Chapter 34 Nutrition and Digestion Lecture Outlines by Gregory Ahearn University of North Florida Copyright 2011 Pearson Education Inc Chapter 34 At a Glance 34 1 What Nutrients Do Animals Need 34 2 How Does Digestion Occur 34 3 How Do Humans Digest Food Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Nutrients are substances obtained from the environment that organisms need for their growth and survival Nutrients fall into six major categories Carbs Lipids Proteins Minerals Vitamins Water Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Most energy is provided by carbohydrates and fats Cells rely on a supply of energy to maintain their complexity and wide range of activities without this energy cells die within minutes Nutrients that supply energy are lipids carbohydrates and proteins These molecules are broken down by digestion to their subunits which are used during cellular respiration Energy from these subunits is released and is captured in ATP Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Energy from nutrients is measured in calories A calorie is the amount of energy required to raise 1 gram of water 1 degree Celsius Food calorie content is measured in units of 1 000 calories kilocalories also known as Calories capital C Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Energy from nutrients is measured in calories continued The average human burns 70 Calories per hour at rest and up to 20 Calories per minute during exercise However people differ in metabolic rate the speed at which cellular reactions that release energy will occur Exercise significantly boosts Caloric requirements Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Carbohydrates are a source of quick energy Carbohydrates include glucose sucrose and polysaccharides long chains of sugar molecules Cellulose starch and glycogen are all polysaccharides composed of chains of glucose Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Carbohydrates are a source of quick energy continued Cellulose is the major structural component of Starch is the principle energy storage material of Glycogen is used by animals for short term plant cell walls plants energy storage Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Fats and oils are the most concentrated energy source Fats and oils contain over twice as many Calories per unit weight as do carbohydrates or proteins When an animal s diet provides more energy than it expends most of the excess carbohydrates and fats are stored as body fat Fat is hydrophobic and so neither attracts nor dissolves in water as carbohydrates and proteins do Because of this stored fat does not accumulate water and so more energy can be stored per unit of weight from fats than from other molecules Fat deposits also provide insulation for animals living in cold environments such as seals whales and walruses Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Fats and oils are the most concentrated energy source continued The body mass index BMI is a common tool for estimating a healthy weight A BMI between 18 5 and 24 9 is considered healthy The U S Centers for Disease Control and Prevention estimate that about 33 of all U S adults are overweight BMI between 25 and 29 9 and an addition 33 are obese BMI of 30 or more located in Atlanta Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Essential nutrients provide raw materials Our cells can synthesize most of the molecules our bodies require but they cannot synthesize certain raw materials called essential nutrients which must be supplied in the diet Essential nutrients for humans include certain fatty acids and amino acids a variety of minerals and vitamins and water Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Certain fatty acids are essential in the human diet Fats and oils provide a source of energy but also provide essential fatty acids Essential fatty acids serve as raw materials used to synthesize molecules in a wide range of physiological activities They help us to absorb fat soluble vitamins and are important in cell division fetal development and the immune response Sources of essential fatty acids are fish oils canola oil soybean oil flaxseed and walnuts Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Amino acids form the building blocks of protein In the digestive tract protein from food is broken down into its amino acid subunits which can be used to synthesize new proteins Proteins perform many functions in the body acting as enzymes receptors on cell membranes oxygen transport molecules structural proteins antibodies and muscle proteins Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Amino acids form the building blocks of protein continued Humans are unable to synthesize 9 or 10 of the 20 amino acids needed to make proteins Those amino acids that cannot be synthesized must be obtained in the diet and are called essential amino acids Essential amino acids can be obtained from protein rich foods such as meat milk eggs corn beans and soybeans Protein deficiency can result in a number of debilitating conditions including kwashiorkor Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Minerals are elements required by the body Minerals are elements that play many crucial roles in animal nutrition and can only be obtained in the diet or dissolved in drinking water Calcium magnesium and phosphorus are major constituents of bone and teeth Sodium calcium and potassium are needed for muscle contraction and the conduction of nerve impulses Iron is a central component of hemoglobin in the blood and iodine is found in hormones produced by the thyroid gland Animals also require trace amounts of zinc magnesium copper and chromium Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 34 1 What Nutrients Do Animals Need Vitamins play many roles in metabolism Vitamins are organic molecules that animals require in
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