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The fight-or-flight or the fight-flight-freeze-or-fawn[1] (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. [2] It was first described by Walter Bradford Cannon in 1915. [a][3] His theory states that animals react to threats ...
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 receptors in the eye, as ...
Stress (biology) Schematic overview of the classes of stresses in plants. Neurohormonal response to stress. Stress, whether physiological, biological or psychological, is an organism's response to a stressor such as an environmental condition. [1] When stressed by stimuli that alter an organism's environment, multiple systems respond across the ...
Biological processes are made of many chemical reactions or other events that are involved in the persistence and transformation of life forms. [1] Regulation of biological processes occurs when any process is modulated in its frequency, rate or extent. Biological processes are regulated by many means; examples include the control of gene ...
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 orienting response is a reaction to novel or significant stimuli. In the 1950s the orienting response was studied systematically by the Russian scientist Evgeny Sokolov , who documented the phenomenon called " habituation ", referring to a gradual "familiarity effect" and reduction of the orienting response with repeated stimulus presentations.
Classical conditioning occurs when a conditioned stimulus (CS) is paired with an unconditioned stimulus (US). Usually, the conditioned stimulus is a neutral stimulus (e.g., the sound of a tuning fork), the unconditioned stimulus is biologically potent (e.g., the taste of food) and the unconditioned response (UR) to the unconditioned stimulus is an unlearned reflex response (e.g., salivation).
In animals, including humans, the startle response is a largely unconscious defensive response to sudden or threatening stimuli, such as sudden noise or sharp movement, and is associated with negative affect. [1] Usually the onset of the startle response is a startle reflex reaction. The startle reflex is a brainstem reflectory reaction (reflex ...