Section 1 Nutrients Chapter 48 Objectives • Relatethe role of each of the six classes of nutrients in maintaining a healthy body. • Describeeach of the parts of the USDA Food Guide Pyramid. • Identifyfoods containing each of the organic nutrients. • Explainthe importance of vitamins, minerals, and water in maintaining the body’s functions. • Identifythree disorders associated with improper nutrition.

Section 1 Nutrients Chapter 48 Six Classes of Nutrients • Some organisms must obtain energy from nutrients in the food they consume. • A nutrient is a substance required by the body for energy, growth, repair, and maintenance. • All foods contain at least one of the six basic nutrients, and some can contain more. • The six basic nutrients are carbohydrates, proteins, lipids, vitamins, minerals, and water.

Section 1 Nutrients Chapter 48 Types of Nutrients Click below to watch the Visual Concept. Visual Concept

Section 1 Nutrients Chapter 48 Six Classes of Nutrients, continued • Nutritionists classify foods into six groups. • These six groups are: meat, milk, fruits, vegetables, breads/cereals, and fats/oils/sweets. • The USDA Food Guide Pyramid shows the number of servings from each food group needed for a balanced diet. • Nutrients provide energy for powering cellular processes.

Section 1 Nutrients Chapter 48 MyPyramid

Section 1 Nutrients Chapter 48 Carbohydrates, Proteins, and Lipids • The three nutrients needed by the body in the greatest amounts are carbohydrates, proteins, and lipids. • All of these nutrients are called organic compounds, which are compounds that contain the elements carbon, hydrogen, and oxygen. • An example of a carbohydrate is pasta; an example of a protein is chicken; and an example of lipids is olive oil.

Section 1 Nutrients Chapter 48 Nutrients in Food

Section 1 Nutrients Chapter 48 Carbohydrates, Proteins, and Lipids, continued • Carbohydrates • Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen that provide nutrients to the cells of living things. • Carbohydrates contain sugars that can quickly be converted into usable energy.

Section 1 Nutrients Chapter 48 Carbohydrates, Proteins, and Lipids, continued • Carbohydrates, continued • Carbohydrates can be monosaccharides, disaccharides, or polysaccharides. • Monosaccharides are simple sugars. • Disaccharides are sugars that consist of two chemically linked monosaccharides. • Polysaccharides are complex molecules that consist of many monosaccharides bonded together.

Section 1 Nutrients Chapter 48 Carbohydrates, Proteins, and Lipids, continued • Proteins • Proteins are organic compounds that are made of one or more chains of amino acids and are a principle component of all cells. • Most proteins come from animal products such as eggs, milk, fish, and beef.

Section 1 Nutrients Chapter 48 Carbohydrates, Proteins, and Lipids, continued • Lipids • Lipids are nonpolar molecules that are insoluble in water and can be found in fats, oils, and waxes. • Lipids are used to make cell membranes and hormones and to store energy. • The most common fat is called a triglyceride. Triglycerides can be used for energy and to build membranes and other cell parts. • Fats are used in many ways throughout the body but can be harmful if eaten in excess.

Section 1 Nutrients Chapter 48 Carbohydrates, Proteins, and Lipids, continued • Lipids, continued • Fats can either be saturated or unsaturated based on which fatty acid they contain. • Saturated fats contain saturated fatty acids. Saturated fatty acids contain carbon atoms attached to each other with a single bond. • Unsaturated fats have unsaturated fatty acids. Unsaturated fatty acids have at least one double bond between carbon atoms.

Section 1 Nutrients Chapter 48 Vitamins, Minerals, and Water • Vitamins, minerals, and water are nutrients that do not provide energy but are required for proper functioning of the body. • Vitamins are organic compounds that participate in chemical reactions by helping to build various molecules in the body. • Minerals are nutrients that are inorganic compounds and are necessary for certain body processes.

Section 1 Nutrients Chapter 48 Vitamins, Minerals, and Water, continued • Vitamins • Vitamins work as coenzymes to enhance enzyme activity. • A diet should include vitamins because they cannot usually be made in the body. An exception to this is vitamin D. • Vitamins can dissolve in water or fat.

Section 1 Nutrients Chapter 48 Vitamins

Section 1 Nutrients Chapter 48 Food Sources of Vitamins Click below to watch the Visual Concept. Visual Concept

Section 1 Nutrients Chapter 48 Vitamins, Minerals, and Water, continued • Minerals • Minerals are used to make certain body structures, to carry out normal nerve and muscle function, and to maintain osmotic balance. • Minerals can come from plants we eat directly or the plants other animals eat. • Minerals are released out of the body through urine and by perspiration.

Section 1 Nutrients Chapter 48 Food Sources of Minerals Click below to watch the Visual Concept. Visual Concept

Section 1 Nutrients Chapter 48 Vitamins, Minerals, and Water, continued • Water • Water, which is a main component in blood, helps to transport gases, nutrients, and wastes throughout the body. • Water also is a reagent in some of the body’s chemical reactions. • Water also helps regulate body temperature by absorbing and distributing the heat released in cellular reactions.

Section 1 Nutrients Chapter 48 Sources of Water Balance in Humans Click below to watch the Visual Concept. Visual Concept

Section 2 Digestive System Chapter 48 Objectives • Listthe major organs of the digestive system. • Distinguishbetween mechanical digestion and chemical digestion. • Relatethe structure of each digestive organ to its function in mechanical digestion. • Identifythe source and function of each major digestive enzyme. • Summarizethe process of absorption in both the small and large intestine.

Section 2 Digestive System Chapter 48 The Gastrointestinal Tract • The process of breaking down food into molecules the body can use is called digestion. • Digestion occurs in the gastrointestinal tract, or digestive tract, which is a long tube which begins at the mouth and winds through the body to the anus. • Organs next to the digestive tract also aid in the digestion of food through the secretions that they produce.

Section 2 Digestive System Chapter 48 Digestive System in the Human Body

Section 2 Digestive System Chapter 48 Anatomy of the Human Digestive System Click below to watch the Visual Concept. Visual Concept

Section 2 Digestive System Chapter 48 The Mouth and Esophagus • Digestion includes the mechanical and chemical breakdown of food into nutrients, the absorption of nutrients, and the elimination of waste. • Digestion begins in the mouth with the first bite of food.

Section 2 Digestive System Chapter 48 The Mouth and Esophagus, continued • Mouth • Mechanical digestion begins when the teeth cut and grind food. • The tongue also aids in mechanical digestion by keeping the food between the chewing surfaces of the teeth.

Section 2 Digestive System Chapter 48 The Mouth and Esophagus, continued • Mouth, continued • Saliva is produced by the salivary glands to begin chemical digestion of food. • Saliva is a mixture of water, mucus, and a digestive enzyme called salivary amylase. • Salivary amylase is the chemical in saliva that begins the chemical digestion of carbohydrates by breaking down certain starches into maltose.

Section 2 Digestive System Chapter 48 The Mouth and Esophagus, continued • Esophagus • The ball of food is then forced by swallowing action into the pharynx. • The pharynx is an open area that begins at the back of the mout, and serves as a passageway for both air and food. • The ball of food is then forced from the pharynx into the esophagus.

Section 2 Digestive System Chapter 48 The Mouth and Esophagus, continued • Esophagus, continued • The esophagus has two muscle layers and by alternating contractions between these muscle layers, the ball of food can be pushed into the stomach. • This series of alternating rhythmic muscular contractions and relaxation is called peristalsis.

Section 2 Digestive System Chapter 48 Peristalsis Click below to watch the Visual Concept. Visual Concept

Section 2 Digestive System Chapter 48 Stomach • The stomach is an organ involved in both mechanical and chemical digestion. • It is located in the upper left side of the abdominal cavity, just below the diaphragm.

Section 2 Digestive System Chapter 48 Stomach, continued • Mechanical Digestion • The stomach has three layers of smooth muscle—a circular layer, a longitudinal layer, and a diagonal layer. • These muscles churn the food within the stomach and help to carry out mechanical digestion.

Section 2 Digestive System Chapter 48 Stomach, continued • Mechanical Digestion, continued • The inner lining of the stomach is a mucous membrane that is composed of epithelial cells and openings called gastric pits. • Gastric pits are the open ends of gastric glands that release secretions into the stomach. • These secretions form the acidic digestive fluid that digests food in the stomach.

Section 2 Digestive System Chapter 48 Mechanical Digestion Click below to watch the Visual Concept. Visual Concept

Section 2 Digestive System Chapter 48 Stomach, continued • Chemical Digestion • Gastric fluid carries out chemical digestion in the stomach. • Gastric fluid is a liquid that is secreted by the gastric glands in the stomach. • Hydrochloric acid within the gastric fluid helps dissolve food and minerals and keep bacteria at bay.

Section 2 Digestive System Chapter 48 Stomach, continued • Chemical Digestion, continued • Mucus secreted in the stomach forms a coating that protects the lining of the stomach from hydrochloric acid and other digestive enzymes. • An ulcer will result if the mucous layer is absent from the stomach lining. • An ulcer is a lesion of the surface of the skin or a mucous membrane of the stomach.

Section 2 Digestive System Chapter 48 Chemical Digestion Click below to watch the Visual Concept. Visual Concept

Section 2 Digestive System Chapter 48 Stomach, continued • Formation of Chyme • After food enters the stomach, it closes by way of the cardiac sphincter. • The cardiac sphincter is a circular muscle located between the esophagus and the stomach. • While closed, the stomach churns to break up the food and mixes it with the gastric fluid. This process forms a mixture called chyme.

Section 2 Digestive System Chapter 48 Stomach, continued • Formation of Chyme, continued • Peristalsis forces the chyme into the small intestine from the stomach. • The pyloric sphincter controls the amount of chyme that enters the small intestine from the stomach. • Digestion in the stomach is also aided by other organs near the stomach.

Section 2 Digestive System Chapter 48 The Liver, Gallbladder, and Pancreas • The other organs that help digestion are the liver, gallbladder, and pancreas.

Section 2 Digestive System Chapter 48 The Liver, Gallbladder, and Pancreas, continued • Liver • The liver performs numerous function in the body including storing glucose, making proteins, and breaking down toxic substances. • The liver produces bile, which is vital to digesting fats.

Section 2 Digestive System Chapter 48 The Liver, Gallbladder, and Pancreas, continued • Gallbladder • After the liver produces bile it travels through a Y-shaped duct to the gallbladder. • The gallbladder is a saclike organ that stores and concentrates bile. • The gallbladder releases the bile through a common bile duct into the small intestine.

Section 2 Digestive System Chapter 48 The Liver, Gallbladder, and Pancreas, continued • Pancreas • The pancreas is an organ that lies behind the stomach. The pancreas serves two roles in its part in the digestive system. • The first role it plays is to increase the pH of the stomach acid by producing sodium bicarbonate. • The second role it plays is to secrete enzymes that help to further break down carbohydrates, proteins, lipids and nucleic acids.

Section 2 Digestive System Chapter 48 Small Intestine • The small intestine includes three sections—the duodenum, the jejunum, and the ileum. • The chyme from the stomach will further break down in the small intestine.

Section 2 Digestive System Chapter 48 Small Intestine, continued • Absorption • Absorption occurs mostly in the small intestine. Absorption occurs when the end products of digestion are transferred into the circulatory system through the blood and lymph vessels.

Section 2 Digestive System Chapter 48 Small Intestine, continued • Absorption, continued • The surface area of the small intestine is large due to the presence of many folds within the lining of the small intestine and the millions of villi that are also present. • The surface area is further increased by the presence of microvilli. • Microvilli are extensions of the cell membranes present on the villi.

Section 2 Digestive System Chapter 48 Small Intestine, continued • Absorption, continued • Nutrients are sent to the correct place by the lacteals. • The lacteals are capillaries and tiny lymph vessels within the villi. • The lacteals will take the nutrients to either the liver or the lymph vessels, and then the blood will take over delivery of the nutrients to the cells.

Section 2 Digestive System Chapter 48 Cross Section of the Small Intestine

Section 2 Digestive System Chapter 48 Large Intestine • Once absorption is complete in the small intestine, peristalsis will move the remaining contents into the colon or large intestine. • The colon has various sections, and all of these sections work together to finish the absorption of nutrients and water. • The colon initiates contractions that move the material out of the body.

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