CK-12 Biology I - Honors
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(Ascorbic Acid)
Vitamin C
Needed to make many biological chemicals; acts as antioxidant Citrus fruits such as oranges, red peppers, broccoli, kiwi Females: 65 mg
Males: 75 mg
(Ergocalciferol and Cholecalciferol)
Vitamin D
Helps maintain blood levels of calcium; needed for healthy bones and teeth Salmon, tuna, eggs, mushrooms Females: 5 μg
Males: 5 μg
(Tocopherol)
Vitamin E
Acts as antioxidant; protects cell membranes from LDL cholesterol damage
Vegetable oils, nuts, green leafy vegetables, whole grains, fish Females: 15 mg
Males: 15 mg
(Naphthoquinone)
Vitamin K
Helps transport calcium; helps blood clot Kale, spinach, Brussels sprouts, milk, eggs, soy products Females: 75 μg*
Males: 75 μg*
Recommended daily intakes not established; figures given are adequate daily intakes.
Minerals
Dietary minerals are chemical elements that are essential for body processes. Minerals are inorganic, meaning they do not contain carbon. Minerals needed by humans in relatively large amounts (greater than 200 mg/day) are listed in Table below. Minerals not listed in the table are called trace minerals because they are needed in very small amounts. Trace minerals include chromium, iodine, iron, molybdenum, selenium, and zinc.
Minerals Mineral Name (Symbol)
Functions in the Body Good Food Sources Recommended Daily Intakes (mg) for Ages 14–18 yr
(Ca)
Calcium
Needed for nerve and muscle action; builds bone and teeth; helps blood clot Milk, soy milk, green leafy vegetables, sardines Females: 1300*
Males: 1300*
(Cl)
Chloride
Helps maintain water and pH balance; helps form stomach acid Table salt, most processed foods Females: 2300*
Males: 2300*
(Mg)
Magnesium
Needed to form several enzymes Whole grains, green leafy vegetables, nuts, seeds Females: 360
Males: 410
(P)
Phosphorus
Component of bones, teeth, lipids, and other important molecules in the body Meat, poultry, whole grains Females: 1250
Males: 1250
(K)
Potassium
Needed for muscle and nerve function; helps maintain salt-water balance in body fluids Meats, grains, orange juice, potatoes, bananas Females: 4700*
Males: 4700*
(Na)
Sodium
Needed for muscle and nerve function; helps maintain salt-water balance in body fluids Table salt, most processed foods Females: 1500*
Males: 1500*
(S)
Sulfur
Necessary component of many proteins Whole grains, meats, seafood, eggs Females: 1300*
Males: 1300*
Recommended daily intakes not established; figures given are adequate daily intakes.
Minerals play many important roles in the body. Most are found in the blood and cytoplasm of cells, where they control basic functions. For example, calcium and potassium regulate nerve and muscle activity. Several minerals, including zinc, are components of enzymes. Other minerals, including calcium, form the bulk of teeth and bones.
Minerals cannot be synthesized by the body. Good food sources of minerals are listed in Table below. They include dairy products, green leafy vegetables, and legumes. Mineral deficiencies are uncommon, but inadequate intakes of a few minerals may lead to health problems. For example, an inadequate intake of calcium may contribute to osteoporosis, a disease in which bones become brittle and break easily.
Some minerals may be toxic in excess, but overdoses of most minerals are uncommon. Overdoses are more likely when mineral supplements are taken. Salt (sodium chloride) is added to many foods, so the intake of sodium may be too high in many people. Too much sodium in the diet can cause high blood pressure in some individuals.
Other Micronutrients
Recently, new micronutrients called phytochemicals have been found in plants. They occur primarily in colorful fruits and vegetables, like those shown in Figure below. Thousands of phytochemicals have been discovered, and some have already been shown to lower the risk of certain diseases. For example, the phytochemical lutein helps reduce the risk of macular degeneration, an eye disease that leads to blindness. Lutein is found in many yellow and orange fruits and vegetables. Several phytochemicals, including some found in berries, have proven to be powerful antioxidants.
Figure 23.4
Good sources of phytochemicals.
Eating Disorders
Eating disorders are psychiatric illnesses that involve abnormal patterns of eating. A person with an eating disorder has a compulsion to eat in a way that causes physical, mental, and emotional health problems. Typically, the person has an obsession with food and weight. Eating disorders are more common in females. One reason may be society’s focus on female appearance. The most common eating disorders are binge eating disorder, anorexia nervosa, and bulimia nervosa.
Binge Eating Disorder
Binge eating disorder is characterized by compulsive overeating. People with the disorder typically eat very large quantities of food in a short period of time. They may use food as a way to deal with painful emotions or stress. Many people with the disorder are overweight or obese. The disorder is rapidly increasing in prevalence and is now the most common eating disorder in the U.S. The rise in binge eating disorder is one reason for the dramatic increase in obesity in this country
Anorexia Nervosa
Anorexia nervosa is characterized by greatly restricted food intake and low body weight (BMI less than 17.5 kg/m2). People with anorexia nervosa usually have a distorted body image. They think they are too fat when they are actually too thin. They have an obsessive fear of gaining weight and voluntarily starve themselves. They may also exercise excessively to help keep their weight low. Females with anorexia nervosa usually stop having menstrual periods. The disorder mainly affects teenage girls and is extremely serious. At least 10 percent of people with anorexia nervosa die from factors related to the disorder.
Bulimia Nervosa
Bulimia nervosa is characterized by cycles of binge eating followed by purging to eliminate the food from the body. Purging may be achieved through intentional vomiting or excessive use of laxatives. People with this disorder typically have normal weight or weight slightly greater than normal. Repeated purging can lead to dehydration. Excessive vomiting can damage the teeth and organs of the digestive system. Bulimia nervosa occurs most often in teenage girls and young women.
Causes and Treatment
People with eating disorders usually have other mental health problems as well, most commonly depression. Both depression and eating disorders may have the same underlying physiological cause: low levels of the brain chemical serotonin. The process of eating causes serotonin to be released and may lead to a temporary “high.” The process of purging may also have this effect in people with bulimia nervosa.
Environmental factors play a role in most cases of eating disorders, as they do with depression and other mental health problems. Childhood abuse may be one of these environmental factors. Many people with eating disorders report having been abused as children.
Eating disorders can be treated with psychiatric therapy or psychological counseling. Medications may also be prescribed. Treatment usually includes resolving underlying emotional problems, as well as treating depression or other mental health disorders that are also present. In patients with anorexia nervosa, weight gain is also an important goal of treatment.
Lesson Summary
Macronutrients include carbohydrates, proteins, and lipids. They are needed in relatively large amounts to supply the body with energy and building materials.
Balanced eating can provide the body with the nutrients it needs without causi
ng weight gain. Balanced eating includes eating a wide variety of healthful foods.
Vitamins and minerals are micronutrients. They are needed in relatively small amounts to control many body processes.
Eating disorders are serious but treatable psychiatric illnesses. They involve abnormal eating patterns and an obsession with food and weight.
Review Questions
Which classes of nutrients provide the body with energy?
How is obesity diagnosed?
Identify the two main classes of micronutrients and give an example of each.
What is an eating disorder?
If Jera is a 15-year-old female, how many grams of carbohydrates and proteins should she eat each day?
How can MyPyramid help you have a balanced diet?
Why is it more dangerous to consume too much of a fat-soluble vitamin than a water-soluble vitamin?
Compare and contrast anorexia nervosa and bulimia nervosa.
Further Reading / Supplemental Links
Sizer, Frances and Whitney, Ellie, Nutrition: Concepts and Controversies (10th edition). Brooks Cole, 2005.
Whitney, Eleanor Noss and Rolfes, Sharon Rady, Understanding Nutrition (11th edition). Wadsworth Publishing, 2007.
Willett, Walter, M.D. and Skerrett, P.J., Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating. Free Press, 2005.
National Academy of Sciences, Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride. NAS, Institute of Medicine, Food and Nutrition Board, 1997. Available on the Web at
http://www.nap.edu
National Academy of Sciences, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. NAS, Institute of Medicine, Food and Nutrition Board, 2002. Available online at:
National Academy of Sciences, Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. NAS, Institute of Medicine, Food and Nutrition Board, 1998. Available online at:
National Academy of Sciences, Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. NAS, Institute of Medicine, Food and Nutrition Board, 2001. Available online at:
National Academy of Sciences, Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. NAS, Institute of Medicine, Food and Nutrition Board, 2000. Available online at:
Duyff, Roberta Larson, American Dietetic Association Complete Food and Nutrition Guide (3rd revised edition). Wiley, 2006.
Haas, Elson M. and Levin, Buck, Staying Healthy with Nutrition, 21st Century Edition: The Complete Guide to Diet and Nutritional Medicine. Celestial Arts, 2006.
Kotz, Deborah, “Eating Disorders: Binge Eating More Common than Anorexia and Bulimia.” U.S. News & World Report, 2007. Available online at:
http://health.usnews.com/usnews/health/articles/070205/5health.binge.htm.
Leitzell, Katherine, “‘Good Carbs’ Yield Newfound Benefits.” U.S. News & World Report, 2007. Available online at:
http://health.usnews.com/usnews/health/articles/070719/19glycemia.htm.
Meadows, Michelle, “Nutrition: Healthy Eating.” MedicineNet, Inc., 2006. Available online at:
http://www.medicinenet.com/nutrition/article.htm.
www.cdc.gov/nccdphp/dnpa/nutrition.htm
http://www.medicinenet.com/script/main/art.asp?articlekey=10289
http://www.keepkidshealthy.com/adolescent/adolescentnutrition.html
www.kidshealth.org/teen/nutrition
www.mypyramid.gov/
www.nlm.nih.gov/medlineplus/nutrition.html
www.nutrition.gov/
www.pamf.org/teen/health/nutrition/veggieteens.html
www.sciencedaily.com/news/health_medicine/nutrition
http://en.wikipedia.org
Vocabulary
anorexia nervosa
Eating disorder characterized by greatly restricted food intake and low body weight.
bulimia nervosa
Eating disorder characterized by cycles of binge eating followed by purging to eliminate the food from the body.
binge eating disorder
Eating disorder characterized by compulsive overeating. People with the disorder typically eat very large quantities of food in a short period of time.
carbohydrates
Organic (or carbon-containing) compounds consisting of the elements carbon, hydrogen, and oxygen; provides the body with energy.
complete proteins
Contain all ten essential amino acids; found in animal foods such as milk and meat.
eating disorder
Psychiatric illnesses that involve abnormal patterns of eating.
essential amino acids
Amino acids that cannot be synthesized and must be obtained from the diet.
hyponatremia
A condition in which the brain swells with water, causing symptoms such as nausea, vomiting, headache, and coma.
incomplete proteins
Proteins that are missing one or more essential amino acids; found in plant foods such as legumes and rice.
lipids (fatty acids)
Organic compounds that consist of repeating units of carbon, hydrogen, and oxygen; provide the body with energy.
macronutrients
Nutrients that the body needs in relatively large amounts; include carbohydrates, proteins, lipids, and water.
metabolic syndrome
A cluster of conditions that together greatly increase the risk of cardiovascular disease; include type 2 diabetes, high blood pressure, and high blood levels of LDL cholesterol and triglycerides.
micronutrients
Nutrients the body needs in relatively small amounts; include vitamins and minerals.
minerals
Inorganic chemical elements that are essential for body processes.
MyPyramid
A visual representation of how much you should eat each day of foods in different food groups.
nutrients
Chemical elements or compounds that the body needs for normal functioning and good health.
obesity
Occurs when the body mass index is 30.0 kg/m2 or greater.
proteins
Relatively large organic compounds containing carbon, hydrogen, oxygen, and nitrogen; made of amino acids.
saturated fatty acids
Fatty acids with only single bonds between carbon atoms.
triglyceride
Fat; a particular type of lipid in which three fatty acids are bound to a compound called glycerol.
unsaturated fatty acids
Fatty acids with at least one double bond between carbon atoms.
vitamins
Organic compounds that are needed by the body to function properly. There are 13 vitamins that humans need.
Points to Consider
You need nutrients for energy and building materials. Balanced eating provides you with foods that contain the nutrients you need. How does your body obtain the nutrients from food?
What processes break down food and make nutrients available to the body? What organs carry out the processes?
Lesson 23.2: Digestive System
Lesson Objectives
Describe the organs and major functions of the digestive system.
Explain how the mouth, esophagus, and stomach start the digestion of food.
Explain how the small intestine completes digestion and absorbs nutrients.
State the functions of the large intestine and the roles of intestinal bacteria.
Identify and describe diseases of the digestive system.
Introduction
Suppose you are studying and having trouble concentrating. You decide to eat an apple for energy. How does energy stored in the apple get into your cells? What organs and processes break down the apple into nutrients that the body can use for fuel? What or
gans and processes let the nutrients enter your bloodstream so they can travel to the cells where they are needed? The basic processes involved are digestion and absorption. The organs involved are the organs of the digestive system.
Organs and Functions of the Digestive System
Organs that make up the digestive system are shown in Figure below. Most of the organs form the gastrointestinal tract. Other digestive organs are called accessory organs. As you read about the organs below, refer to Figure below for reference.
Figure 23.5
Organs of the digestive system.
Gastrointestinal Tract
The gastrointestinal (GI) tract is a long tube that connects the mouth with the anus. It is more than 9 meters long in adults. The GI tract can be divided into an upper and lower part. The upper GI tract includes the mouth, esophagus, and stomach. The lower GI tract includes the small and large intestines. Food enters the mouth, passes through the upper and lower GI tracts, and then exits the body as feces through the anus.