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Where does the energy that makes life possible come from? Humans obtain energy from three classes of fuel molecules: carbohydrates, lipids, and proteins.
- Cell Metabolism
Catabolic pathways involve the breakdown of nutrient...
- Cell Metabolism
Dietary sources of energy. The typical human diet consists chiefly of carbohydrates, fats, proteins, water, ethanol, and indigestible components such as bones, seeds, and fibre (mostly cellulose). Carbohydrates, fats, and proteins typically comprise ninety percent of the dry weight of food. [10] .
Human nutrition is the process by which substances in food are transformed into body tissues and provide energy for the full range of physical and mental activities that make up human life. Foods supply nutrients that are critical for human growth.
In food and components of the human body, potential energy resides in the chemical bonds of specific molecules such as carbohydrates, fats, proteins, and alcohol. This potential energy is converted into kinetic energy in the body, driving many body functions ranging from muscle and nerve function to driving the synthesis of body protein for growth.
How Cells Obtain Energy from Food. As we have just seen, cells require a constant supply of energy to generate and maintain the biological order that keeps them alive. This energy is derived from the chemical bond energy in food molecules, which thereby serve as fuel for cells.
28 Οκτ 2010 · Energy is defined as the ability of a system to perform work. Energy is present in many forms, such as luminous energy coming from sun or kinetic energy obtained from wind and water. Humans obtain their energy from foods which is stored in the CH bonds of carbohydrates, lipids, proteins, and alcohol.
The usable energy in food is measured in units called kilocalories or, simply, calories. About two-thirds of the energy the body uses goes to keeping body temperature constant, repairing internal organs and skin, keeping the heart beating and lungs breathing, and ensuring the proper chemical balance inside and outside the body's cells.
