A unit of energy. Two units are called by this name. The small calorie, or gram calorie, is the amount of heat required to raise one gram of water one degree centigrade in temperature.
The large Calorie or kilocalorie, which is used in the study of dietetics and physiological processes, is the amount of heat required to raise one kilogram of water one degree centigrade in temperature. The number of Calories required to carry on the processes necessary for life and body warmth – such as the beating of the heart, the movements of the chest in breathing, and the chemical activities of the secreting glands – is, for an adult person of ordinary weight, somewhere in the neighbourhood of 1,600. For ordinary sedentary occupations an individual requires about 2,500 Calories; for light muscular work slightly over 3,000 Calories; and for hard continuous labour around 4,000 Calories daily.
Under the International System of Units (SI UNITS – see APPENDIX 6: MEASUREMENTS IN MEDICINE) the kilocalorie has been replaced by the joule, the abbreviation for which is J (1 kilocalorie=4,186·8 J). The term Calorie, however, is so well established that it has been retained in this edition. Conversion from Calories (or kilocalories) to joules is made by multiplying by 4·2 .... calorie
The unit of energy in the International System of Units. The o?cial abbreviation is J. 4,186·8 J = 1 CALORIE (or kilocalorie). (See also BRITISH THERMAL UNIT (BTU); WEIGHTS AND MEASURES.)... joule
The measurement of the calorie value of foodstuffs or the energy expenditure of a person. In direct calorimetry, a small measure of food is burned up inside a sealed container, which is immersed in water. The rise in water temperature that results is used to calculate the calorie value.
Energy production in humans is measured by oxygen uptake.
Every litre of oxygen taken into the body produces 4.8 kilocalories of energy.
Energy production is calculated by comparing the percentage of oxygen in air inhaled and exhaled.... calorimetry
The capacity to do work or effect a physical change. Nutritionists refer to the fuel content of a food as its energy.
There are many forms of energy, including light, sound, heat, chemical, electrical, and kinetic, and most of them play a role in the body. For instance, the retina converts light energy to electrical nerve impulses, making vision possible. Muscles use chemical energy obtained from food to produce kinetic energy, movement, and heat.
Energy is measured in units called calories and joules.
Because these units are extremely small, more practical units used in dietetics are the kilocalorie (kcal, 1,000 calories), and kilojoule (kJ, 1,000 joules).
Carbohydrates and proteins provide 4 kcal per gramme (g), fats provide 9 kcal per g (see metabolism).
In general, the energy liberated from the breakdown of food is stored as chemical energy in ATP molecules.
The energy in these molecules is then available for processes that consume energy, such as muscle contraction.... energy
A collective term for all the chemical processes that take place in the body. It is divided into catabolism (breaking down of complex substances into simpler ones) and anabolism (building up of complex substances from simpler ones). Usually, catabolism releases energy, while anabolism uses it.
The energy needed to keep the body functioning at rest is called the basal metabolic rate (BMR). It is measured in joules (or kilocalories) per square metre of body surface per hour. The BMR increases in response to factors such as stress, fear, exertion, and illness, and is controlled principally by various hormones, such as thyroxine, adrenaline (epinephrine), and insulin. (See also metabolism, inborn errors of; metabolic disorders.)... metabolism
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