Today: FoodToday: Food

Updated Class Schedule:Week of 4/4 Grizzly Bears and NutritionWeek of 4/11 Sensing and Responding...

HumansBears

Both humans and grizzly bears are omnivores.Our digestive systems can tell us about our ancestors.

Fig 41.19

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.

Physical digestion:liquefying of food

Chemical digestion:breaking large moleculesinto small molecules

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Amylasein mouth

Chewing and adding saliva begins the process of liquification

Amylase begins the chemical digestion of carbs

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The primary function of the stomach is food storage

CB 41.10

Pepsinin stomach

Pepsin begins the chemical digestion of proteins.

In the stomach liquification continues.

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The Digestive System

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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

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Absorptionin the SmallIntestine

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The Digestive System

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HumansBears

Both humans and grizzly bears are omnivores.Our digestive systems can tell us about our ancestors.

CB41.19

Chimps commonly hunt small animals including other smaller primates.Hunting encourages cooperative behavior and may help produce more cohesive and advanced societies.

http://www-rcf.usc.edu/~stanford/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

Table 2 Annual Review of Nutrition Vol. 27: 311-327 Effects of Brain Evolution on Human Nutrition and Metabolism

Brain size, body size, and molar (grinding) tooth area

Food Web

Ecological Interconnections

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Producers and Consumers

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Higher consumers are usually larger and fewer in number than lower consumers

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Energy is lost in each consumer

1000

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1000

Energy is lost as it is consumed: where does it go?

only a small percent of energy from plants enters the food chain

CB 55.9only a small percent of energy is stored in organism

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Energy is lost in each consumer: the 10% rule

In the U.S. we eat an avg. of ~2800 Cal/dayWe 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/dayWe produce ~3774 Cal/person/daySo 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/dayWe produce ~3774 Cal/person/daySo 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 NutritionWeek of 4/11 Sensing and Responding...