Today: Food Updated Class Schedule: Week of 4/4 Grizzly Bears and Nutrition Week of 4/11 Sensing and Responding... Bears Both humans and grizzly bears are omnivores. Our digestive systems can tell us about our ancestors. Fig 41.19 Humans During digestion complex molecules are broken down and then used to build needed molecules and to produce energy Animals take in complex molecules from the environment for energy production Animal digestion occurs outside of our cells. animal and fungal digestion occurs outside of our cells. CB 41.13 Physical digestion: liquefying of food Chemical digestion: breaking large molecules into small molecules Cb 41.11 Chewing and adding saliva begins the process of liquification Amylase in mouth Amylase begins the chemical digestion of carbs CB 41.10 The primary function of the stomach is food storage In the stomach liquification continues. Pepsin in stomach Pepsin begins the chemical digestion of proteins. CB 41.12 CB 41.10 The Digestive System CB 41.15 Most chemical digestion occurs in the first part of the small intestine CB 41.15 The small intestine has a large surface area to aid in absorbption of nutrients CB 41.15 Absorption in the Small Intestine CB 41.10 The Digestive System CB 41.11 CB 41.19 Bears Both humans and grizzly bears are omnivores. Our digestive systems can tell us about our ancestors. Humans Chimps commonly hunt small animals including other smaller primates. Hunting encourages cooperative behavior and may help produce more cohesive and advanced societies. http://wwwrcf.usc.edu/~stanfor d/chimphunt.html Percent of resting metabolic rate needed for brain (adults): Human = 20-25% Other primates = 8-10% Nonprimate mammals = 3-5% Leonard WR, Robertson ML. 1994. Evolutionary perspectives on human nutrition: the influence of brain and body size on diet and metabolism. Am. J. Hum. Biol. 6:77–88 Brain size, body size, and molar (grinding) tooth area Table 2 Annual Review of Nutrition Vol. 27: 311-327 Effects of Brain Evolution on Human Nutrition and Metabolism Food Web Ecological Interconnections CB 54.11 Producers and Consumers CB 54.11 Higher consumers are usually larger and fewer in number than lower consumers CB 55.10 Energy is lost in each consumer 1000 CB 55.10 Energy is lost as it is consumed: where does it go? 1000 only a small percent of energy from plants enters the food chain only a small percent of energy is stored in organism CB 55.9 CB 55.10 Energy is lost in each consumer: the 10% rule In the U.S. we eat an avg. of ~2800 Cal/day We produce ~3774 Cal/person/day So we waste over 25% of the food we produce http://www.boingboing.net/2010/08/03/theres-more-energy-i.html In the U.S. we eat an avg. of ~2800 Cal/day We produce ~3774 Cal/person/day So we waste over 25% of the food we produce 8,080,000,000,000,000 btu to produce our food (quadrillion) 2,030,000,000,000,000 btu of this energy is wasted Wasted Food, Wasted Energy: The Embedded Energy in Food Waste in the United States. Amanda D. Cullar, Michael E. Webber (2010) Environmental Science & Technology DOI: 10.1021/es100310d In the U.S. we eat an avg. of ~2800 Cal/day We produce ~3774 Cal/person/day So we waste over 25% of the food we produce 8,080,000,000,000,000 btu to produce our food 2,030,000,000,000,000 btu of this energy is wasted = ~2% of total U.S. energy production Wasted Food, Wasted Energy: The Embedded Energy in Food Waste in the United States. Amanda D. Cullar, Michael E. Webber (2010) Environmental Science & Technology DOI: 10.1021/es100310d CB 55.10 Energy is lost in each consumer: the 10% rule Human impact: As consumers Use of agriculture in the U.S. About 1/2 of water and ~80% of agricultural land is used for raising animals. Fossil Fuels: Producing beef consumes over 100 times more fossil fuel than producing potatoes. The typical American could save almost as much gas by going vegetarian as by not driving. http://bicycleuniverse.info/transpo/beef.html Updated Class Schedule: Week of 4/4 Grizzly Bears and Nutrition Week of 4/11 Sensing and Responding...