PowerPoint ® Lectures created by Edward J. Zalisko for Campbell Essential Biology, Sixth Edition, and Campbell Essential Biology with Physiology, Fifth.

PowerPoint ® Lectures created by Edward J. Zalisko for Campbell Essential Biology, Sixth Edition, and Campbell Essential Biology with Physiology, Fifth Edition – Eric J. Simon, Jean L. Dickey, Kelly A. Hogan, and Jane B. Reece Chapter 22 Nutrition and Digestion © 2016 Pearson Education, Inc.

Figure 22.0-1 Why Nutrition and Digestion Matter

Biology and Society: The “Secret” to Shedding Pounds Each year, about one in seven Americans (roughly 50 million) starts a diet. Weight loss is big business. But only about 5% of dieters are able to reach their goal weight and maintain it for the long term. © 2016 Pearson Education, Inc.

Figure 22.0-2 Chapter Thread: Controlling Your Weight

Biology and Society: The “Secret” to Shedding Pounds More than a third of American adults are obese (very overweight). Obesity contributes to heart disease, diabetes, cancer, and other health problems—to the tune of 300,000 preventable deaths per year in the United States. © 2016 Pearson Education, Inc.

Biology and Society: The “Secret” to Shedding Pounds There really is no trick to managing your weight. Add up the calories from the food you eat. Subtract the calories that your body burns. If you take in more than you burn, you will gain weight. If you burn more than you take in, you will lose weight. Weight control can be summed up in a five-word “secret”: Eat less and exercise more! © 2016 Pearson Education, Inc.

Biology and Society: The “Secret” to Shedding Pounds Caloric balance alone does not ensure good nutrition. Food must also provide the raw materials for building healthy cells and tissues. You are what you eat: Your health and appearance depend on the quality of your diet and the proper functioning of your digestive system. © 2016 Pearson Education, Inc.

An Overview of Animal Nutrition As animals, we must eat other organisms to acquire nutrients. Food provides the raw materials we need to build tissue and fuel cellular work. However, food primarily consists of large, complex molecules that are not in a form an animal’s cells can use. Thus, the body must break down these nutrients— digest them—to make them useful. © 2016 Pearson Education, Inc.

Animal Diets All animals eat other organisms, dead or alive, whole or by the piece. Beyond that generalization, however, animal diets vary extensively. Herbivores feed mainly on plants and/or algae. Carnivores mainly eat other animals. Omnivores eat animals as well as plants and/or algae. © 2016 Pearson Education, Inc.

Figure 22.1 ANIMAL DIETS Herbivore (mainly eats plants or algae) Carnivore (mainly eats animals) Omnivore (regularly eats animals as well as plants or algae)

The Four Stages of Food Processing There are four stages of food processing. 1. Ingestion is another word for eating. 2. Digestion is the breakdown of food into molecules small enough for the body to absorb. 3. Absorption is the uptake of the small nutrient molecules by cells lining the digestive tract. 4. Elimination is the disposal of undigested materials left over from food. © 2016 Pearson Education, Inc.

Digestion: A Closer Look The dismantling of food molecules is necessary because food molecules are too large to cross the membranes of animal cells and different from the molecules that make up an animal’s body. © 2016 Pearson Education, Inc.

Figure 22.2 Amino acid monomer Cheese protein (a polymer of amino acids in a specific sequence) Breakdown of protein by human digestive system Amino acids Absorption of amino acids by cells lining the small intestine; transport via bloodstream to other cells Human protein Cells use amino acids from the cheese and other foods to produce new human proteins 1 2 3

© 2016 Pearson Education, Inc. Figure 22.2-2 Absorption of amino acids by cells lining the small intestine; transport via bloodstream to other cells Human protein Cells use amino acids from the cheese and other foods to produce new human proteins 2 3

Digestion: A Closer Look Mechanical digestion begins the process, involves physical processes like chewing, and breaks chunks of food into small pieces, exposing them to chemical digestion, the breakdown of food by digestive enzymes. © 2016 Pearson Education, Inc.

Digestion: A Closer Look Chemical digestion happens via hydrolysis, chemical reactions that break down large biological molecules by the addition of water molecules. Like most biological reactions, it requires enzymes. © 2016 Pearson Education, Inc.

Figure 22.3 Protein Carbohydrate Enzyme (pepsin) H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O Amino acid Sugar Fatty acid Glycerol Enzyme (lipase) Enzyme (amylase) Fat H OH H H H H

Digestive Compartments How can an animal digest its food without also digesting its own tissues? In animals, chemical digestion proceeds safely within some kind of compartment. © 2016 Pearson Education, Inc.

Digestive Compartments The simplest type of digestion occurs within a cellular organelle. As a cell engulfs food by phagocytosis, a food vacuole forms, which then fuses with a lysosome containing enzymes and forms a digestive compartment. As food is digested, small food molecules pass through the vacuole membrane into the cytoplasm and nourish the cell. © 2016 Pearson Education, Inc.

Digestive Compartments Sponges are the only animals that digest food solely within their cells. Most animals use a digestive compartment to process food. Simpler animals, including cnidarians (such as hydras and jellies) and flatworms, have a gastrovascular cavity, a digestive compartment with a single opening that functions as both the entrance for food (like a mouth) and the exit for undigested wastes (like an anus). © 2016 Pearson Education, Inc.

Figure 22.4 MAIN TYPES OF DIGESTIVE COMPARTMENTS Single opening Digested food particle Food (water flea) Gastrovascular cavity Hydra Newly engulfed food particle Earthworm Interior of intestine Intestine Anus Mouth Alimentary Canal (Digestive Tract) (tube from mouth to anus) Gastrovascular Cavity (compartment with single opening)

© 2016 Pearson Education, Inc. Figure 22.4-1 Single opening Digested food particle Food (water flea) Gastrovascular cavity Hydra Newly engulfed food particle Gastrovascular Cavity (compartment with single opening)

Digestive Compartments The vast majority of animals, including earthworms and humans, have a digestive tube with two separate openings, a mouth at one end and an anus at the other. Such a tube is called an alimentary canal, or digestive tract. Food moves through specialized regions that digest and absorb nutrients in a stepwise fashion. This adaptation allows for much more efficient food processing. © 2016 Pearson Education, Inc.

System Map The human digestive system consists of an alimentary canal and several accessory organs (salivary glands, pancreas, liver, and gallbladder). The accessory organs secrete digestive chemicals into the alimentary canal via ducts (thin tubes). The alimentary canal is divided into specialized digestive organs along its length. © 2016 Pearson Education, Inc.

Figure 22.5 Oral cavity (mouth) Tongue Pharynx Esophagus Stomach Small intestine Colon of large intestine Appendix Rectum Anus Liver Gallbladder Pancreas Salivary glands ACCESSORY ORGANS ALIMENTARY CANAL

The Mouth The mouth, or oral cavity, ingests (takes in) food and begins to digest it. Mechanical digestion begins here as the teeth cut, smash, and grind the food. Chemical digestion begins in the mouth with the secretion of saliva from salivary glands. © 2016 Pearson Education, Inc.

Figure 22.6 Incisors Canine Premolars Molars Wisdom tooth Tongue Opening of a salivary gland duct Teeth

The Pharynx The pharynx connects the mouth to the esophagus and opens to the trachea, or windpipe, which leads to the lungs. During swallowing, a reflex moves the opening of the trachea upward and tips a door-like flap called the epiglottis to close the trachea entrance. © 2016 Pearson Education, Inc.

Figure 22.7 Pharynx Epiglottis up Air flowing into open trachea (windpipe) Esophagus closed Epiglottis down Food flowing into open esophagus Adam’s apple Trachea closed BREATHING SWALLOWING

The Esophagus The esophagus is a muscular tube, connects the pharynx to the stomach, and moves food by peristalsis, alternating waves of muscular contraction and relaxation that squeeze the food ball along the esophagus. © 2016 Pearson Education, Inc.

Figure 22.8 Food ball Relaxed muscles Contracted muscles Relaxed muscles Esophageal sphincter (contracted) Stomach

The Stomach The human stomach is a large organ that acts as an expandable storage tank, holding enough food to sustain you for several hours. The cells lining the stomach’s interior secrete a digestive fluid called gastric juice, made up of hydrochloric acid, digestive enzymes including pepsin, which breaks proteins into smaller pieces, and mucus. © 2016 Pearson Education, Inc.

Stomach lining secretes gastric juice (acid, enzyme molecules, and mucus) Sphincters control the flow into and out of the stomach Accordion-like folds allow the stomach to expand. Esophagus Small intestine Food particle Figure 22.9

The Stomach When food passes from the esophagus into the stomach, the muscular stomach walls begin to churn, mixing the food and gastric juice into a thick soup called chyme. © 2016 Pearson Education, Inc.

The Stomach What keeps the stomach from digesting itself? Mucus coating the stomach lining helps protect it from gastric juices and from abrasive materials in food. Nerve and hormone signals regulate the secretion of gastric juice so that it is discharged only when food is in the stomach. But gastric juice can still erode the stomach lining, requiring the production of new cells by cell division. Your stomach replaces its lining about once every three days! © 2016 Pearson Education, Inc.

Stomach Ailments Heartburn is caused by backflow of chyme into the esophagus. Some people suffer this backflow frequently and severely enough to harm the lining of the esophagus, a condition known as acid reflux or GERD. Gastric ulcers are erosions of the stomach lining and often caused by an acid-tolerant bacterium called Helicobacter pylori. © 2016 Pearson Education, Inc.

Weight Loss Surgeries The most common weight loss surgery in the United States is gastric bypass. Staples are used to reduce the stomach to about the size of a chicken egg, and the first 18 inches of the small intestine are bypassed by attaching the downstream intestine directly to the reduced stomach pouch. As a result, patients quickly feel full when eating and the body’s ability to absorb food is reduced. © 2016 Pearson Education, Inc.

Figure 22.10 Small stomach pouch Staples New attachment Bypassed portion of stomach Tube through which food is bypassed Small intestine Esophagus

The Small Intestine The small intestine is the longest part of the alimentary canal and the major organ for chemical digestion and absorption of nutrients into the bloodstream. © 2016 Pearson Education, Inc.

Chemical Digestion in the Small Intestine Enzymes are mixed with chyme in the first 25 cm or so (about a foot) of the small intestine, the region called the duodenum. The duodenum receives digestive juices from the pancreas, liver, gallbladder, and intestinal lining. © 2016 Pearson Education, Inc.

Figure 22.11 Liver Bile Gallbladder Intestinal enzymes Duodenum of small intestine Pancreas Stomach Chyme Pancreatic juice

Chemical Digestion in the Small Intestine The pancreas is a large gland that secretes pancreatic juice into the duodenum via a duct. Pancreatic juice neutralizes the stomach acid that enters the duodenum and contains enzymes that aid in digestion. As peristalsis propels the mix along the small intestine, these enzymes contribute to the breakdown of food molecules. © 2016 Pearson Education, Inc.

Chemical Digestion in the Small Intestine Bile is a juice produced by the liver, stored in the gallbladder, and secreted through a duct into the duodenum. Bile contains salts that break up fats into small droplets that are more susceptible to dismantling by digestive enzymes. © 2016 Pearson Education, Inc.

Structure/Function: Absorption of Nutrients The alimentary canal is a tube running through the body, and its cavity is continuous with the great outdoors. The doughnut analogy shown in Figure 22.12 should convince you that this is so. Until nutrients actually cross the tissue lining the alimentary canal and enter the bloodstream, they are still outside the body. If it were not for nutrient absorption, we could eat and digest huge meals but still starve. © 2016 Pearson Education, Inc.

Figure 22.12 Alimentary canal Mouth A finger through a hole Food through the alimentary canal Anus

Structure/Function: Absorption of Nutrients The structure of the intestinal lining, or epithelium, is specialized for nutrient absorption. The intestinal lining has large folds, as well as finger-like outgrowths called villi (singular, villus), making the epithelium something like the absorptive surface of a fluffy bath towel. Each cell of the epithelium also has microscopic projections called microvilli, which add even more surface area. Absorbed small molecules pass from the digestive tract into the network of small blood vessels and lymphatic vessels in the core of each villus. © 2016 Pearson Education, Inc.

Figure 22.13 Blood vessels Interior of intestine Nutrient absorption Muscle layers Intestinal wall Villi Interior of intestine Nutrient absorption Nutrient absorption Epithelial cells Blood capillaries Lymphatic vessel Blood Lymph Epithelial cells and blood capillary Microvilli Villi

The Large Intestine The large intestine is shorter than the small intestine but almost twice as wide and about 1.5 meters in length. At the junction of the small and large intestine is a small, finger-like extension called the appendix. The appendix contains white blood cells that make minor contributions to the immune system. Appendicitis is a bacterial infection of the appendix. © 2016 Pearson Education, Inc.

Figure 22.14 Colon of large intestine Small intestine Rectum Anus Sphincter End of Nutrient flow Appendix small intestine

The Large Intestine The colon forms the main portion of the large intestine, absorbs water from the alimentary canal, and produces feces, consisting of undigested material. © 2016 Pearson Education, Inc.

The Large Intestine About one-third of the dry weight of feces consists of bacteria from the colon. Most colon bacteria are harmless. Some, such as Escherichia coli, produce B vitamins and vitamin K that are absorbed through your colon wall and help supplement your diet. © 2016 Pearson Education, Inc.

The Large Intestine If the lining of the colon is irritated by a viral or bacterial infection, the colon may be unable to reabsorb water efficiently, resulting in diarrhea. Prolonged diarrhea can cause life-threatening dehydration, particularly among the very young and very old. © 2016 Pearson Education, Inc.

The Large Intestine Constipation occurs when peristalsis moves feces along too slowly and the colon reabsorbs so much water that the feces become too compacted. It can result from lack of exercise or a diet that does not include enough plant fiber. © 2016 Pearson Education, Inc.

The Large Intestine Several intestinal disorders are characterized by inflammation (painful swelling) of the intestinal wall. Celiac disease results when gluten, a protein found in wheat, triggers an immune reaction that leads to swelling and a lack of nutrient absorption. An inappropriate immune response causes Crohn’s disease, a chronic inflammation that can periodically flare up along any part of the alimentary canal. © 2016 Pearson Education, Inc.

The Large Intestine The rectum, the last 15 cm (6 inches) of the large intestine, stores feces until they can be eliminated. Two rectal sphincters, one voluntary and the other involuntary, regulate the opening of the anus. When the voluntary sphincter is relaxed, contractions of the rectum expel feces. © 2016 Pearson Education, Inc.

Figure 22.15-s1 Mouth Stomach Small intestine Large intestine Anus Ingestion Food into mouth Food

© 2016 Pearson Education, Inc. Figure 22.15-s2 Mouth Stomach Small intestine Large intestine Anus Ingestion Food into mouth Food Digestion Mechanical digestion Chewing in mouth Churning in stomach Chemical digestion Saliva in mouth Acid and pepsin in stomach Enzymes in small intestine

© 2016 Pearson Education, Inc. Figure 22.15-s3 Mouth Stomach Small intestine Large intestine Anus Ingestion Food into mouth Food Digestion Mechanical digestion Chewing in mouth Churning in stomach Chemical digestion Saliva in mouth Acid and pepsin in stomach Enzymes in small intestine Absorption Nutrients and water in small intestine Water in large intestine

© 2016 Pearson Education, Inc. Figure 22.15-s4 Mouth Stomach Small intestine Large intestine Anus Ingestion Food into mouth Food Digestion Mechanical digestion Chewing in mouth Churning in stomach Chemical digestion Saliva in mouth Acid and pepsin in stomach Enzymes in small intestine Absorption Nutrients and water in small intestine Water in large intestine Feces Elimination Feces formed in large intestine Elimination from anus

Energy Transformations: Food as Fuel All living cells take in energy, convert it to useful forms, and expel energy. Cells can extract energy stored in the organic molecules of food through the process of cellular respiration and expend that energy as cellular work. © 2016 Pearson Education, Inc.

Energy Transformations: Food as Fuel Using oxygen, cellular respiration breaks down sugar and other food molecules, generates many molecules of ATP for cells to use as a direct source of energy, and releases carbon dioxide and water as waste “exhaust.” © 2016 Pearson Education, Inc.

Figure 22.16 “Fuel” (organic molecules such as glucose) Digestion Mitochondrion Cellular respiration (energy for cellular work) Cell ATP “Exhaust” and H2OH2O CO 2 O2O2 C 6 H 12 O 6 Food

Calories One calorie is the amount of energy required to raise the temperature of one gram of water by 1°C. A kilocalorie (kcal) is 1,000 calories, the unit listed on food labels, and often called a Calorie, with an uppercase C. © 2016 Pearson Education, Inc.

Metabolic Rate The rate at which your body consumes energy is called your metabolic rate. A person’s metabolic rate consists of the basal metabolic rate (BMR), the amount of energy it takes to maintain body functions, and any additional energy consumption above that base rate. The more active you are, the greater your actual metabolic rate and the greater the number of calories your body uses per day. © 2016 Pearson Education, Inc.

Metabolic Rate Metabolic rate also depends on other factors, such as body size, age, stress level, and heredity. The examples in Table 22.1 give you an idea of the amount of activity that it takes to use up the kilocalories in several common foods. © 2016 Pearson Education, Inc.

Table 22.1

Food as Building Material Your health depends on the continuous repair and maintenance of your tissues. The building materials required for such work are provided by the small organic molecules (monomers) produced during the digestion of food. Your cells can reassemble those smaller molecules into various large biological molecules (polymers), such as your own unique proteins and DNA. © 2016 Pearson Education, Inc.

Food as Building Material Within limits, your metabolism can change organic material from one form to another and compensate for nutrients that are lacking in your diet. However, essential nutrients cannot be made from any other materials, so the body needs to receive them in preassembled form. © 2016 Pearson Education, Inc.

Essential Amino Acids All proteins are built from 20 different kinds of amino acids. In humans, eight essential amino acids must be obtained from the diet and are in different proportions in different foods. © 2016 Pearson Education, Inc.

Essential Amino Acids All eight essential amino acids can be consumed by eating meat, eggs, or milk or the combination of grains and legumes such as beans, peanuts, and peas. © 2016 Pearson Education, Inc.

Figure 22.17 Essential amino acids Corn Beans and other legumes Complete meals Rice and beans Bread and peanut butter Rice and tofu Methionine Valine Threonine Phenylalanine Leucine Isoleucine Tryptophan Lysine

Table 22.2

Vitamins People who eat a balanced diet should be able to obtain enough of all needed nutrients in their food. For others, vitamin supplements can fill in the gaps, but supplements should not be used indiscriminately because overdoses of some vitamins (such as A, D, and K) can be harmful. © 2016 Pearson Education, Inc.

Minerals We also require smaller amounts of 21 other chemical elements that are acquired mainly in the form of inorganic nutrients called minerals. Like vitamin deficiencies, mineral deficiencies or overdoses can cause health problems. Too little calcium can result in the degenerative bone disease osteoporosis. Excess sodium can contribute to high blood pressure. © 2016 Pearson Education, Inc.

Essential Fatty Acids Our cells make fats and other lipids by combining fatty acids with other molecules, such as glycerol. Essential fatty acids must be obtained in the diet. © 2016 Pearson Education, Inc.

Decoding Food Labels The U.S. Food and Drug Administration (FDA) requires two blocks of information on labels: 1.The ingredients (by weight) from greatest amount to least 2.Key nutrients, emphasizing the ones associated with disease and the ones associated with a healthy diet © 2016 Pearson Education, Inc.

Figure 22.18

Malnutrition Malnutrition refers to health problems caused by an improper or insufficient diet. Protein deficiency is most common in less industrialized countries where there is a great gap between food supply and population size. People forced by economic necessity to get almost all their calories from a single plant staple, such as corn or potatoes, will suffer deficiencies of essential amino acids. Most victims of protein deficiency are children, who are likely to develop poorly both physically and mentally. © 2016 Pearson Education, Inc.

Figure 22.19

Eating Disorders Millions of Americans, mostly female, are affected by malnutrition not because they lack access to food, but because they have an eating disorder. Anorexia nervosa is characterized by self- starvation due to an intense fear of gaining weight, even when the person is underweight. Bulimia is a behavioral pattern of binge eating followed by purging through induced vomiting, abuse of laxatives, or excessive exercise. Both disorders are characterized by an obsession with body weight and shape and can result in serious health problems. © 2016 Pearson Education, Inc.

Obesity is a too-high body mass index (BMI), is the nutritional disorder of greatest concern, affects about one-third of all Americans, and increases the risk of heart attack, diabetes, cancer, and several other diseases. BMI charts show a range of acceptable values. © 2016 Pearson Education, Inc.

Figure 22.20 Underweight BMI <18.5 Normal BMI 18.5–24 Overweight BMI 25–29 Obese BMI 30–39 Extremely obese BMI >39 Weight (pounds) Height 6’4” 100 110120 130 140 150 160 170 180 190 200 210 220 230 240250 260 6’3” 6’2” 6’1” 6’0” 5’11” 5’10” 5’9” 5’8” 5’7” 5’6” 5’5” 5’4” 5’3” 5’2” 5’1” 5’0” 4’11” 4’10”

The Process of Science: Can a Gene Make You Fat? Observation: A mutation in a particular gene in mice leads to a significant increase in body fat. Question: How does a small change in DNA cause such a large change in the body? Hypothesis: The mutant mice become overweight because their obese gene fails to produce a protein called leptin. Prediction: Injecting leptin into mutant mice would overcome the effects of the defective obese gene. © 2016 Pearson Education, Inc.

Figure 22.21

The Process of Science: Can a Gene Make You Fat? Experiment: Mutant and normal mice were injected with leptin or a saline control. Results: Mutant mice that received leptin ended the study weighing about half as much as those that received saline. More than 100 genes are known to contribute to weight maintenance in humans. Genetics only partially explains why certain people must fight hard to control their weight. © 2016 Pearson Education, Inc.

Figure 22.22 Mutant mice with defective obese gene Mice with normal obese gene 0102030405060 Ending body mass (g) Injected with saline Injected with leptin

Evolution Connection: Fat and Sugar Cravings The majority of Americans crave fatty and/or sweet foods. For most of human history, our ancestors were continually in danger of starvation. On the African savanna, fatty or sweet foods were probably hard to find. © 2016 Pearson Education, Inc.

Evolution Connection: Fat and Sugar Cravings In such a feast-or-famine existence, natural selection may have favored individuals who gorged themselves on the rare occasions when rich, fatty foods were available. With their ample reserves, they were more likely than thinner peers to survive the inevitable famines. Today most people typically hunt and gather in grocery stores, restaurants, and cafeterias. © 2016 Pearson Education, Inc.

Figure 22.23

© 2016 Pearson Education, Inc. Figure 22.UN02 Ingestion Food Food in mouth Chemical digestion via enzymes Mechanical digestion Digestion Small molecules Absorption Inside body Elimination Undigested materials 3 4 2 1

© 2016 Pearson Education, Inc. Alimentary canal Mouth (oral cavity) Pharynx and esophagus Stomach Small intestine Large intestine Anus Accessory organs Salivary glands Liver, gallbladder, pancreas Digestion Chemical Mechanical Chewing Salivary amylase Churning Other enzymes Nutrients and water Water Absorption Acid and pepsin (in gastric juice) Figure 22.UN03

© 2016 Pearson Education, Inc. Figure 22.UN05 Calories 140 Calories from Fat 60 % Daily Value* 11% 15% 3% 6% 4% Total Fat 7g Saturated Fat 3g Trans Fat 0g Cholesterol 10mg Sodium 80mg Total Carbohydrate 18g Dietary Fiber 1g Sugars 10g Protein 2g Amount Per Serving Serving Size 1 Cookie (28 g /1 oz) Servings Per Container 8 Nutrition Facts

PowerPoint ® Lectures created by Edward J. Zalisko for Campbell Essential Biology, Sixth Edition, and Campbell Essential Biology with Physiology, Fifth.

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PowerPoint ® Lectures created by Edward J. Zalisko for Campbell Essential Biology, Sixth Edition, and Campbell Essential Biology with Physiology, Fifth.

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