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Name: Tasha P.
Status: student
Age: 16
Location: N/A
Country: N/A
Date: 2/12/2004

How does food produce heat in the body?


The potential energy of food is released when it is "burned" by the body's metabolic processes. In fact, the processes involved extend all the way back to the sun. Sunlight provides the energy necessary to enable green (photosynthesizing) plants to grow as they convert carbon dioxide, water, and other nutrients into plant tissue that itself represents a kind of energy storehouse. We can access that stored energy when we eat those plants -- or animals that have eaten plants. In the end, our metabolic processes release some of the food energy as heat as we convert the food back into carbon dioxide, water, and other products from the processes that enable us to thrive, grow, and repair injuries to our body. So, in a sense, the body is solar-powered.

ProfHoff 800

Hi Tasha!

Energy must be generated in order life to be maintained. Heat is a form of energy. As you said energy is generated from the food eaten (or absorved).

This is done by a highly integrated network of chemical reactions that receive the collective name of metabolism.

A scientist named Hans Krebs described 3 stages in the generation of energy from the oxidation of foodstuffs.

-In the first stage, large molecules in food are broken down to smaller units. Proteins are hydrolyzed to their twenty constituent amino acids, polysaccharides are hydrolized to simple sugars, as glucose, and fats are hydrolized to glycerol and fatty acids. In that phase no useful energy is generated.

- In the second stage, these numerous small molecules are degraded to a few simple units that play a central role in metabolism. Most of them sugars, fatty acids, glycerol and many amino acids are converted into the acetyl unit of the acethyl CoA. (coenzime A)

- The third stage consists of the citric acid cycle and oxidative phosphorilation, which are the final commom pathways in the oxidation of fuel molecules when they are completely oxidized to CO2 and ATP (Adenosine triphosphate) is generated as electrons flow from the reduced forms of these carriers to O2, completing the process.

Thanks for asking NEWTON!

(Dr. Mabel Rodrigues)

Tasha P.,

All food energy comes from sunlight. In photosynthesis, plants capture solar energy and use it to make large, energy-rich molecules from smaller, simpler ones. The sun's energy is converted to chemical energy that is stored within the structures of these molecules. We recover some of this stored energy when we eat the plants--or dine on meat and dairy products from animals that consumed green plants. When these energy giving chemicals are digested, some of these chemical are further broken down in your body's cells and converted into heat energy.

I hope that this helps.


Bob Trach

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