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Thus, to Barcroft homeostasis was not only organized by the brain—homeostasis served the brain. [13] Homeostasis is an almost exclusively biological term, referring to the concepts described by Bernard and Cannon, concerning the constancy of the internal environment in which the cells of the body live and survive.
Energy intake is measured by the amount of calories consumed from food and fluids. [1] Energy intake is modulated by hunger, which is primarily regulated by the hypothalamus, [1] and choice, which is determined by the sets of brain structures that are responsible for stimulus control (i.e., operant conditioning and classical conditioning) and cognitive control of eating behavior.
The first GCSE exams were sat in 1988. [6] They replaced the former CSE and O-Level qualifications, uniting the two qualifications to allow access to the full range of grades for more pupils. However the exam papers of the GCSE sometimes had a choice of questions, designed for the more able and the less able candidates.
Acid–base homeostasis is the homeostatic regulation of the pH of the body's extracellular fluid (ECF). [1] The proper balance between the acids and bases (i.e. the pH) in the ECF is crucial for the normal physiology of the body—and for cellular metabolism . [ 1 ]
In August 2018, Ofqual announced that it had intervened to adjust the GCSE Science grade boundaries for students who had taken the "higher tier" paper in its new double award science exams and performed poorly, due to an excessive number of students in danger of receiving a grade of "U" or "unclassified". [3]
A circadian rhythm (/ s ər ˈ k eɪ d i ə n /), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours.Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrained by the environment).
The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system, thus protecting the brain from harmful or unwanted substances in the blood. [1]
A simple negative feedback system is descriptive, for example, of some electronic amplifiers. The feedback is negative if the loop gain AB is negative.. Negative feedback (or balancing feedback) occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by ...