growth curve

curve

 [kerv] a line that is not straight, or that describes part of a circle, especially a line representing varying values in a graph.dose-effect curve (dose-response curve) a graphic representation of the effect caused by an agent (such as a drug or radiation) plotted against the dose, showing the relationship of the effect to changes in the dose.growth curve the curve obtained by plotting increase in size or numbers against the elapsed time.oxyhemoglobin dissociation curve a graphic curve representing the normal variation in the amount of oxygen that combines with hemoglobin as a function of the partial pressures of oxygen and carbon dioxide. The curve is said to shift to the right when less than a normal amount of oxygen is taken up by the blood at a given Po₂, and to shift to the left when more than a normal amount is taken up. Factors influencing the shape of the curve include changes in the blood pH, Pco₂, and temperature; the presence of carbon monoxide; alterations in the constituents of the erythrocytes; and certain disease states.pulse curve sphygmogram.Spee curve (curve of Spee) the anatomic curvature of the occlusal alignment of teeth, beginning at the tip of the lower canine, following the buccal cusps of the premolars and molars, and continuing to the anterior border of the ramus.strength-duration curve a graphic representation of the relationship between the intensity of an electric stimulus at the motor point of a muscle and the length of time it must flow to elicit a minimal contraction; see also chronaxie and rheobase. In cardiac pacing it is useful in determining characteristics of a particular pacing electrode and determining the most efficient selection of pacing parameters for an appropriate safety margin.survival curve a graph of the probability of survival versus time, commonly used to present the results of clinical trials, e.g., a graph of the fraction of patients surviving (until death, relapse, or some other defined endpoint) at each time after a certain therapeutic procedure.

growth curve

a graphic representation of the change in size of an individual or a population over a period of time.

Fig. 182 Growth curve . A growth curve in a microbial culture.Fig. 181 Growth curve . (a) Exponential. (b) Logistic.

growth curve

the graphic representation of the growth of a population, which could be exponential where (theoretically) the density would eventually be increasing at an infinite rate, or could be logistic (see LOGISTIC CURVE where the density would stabilize near the CARRYING CAPACITY of the population. See Fig. 181 . Populations of microorganisms tend to go through a classic four-stage growth curve (see Fig. 182 ). The ‘lag’ phase is a time of adaptation to the new environment where such processes as ENZYME INDUCTION take place and reproduction rate equals death rate. The ‘log’ phase is a period of exponential growth (reproduction rate much greater than death rate). The ‘stationary’ phase is a time of equilibrium, representing the response to a limiting factor such as nutrient source, while little or no reproduction occurs during the ‘death’ phase, so the population declines.