Ch. 18 Nutrients and Digestion Human Anatomy & Physiology

Section 1 – Nutrition Learning Objectives Distinguish among the six classes of nutrients Identify the importance of each type of nutrient Explain the relationship between diet and health

Section 1 – Nutrition A. Your body needs nutrients found in foods. Nutrients provide energy and materials for cell development, growth, and repair. You need energy for every activity and to maintain a steady internal temperature.

B. Classes of Nutrients Proteins Used for replacement and repair of body cells and for growth Made up of amino acids Found in eggs, milk, cheese, and meat Essential amino acids must be supplied by food

a. The main source of energy for your body 2. Carbohydrates a. The main source of energy for your body b. Made up of carbon, hydrogen, and oxygen atoms; energy holds these atoms together c. Sugars are  simple carbohydrates; starch and fiber are  complex carbohydrates.

d. Sugars are found in fruits, honey, and milk. e. Starches are found in potatoes and pasta. f. Fiber is found in whole-grain breads, beans, and peas.

3. Fats a. Also called lipids b. Provide energy and help your body absorb vitamins c. Because fat is a good storage unit for energy, any excess energy is converted to fat. d. Classified as unsaturated or saturated based on their chemical structure e. Saturated fats are associated with high cholesterol.

4. Vitamins Needed for growth, regulating body functions, and preventing disease A well-balanced diet usually gives your body all the vitamins it needs. Two groups: water-soluble and fat-soluble

a. Are inorganic nutrients 5. Minerals a. Are inorganic nutrients b. Regulate many chemical reactions in your body c. Calcium and phosphorus are used most by the body.

a. Required for survival 6. Water a. Required for survival b. Cells need water to carry out their work. c. Most nutrients your body needs must be dissolved in water. d. The human body is about 60% water. e. You lose water each day when you perspire (sweat), exhale, and get rid of wastes.

C. Food Groups 1. Because no food has every nutrient, you should eat a variety of foods. 2. The food pyramid helps people select foods that supply all the nutrients they need. 3. Foods that contain the same nutrients belong to a food group. 4. Five food groups: a. Bread and cereal (grains) b. Vegetable c. Fruit d. Milk,cheese,yogurt (dairy) e. Meat

Discussion Question How can the food pyramid help you maintain good health?

Discussion Question How can the food pyramid help you maintain good health?  The food pyramid tells you how many servings of each food group to eat every day. The recommended daily amount for each food group will supply your body with the nutrients it needs.

Section 2 – The Digestive System Learning Objectives Distinguish the differences between mechanical digestion and chemical digestion Identify the organs of the digestive system and what takes place in each. Explain how homeostasis is maintained in digestion.

Section 2 – The Digestive System Digestion – breaks food down into small molecules that can be absorbed by blood 1. Mechanical digestion – food is chewed, mixed, and churned 2. Chemical digestion – chemical reactions break down food

B. Enzymes 1. Type of protein that speeds up the rate of a chemical reaction in your body 2. Many enzymes are involved in the digestion of carbohydrates, proteins, and fats.

C. Organs of the digestive system 1. Accessory organs – food does not pass through them a. Include the tongue, teeth, salivary glands, liver, gallbladder, and pancreas

2. Digestive tract a. Mouth – Here, your tongue, teeth, and saliva change food into a soft mass. b. Esophagus – muscular tube moves food to the stomach using peristalsis, or waves of muscle contractions c. Stomach – Here, food is digested mechanically by peristalsis and chemically by digestive solutions with the help of enzymes. Food becomes a thin, watery liquid called chyme.

d. Small intestine – Villi increase the surface area to increase absorption. Blood transports the absorbed nutrients to cells. e. Large intestine – Absorbs water from undigested chyme. Peristalsis slows down so chyme can be in the large intestines as long as three days. The rectum and anus control the release of solid wastes from the body.

D. Bacteria live in many of the organs of your digestive D. Bacteria live in many of the organs of your digestive tract and make vitamins your body needs.

Discussion Question Describe step by step what happens to a piece of potato as it is digested in your body.

Discussion Question Describe step by step what happens to a piece of potato as it is digested in your body.  In the mouth, the tongue and teeth begin to break the potato down into smaller particles. Saliva begins chemical digestion, breaking down starch into sugar. Then the esophagus moves the potato particles into the stomach. In the stomach, food is mixed mechanically by peristalsis. It is also broken down by acids with the help of enzymes and changed into chyme. The chyme flows into the small intestine, where it is further digested chemically. Nutrients are absorbed by the villi into blood vessels, and then transported to all the cells of the body. The remaining undigested materials move into the large intestine, where water is absorbed from it and it becomes more solid. Finally, the rectum and anus control the release of the remaining solid wastes.