Enrique Morgado

Allometric scaling of biological rhythms in mammals

A wide spectrum of cyclic functions in terrestrial mammals of different size, from the 3-gram shrew to the 3-ton elephant, yields an allometric exponent around 0.25, which is correlated--as a kind of common denominator--with the specific metabolic rate. Furthermore, the applicability of these empirical findings could be extrapolated to chronological events in the sub-cellular realm. On the other hand, the succession of growth periods (T98%) until sexual maturity is reached also follows the 1/4 power rule. By means of Verhulsts logistic equation, it has been possible to simulate three different biological conditions, which means that by modifying the numerical value of only one parameter, revertible physiological and pathological states can be obtained, as for instance isostasis, homeostasis and heterostasis.

Body mass and body weight: a dual reference system in biology

The aim of the present study was to compare two different biological similarity criteria, one was based on body mass (M) as a theoretical reference system in accordance with the MLT-system of physics, while the other utilized the body weight (W) for the same purpose. The mass-dependent allometry should be applied during space flights as well as during fetal and newborn conditions of life, whereas the weight-dependence should prevail in earth-bound physiology. The above mentioned distinctions are relevant not only for the specific metabolic rates but also for numerous biological time functions, as for instance for the heart and respiratory rates of all mammals, whose allometric exponent is b = - 0.09 during fetal life, and b = - 0.25 in all adult specimens.

An invariant number of the respiratory system of mammals: newborn and adult

From four empirical allometric equations concerning the dynamics of the respiratory functions of mammals, it has been possible to obtain an invariant and dimensionless number after applying Buckinghams pi-theorem. In the present study, this invariant number (IN(R)), whose origin was interspecies comparisons in mammals of different sizes, was assayed with the aim to compare in a quantitative manner the possible difference between newborn and adult mammals. The results were compared with the predicted values from two theories of biological similarity, one mass-dependent, valid for newborns, and the other, weight-dependent, valid for adult mammals. Finally, we utilized Stahls residual mass exponents (RME) to test the validity of the empirical and theoretical approaches.