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Digestive and Excretory SystemsStudy Guide Answer KeySection 1. Nutrients and Homeostasis1.water—fluid balance, chemical reactions2.carbohydrates, simple and complex—energy3.proteins—growth, repair, enzymes, hormones4.fats, saturated and unsaturated—energy, used in many structures5.minerals—homeostasis, building, repair tissues6.vitamins, water– and fat-soluble—regulate cell functions, growth, development7.you lose about this much each day through sweat, urine, and respiration8.vegans must combine plant foods such as beans and rice to obtain all eight essential amino acids9.saturated fats are solid at room temperature; unsaturated fats are liquid at room temperature10.carbohydrates and fats11.to provide adequate amounts of all six nutrients for the rapid growth that occurs during these years12.these foods, unlike high-sugar or processed foods, are rich in fiber, vitamins, and minerals13.the number of Calories and Calories from fat must be multiplied by the number of servings per product to get an accurate Calorie count14.It helps you to compare the number of Calories, and type and amount of nutrients among products, then choose the best one.15.calorie is the amount of energy required to raise one gram of water one degree Celsius; Calorie is a measure of energy from food and equals 1000 calories16.vitamins are necessary to support the many life functions of cells, the smallest unit of lifeSection 2. Digestive System1.to break down large complex molecules in food into smaller molecules that can be used by the body2.mechanical digestion: chewing food, smooth muscles churning and mixing food; chemical digestion: enzymes breaking down food, stomach acid digesting protein, or other chemicals such as bile breaking down fats3.smooth muscles contract and relax to keep food moving, and sphincters prevent food from backing up.4.nutrients are absorbed and distributed to the cells; undigested materials are eliminated as liquid and solid wastes5.salivary amylase, amylase: break down starches into simpler sugars; pepsin, peptides: break down proteins; lipase: breaks down fatsProcess Diagram: Mouth—salivary amylase break down starches into simple sugars; Stomach—HCl and pepsin break down proteins; chyme forms; Small Intestine—pancreas helps finish digestion of sugars and break down fats; liver and gallbladder release bile to digest fats6.Pepsin is active only when there is food in the stomach; a layer of mucus keeps stomach acids from digesting the lining7.esophagus “carries food” from the mouth to the stomach8.Examples: two hands squeezing dough out of a plastic tubing; squeezing toothpaste out of a tubeStudy Guide B continuedSection 3. Absorption of Nutrients1.Absorption is the process by which nutrients move out of the digestive system and into the circulatory and lymphatic system. Without absorption, nutrients cannot reach the cells.2.lining of the small intestine, villi, microvilli3.the lining is ridged and folded, thousands of villi cover the lining, and thousands of microvilli cover each villi, greatly increasing surface area4.to allow more time for nutrients to be absorbed5.Materials absorbed— simple sugars, amino acids, minerals; Distribution— circulatory and lymphatic systems Part of intestine: jejunum; Materials absorbed: glucose, amino acids, vitamin C, B vitamins, some water Part of intestine: ileum; Distribution: circulatory and lymphatic systems6.Enzymes use some of the nutrients to build more complex molecules that cells need; the liver stores some nutrients for future use.7.by absorbing some water and salts8.undigested plant fiber, bile pigments, dead bacteria, traces of undigested fat and protein9.helpful—some bacteria synthesize vitamins K and B12; harmful—if some harmless bacteria overgrow other bacteria, they can reduce water absorption and cause severe diarrhea10.the rectum stores the feces; feces pass out of the body through the anus.11.they can help students remember that the microvilli are very tiny, hairlike projections on the villi.12.Sample answers: Students might sketch a paper towel absorbing a spill or think of clothes absorbing liquids spilled on them, paper absorbing ink, or chemicals absorbing oil spilled on a beachSection 1: Nutrients and HomeostasisStudy Guide Key ConceptCells require many different nutrients.VocabularymineralCalorievitaminMain Idea: Six types of nutrients help to maintain homeostasis.Fill in the concept map to summarize what you know about the six nutrients.-15240229870Six nutrients needed every day6. vitamins, water- and fat-soluble4.2.needed forneeded forneeded for3.1. water5.energyregulate cell functions, growth, developmentneeded forneeded forneeded forgrowth, repair, enzymes, hormones00Six nutrients needed every day6. vitamins, water- and fat-soluble4.2.needed forneeded forneeded for3.1. water5.energyregulate cell functions, growth, developmentneeded forneeded forneeded forgrowth, repair, enzymes, hormones7.Many dietary experts recommend drinking about 8 glasses of water a day. Why do you need this much fluid to maintain homeostasis?8.Explain why vegans, who eat no animal products, might have difficulty obtaining all 8 essential amino acids from their diet.Study Guide continued9.What is the difference between saturated and unsaturated fats?10.Which of the six nutrients supply the body with energy?Main idea: Meeting nutritional needs supports good health.11.Why is eating a balanced diet particularly important during pre-teen and teen years?12.Why do most dietary experts recommend that you obtain most of your Calories from whole grains, vegetables, and fruits?13.You are checking the number of Calories, and Calories from fat, on a food label. What other information do you need to know to get accurate Calorie counts?14.How can the information on a food label help you make good eating choices?Vocabulary Check15.The words calorie and Calorie both refer to a unit of energy. What is the difference in meaning between these two words?16.The Latin term vita means “life.” How does this meaning relate to the function of vitamins?Section 2: Digestive SystemStudy Guide Key ConceptThe digestive system breaks down food into simpler molecules.Vocabularydigestionesophaguschymedigestive system peristalsissmall intestinesphincterstomachbileMain Idea: Several digestive organs work together to break down food.1.What is the main function of digestion?2.Give an example of mechanical and chemical digestion.3.How do smooth muscles and sphincters keep food moving in one direction throughout the digestive system?4.What happens after digestion is completed?Main Idea: Digestion begins in the mouth and continues in the stomach.5.Fill in the chart below to help you remember facts about key digestive enzymes.EnzymeFunctionsalivary amylase, amylasepepsin, peptideslipaseStudy Guide continuedMain Idea: Digestion is completed in part of the small intestine.Fill in the process diagram below to summarize the digestion of food as it moves through the mouth, stomach, and small intestine. Use Figure 2.4 to help you.1206590805Stomach? Smooth muscles churn and mix food.Mouth? Food is chewed and shredded.? Food is swallowed.Small Intestine? Smooth muscles churn and mix food.? Protein digestion finished.00Stomach? Smooth muscles churn and mix food.Mouth? Food is chewed and shredded.? Food is swallowed.Small Intestine? Smooth muscles churn and mix food.? Protein digestion finished.6.What keeps the stomach from digesting itself?Vocabulary Check7.The word esophagus is based on the Greek terms ois-, which refers to “carrying something,” and phagos, which means “food.” How can these Greek terms help you remember the meaning of esophagus?8.Think of an analogy that might help you to explain the meaning of peristalsis to someone who does not know the word.Section 3: Absorption of NutrientsStudy Guide Key ConceptNutrients are absorbed and solid wastes eliminated after digestion.VocabularyabsorptionmicrovillivilliMain Idea: Most absorption of nutrients occurs in the small intestine.1.What is absorption, and why is it important to your body?2.Name the three structures in the small intestine that absorb most of the nutrients from chyme.3.How do these three structures increase the surface area of the small intestine?4.Why is it important that food move slowly through the small intestine?5.Fill in the chart summarizing absorption in the three parts of the small intestine.Part of Small IntestineMaterials AbsorbedDistributionduodenumcirculatory systemfat-soluble vitamins, vitamin B12, fatty acid, cholesterol, some waterStudy Guide continued6.What happens when nutrient-rich blood leaves the small intestine and enters the liver?Main Idea: Water is absorbed and solid wastes are eliminated from the large intestine.7.How does the large intestine help to maintain the body’s fluid balance, or homeostasis?8.What materials make up the feces?9.In what ways can bacteria in the large intestine be helpful or harmful?10.How is solid waste eliminated from the body?Vocabulary Check11.The Latin word villus means “shaggy hair,” and micro refers to something that is unusually small. How can these two terms help you remember the meaning of microvilli?12.Draw a sketch or think of an analogy to illustrate the meaning of absorption. Think of times you have watched water or other liquids being absorbed by something. ................
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