Name Class Date Chapter 38 Summary Digestive and Excretory Systems 38-1 Food and Nutrition Cells use the chemical energy stored in food to meet their energy needs. The amount of energy in food is measured in calories. Scientists refer to the energy stored in food as dietary Calories with a capital C. The number of Calories you need each day depends on your size and level of activity. Nutrients are substances in food that supply the energy and raw materials the body uses for growth, repair, and maintenance. Nutrients include water, carbohydrates, fats, proteins, vitamins, and minerals. Every cell in the human body needs water, because many of the body's processes take place in water. Simple and complex carbohydrates are the main source of energy for the body. Carbohydrates include sugars, starches, and fiber. Fats are formed from fatty acids. The body needs fatty acids to make cell membranes and certain hormones. Deposits of fat protect body organs and insulate the body. Proteins are formed from amino acids. Proteins supply raw materials for growth and repair of the body. In addition, many hormones are proteins. Vitamins are organic molecules that help regulate body processes. They include water-soluble vitamins and fat-soluble vitamins. A diet lacking certain vitamins can have serious consequences. Minerals are inorganic nutrients that the body needs, usually in small amounts. Examples of minerals are calcium and iron. The new food pyramid-mypyramidclassifies foods into six categories: grains; vegetables; fruits; milk; meat and beans; and fats, sugar, and salts. The pyramid can be used to illustrate the main characteristics of a balanced diet. Each color in the pyramid represents a different food category. Grains, especially whole grains, should make up the largest part of your diet, while fats, sugar, and salts should be used sparingly. In addition to a balanced diet, you should try to get at least 30 minutes of exercise each day. 38-2 The Process of Digestion The function of the digestive system is to break down food into simpler molecules that can be absorbed and used by the cells. The hllllal1 digestive system is a one-way tube that includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. Other structures--including the salivary glands, pancreas, and liveradd secretions to the digestive system. Digestion starts in the mouth. The teeth tear and crush food. This begins the process of mechanical digestion. Mechanical digestion is the physical breakdown of large pieces of food into smaller pieces. Salivary glands in the mouth secrete saliva, which contains the enzyme amylase. Amylase breaks down starches into sugars. This begins the process of chemical digestion. Chemical digestion is the breakdown of large food molecules into smaller molecules. The chewed clump of food that is swallowed is called a bolus. It passes through the pharynx and into the esophagus. The esophagus is a tube that connects the throat with the stomach. Muscle contractions, called peristalsis, squeeze the food through the esophagus. Food from the esophagus empties into the stomach. The stomach is a large muscular sac. Both chemical and mechanical digestion take place in the stomach. Glands in the lining of the stomach produce an acid and the enzyme pepsin. The acid and pepsin work together to begin the chemical Pearson EducaHon, Inc., publishing as Pearson PrenHce Hall. 148
Name Class Date --------------------------- digestion of protein. Stomach muscles also contract to churn and mix the stomach contents. This mechanical digestion produces a liquid mixhue called chyme. From the stomach, chyme passes into the small intestine. Most of the chemical digestion and absorption of food occurs in the small intestine. Enzymes from the pancreas help digest starch, protein, and fat. A liquid called bile from the liver dissolves and breaks up fat droplets. The lining of the small intestine also produces several enzymes that help break down carbohydrates and proteins. Nutrients are absorbed by cells lining the surface of the small intestine. The surface area is greatly increased by tiny fingerlike projections called villi (singular: villus). By the time chyme reaches the end of the small intestine, virtually all the nutrients have been absorbed. Chyme next enters the large intestine. The primary function of the large intestine is to remove water from the undigested material. After most of the water has been removed, the remaining waste passes out of the body. Digestive system disorders include peptic ulcers, diarrhea, and constipation. Peptic ulcers are caused by bacteria. Diarrhea occurs when too little water is removed from waste in the large intestine. Constipation occurs when too much water is removed. 38-3 The Excretory System During normal metabolism, cells produce wastes such as carbon dioxide and urea. Excretion is the process by which the body eliminates these wastes. The main organs of excretion are the kidneys. The kidneys play an important role in homeostasis. They remove waste products from blood, maintain blood ph, and control water content of blood. The two kidneys are located in the lower back. Blood containing wastes enters the kidneys. The kidneys remove urea, excess water, and other substances from the blood. Some of the substances are later rehuned to the blood. The wastes are excreted. The purified blood leaves the kidneys and returns to circulation. The basic unit of function of a kidney is the nephron. Each nephron is a small independent processing unit. Blood goes through two separate processes in a nephron: filtration and reabsorption. Filtration removes wastes from the blood. It occurs in a structure of the nephron known as the glomentlus. The glomerulus is enclosed within another structure called Bowman's capsule. Reabsorption returns some of the filtered materials back to the blood. These materials include food molecules and water. The fluid that remains is called urine. Urine contains urea, excess salts, and other substances. Some of the water is removed from the urine in a structure called the loop of Henle. A tube called the ureter leaves each kidney and carries urine to the urinary bladder. The urinary bladder is a saclike organ that stores urine until it can be released from the body. Urine passes from the body through a tube called the urethra. The kidneys are controlled by hormones and by the composition of the blood. If the blood becomes too concentrated, the kidneys return more water to the blood. If the blood becomes too diluted, the kidneys return less water to the blood. A person can survive with only one kidney. If both kidneys fail, the person must receive a kidney transplant or undergo dialysis in order to survive. Dialysis purifies the blood by passing it through a filtering machine. Pearson Education, Inc., publishing as Pemson Prentice Hall. 149
Name Class Date Chapter 38 Digestive and Excretory Systems Section 38-1 Food and Nutrition (pages 971-977) ~ Key Concepts What are the nutrients your body needs? Why is water such an important nutrient? Food and Energy (page 971) 1. Cells convert the chemical energy in glucose and other molecules into 2. The energy stored in food is measured in units called 3. Is the following sentence true or false? Your body can extract energy from almost any type of food. 4. Besides supplying fuel, what are other important functions of food? 5. What is the study of nutrition? Nutrients (pages 972-975) 6. Substances in food that supply the energy and raw materials your body uses for growth, repair, and maintenance are called 7. List the six nutrients that the body needs. a. d. b. e. c. f. 8. Circle the letter of each sentence that is true about water as a nutrient. a. Water is the most important of all nutrients. b. Every cell in the human body needs water. c. Many of the body's processes take place in water. d. Water makes up the bulk of bodily fluids, including blood. Pearson Education, Inc., publishing as Pearson Prentice Hall. 150
Nmne CI~s Date 9. How is water lost from the body? 10. If enough water is not taken in to replace what is lost, can result. 11. Complete the concept map. Carbohydrates include c * ~ i suga~ cane Vegetables found in Honey Potatoes 12. Why do you need fjber in your diet? 13. Circle the letter of each choice that is a function of fat. a. Protecting body organs c. Storing energy b. Insulating the body d. Transporting oxygen 14. List four increased health risks associated with a met high in fat. a. c. b. d. 15. Circle the letter of each choice that is a function of protein. a. Supplying raw materials for growth and repair b. Making up enzymes c. Helping the body absorb certain vitamins d. Producing cell membranes 16. The eight amino acids that the body is unable to produce are called amino acids. Pemson Education, Inc., publishing os Peorson Prentice Holi. 151
Narne Class Date Match each vitamin with its function. Vitamin Function 17. A a. Preventing cellular damage 18. D b. Promoting bone growth 19. E c. Repairing tissues and healing wounds 20. C d. Promoting growth of skin cells Match each mineral with a food that supplies it. Mineral Food 21. calcium a. Table salt 22. zinc b. Dairy products 23. chlorine c. Eggs 24. iron d.seafood Nutrition and a Balanced Diet (pages 976-977) 25. Which food category should make up the largest part of your diet? 26. In addition to eating properly, one should try to get at least minutes of exercise each day. Pearson EducaHon, Inc., publishing as Pearson PrenHce Hall. 152
Name Class Date Section 38-2 The Process of Digestion (pages 978-984) ~ Key Concepts What are the organs of the digestive system? What is the function of the digestive system? Introduction (page 978) 1. What is the function of the organs of the digestive system? The Mouth (pages 978-979) 2. The physical breakdown of large pieces of food into smaller pieces is referred to as digestion. 3. The breakdown of large food molecules into smaller molecules that can be absorbed into the bloodstream is called digestion. 4. Label the drawing of the digestive system with the following structures: mouth, esophagus, stomach, liver, small intestine, and large intestine. Salivary glands --==;;;:;;~=~===Jf:~~ ffl+-~----- Pharynx '~~f----- Pancreas Gallbladder -----;~~~~~~~ 'T-.,oi'"-'IMHr----- Rectum ----f----->i1w Pearson Education, Inc., publishing as Pearson Prentice Hall. 153
~ame Class Date 5. What i" the role of teeth in digestion? The Esophagus (page 980) Match each term with its definition. Term Definition 6. bolus a. Contractions of smooth muscle that aid in swallowing 7. esophagus b. Clump of chewed food 8. peristalsis c. Food tube connecting the mouth and stomach 9. Is the following sentence true or false? The pyloric valve prevents the contents of the stomach from moving back up into the esophagus. The Stomach (pages 980-981) 10. Circle the letter of each sentence that is tme about the stomach. a. It produces hydrochloric acid. b. It produces trypsin. c. It helps in the mechanical digestion of food. d. It produces amylase. 11. Is the following sentence true or false? Pepsin cannot work W1der the acidic conditions present in the stomach. 12. A.mixture of stomach fluids and food is referred to as The Small Intestine (pages 981-982) 13. Where does most chemical digestion take place? 14. Circle the letter of each sentence that is true about the pancreas. a. It produces amylase. b. It produces sodium bicarbonate. c. Its enzymes help break down lipids and nucleic acids. d. It produces lactase. 15. What role does the liver play in digestion? 16. Bile is stored in a small pouchlike organ caljed the Pearson Education, Inc., publishing as Pearson Prentice Hall. 154
Name Class Da te Use the table to answer the questions. Digestive Enzymes Enzyme Site of Action Site of Production Nutrient Digested Amylase Pepsin Lipase Amylase Trypsin Lactase Maltase Sucrase Peptjdase Mouth Stomach Salivary glands Lining of stomach Pancreas Pancreas Pancreas Lining of small intestine Lining of small intestine Lining of small intestine Lining of small intestine Carbohydrate Protein Fat Carbohydrate Protein Carbohydrate Carbohydrate Carbohydrate Protein 17. Where are the majority of digestive enzymes active? 18. Which organ or gland produces the greatest number of different digestive enzymes? 19. Wruch digestive enzyme has more than one site of action and production? 20. Which digestive enzymes are active at a site different from the site where they are produced? 21. Which nutrient is digested by more enyzmes than any other nutrient? Absorption in the Small Intestine (pages 982-983) 22. Name the two parts of the small intestine where nutrients are absorbed. a. b. 23. Projections that cover the folds of the small intestine are called 24. Is the following sentence true or false? Molecules of undigested fat and some fatty acids are absorbed by lymph vessels called lacteal". 25. Is the following sentence true or false? The appendix plays an important role in human digestion. The Large Intestine (page 984) 26. What is the primary job of the large intestine? Pearson Educo~on, Inc., publishing os Pearson Prentice Holi. 155
~arne Class Date Digestive System Disorders (page 984) 27. A hole in the stomach wall is known as a(an) 28. When something happens that interferes with the removal of water by the large intestine, a condition known as results. Reading Skill Practice When you read about a complex process, representing the process with a flowchart can help you better understand and remember it. Make a flowchart to show how food travels through the digestive system and is broken down into simpler molecules that the body can use. For more information on flowcharts, see Appendix A of your textbook. Do your work on a separate sheet of paper. Pearson EduCllnon, Inc., publishing as Pearson Prentice Hall. 156
Name CI~s Date -------------------------- Section 38-3 The Excretory System (pages 985-989) ~ Key Concepts What are the functions of the kidneys? How is blood filtered? Functions of the Excretory System (page 985) 1. The process by which metabolic wastes are eliminated is called 2. List four organs that are w,ed for excretion. a. c. b. d. 3. List three ways that the kidneys help maintain homeostasis. a. b. c. The Kidneys (pages 986-988) 4. Circle the letter of each sentence that is true about the kidneys. a. They are the main organ.c:; of the excretory system. b. They are located on either side of the spinal column. c. They remove excess water and waste products from the urine. d. They receive blood through the renal vein. Match each tenn with its definition. Term Definition s. ureter a. Saclike organ where urine is stored 6. urinary bladder b. Ftmctional unit of the kidney 7. renal medulla c. Outer part of the kidney 8. renal cortex d. Tube that carries urine from the kidney to the urinary bladder 9. nephron e. Inner part of the kidney 10. Is the following sentence true or false? Nephrons are located in the renal medulla. 11. What ends up in the collecting duct? 12. List the two processes involved in blood purification. a. b. 13. The small network of capillaries in the upper end of the nephron is referred to as the 14. TIle glomerulus is enclosed by a cup-shaped structure called the Peorson EducoHon, Inc., publishing os Pearson PrenHce Hollo 1S7
Name Class Date -------------------------- 15. Complete the Venn diagram. Filtration Reabsorption Processes that take place in the nephron 16. The materials that are filtered from the blood are collectively called the 17. List six materials that are filtered from blood. a. c. e. b. d. f. 18. Which substances are removed from the filtrate and reabsorbed by the capillaries? 19. What happens during the process of secretion? 20. Circle the letter of each sentence that is true about urine. a. It is the material that remains after reabsorption. b. It contains only urea and water. c. It is concentrated in the loop of Henle. d. It is released from the body through the urethra. Control of Kidney Function (page 988) 21. How are the activities of the kidneys controlled? 22. Is the following sentence true or false? As the amount of water in the blood increases, the rate of water reabsorption in the kidneys increases. Homeostasis by Machine (pages 988-989) 23. Is the following sentence true or false? Humans cannot survive with only one kidney. 24. The removal of wastes from blood using a machine is called Pearson Education, Inc, publishing as Pearson Prentice Hall. 158
Name Class Date Chapter 38 Digestive and Excretory Systems Vocabulary Review Completion Fill in the blanks with terms from Chapter 38. 1. The main source of energy for the body comes from 2. Nutrients that are formed from fatty acids and glycerol are 3. are needed for growth and repair of structures such as skin and muscle. 4. Saliva contains the enzyme tha t breaks the chemical bonds in starches. 5. The contractions that push food through the esophagus into the stomach are called 6. Organic molecules that help regulate body processes are called 7. The tube that connects the tluoat with the stomach is the 8. The organ that produces bile is the 9. The mixture of partly digested food that leaves the stomach is called 10. The lining of the small intestine is covered with fingerlike projections called 11. The primary organ of excretion is the 12. The ftmctional units of the kidney are called 13. The process of filtration takes place in a structure called the 14. The saclike organ that stores urine is the 15. Urine leaves the body through a tube called the 16. The cuplike structure that encases the glomerulus is called 17. Urea is primarily concentrated in the Pearson EducoHon, Inc., publishing as Pearson Prentice Hall. 159