulsifier that prepares fats and oils for digestion. An exocrine secretion made by the liver, stored in the gallbladder, and released into the small intestine when needed o Emulsifier: a substance with both water soluble and fat soluble portions that promotes the mixing of oils and fats in a watery solution o Liver: manufactures bile salts, detergent like substances, to help digest fats Stools: waste matter discharged from the colon ABSORPTION: the uptake of nutrients by the cells of the small intestine for transport into either the blood or the lymph Villi: fingerlike projections from the folds of the small intestines. Lined with thin sheet of muscle so it can wave, squirm, and wriggle like tentacles of sea anemone Microvilli: tiny hair like projections on each cell of every villus that can trap nutrient particles and transport them into the cells Crypts: tubular glands that lie between the intestinal villi and secrete intestinal juices into the small intestine Goblet cells: cells of the GI tract and lungs that secrete mucus When nutrient molecule has crossed the cell of a villus, it enters either the bloodstream or lymphatic system o Water soluble nutrients and smaller products of fat digestion are released directly into the bloodstream and guided directly to liver, where their destination will be determined o Larger fats and the fat-soluble vitamins are insoluble in water. The intestinal cells assemble many of the products of fat digestion into larger molecules that cluster together with special proteins forming chylomicrons Chylomicrons carry fats and are released into lymphatic system. They move through the lymph until they can enter the bloodstream at a point near the heart. They bypass the liver at first o Some foods eaten together can enhance each other’s use into the body. Simple diffusion: (water and small lipids). They cross into intestinal cells freely Facilitated diffusion: (water soluble vitamins) nutrients need a specific carrier to transport them from one side of the cell membrane to the other. May occur when carrier changes the cell membrane in such a way that the nutrients can pass though Active transport: (glucose and amino acids) nutrients move against a concentration gradient, which requires energy Endocytosis: cell membrane engulfs the molecule, forming a sac that separates from the membrane and moves into the cell THE CIRCULATORY SYSTEMS Vascular system (blood circulatory): closed system of vessels through which blood flows continuously with the heart serving as the pump. As the blood circulates through the system it picks up and delivers materials as needed All body tissues derive nutrients and oxygen from the blood and deposit carbon dioxide and other wastes back into the blood o Lungs exchange oxygen and carbon dioxide o Kidneys filter wastes out of blood to be excreted in urine o Blood leaves right side of heart, circulates through the lungs and back to the left side of the heart. Then pumps blood out of the aorta through arteries to all systems of the body. Blood circulates in the capillaries where it exchanges material with the cells and then collects into veins which return it again to the right side of the heart Heart-arteries-capillaries-veins-heart Aorta: large primary artery that conducts blood from the heart to the body’s smaller arteries Arteries: vessels that carry blood from the heart to the tissues Capillaries: small vessels that branch from an artery. Capillaries connect arteries to veins. Exchange of oxygen, nutrients, and waste materials take place across capillary walls Veins: vessels that carry blood to the heart o Hepatic portal vein: the vein that collects blood from the GI tract and conducts it to the liver o Hepatic vein: the vein that collects blood from the liver and returns it to the heart Heart-arteries-capillaries-hepatic portal vein- capillaries-hepatic vein-heart Liver is first to receive nutrients from GI tract Lymphatic System: a loosely organized system of vessels and ducts that convey fluids toward the heart. The GI part of the system carries the products of fat digestion into the bloodstream Lymph: a clear yellowish fluid that is similar to blood except that it contains no red blood cells or platelets. Lymph from the GI tract transports fat and fat soluble vitamins to the bloodstream via lymphatic vessels o Circulates between cells of the body and collects into tiny vessels. Fluid moves as muscles contract and create pressure here and there o Thoracic duct: the main lymphatic vessel that collects lymph and drains into the left subclavian vein o Subclavian vein: the vein that provides passageway from the lymphatic system to the vascular system Nutrients that enter the lymphatic system (large fats and fat soluble vitamins) ultimately enter the bloodstream and circulate normally but they bypass liver at first HEALTH AND REGULATION OF GI TRACT Infants often spit up due to poor coordinated peristalsis and sphincter action Older adults experience constipation because intestinal wall loses strength and elasticity with age Diseases can interfere with digestion and absorption and can lead to malnutrition Lack of nourishment can alter the structure and functions of GI cells Gastrointestinal microbiome Microbes: microscopically small organisms including bacteria, viruses, fungi, and protozoa, and other microorganisms Human microbiome: the collection of microbes found in or on the human body o 100 trillion outnumber the body’s cells tenfold representing more than 400 species o Few can live in low pH of stomach with rapid peristalsis but large intestine permits the growth of abundant population Prebiotics: food components (such as fibers) that are not digested by the human body but are used as food by the GI bacteria to promote their growth and activity o May reduce risk of GI infections, inflammation, and disorders Probiotics: living microorganisms found in foods and dietary supplements that when consumed in sufficient quantities are beneficial to health o Yogurt: milk product that results from the fermentation of lactic acid in milk by Lactobacillus bulgaricus and streptococcus thermophiles o Health benefits to probiotics include alleviating diarrhea, constipation, inflammatory bowel disease, ulcers, allergies, lactose intolerance, infant colic, enhance immune function, and protect against colon cancer o Bacteria can produce biotin, vitamin K, foliate, pantothenic acid, riboflavin, thiamin, vitamin B6, vitamin B12 Gastrointestinal hormones and nerve pathways Homeostasis: maintenance of constant internal conditions by the body’s control systems. Constantly reacting to external forces to maintain limits set by the body’s needs Hormones: chemical messengers. Secreted by a variety of glands in response to altered conditions into eh body. Each hormone travels to one or more specific target tissues or organs where it elicits a specific response to maintain homeostasis Feedback mechanisms: a certain condition demands a response. The response changes that condition, and the change then cuts off the response o Gastrin: food enters the stomach and stimulates cells in stomach wall to release gastrin. Gastrin stimulates stomach glands to secrete hydrochloric acid. When the pH is reached, they stop producing gastrin o Pyloric sphincter opens to let out a little chyme then closes again o Secretin: hormone produced by cells in the duodenum wall. It stimulates the pancreases to secrete bicarbonate rich pancreatic juice to maintain alkaline pH o Pancreas secretes a mixture of enzymes to digest carbs fats and proteins. The composition of the mixture depends on what foods you have eaten o Pancreas protects itself from harm by producing an inactive form of the enzymes and releases the proteins into the small intestine where they are activate to become enzymes o Cholecystokinin (CCK): Fat in the intestine stimulates intestinal walls to release CCK. The hormone travels by blood to the gallbladder and stimulates release of bile into small intestine. Also travels to the pancreas to stimulate its juices, which release bicarbonate and enzymes into small intestine. Also slows GI motility in response to fat and protein Intestinal ischemia: diminished blood flow to the intestine that is characterized by abdominal pain, forceful bowel movements, and blood in the stool Lifestyle factors: Sleep allows for repair and maintenance of tissue and removal of wastes that might impair efficient functioning Activity promotes healthy muscle tone Stress alters GI motility, secretions, permeability, blood flow, and bacteria CHOKING When food slips into trachea and completely blocks air passageways. The person cannot cough or breath o Trachea (windpipe): air passageway from larynx to lungs. o Larynx (voice box): the entryway to the trachea the contains the vocal chords Vomiting: expulsion of the contents of the stomach up through the esophagus to the mouth Diarrhea: the frequent passage of watery bowel movements… treatment is rehydration Intestinal contents have moved too quickly through the intestines for fluid absorption to take place or that water has been drawn from the cells lining the intestinal tract and added to the food residue Irritable bowel syndrome: an intestinal disorder of unknown cause. Symptoms include abdominal discomfort and cramping, diarrhea, constipation, or alternating diarrhea and constipation o Most cases GI contractions are stronger and last longer than usual forcing intestinal contents through quickly causing gas, bloating, and diarrhea o Some cases the GI contractions are weaker than normal and causes constipation o Bloating: uncomfortable abdominal fullness or distension o Symptoms worse after certain foods and stress o Medication such as antispasmodic drugs and peppermint oil Colitis: inflammation of the colon, may suffer from severe diarrhea. Benefit from bowel rest and medication. Surgery to remove rectum and colon may be necessary Celiac disease: an intestinal disorder in which the inability to absorb the protein portion of gluten results in an immune response that damages intestinal cells Gluten triggers inflammation which damages villi and decreases nutrient absorption Symptoms include abdominal pains, bloating and gas, and diarrhea Constipation: the condition of having infrequent or difficult bowel movements Symptoms are strain during bowel movements, hard stools, infrequent bowel movements, abdominal discomfort, headaches, backaches, and passing of gas If you don’t respond to bodies sign to defecate the body continues to withdraw water making it harder to defecate later Increased fiber, fluids, and exercise are recommended before use of medication Fibers found in fruits, vegetables, and whole grains increase fecal mass attracting water creating soft bulky stools Eating prunes and exercising help Hemorrhoids: painful swelling of the veins surrounding the rectum Diverticula: sacs or pouches that develop in the weekend areas of the intestinal wall Diverticulitis: infected or inflamed diverticula Diverticulosis: the condition of having diverticula Laxatives: substances that loosen the bowels and thereby prevent or treat constipation Mineral oil: purified liquid derived from petroleum and used to treat constipation Colonic irrigation (colonic hydrotherapy): popular but potentially harmful practice of washing the large intestine with a powerful enema machine o Enema: solution inserted into the rectum and colon to stimulate a bowel movement and empty the lower large intestine o Side effects include cramping, abdominal pain, bloating, nausea, vomiting, infections, kidney failure, pancreatis, heart failure, death Belching: results from swallowing air. The release of air or gas from the stomach through the mouth Eating too fast, chewing gum, carbonated beverages Flatulence: passage of excessive amounts of intestinal gas Foods rich in carbs, sugars, starches, and fibers When partially digested carbs reach the large intestine bacteria digest them giving off a gas byproduct Gastroesophageal reflux: the backflow of stomach acid into the esophagus, causing damage to the cells of the esophagus and the sensation of heartburn Tight clothing, changes in position, weight gain increases the severity Eat less in a sitting, eat more slowly, chew food more thoroughly, loose weight, drink between meals, eat small meals, wait before lying down or exercising, refrain from smoking, Indigestion: incomplete or uncomfortable digestion, usually accompanied by pain, nausea, vomiting, heartburn, intestinal gas, or belching Acid controllers: medications used to prevent or relieve indigestion by suppressing production of acid in the stomach. Pepcid AC, Zantac, Axic AR Antacids: medications used to relieve indigestion by neutralizing acid in the stomach. Alka seltzer, Maalox, Rolaids, tums Ulcer: a lesion of the skin or mucous membranes characterized by inflammation and damaged tissues Bacterial infection H.pylori, use of anti inflammatory drugs such as aspirin, ibuprofen, and naproxen, and disorders that cause excessive gastric acid secretion Avoid alcohol and caffeine If ulcer is bacterial, over the counter medications causes inflammation Peptic ulcer: a lesion in the mucous membrane of either the stomach or duodenum Chapter 4 Carbohydrates: compounds composed of carbon, oxygen, and hydrogen, arranged as monosaccharaides or multiples of monoscaccarhides. Most but not all carbs have a ration of one carbon molecule to one water molecule Provide about half of the energy muscles and body tissues use, the other half comes from fat All plant foods (whole grains, vegetables, legumes, and fruits) and milk provide carbohydrate Each atom can form a certain number of chemical bonds with other atoms o Hydrogen-1 o Oxygen-2 o Nitrogen-3 o Carbon-4 Monosaccharides: carbohydrates of the general formula C H O n 2n n that typically form a single ring o Hexoses: sugars with six atoms of carbon and the formula C H O . 6 12 6 o Glucose: sometimes known as blood sugar in the body or dextrose in foods One of two sugars in every disaccharide and unit from which polysaccharides are made o Fructose: sometimes known as fruit sugar or laevulose. Found abundantly in fruits, honey, and saps Sweetest of sugars Arrangement of atoms stimulates the taste buds to produce the sweet sensation o Galactose: part of the disaccharide lactose Appears naturally in foods as a single sugar in very small amounts Disaccharides: sugars composed of pairs of monosaccharides (simple carb) o Condensation: a chemical reaction in which water is released as two molecules combine to form one larger product o Hydrolysis: a chemical reaction in which one molecule is split into two molecules with hydrogen added to one and a hydroxyl group to the other Commonly occur during digestion o Maltose: disaccharide composed of two glucose units sometimes known as malt sugar Produced whenever starch breaks down Occurs during fermentation process that yields alcohol Minor constituent of a few foods, like barley o Sucrose: a disaccharide composed of glucose and fructose, commonly know as table sugar, beet sugar, or cane sugar. Occurs in many fruits and some vegetables and grains Sweetest of disaccharides because it contains fructose To make table sugar, sucrose is refined from the juices of sugarcane and sugar beets then granulated. Depending on the level it was refined becomes the brown, white, and powdered sugars o Lactose: disaccharide composed of glucose and galactose, commonly known as milk sugar Contributes half of energy provided by fat-free milk Polysaccharides: large molecules composed of chains of monosaccharides (complex carbs) o Glycogen: an animal polysaccharide composed of hundreds of glucose units in highly branched chains. Each new molecule needs a special protein for the attachment of the first glucose Storage form of glucose manufactured and stored in the liver and muscles Not a significant food source of carbohydrate and is not counted as a dietary carbohydrate in foods Found to a limited extent in meats and not at all in plants When hormones tell the liver to release energy, enzymes respond by attacking the branches of glycogen simultaneously, making a surge of glucose available o Starches: plant polysaccharides composed of hundreds of glucose molecules Long branched (amylopectin) or unbranched (amylose) chains of hundreds or thousands of glucose molecules linked together Grains, rice, Tubers (yams and potatoes), legumes (peas and beans) When you eat the plant, body hydrolyzes the starch to glucose and uses the glucose for its own energy purposes Grains are richest food source of starch, providing much of food energy for people all over the world o Fibers Dietary fibers: in plant foods, the nonstarch polysaccharides that are not digested by human digestive enzymes, although some are digested by GI tract bacteria Often described as nonstarch polysaccharides Contribute no monosaccharides and therefore very little energy Soluble fibers dissolve in water to form a gel (viscous) and are easily digested (fermented) by bacteria in colon. An example is pectin from fruit used to thicken jellies o Found in oats, barley, legumes, and citrus fruits o Associated with protecting against heart disease and diabetes by lowering blood cholesterol and glucose levels Insoluble fibers: do not dissolve in water or form gels and are less readily fermented. Examples are skins of corn kernels and stings in celery o Mostly in whole grains and vegetables o Promote bowel movements, prevent diverticular disease Functional fibers: manufactured and then added to foods or used in supplements Total fiber: sum of dietary fibers and functional fibers Resistant starches: starches that escape digestion and absorption in small intestine of healthy people o Commonly in whole or partially milled grains, legumes, and just ripened bananas. Cooked potatoes, pasta and rice that have all been chilled contain resistant starch o May support a healthy colon Phytic acid (phylate): non-nutrient compound of plant seeds. Occurs in husks of grains, legumes, and seeds and is capable of binding minerals such as zinc, iron, calcium, magnesium, and copper in insoluble complexes in the intestine which the body excretes unused Sugars: simple carbohydrates composed of monosaccharides, disaccharides, or both DIGESTION MOUTH: o Chewing slows eating and stimulates flow of saliva o Amylase: an enzyme that hydrolyzes amylose (form of starch) to shorter polysaccharides and to the disaccharide maltose o Carbohydrase: enzyme that breaks down carbohydrates STOMACH: o Stomach acid inactivates the amylase. o Fibers are not digested and linger in the stomach, delaying gastric emptying, providing satiety o Satiety: feeling of fullness and satisfaction that occurs after a meal and inhibits eating until the next meal. Determines how much time passes between meals SMALL INTSESTINE: o Pancreatic amylase enters the intestine via the pancreatic duct and continues breaking down polysaccharides to shorter glucose chains and maltose o In outer membranes of cells specific enzymes break down specific disaccharides Maltase breaks maltose into two glucose molecules Sucrase breaks sucrose into one glucose and one fructose molecule Lactase breaks lactose into one glucose and one galactose molecule LARGE INTESTINE o Within 1-4 hours after a meal all the sugars and most of starches have been digested o Fibers in the large intestine attract water which softens stools for passage o Bacteria in GI ferment some fibers which generates water, gas, and short chain fatty acids o Cells of colon use small fat molecules for energy o Metabolism of short-chain fatty acids also occurs in cells of the liver ABSORPTION Glucose can be absorbed to some extent through the lining of the mouth Glucose and galactose enter the cells lining the small intestine by active transport Fructose is absorbed by facilitated diffusion As blood from small intestine circulates through the liver, cells take up fructose and galactose and most often convert them to compounds within the same metabolic pathways as glucose Fructose and galactose are mostly metabolized in liver whereas glucose is sent out to the body’s cells for energy All disaccharides provide at least one glucose molecule directly and they can provide the equivalent to another one indirectly though the metabolism of fructose and galactose in the liver 1. Monosaccharides enter the capillaries of intestinal villi 2. Monosaccharides travel to liver via the portal vein 3. In the liver galactose and fructose share metabolic pathways with glucose 4. Glucose is used by most cells in the body Normally intestinal cells produce enough lactase to ensure that lactose found in milk is both digested and absorbed efficiently o Lactase activity is highest after birth and declines during childhood and adolescence. About 30% of people in the world retain enough lactase to digest and absorb lactose efficiently throughout adult life o Lactose intolerance: a condition that results from the inability to digest the milk sugar lactose; characterized by bloating, gas, abdominal discomfort, and diarrhea. Differs from milk allergy which is caused by an immune reaction to the protein in milk o Lactase deficiency: the lack of lactase May develop when villi are damaged by disease, certain medications, prolonged diarrhea, or malnutrition May be temporary or permanent Extreme cases infants are born with deficiency Prevalence is lowest among Scandinavians and Northern Europeans, highest among North Americans and southeast Asians 30-50 million people in US are lactose intolerant Many people can consume foods containing up to 6g of lactose without symptoms Increase milk products gradually, consume with other foods in meals, spread their intake throughout the day Yogurt improves lactose intolerance A change in number, type, and activity of GI bacteria accounts for ability to adapt to milk products Kefir: fermented milk created by adding Lactobacillus acidophilus and other bacteria that break down lactose to glucose and galactose producing a sweet lactose free product Hard cheeses such as cheddar and cottage cheese are often well tolerated because most of lactose is removed with the whey during manufacturing Lactose continues to diminish as cheese ages You can add enzyme tablets to milk People who consume few milk products need to be careful to get enough riboflavin, vitamin D, and calcium needs GLUCOSE Primary role is to provide energy for the body Sugars attached to a protein change the proteins shape and function; when they bind to lipids in a cell’s membranes, sugars alter the way cells recognize one another After a meal, blood glucose rises, liver cells link excess glucose molecules by condensation reactions into long, branching chains of glycogen. When blood glucose falls, the liver cells break down glycogen by hydrolysis reactions into single molecules of glucose and release them into the bloodstream Liver stores about 1/3 of body’s total glycogen and releases glucose when needed Muscles store glycogen but use most of it during exercise Brain retains small amount of glycogen for times of severe deprivation Glycogen holds water and is bulky o Body can only store enough glycogen to provide energy for relatively short periods of time o For long term energy reserves the body uses fat Inside a cell a series of reactions break glucose into smaller compounds that yield energy when broken down completely to carbon dioxide and water Gluconeogenesis: the making of glucose from a noncarbohydrate source such as amino acids or glycerol Protein sparing action: action of carbohydrate and fat in providing energy that allows protein to be used fro other purposes With less carbohydrate providing glucose, fat takes an alternative metabolic pathway o Instead of entering the main pathway, fat fragments combine with one another forming ketone bodies o Ketone bodies: acidic compounds produced by the liver during the breakdown of fat when carbohydrate is not available o Ketosis: an undesirably high concentration of ketone bodies in the blood and urine o Acid-base balance: the equilibrium in the body between acid and base concentrations o Body needs at least 50-100g of carbohydrates a day When glucose is abundant energy metabolism shifts to use more glucose instead of fat, if that isn’t enough to liver breaks glucose into smaller molecules and puts them together into fat. The fat then travels to fatty tissues of the body for storage. Fat cells can store unlimited quantities of fat If blood glucose falls below normal a person may become dizzy and weak, if it rises above normal a person may become fatigued o Insulin: hormone secreted by special cells in pancreas in response to elevated blood glucose concentration. Controls the transport of glucose from the bloodstream into the muscle and fat cells As circulating insulin contacts the body’s cells, receptors respond by ushering glucose from the blood into the cells Most of cells take only the glucose they can use right away but liver and muscle cells assemble the small glucose units into long branching chains of glycogen for storage o Glucagon: hormone secreted by special cells in the pancreas in response to low blood glucose concentration. Elicits release of glucose from liver glycogen stores o Epinephrine: hormone of adrenal gland that modulates the stress response. When administered by injection epinephrine counter acts anaphylactic shock by opening the airways and maintaining heart beat and blood pressure Works to release glucose from liver glycogen to the blood Diabetes: metabolic disorder characterized by elevated blood glucose resulting from insufficient insulin, ineffective insulin, or both. When blood glucose levels are higher than normal but below the diagnosis of diabetes, the condition is called prediabetes o Hyperglycemia: elevated blood glucose concentrations o Fasting plasma glucose: a test that measures plasma glucose after a person has fasted for at least 8 hours o A1C: a test that measures the percentage of hemoglobin that has glucose attached, which helps to diagnose diabetes and evaluate long term glycemic control. The higher the percentage, the higher a persons blood glucose levels have been over time o 7th among leading causes of death o Contributes to heart disease, stroke, hypertension, blindness, and kidney failure o Glucose fails to get to cells and accumulates in blood. Elevated glucose alters glucose metabolism in every cell of body Some cells convert excess glucose to sugar alcohols causing toxicity and cell distention Some cells produce glycoproteins by attaching excess glucose to an amino acid in a protein leading to blood vessels and nerves to be damaged leading to loss of circulation and nerve function Poor circulation and glucose rich blood and urine lead to infections o Type 1: less common type in which the pancreas produces little or no insulin. Usually results from autoimmune destruction of pancreatic beta cells Autoimmune disorder: a condition in which the body develops antibodies to its own proteins and then proceeds to destroy cells containing these proteins Body develops antibodies to its insulin and destroys the pancreatic cells that produce the insulin creating an insulin deficiency Commonly occurs in childhood or adolescence but can occur at any age Must receive insulin by injection or pumps. Cannot be taken orally because it is a protein and the enzymes would digest it Controlling blood glucose, achieving a desirable blood lipid profile, controlling blood pressure, monitor physical activity with blood glucose o Type 2: more common 90-95% of cases, cells fail to respond to insulin. Usually accompanies obesity and results from insulin resistance coupled with insufficient insulin secretion Muscle and adipose cells cannot remove glucose from the blood and liver cells continue to make glucose. To compensate the pancreas secretes more insulin and plasma insulin concentrations rise to abnormally high levels (hyperinsulinemia) Over time the pancreas become less able to compensate for cells reduced sensitivity and hyperglycemia worsens High demand for insulin can exhaust the beta cells of the pancreas and lead to impair insulin secretion and reduced plasma insulin concentrations The amount of insulin is insufficient to compensate for its diminished action in cells Caused by obesity, poor dietary habits, smoking, excessive alcohol, aging, physical inactivity More common in Native Americans, Hispanic Americans, Mexican Americans, African Americans, Asian Americans, and pacific islanders Inflammation contributes to insulin resistance o Helps to eat meals and snacks at regularly scheduled times, eating similar amounts of food at each meal, choose nutritious foods that will promote healthy body weight High fiber foods recommended, reduce the intake of added sugars, reduce saturated fat to less than 10% kcal, limit cholesterol to less than 300 mg, limit trans fat as much as possible, foods rich in Omega 3 are recommended, drink alcohol in moderation o Atherosclerosis is more severe in people with diabetes o Microangiopathies: disorder of small blood vessels (capillaries) Can lead to loss of kidney function and retinal degeneration with accompanying loss of vision o Nerve tissue deteriorates expressed as a painful prickling sensation often in arms or legs, later a person can loose feeling in hands or feet Loss of circulation and nerve function can lead to an undetected injury or infection and can lead to death of tissue (gangrene) necessitating amputation Hypoglycemia: abnormally low blood glucose concentration o Symptoms: weakness, rapid heartbeat, sweating, anxiety, hunger, trembling
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