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Metabolism (/ m ə ˈ t æ b ə l ɪ z ə m /, from Greek: μεταβολή metabolē, "change") is the set of life-sustaining chemical reactions in organisms.The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks of proteins, lipids, nucleic acids, and some carbohydrates; and the ...
The brain is the central organ of the human nervous system, and with the spinal cord, comprises the central nervous system. It consists of the cerebrum, the brainstem and the cerebellum. The brain controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sensory nervous system.
The amount of energy taken in through nutrition needs to match the amount of energy used. To achieve energy homeostasis appetite is regulated by two hormones, grehlin and leptin . Grehlin stimulates hunger and the intake of food and leptin acts to signal satiety (fullness).
In the philosophical context, the term "energy" may have the literal meaning of "activity" or "operation". Henry More, in his 1642 Psychodia platonica; or a platonicall song of the soul, defined an "energy of the soul" as including "every phantasm of the soul". In 1944 Julian Sorell Huxley characterised "mental energy" as "the driving forces of ...
t. e. A quantum mechanical system or particle that is bound —that is, confined spatially—can only take on certain discrete values of energy, called energy levels. This contrasts with classical particles, which can have any amount of energy. The term is commonly used for the energy levels of the electrons in atoms, ions, or molecules, which ...
Energy homeostasis. In biology, energy homeostasis, or the homeostatic control of energy balance, is a biological process that involves the coordinated homeostatic regulation of food intake (energy inflow) and energy expenditure (energy outflow). [1][2][3] The human brain, particularly the hypothalamus, plays a central role in regulating energy ...
Allostasis. Allostasis (/ˌɑːloʊˈsteɪsɪs/) is a physiological mechanism of regulation in which an organism anticipates and adjusts its energy use according to environmental demands. First proposed by Peter Sterling and Joseph Eyer in 1988, the concept of allostasis shifts the focus away from the body maintaining a rigid internal set-point ...
Category. v. t. e. In physiology, a stimulus[1] is a change in a living thing's internal or external environment. This change can be detected by an organism or organ using sensitivity, and leads to a physiological reaction. [2] Sensory receptors can receive stimuli from outside the body, as in touch receptors found in the skin or light ...