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The Human Body: Are We Really What We Eat? Why Do We Eat? Food provides us with Food is intimately connected to our sense of taste, but also stimulates our senses of This ultimately impacts the following: ________________________________: psychological desire to eat certain foods Aroused by environmental cues Strong cravings in the absence of hunger ________________________________: physiological sensation that prompts us to eat ________________________________: the feeling of being full How are these three factors controlled? ____________________ System and ________________________________ System Signals from the brain cause hunger and satiation (_________________________ phase of nervous system) Nerve receptors in the stomach and small intestine send signals to the brain to indicate if they are _______________ or _______________________ Blood glucose levels trigger the release of ____________________ called insulin and glucagon The _______________________ region of the brain receives these signals The hypothalamus then proceeds to release ______________________________. Hormones/Endocrine system Hormones: Some hormones stimulate food ________________________ Some hormones produce a feeling of __________________________ Nervous System “__________________________ Phase” - Stomach distension by food stimulates the release of gastric juices and other hormones. Not all foods have the same effects on our feelings of hunger What Happens to the Food We Eat? Food undergoes three processes: _____________________________ - large food molecules are broken down to smaller molecules, ___________________________ and __________________________ _________________________ - process of taking these products through the intestinal wall _________________________ - undigested portions of food and waste products are removed from the body Gastrointestinal (GI) tract: The GI tract includes: Organs such as the stomach, intestines Sphincters: The Flow of Digestion Digestion begins in the _________________________ ______________________ phase of digestion: Hunger and appetite work together to prepare the GI tract for digestion First thought of food (______________________ system) stimulates the release of digestive juices ________________________ moistens the food and mechanically breaks it into smaller pieces ______________________ contains digestive juices secreted by the salivary gland in the mouth Bicarbonates _______________________ acids Mucus _________________________ the food and oral cavity Antibodies and ___________________________ fight oral bacteria _________________________________ (enzyme) begins chemical digestion of starch in the mouth The mass of food chewed and moistened in the mouth is called _____________________ The _____________________________ covers the opening to the trachea during swallowing Food travels from the mouth to the stomach through the ____________________________ How does food travel through the Esophagus to the Stomach? Digestion in the Stomach ___________________ - a hormone secreted by stomach lining cells that stimulates gastric juice _______________________________ contains ______________________________ (______) denatures proteins and activates pepsin _____________________________ – enzyme to digest protein _____________________________ – enzyme to digest fat _______________________________________ – protein to absorb vitamin B12 Stomach does more than help with chemical digestion Chyme: How is the stomach protected from the gastric juices? Digestion in the Small Intestine From the stomach, chyme is slowly released through the _______________________________ to the small intestine Small intestine is composed of 3 sections _________________________________ (sphincter) connects the small intestine to the large intestine Most of the _____________________ and ______________________ take place in the small intestine Digestion in the Large Intestine The large intestine is also referred to as the __________________ or ______________________ ______________________________ assist with final digestion Its main function is to __________________ undigested food material and absorb water, short chain fatty-acids, and electrolytes Are we forgetting something? How is Chemical Digestion Accomplished? Enzymes Speeds Up Digestion Enzymes are Enzymes are _______________ to carbohydrate, protein, and fat digestion Hormones Assist in Digestion Hormones are ________________________________________: amines, peptides, or steroids They are released into the blood stream to __________________________________ that contain the ___________________________________________ for that given hormone Hormones bind to the receptor on the cell membrane for activation Key hormones involved in digestion: Accessory Organs Produce, Store, and Secrete Chemicals that also Aid in Digestion Accessory Organ: ________________________ Manufactures, holds, and secretes ______________________________________ Stores enzymes in the _________________________ form (to be activated in the small intestine) __________________________ digests carbohydrates __________________________ digests fats __________________________ digests proteins _____________________ and _________________ (hormones) are produced to regulate blood glucose _________________________________ is secreted to neutralize chyme Accessory Organ: _______________________ The liver is one of the most important organs in the body ___________________________ chemicals for metabolism Produces bile for ___________________________ of fats, (stored in the ________________ until needed) Receives the products of digestion via the ____________________________________ Releases glucose from glycogen stores Stores vitamins Manufactures blood proteins Absorption Process of taking A small amount of absorption occurs in the _________________________ Most absorption of nutrients occurs in the __________________________________________ Types of Absorption Passive Diffusion Passive diffusion - Going from higher to lower concentration No energy expended Facilitated Diffusion Going from higher to lower concentration No energy expended Active Transport Endocytosis What happens to the nutrients after absorption? Nutrient Transport Digestive Disorders ____________________________________ (burping) is primarily caused by swallowed air, eating too fast, improperly fitted dentures, chewing gum _______________________________ (intestinal gas) is a normal process which may be caused by… Foods rich in fiber, starches, and sugar (beans, dairy, some vegetables) Bacteria that act on partially digested carbohydrates Fat substitute olestra and sugar alcohol Beano can offer some relief The lining of the stomach is designed to cope with hydrochloric acid but other regions of the GI tract are not. _______________________________ is caused by hydrochloric acid in the esophagus. _______________________________________________________, is painful, persistent heartburn. Causes of _____________________ include ___________________________________ occurs when the upper part of the stomach lies above the diaphragm muscles. Stomach acids can enter the esophagus. Cigarette smoking or alcohol use Overweight Pregnancy Chocolate, citrus, spicy or fried foods Large high-fat meal _______________________________ are areas of the GI tract that have been eroded by HCL and pepsin The bacterium Helicobacter pylori contributes to the production of both gastric and duodenal ulcers Celiac disease (celiac sprue) Immune cells respond by damaging the small intestine leading to poor nutrient absorption Requires a diet lacking wheat, rye, and barley Early diagnosis avoids delayed growth in children and malnutrition in adults Crohn’s disease Possible cause is immune system reaction to a virus or bacteria Symptoms include diarrhea, abdominal pain, rectal bleeding, weight loss, fever, anemia Children can experience delayed growth Ulcerative colitis Possible cause is an immune response to a virus or bacteria Symptoms are similar to Crohn’s disease Although not caused by food, patients may have to avoid foods that cause GI discomfort Diarrhea Usually caused by the infection of the GI tract, stress, food intolerances, reactions to medications, or bowel disorders Can lead to severe dehydration Is more dangerous for children and the elderly Constipation Prevention includes increasing fiber-rich foods and fluids, and regular exercise Irritable bowel syndrome (IBS) Symptoms of IBS include Abdominal cramps and bloating Either diarrhea or constipation Associated with stress, caffeine, large meals, chocolate, alcohol, dairy, wheat IBS is more common in women than in men Treatment includes stress management, high fiber diet, fluids, avoiding offending foods Probiotics and Human Health Probiotics Bacteria in the Colon Protection against invading microorganisms Synthesizing vitamins (Vit K) Reduce ulcers Reduce inflammation Prevention of diarrheal diseases Introduction to Chemistry Chemistry Atom Composed of 3 subatomic particles: Draw the structure of the atom and describe the characteristics of the subatomic particles. How do we calculate the # of subatomic particles in each atom? Atomic number Atomic mass How can we determine the number of neutrons in an atom? Do all carbon atoms have the same number of protons? Do all carbon atoms have the same number of neutrons? Isotopes Molecule How do they come together? Chemical Bonds __________________________ bonds - form when atoms share electron pairs. strongest type of bond can be nonpolar or polar _______________________ bonds - form when oppositely charged ions are attracted to each other. weaker than covalent bonds form salts _______________________ bonds - form when opposite charges on two molecules are attracted to each other. weakest type of bond* Chemical Reactions Acids and Bases Carbohydrates: Bountiful Sources of Energy and Nutrients What Are Carbohydrates? One of the three ______________________________ Composed of carbon, hydrogen, oxygen Good sources: fruits, vegetables, and grains Types of Carbohydrates ________________________ Carbohydrates Contain one (________________________) or two molecules (__________________________) Commonly referred to as _______________________ _____________________________ _____________________________ Complex carbohydrates Starch We digest (break down) ___________________ to __________________________ Good sources: grains, legumes, and tubers Glycogen Stored in the ____________________ and ___________________________ Not found in food and therefore not a source of dietary carbohydrate Fiber Dietary fiber is the Grains, seeds, legumes, fruits Functional fiber is carbohydrate extracted from plants or manufactured Total fiber = _________________________ + __________________________ fiber Food labels only list dietary fiber Soluble Fibers Associated with risk reduction of cardiovascular disease and type 2 diabetes Examples: pectin, gum, mucilage Found in citrus fruits, berries, oats, beans Insoluble Fibers Promote regular bowel movements Examples: lignins, cellulose, hemicelluloses Good sources: whole grains, seeds, legumes, fruits, and vegetables Carbohydrate Digestion Carbohydrate Digestion: Mouth Carbohydrate Digestion: Stomach Carbohydrate Digestion: Small Intestine All monosaccharides are converted to glucose by the liver. Glucose circulating in the blood is our primary energy source. Excess glucose is converted to glycogen by the liver. We do not have the enzymes necessary to digest fiber. Bacteria in the large intestine can break down some fiber. Most fiber remains undigested and is excreted in the feces. Blood Glucose Regulation Blood glucose level must be closely regulated. Hormones control blood glucose levels: _________________________________ Produced by _________________ cells of the pancreas Stimulates glucose transporters (carrier proteins) to help take glucose from the blood across the cell membrane Stimulates the liver to take up glucose and convert it to ___________________________ _________________________________ Produced by ___________________ cells of the pancreas Stimulates the liver to breakdown glycogen to glucose, making glucose available to body cells Stimulates the breakdown of body proteins to amino acids to form new glucose - ___________________ Epinephrine & Norepinephrine Stimulates the liver to breakdown _______________________ to ________________________ Responsible for our “______________________________________” reactions to danger Cortisol & Growth Hormone Cortisol increases gluconeogenesis and decreases the use of glucose by muscles Growth hormone increases fatty acid mobilization and utilization, and increases liver’s output of glucose Glycemic Index Compared with glucose or white bread Varies with food preparation methods Food’s fat and fiber affect absorption Most foods are eaten in combination in a meal Glycemic Load Better indicator of effect of food on blood glucose? Value of Lower Glycemic Index Less dramatic fluctuations in blood glucose Risk reduction for heart disease and colon cancer High fiber helps to improve fat levels in the blood (higher HDL and lower LDL) Foods with lower glycemic index: Beans, fresh vegetables, whole wheat bread The Role of Carbohydrates _______________________________ Each gram of carbohydrate: ____ kcal Red blood cells rely only on glucose for their _______________________ supply Both carbohydrates and _______________ supply energy for daily activities ____________________________ is especially important for energy during exercise ________________________________ Sufficient energy from carbohydrates prevents the production of ketones as an alternate energy source Excessive ketones can result in high blood acidity and _________________________________ ________________________________ May reduce the risk of __________________________ cancer Help prevent hemorrhoids, constipation, and other intestinal problems May reduce the risk of ________________________________ May reduce the risk of heart disease May enhance weight loss May lower the risk of type 2 diabetes How Much Carbohydrate? Recommended Dietary Allowance (RDA) is 130 grams/day just to supply the brain with glucose. Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates: 45-65% of daily calorie intake. _______________________ on _________________________________ carbohydrates. Simple Carbohydrates Diets high in simple sugars: Can cause dental problems such as cavities and gum disease Are associated with increased levels of “bad cholesterol” Are associated with decreased levels of “good cholesterol” May contribute to obesity Complex Carbohydrates Adequate Intake (AI) fiber is 14 g/1000 kcal Most Americans eat only half the recommended amounts of fiber. It is best to get fiber from food (also a source of vitamins and minerals). An adequate fluid (at least eight 8-oz./day) with high fiber diets is recommended. Sugar Substitutes in the Diet _____________________________--benchmark of all sweeteners Alternative Sweeteners: _____________________________________ ________________________ sweeter than sucrose Can be heated Initial studies showed excessive intake is linked to bladder cancer in lab animals ________________ longer considered having cancer causing potential Not a potential risk in humans Alternative Sweeteners: ________________________________ ______________________ sweeter than sucrose 4 kcals/g, but only a trace amount is needed to sweeten foods Not heat stable Complaints of sensitivity to aspartame headaches, dizziness, seizures, nausea, etc. Not recommended for people with phenylketonuria (PKU) Alternative Sweeteners: _________________________________ ____________________________ times sweeter than sucrose Structure is similar to aspartame (but not a risk for PKU) Heat stable Safe for use by the general population (including children, diabetics, pregnant and lactating women) Used in a variety of products Alternative Sweeteners: ________________________________ K for _________________________ 200x sweeter than sucrose Not digested by the body Heat stable AKA Sunette Alternative Sweeteners: ____________________________________ ________________ sweeter than sucrose Heat stable Excreted in feces (small amount in urine) “Made from sugar so it tastes like sugar" Health Disorders Three health disorders related to carbohydrate metabolism are __________________________________ Three types: Uncontrolled diabetes can cause nerve damage, kidney damage, blindness, and can be fatal Diabetes – Type 1 Accounts for 10% of all cases Patients do not produce enough _______________________ Causes ___________________________________ (high blood glucose) Once known as juvenile-onset diabetes or insulin dependent diabetes mellitus (IDDM) Treatment for Type 1 DM Diabetes – Type 2 Most diabetics have type 2 diabetes Progressive disease with Body cells Hyperglycemia results when cells cannot take in the glucose from the blood Once known as non-insulin dependent diabetes mellitus (NIDDM) Cause is unclear but genetics, obesity, and physical inactivity play a role Treat with weight-loss diet, regular exercise, and, if necessary, medications Healthy lifestyle choices may prevent or delay the onset of type 2 diabetes: Hypoglycemia Causes shakiness, sweating, anxiety Reactive hypoglycemia: pancreas secretes too much insulin after a high-carbohydrate meal Fasting hypoglycemia: pancreas produces too much insulin, even when someone has not eaten. Lactose Intolerance Symptoms: gas, bloating, cramping, diarrhea Extent of intolerance: mild to severe Persons with lactose intolerance may need to find alternate sources of calcium Coping with lactose maldigestion Determine tolerated amount Eat dairy with fat Cheese and yogurt more easily tolerated Lactase pills Health Concerns: Dental Caries Infectious disease which damages the structures of Teeth Bacteria collect around the teeth and gums in a sticky, creamy-coloured mass called ________________ Prevented by eating sugar-free products Personal hygiene care consists of proper brushing and flossing daily
