Preksha Dhyana Human Body Part 2

Author(s): Jethalal S Zaveri
Publisher: Jain Vishva Bharati

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every day, but in order to maintain homeostasis1, we need about 10 time that amount. Water not only participates in reactions of digestion and other reactions but is also lost in urine, feces, sweat etc. Food and drinks make up the difference of our daily fluid needs. Most solid foods also contain substantial amounts of water.
Energy Metabolism
Virtually all the processes and activities that go on in the human body require a continual supply of energy. The energy that powers the human body is chemical energy. The energy metabolism of the body consists of a sequence of reactions that has much in common with the burning of a sigree or a stove. Fuel is oxidized by oxygen in both cases, releasing the energy and forming carbon-dioxide and water. But there are a number of important distinctions. A fire burns rapidly and the energy released is given off all at once in the form of heat and light. The burning of the fuel in the body proceeds in a series of small controlled steps; much of the energy released in each step is recaptured and stored. Chemical energy is used in the body to do work. It may be converted to mechanical energy (to lift a load) or electrical energy (for transmission of nerve-impulses) or it may be used as chemical energy to build up complex body chemicals.
Part of the body energy is given off as heat at the time of release. Further energy is lost as heat during the performance of the work. Ultimately all the chemical energy is directly or indirectly converted to heat, but heat-production is not entirely useless. It helps to maintain body-temperature at the optimum level for enzyme-catalyzed reactions. But often the heat production is in excess of the body's needs and special mechanisms are provided to get rid of the excess. Although the energy of food is not used directly as heat, it is customarily measured in heat units; the unit commonly used in physiology is called Calories.2
1. Optimum internal conditions of health.
2. Spelled with a capital C. It is the amout of heat required to raise the temperature of 1 kg. of water by 1° C.
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