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BPK/KIN110 MIDTERM NOTES (CH1-5).docx

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Department
Biomedical Physio & Kines
Course
BPK 110
Professor
Diana Bedoya
Semester
Fall

Description
CHAPTER 1Nutrition Food choices and Nutrient Intake  Nutrients: Substances in food that humans need to live and grow.  Essential Nutrients: nutrients that body cannot make itself, but human must consume to maintain health o The body need +40 essential nutrients to stay healthy  Calorie: amount of energy provided by food. 1 kilocalorie = 1 Calorie = 1000 calories o Carbohydrates, fats and protein are nutrients that provide us with energy  Chronic diseases: long term diseases such as heart disease or obesity that often negatively affect physical and mental health and increase risk of early morality o Develop due to overconsumption of energy and nutrients such as fats and sodium  Nutrient density: a measure of nutrients provided by a food relative to its calorie content o Choosing food high in nutrient density allows you to obtain more nutrients in fewer calories o If your diet consist of foods that are mostly low in nutrient density (chips, pop), you will exceed calorie needs before meeting nutrient needs  Fortified foods: foods to which one or more nutrients have been added (eg vitamin water)  Dietary supplements: products that supplement the diet - may include nutrients (eg vitamins), enzymes, herbs or other substances – eg multivitamins o Supplements provides nutrients but do not offer all benefits of food, may provide false sense of security regarding health, increase risk of consuming toxic levels of a nutrients What determines Food Choices?  Taste, smell, appearance, and texture, Emotional attachments to certain foods, Cultural and societal norms, Geographic availability, Environment, Health consciousness, Psychological states, Price, convenience, accessibility, Social Influences Six Classes of Nutrients and Their Functions  Macronutrients: needed in large amount (carbs, lipids, proteins, water)  Micronutrients: needed in small amount (vitamins and minerals)  Organic compounds: substances that contain carbon bonded hydrogen in their molecular structure o Carbs, lipids, proteins are classified as organic compounds b/c they all contain carbon in their structure 1. Carbohydrates: sugars, starches, and fibres  Organic o Example: rice, pasta, bread (high in starch); Berries, broccoli (high in fibre); Cookies, cake, soda (high in sugar); Vegetables and fruits – excellent source of carbs with vitamins, minerals and fibre  Fibre: a type of carbs that cannot be digested by human enzymes (help you poo) 2. Lipids: fats : cholesterol, saturated fats, unsaturated fats  Organic - most do not dissolve in water o Example: high fat plant food (veg oils, olives, nuts, avocadoes) – no cholesterol and high in unsaturated fat; high fat animal foods (butter, meat, whole milk) high in saturated fat and cholesterol  Cholesterol: found in diet and in blood, essential component of every cell and can be used to form hormones, bile and vitamin D (High blood levels of cholesterol can increase the risk of heart disease)  Saturated fats: lipids that contain no double bonds in their structure, are most abundant in solid animal fats and may be associated with an increased risk of heart disease  Unsaturated fats: lipids that contain one or more double bonds in their structure, most abundant in plant oils, may be associated with a reduced risk of heart disease 3. Proteins: made up of units called amino acids that link together in different combinations to form different proteins  Organic - promote growth and development of body o Example: meat, fish ,eggs – match our amino acid needs better than plants (nuts, beans) 4. Water: the only single substance nutrient – inorganic because no carbon  Body cant store it so we lose it through sweat, urination 5. Vitamins: Organic molecules that are needed in small amounts to maintain health – fat soluble & water soluble 6. Minerals: Non-organic chemical elements (found on periodic table) – eg iron, calcium Body Weight = 6% minerals, carbs, other, 16% fat, 16% protein, 60% water Functions of Nutrients A. Energy for body processes and physical activity o Carbs, lipids, proteins are energy-yielding nutrients and can be measured in calories (typically kilocalories)  Fats (9 kcal/g) – major form of stored energy  Carbohydrates (4 kcal/g) – most immediate source of energy  Protein (4 kcal/g) – not immediate choice for energy needs, because protein’s have other vital roles  (Note: Alcohol provides 7 kcal/gram, but is not a nutrient)  Water, minerals and vitamins do not provide energy o Energy allow body to perform various body processes, eg carrying nerve signals o If intake more energy than is needed for basic body processes plus physical activity, excess is stored as fat tissue for later use B. Forming/Maintaining Body structure o All but vitamins  Examples: Fats under skin provides cushioning and insulation for body, Proteins form ligaments and tendons that hold bones together, and attach muscles to bones, Minerals harden bone, Protein and water make up structure of muscles C. Regulating Body Processes o All nutrients help control how quickly chemical reactions take place throughout the body, these reactions are needed to maintain relatively temperature, blood pressure, blood sugar level and blood acidity.  Example: fats and proteins are needed to make regulatory molecules called hormones that stimulate/inhibit various body processes Additional health benefits from foods (non-nutritive substances) Phytochemicals: substances found in plant foods that are not essential nutrients but may have health promoting properties  Fruits vegetables and whole grains provide a variety of phytochemicals; although individual phytochemicals are available to as dietary supplements, there's little evidence that they provide the same health benefits  Garlic, broccoli, and onions provide sulphur-containing phytochemicals that help protect us from some form of cancer by in activating carcinogens or stimulating the body's natural defenses  Yellow orange fruits and vegetables (Peaches, carrots, cantaloupe, leafy greens) are rich in carotenoids, which are phytochemicals that may prevent oxygen from damaging ourselves Functional foods: Foods that have health promoting and/or disease preventing properties beyond basic nutritional functions  Examples – blueberries may help reduce the risk of heart disease and cancer, Whole-grain bread – help reduce the risk of obesity and diabetes  Neutraceuticals/ designer foods = food that are fortified with nutrients or enhanced with phytochemicals (Vitamin Water, Omega-3 eggs) Nutrition in Health and Disease Malnutrition : Consuming too much or too little of one or more nutrition or energy  Undernutrition = when intake doesn't meet the bodies needs o Dehydration = Deficiency of water, symptoms appear in a few hours ( headache, fatigue dizziness) o Osteoporosis = Deficiency of calcium, Bones become weak and break easily, symptoms occurs after years  Overnutrition = An excess intake of calories or nutrition that exceeds body needs o Overdose of iron can cause liver failure, too much vitamin D can cause nerve damage - Foods generally do not contain high concentration of nutrients to be toxic, these toxicities usually result from taking large doses of vitamin and minerals supplements o Health problems (obesity) can also result from chronic overconsumption of calories and certain nutrients from food o Canadian diet usually provides more calories than needed, resulting in the epidemic of obesity - 60% of Canadians are overweight or obese Diet – Gene Interactions  Genes can increase or decrease risk of developing heart disease, cancer, high blood pressure, and type 2 diabetes  The nutrients and food components you consume and amount of exercise, can increase/decrease your risk of developing nutrition-related disease o Nutritional genomics/ nutrigenomics - Study of how diet affects our genes and how individual genetic variation can affect the impact of nutrients or other food components on health Choosing a healthy diet  Variety = Choosing foods from different groups, diverse foods from within these groups – Different foods provide different nutrients and health-promoting substances  Moderation = Not too much or too little, help maintain weight and prevent chronic diseases  Balance = Balance less healthy choices with healthier choices, Balance nutrients, Balance energy in and energy out Evaluating Nutrition Information  Credible nutrition information is founded on reputable studies based on the scientific method  This process typically begins with a hypothesis, a proposed explanation for a problem that can be tested Epidemiological studies  Observations are made without manipulation of variable, to find patterns, trends and associations o Example hypothesis: ‘Population A has a higher consumption of omega-3 fatty acids than population B. Does population A thus have a lower risk of heart disease?’  It is critical to remember that association does not equal causation; we cannot fully account for all the possible reasons for the observed outcome o Ex. If population A has lower iheart disease risk, it could be due to their physical activity patterns, genetics, other dietary patterns, or more likely than not, a combination of factors. Experimental studies  A hypothesis is tested under controlled conditions  Typically use 2 groups of similar subjects o Treatment group: undergoes the treatment o Control group: does not undergo treatment, may receive placebo o Observe differences between groups when only one/few variables are changed between the two groups  A study is increasingly credible if it is o Blind: the subjects don’t know which group they are in o Double-blind: both the researchers and the subjects don’t know who is in which group  Biochemistry, molecular biology and computer modelling techniques can also be used to study nutrition using the scientific method  Collecting data is important, but it is also imperative that this data is analyzed properly, and that accurate conclusions are drawn  The peer-review process that scientists undergo to submit studies for publication helps ensure that studies have been properly conducted and that results have been properly analyzed  Anecdotal evidence is not proof – story you hear from someone else CHAPTER 2Guidelines forHealthyDiet Nutrition Recommendations  Recommended Nutrient Intakes – first food guidelines Canada released during WW2 o Provided info on the amount of essential nutrients needed to meet needs o Canada’s Official Food Rules 1942 – first food guide, based on RNI  Today RNI has become the Dietary Reference Intakes (DRIs), focus on promoting health and preventing chronic disease and nutrient deficiencies  Dietary recommendations can be used as a standard for assessing the nutritional status of individual/population o NS = individual’s health as it is influenced by intake and utilization of nutrients  Info about food intake, nutritional status, food availability, can help identify potential nutrient deficiencies/excesses  These evaluations is important for developing public health measures that address nutritional problems – eg 2004 survey found 70% male and 50% female exceed daily caloric intake, and magnesium and vitamin A were common nutrient deficiencies  this led health experts to develop programs and recommendations, update good guide to improve health of Canadians Dietary Reference Intakes (DRIs)  DRI = Recommendations for the amounts of energy, nutrients, and other food components that should be consumed by healthy people to promote health, reduce chronic disease, prevent deficiencies o Health Canada compare what people consume and what is recommended on DRI, and make recommendations accordingly. Eg 2004 many Canadians lack Vitamin A (increase risk for vision problems), now change good guide to advise to eat one orange vegetable (excellent sources of vitamin A) o DRI replaced RNI and includes several types of recommendations that address both nutrient and energy intake and include values that are appropriate for people of different genders and stages of life – take into account the physiological differences Recommendations for Nutrient Intake  Estimated Average Requirements (EARs) – Nutrient intakes estimated to meet the needs of 50% of the healthy individuals in a given gender and life-stage group  what we figure out from lab test o Determined from data on nutrient needs and are used to assess adequacy of a population’s food supply or typical intake o Not appropriate for evaluating individual’s intake but used to calculate RDA  Recommended Dietary Allowances (RDAs) – Nutrient intakes that are sufficient to meet the needs of almost all healthy people in a specific gender and life-stage group  use EAR to find RDA to set standard for everyone o Recommend nutrient intake required to meet 98% of population’s needs, typically 20% above EAR values o Most recommendations for adequate nutrient intake levels are based on RDA for each specific nutrient  Adequate Intakes (AIs) – Nutrient intakes that should be used as a goal when no RDA exists. o Sometimes not enough data to establish EAR/RDA, so AI values are set, based on typical intake levels of people that are said to be healthy and show no symptoms of deficiency/toxicity  RDA and AI can be used as goals for individual intake and to plan and evaluate individual diets o These values represent the amounts most health people consume on average over days/weeks, not everyday o Values meet 98% of people, so intake below RDA or AI does not mean deficiency, but risk of deficiency is greater  Tolerable Upper Intake Levels (ULs) – maximum daily intake levels that are unlikely to pose risks of adverse health effects to almost all individuals in a given gender and life-stage group o Maximum amount of nutrient that most people can consume on a daily basis without some adverse effect o Usually, can’t exceed UL by consuming food, but dietary supplements/fortified foods may cause toxicity Recommendations for Energy Intake  Estimated Energy Requirements (EERS) – estimates number of kilocalories needed to keep body weight stable. o Include age, gender, weight, height, weight, level of physical activity  Acceptable Macronutrient Distribution Ranges (AMDRs) – healthy range of intake for carbs, fat, proteins – expressed as a percentages of total energy intake o 10-35% calories of protein o 45-65% carbs o 20-35% fat o Recommend healthy intake while range allow flexibility in food intake patterns “Eating Well with Canada’s Food Guide 2007“ Vegetables and Fruit  Excellent source of vitamins, minerals, fibre, phytochemicals  Recommend: one dark green + one orange vegetable/ day o Dark green= eg broccoli, romaine lettuce, spinach  decrease risk of heart disease/cancer o Orange = carrots, sweet potatoes, winter squash  rich in vitamin A, vital for proper eye function  Choose them with no added fat/salt/sugar, steamed, baked or stir fried instead of deep fried  Eat in natural form, more veg/fruits than juice, consume most % of nutrients  Frozen/canned is okay too, similar in nutritional content as fresh if frozen quickly  Be wary of products that include ‘veg’ or ‘fruit’ – eg candies, ketchup, jam – has much added sugar and fat, little nutrient Grain Products  Best source of fibre, low in fat  Only promote weight gain if consumed in an amount that increases overall energy intake beyond required level – leading to storage of energy as fat tissue  Recommend: make at least half of grain product as whole grain/day o Barley, brown rice, oats, quinoa, wild rice, whole grain bread, whole wheat pasta o Decrease heart disease/type 2 diabetes o White/bleached/refined do not provide same benefits  Check labels – make sure is not white coloured with molasses - choose low in fat, sugar or salt check first ingredients (should be whole wheat/oats/etc)  Limit cookies, cakes, pastries, pies Milk and Alternatives  Rich source of calcium and vitamin D o Calcium – numerous body processes such as muscle contraction, hormone secretion and nerve conduction o Vita, min D – vital for strong bones/teeth  Recommend: 500ML (2 cups) of milk/soy everyday  If choose milk alternatives – choose lower fat with less than 20% milk fats, eg on yogurts or cheese  Use less cream cheese, ice cream, coffee, whipping cream, sour cream, etc – high in fats and calories Meat and meat alternatives  Rich source of protein, fats and iron, vitamin B and essential for energy regulation  Many meat are dense in nutrients, so only a small amount is needed to satisfy needs  Should not over consume meats is because they are high in saturated fat  Have meat alternatives such as beans, lentils and tofu often  cheap, high in fibre, low in fat, dense in nutrients  Select lean meat with little salt/added fat  Recommend: Eat at least two servings of fish – eg char herring mackerel salmon sardines trout o Fish – high in omega 3 fatty acids, improve heart health o Large fish – eg tuna, shark – concentrate heavy metals such as mercury – esp albacore tuna o Most canned tuna use younger tuna, less mercury o Salmon, smelt, shellfish, clams mussel – relatively low in mercury  Water - Essential to many body process, maintain blood pressure, regulate temperature, esp during exercising and during hot weather  Vitamins o Pregnant women – consume folic acid supplement o Vitamin D for people 50+ Food and Natural Health Product Labels Food Labels Basic labelling requirements 1. Statement of identity 2. Net Content of the Package (eg 50 g) 3. Name and address of manufacturer, packer, distributor 4. List of ingredients (listed in descending order by weight) 5. Nutrient information – nutrient facts panel) o Durable life date – amount of time produce retain its freshness, taste, quality o Nutrition Facts Panel – info on nutrients, serving size, calories  Daily Value – a reference value for the intake of nutrients used on food labels to help consumers see how a given food fits into their overall diet  Amount recommended for a 2000 kcal diet, eg 10% of a 2000 kcal diet  Nutrient content claims – describe the amount of nutrient in a food eg fat free, low sodium  Diet-related health claims o Disease-reduction - eg “diet rich in fruits, may reduce risk of some cancer; product X is rich in veg and fruit”  Cannot say ‘product X reduce cancer’ – too much importance on consumption of the product itself, not on tis health promoting ingredients o Function claims – eg relate to well-established beneficial effects of food on the normal function of the body  eg calcium helps promote bone and teeth, fibre maintain bowel regularity Natural Health Product Labels  NHP eg multivitamin pills, herbal remedies, probiotics etc  They are regulated by the National Health Products Directorate, a branch of Health Canada  Must be approved, get a license to be sold, get a Natural Product Number  Must include name, license number, list of ingredients, recommended uses, any cautionary statement  Do not need to include Nutrition Facts Panel CHAPTER 3Digestion Organization of Life  Atoms form molecules, form cells, form tissues, form organs, form organ systems, form the entire organism o Nutrient molecules make cells, Cells outside fats – inside mostly water  11 major organ systems  Digestive system bring nutrients to other systems, and other assist the digestive in return o Eg - Endocrine – produce and release hormones (help regulate how much we eat and how quickly food and nutrients travel through the digestive system Digestive System  Primarily responsible for digestion and absorption of nutrients o Must first break down foods into small pieces (digestion) o Before they can enter the blood stream/lymphatic system (absorption)  Water, vitamins and minerals can be absorbed by the body  Proteins  amino acids, carbs  sugars/glucose, fats  fatty acids, before they can be absorbed  Fibre cannot be digested/absorbed, but promote digestive health as it travels through us untouched, eliminated in feces, including unabsorbed food residue, bacteria, mucus, dead cells Structure of Digestive System  Digestive system  o Digestive tract (mouth, pharynx, esophagus, stomach, small intestine, large intestine)  DT = Hollow tube 9m, from mouth to anus, also called Gastrointestinal tract  Lumen = inside hole area of tube with digestive liquid, and a layer of mucosal cells o Accessory organs (salivary glands, liver, gallbladder, pancreas)  Transit time from mouth to anus is typically 24-72 hours – varies with diet, physical activity, emotional state, health status and medication us  Mucus = lubricates, moistens, protect the digestive tract  Enzymes = protein molecules that accelerate the rate of specific chemical reactions without being changed themselves o The process of hydrolysis uses water to break down larger molecules into smaller ones o The process of condensation, take out water, brings two smaller molecules together to form a larger one o Both can occur with or without an enzymes, but most do because they vastly increase their speed o Lactase break down lactose – sucrase  sucrose (glucose and fruitcose) ? Digestion and Absorption of Nutrients MOUTH  Chemical digestion: food stimulates flow of saliva from various salivary glands o Saliva contains the enzymes:  salivary amylase - breaks down carbohydrates (starches)  lingual lipase - breaks down lipids o Also contains lysozyme - an antibacterial substance, prevent tooth decay o Primarily composed of water, which act as a solvent  Mechanical digestion: use of tongue, teeth (32) to physically digest food PHARYNX (aka throat)  Conduit where food or air passes through  The epiglottis (flap that covers the lungs during swallowing) lies between the pharynx and esophagus/treachea o directs a bolus (mass of chewed food mixed with saliva) from the pharynx to the esophagus when closed o directs air from the pharynx to the trachea (windpipe) when open ESOPHAGUS  Passageway and mechanical assistance for moving food between pharynx and the stomach o Does not participate in digestion  Food is moved by peristalsis (contraction of smooth muscle to move food down the GI tract ) Spincter  From Esophagus to stomach, food must pass through a sphincter (layer of muscle that encircles the DT and act as valve) o When contract, valve is closed; relaxes is open o (TOP) Lower Esophageal Sphincter (between stomach and esophagus) prevents food from moving back into esophagus  Acidic stomach content can leak up through a weakened sphincter into the esophagus, causing a “heart burn” o (BOTTOM) Pyloric Sphincter (at the bottom of the stomach) controls how long food stays in the stomach STOMACH  The stomach has three layers of smooth muscle: longitudinal, horizontal and diagonal o Powerful contractions allow for optimal churning and mixing.  Temporary storage for food  Turns the bolus into a semiliquid chyme (very acidic)  Lining of stomach covered with gastric pits, which contains cells that produce the contents of gastric juice Gastric Juice  Helps chemical digestion in stomach (protein mostly)  Contents: o Water: acts as a solvent o Mucus: protects the proteins that make up the stomach wall from hydrochloric acid and pepsin o Pepsinogen: inactive form of the enzyme pepsin (digest protein) o Hydrochloric acid: turn pepsinogen into pepsin (activates it) denatures proteins, activates pepsin o * pepsin is secreted in the inactive form so it will not damage the gastric glands that produce it Regulation of Stomach Motility and Secretion 1. Sensory of food causes brain to send nerve signals that stimulate gastric secretions and increase the rate of stomach churning or motility, preparing stomach to receive food 2. Stomach stretches due to food intake, signal brain to stimulate the secretion of gastrin (hormone that increase the release of gastric juice) 3. When fat/carbs chyme enter SI, trigger release of hormone GIP, contracts pyloric sphincter, ensure amount of chyme entering SI do not exceed the intestine’s ability to process it 4. When amino acids/fats chyme enters SI, hormone CCK is released  a. stimulates contraction of gallbladder, release bile to help digest fat b. (5) CCK also stimulate pancreas to secrete proteases, lipases, and amylase to SI to help digest protein, fats, carbs 6. Acidic chyme entering SI release the hormone secretin. Secretin stimulates pancreas to secrete bicarbonate into SI to neutralize the acidity of chime SMALL INTESTINE  Majority of digestion and absorption occurs here  Both peristalsis and segmentation occur here o Segmentation = another type of movement called, muscular contractions, mix chyme with digestive enzymes and help absorption (doesn’t move food forward) that aid in digestion and absorption, do not significantly propel chyme forward  3 segments: duodenum (25-30 cm), jejunum (1.2m) and the ileum (1.5m) o Most digestion in duodenum, absorption occurs along the entire length  Structure: Narrow 6m tube - Long length - Massive surface area! - About the size of a tennis court! o Large circular o 1 folds increase surface are in contact with nutrients  Entire inner surface is covered with finger-like projections called villi, covered with microviolli – nutrients must pass through to go to bloodstream Secretions found in the SI  Pancreas secretes pancreatic juice, which contains these enzymes: o Bicarbonate: neutralize the acidity of chyme o Pancreatic amylase: converts starches into sugars o Pancreatic protease: protein-digesting enzymes (also released in inactive form) o Lipases: break down lipids into fatty acids  Liver makes Bile (aid if digestion /absorption of fats), stored in Gallbladder, then secrets into SI o When fat enter small intestine, hormone CCK tells gallbladder release bile into SI o Bile helps package fat into carrier molecules called micelle, which help travel to wall of intestine  SI intestinal digestive enzymes o Aid digestion of disaccharides (double sugars to single), short amino acids chains (into single amino acid) o Then all pass into blood and are delivered to the liver (gatekeeper, decides what to do with carbs/amino acids) Chemical Digestion in Small intestine Carbs  Pancreatic amylase digest Starch -> double sugar/short sugar  Enzymes in microvilli digest double into single, then absorbed into blood to liver  Fibre cannot be digested, passes to large intestine Protein  Pancreatic protease digest proteins (long amino acid chains) -> short amino acid chains  Enzymes in microvilli break short into single AA, absorbed into muscosal cells, to blood to liver Lipid  Bile help divide large fat globules  Pancreatic lipases digest fat molecules -> fatty acids that combine with bile and other lipids to form small droplets  Small droplets aid the absorption of fatty acids and other fat soluble substances into muscosal cells  Absorbed fats are incorporated into transport particles o Larger fatty particles pass into the lymph, smaller may pass directly to blood stream Absorption Mechanisms  After food breaks down into subunits, now must be absorb into circulatory system where they can be stored, excreted or transported to where needed  Small intestine – main site for absorption  To be absorbed, must pass form lumen, through mucosal cells, then into bood/lymph  Depending on the nutrient, it is absorbed in one of the following ways: o Simple diffusion: substance pass freely across cell membrane, from an area of higher concentration to an area of lower concentration, no energy is required o Osmosis: passage of water molecules (from an area of lower concentration of dissolved substances to high) o Facilitated diffusion: requires a carrier molecule (blue), molecules from high to low o Active transport: requires a carrier molecule AND energy, molecules move from low to high LARGE INTESTINE  Absorb water and some vitamins and minerals  Materials not absorbed in the small intestine pass through a sphincter between SI and LI o The sphincter prevents material from larger intestine from re-entering the small intestine o Materials can be broken down by colonic bacteria and then absorbed o Remaining undigested is packaged into feces for excretion into the external environment via the anus  Approx. 1.5 metres long, divided into the ceacum, colon (majority), rectum, anus o Colon – 4 segments: ascending colon, transverse colon, descending colon, sigmoid colon o Rectum – temporary holding point for feces o Anus – digestive tract opens to the exterior of body  Peristalsis is slower here than in SI  Materials spend 24 hours here (3-5 in SI) o Slow movement help growth of intestinal microbiota = native bacteria which promote digestion  Break down undigested food (fibre), produce nutrients for microbiota  Synthesize small amounts of B vitamins and vitamin K  Produce gas! Causes flatulence (bloating)  If body lack appropriate enzymes to break down carbs in beans/milk (lactose), colonic microbiota take over the task but might cause much bloating  Unabsorbed matter is packaged into feces for excretion  segmental structure and muscle contractions force feces to be sectioned  pass into rectum, stored temporarily o Feces are a mixture of undigested absorbed matter, dead cells, secretions form GI tract, water, bacteria  Fiber and fluid rich diets promote more water in feces  easier to excrete Bacteria in the Large Intestine  300-500 species of bacteria in large intestine  Contribute to immune functions, growth and development of colon cells, intestinal motility/transit time, digestion, prevention of diarrhea (with antibiotic use),  Probiotic: a living organisms (typically bacteria) found in food that contributes to intestinal health (IS ALIVE BACTERIA)  Prebiotic: a dietary fibre that promotes the growth of healthy intestinal bacteria (IS FOOD FOR BACTERIA) o Eg yogurts Digestion in Health and Disease  Virus/Bacteria have an antigen on their surface that identifies them as foreign from the body’s cells.  When it enters the body/lumen, immune cells in the mucosa of GI tract will eliminate it o ex. phagocytes (“eaters”), first o ex. Lymphocytes, second  T lymphocytes kill infected cells directly  B lymphocytes secrete antibodies- bind with antigen and prevent it from entering body cells  Antibodies are specific for each antigen, body remembers Common Discomforts  Food Allergies o Allergic reaction occurs when the immune system reacts to non-harmful antigens (proteins) called allergens , then produces antibodies causing symptoms  Ex. Proteins in Nuts, eggs, milk, seafood o First exposure: begins the process with production of antibodies o Second exposure: allergens bind to antibodies and cause release of histamine o Symptoms (eg redness, swelling)  Enter mouth (itching, tingling on tongue/lips); Stomach/intestines (vomiting, cramps)  Absorbed into bood (drop in blood pressure, hives, breathing difficulties) o Different from food intolerances (eg lactose), which do not involve immune system  Celiac disease o Gluten in wheat, barley, or rye – trigger immune response that damages or destroys villi of SI o Consume tiny amount can cause: abdominal pain, diarrhea, fatigue  to malnutrition, weight loss, anemia, osteoporosis, intestinal cancer, and other chronic illnesses o Inherited disease  “Heart Burn” and GERD o Gastroesophageal reflux = “Heart burn”  When acidic stomach contents leak back into the esophagus, passing the lower esophageal sphincter  “Heart burn” , cause a burning sensation in the middle chest caused o If it occurs 2+ times per week = Gastoesophageal reflux disease (GERD)  Can lead to bleeding, ulcers and cancers o To minimize risk, In diet: Avoid fatty and fried foods, chocolate, peppermint, caffeine, spicy foods (increase acidity, slow stomach emptying), Reduce volume of stomach during meals, Eat smaller meals, consume beverages between (not with) meals, remain upright when eating, loose clothing, avoid smoking, alcohol, reduce weight  May require medications that minimize stomach acidity or manage symptoms  Peptic Ulcers o Occur when protective mucus layer of stomach/esophagus/upper SI is penetrated, resulting in an open lesion (wound) o Symptoms range from abdominal pain to severe bleeding o Result from GERD or abuse of aspirin, motrin, advil, or infection by H. Pylori bacteria  Gallstones o Solid materials that accumulate in the gallbladder or bile duct o Cause pain when gallbladder contract in response to fat in SI  interfere with bile secretion, reduce fat absorption o Typically treated by removing gallbladder Common problems relating to intestines:  Diarrhea = Frequent, watery stools (poo) o Occurs when  material moves through colon too quickly for suffic
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