3 1 Nutrients Macronutrients Nutrients substances in foods

3. 1 Nutrients - Macronutrients § Nutrients: substances in foods that provide structural materials or energy § Macronutrients: nutrients that are required in large amounts (vs. micronutrients) § Water § Adults need about 3 liters per day § Too little leads to dehydration § Maintains blood pressure § Involved in all cellular activities § Dilutes waste products § Cooling by evaporation © 2013 Pearson Education, Inc.

§ Now we will talk about Macronutrients: § Carbs (carbohydrates) § Proteins § Fats © 2013 Pearson Education, Inc.

§ Carbohydrates: main energy source § Simple sugars (glucose) enter our system quickly § Complex carbohydrates (branching chains of simple sugars) are digested more slowly § Starch: complex carbohydrate from plants § Glycogen: complex carbohydrate from animals © 2013 Pearson Education, Inc.

§ Processed food § Food that has undergone processing that has stripped it of its nutritional value § side effects of its preservation § Whole foods § Foods that have not been stripped of their nutrition § Fiber: indigestible complex carbohydrates § Essential for large intestine function § Lowers cholesterol (by binding and preventing reabsorption of bile salts) and reduces cancer risk © 2013 Pearson Education, Inc.

§ Proteins § Polymers of amino acids § Essential amino acids: we cannot make these ourselves; must obtain them from food § Complete proteins: contain all the essential amino acids we need Plant proteins can be combined to make them complete. © 2013 Pearson Education, Inc.

§ Fats § Energy storage molecules § Acts as a cushion and insulator § Consist of a glycerol attached to fatty acid tails § Essential fatty acids: we cannot make these ourselves (e. g. , omega-3 and omega-6) § Necessary for proper immune function § Omega-6: initiate inflammation when necessary § Omega-3: attenuate excessive inflammation (brain, eyes, hair, degenerative diseases) © 2013 Pearson Education, Inc.

§ Fats § Saturated fats: fatty acid carbons are bound to as much hydrogen as possible – maximum energy stored § Lack C=C double bonds § Solid at room temperature § Most animal fats are saturated § shortening, lard (pigs), butter (from milk fat) © 2013 Pearson Education, Inc.

§ Fats § Unsaturated fats are not bound to as much hydrogen as possible § Contain double bonds which give kinks in the tails § Liquid at room temperature (oils) § Most plant fats are unsaturated or polyunsaturated § (corn oil, olive oil, avocado oil, etc. ) © 2013 Pearson Education, Inc.

§ Fats § Polyunsaturated fats § Have many double bonds preventing it from tightly packing – needed for immune function § Hydrogenation § Process that adds hydrogen atoms to unsaturated fats to make it a solid (sticks and more stable) § Our body only makes and uses cis fats § Trans fats are chemically produced by incomplete hydrogenation and not beneficial § May be linked to an increased risk of heart disease and diabetes § Margarine made from vegetable (commonly) or butter (less commonly) © 2013 Pearson Education, Inc.

Vegetable oil Count the number of hydrogen atoms in the oil and in the margarine. Which has more? Margarine Cis fatty acid High pressure Hydrogenation Saturated fatty acid Hydrogen gas Liquid Copyright © 2010 Pearson Education, Inc. Solid Trans fatty acid

(a) Structural Proteins ATP Steak Protein Amino acids Structural proteins, enzymes and energy (b) Carbohydrate breakdown Structural components Apple ATP Carbohydrates Energy production (c) Fat breakdown Build membranes Butter Fat droplet Glycerol and fatty acids Stored energy Copyright © 2010 Pearson Education, Inc. ATP

What serves as the major source of energy for cells? § water molecules § carbohydrates § dietary fiber § proteins © 2013 Pearson Education, Inc.

What serves as the major source of energy for cells? § water molecules § carbohydrates § dietary fiber § proteins © 2013 Pearson Education, Inc.

Which of the following describes a processed food? § foods that have been stripped of most of their nutritional value § foods that have not been stripped of their nutritional value § foods that are also called roughage and cannot be digested § foods that have additional vitamins and minerals added © 2013 Pearson Education, Inc.

Which of the following describes a processed food? § foods that have been stripped of most of their nutritional value § foods that have not been stripped of their nutritional value § foods that are also called roughage and cannot be digested § foods that have additional vitamins and minerals added © 2013 Pearson Education, Inc.

§Now we will talk about micronutrients: § Vitamins § Minerals § antioxidants © 2013 Pearson Education, Inc.

§ Micronutrients: nutrients that are needed in small quantities § Vitamins: Table 3. 1 lists the various vitamins § organic substances which usually function as coenzymes § Vitamin D the only one we can synthesize § Sunlight is required for synthesis § Water-soluble vitamins § Not stored in the body and typically the cause of nutritional-based deficiencies § Fat-soluble vitamins § Stored in fat and can cause problems in excess © 2013 Pearson Education, Inc.

§ Minerals: inorganic substances § Do not contain carbon but essential for cell functions § Must be supplied through diet and are water soluble § Calcium is a very important mineral that plays a role in bones, clotting, muscle contraction and nerve impulses § Iron is involved in oxygen binding and transport to cells of the body from the lungs § Table 3. 2 lists the various minerals and their functions © 2013 Pearson Education, Inc.

§ Antioxidants § Found in whole foods § Most important one: Vitamin C § Protect cells from damage by free radicals § Many come from activation of the immune system § Free radicals can damage DNA and cell membranes § Table 3. 3 describes food sources of antioxidants (fun to know; do not memorize for exam) © 2013 Pearson Education, Inc.

Membrane Transport §All of these nutrients have to enter the cell THROUGH THE MEMBRANE in order to be used §The cell membrane is composed of phospholipids © 2013 Pearson Education, Inc.

Membrane Transport §The cell membrane is semipermeable §Carbon dioxide, oxygen and water move freely across the membrane §Larger molecules and charged molecules cannot pass through membranes without help §Larger molecules and charged molecules can only enter the cell by moving through protein channels embedded in the membrane © 2013 Pearson Education, Inc.

§All molecules want to be in a state of equilibrium § By moving randomly, all molecules tend to move from an area of high concentration to an area of low concentration § Think of a drop of food coloring in water § Biology promotes two modes of molecular movement: § Passive Transport § Active Transport © 2013 Pearson Education, Inc.

§ Passive Transport § Moving molecules across the membrane from an area of high concentration to an area of low concentration § Requires no energy; used to remove wastes (CO 2, amines) © 2013 Pearson Education, Inc.

§ Active Transport § Moving molecules from an area of low concentration to high concentration (going against where they “want” to go, “pushing” them (think of the time and effort involved in cleaning a mess vs. making the mess in the first place) § Requires energy § We need some ions in higher concentrations inside or out of the cells § Critical to bring in foodstuffs, vitamins, and minerals into cells from the blood for cellular function and life! © 2013 Pearson Education, Inc.

3. 3 Body Fat and Health § Difficult to define “overweight” precisely § Women need more body fat to maintain fertility than men do (lipoproteins transports steroids through body) § Healthy body fat percentages: § Women: 22% § Men: 14% © 2013 Pearson Education, Inc.

§Body Mass Index (BMI): correlates amount of body fat with risk of illness and death, using both height and weight § Not perfect! (e. g. , muscle is heavier than fat, and will give deceptively higher BMI for athletes) § Healthy range of BMI = 20 - 25 § Obesity: BMI of 30 or higher (do not memorize formula) BMI = © 2013 Pearson Education, Inc. weight in lbs. x 703 (height in inches)2 = weight in kg (height in cm)2

§ Risk of obesity is influenced by both lifestyle (diet, exercise) and genetics § Obesity increases risks of all of the following: § Diabetes § Hypertension § Heart disease § Stroke § Joint problems © 2013 Pearson Education, Inc.

§Diabetes: disease of improper carbohydrate metabolism or uptake by cells §Insulin: hormone that triggers cells throughout the body to take up glucose; produced by beta cells of the pancreas Liver Pancreas Insulin Blood sugar is higher following a meal. 1 © 2013 Pearson Education, Inc. Capillary 2 When blood sugar is high, a healthy pancreas secretes insulin into the bloodstream. 4 Excess glucose is stored in the liver as glycogen. 3 Insulin triggers all the body’s cells to take up glucose. Figure 3. 16

§ Type 1 (insulin-dependent): not associated with obesity § Usually arises in childhood § Cannot produce insulin § Immune system mistakenly destroys beta cells § Treated with daily insulin injections § Type 2 (non-insulin-dependent): associated with obesity § Usually arises in adults § Body does not process glucose properly § May be controlled by diet and exercise © 2013 Pearson Education, Inc.

§Hypertension: high blood pressure (the force exerted on blood vessels by the blood) § Systolic: highest blood pressure as the heart contracts and blood is pushed into the arteries § Diastolic: lowest blood pressure while heart is refilling and arteries slowly release the blood into the capillaries © 2013 Pearson Education, Inc.

§Hypertension: high blood pressure (the force exerted on blood vessels by the blood) § Normal blood pressure is about 120 systolic and 80 diastolic (120/80) § Hypertension: persistently over 140/90 § clogged or constricted arteries increase resistance to blood flow; both numbers increase © 2013 Pearson Education, Inc.

§ Cholesterol: a lipid that builds up with fats in the arteries (atherosclerosis), eventually blocking them. § The heart has to beat harder to push blood through tighter arteries § Clots form and are eventually thrown off, clogging elsewhere © 2013 Pearson Education, Inc.

§ Heart attack: a sudden loss of blood to the heart because of blocked arteries § Stroke: a sudden loss of blood to the brain because of blocked arteries © 2013 Pearson Education, Inc.

§Cholesterol is carried in the blood by lipoproteins § Low-density lipoproteins (LDLs): carry cholesterol made in the liver and from foods § High-density lipoproteins (HDLs): contain more protein than cholesterol. They scavenge excess cholesterol from body and take it to the liver, for excretion as bile §Saturated fats may raise cholesterol levels §High cholesterol is defined as total cholesterol level over 200, or LDL levels over 100 © 2013 Pearson Education, Inc.

§Not all cholesterol is bad! §Some cholesterol is needed to build plasma membranes and steroid hormones Cholesterol © 2013 Pearson Education, Inc. Testosterone Estrogen Figure 3. 17

§Anorexia: self-starvation § Can starve heart muscles, producing altered rhythms, increased illness, decreased mental function § Amenorrhea: cessation of menstruation § can be permanent and result in sterility § Increases risk of osteoporosis § Destabilized bones break more easily © 2013 Pearson Education, Inc.

§Bulimia: binge-eating followed by purging § Many of the same health effects as anorexia § May lead to stomach rupture § Dental and gum problems from stomach acid § Dehydration (sometimes fatal) © 2013 Pearson Education, Inc.

§Fitness may be more important than weight §Fit but overweight people are healthier than unfit slender people §Very low levels of fat in the body correlate with increased health problems and decreased ability to fight infections (ultra-athletes, elderly, anorexics) §Key is healthy diet and exercise © 2013 Pearson Education, Inc.

§Now let’s do some review questions © 2013 Pearson Education, Inc.

What serves as the major source of energy for cells? §Water molecules §Carbohydrates §Dietary fiber §Proteins © 2013 Pearson Education, Inc.

What is the only vitamin our cells can synthesize? §Vitamin A §Vitamin B §Vitamin C §Vitamin D © 2013 Pearson Education, Inc.

Which of the following statements is incorrect? §Enzymes raise the activation energy of a reaction. §Enzymes speed up the rate of a reaction. §Substrates bind to an enzyme’s active site. §Enzymes change shape when they bind to a substrate. © 2013 Pearson Education, Inc.

Charged amino acids enter the cell through _____. §passive diffusion §osmosis §facilitated diffusion §exocytosis © 2013 Pearson Education, Inc.

True or False: Type 2 diabetes usually arises in childhood. §True §False © 2013 Pearson Education, Inc.

Which of the following statements is incorrect? §Low-density lipoproteins have a high proportion of cholesterol. §Cholesterol maintains fluidity in cell membranes. §High levels of cholesterol increase the risk of heart disease and stroke. §LDLs return excess cholesterol to the liver where it is used to make bile. © 2013 Pearson Education, Inc.

Which of the following statements is correct? §K+ will move from high concentration to low concentration; ATP is used. §K+ will move from low concentration to high concentration; ATP is used. §K+ will move from high concentration to low concentration; ATP is not used. §K+ will move from low concentration to high concentration; ATP is not used. © 2013 Pearson Education, Inc.