Biology subjects

Pelz, P. F.

Publications and source records attributed to Pelz, P. F..

3 recordsLinked to original sources

bioRxiv2026

Local optimization of oxygen transport gives rise to Kleiber's law

For nearly a century, the physical origin of metabolic scaling has remained unresolved: metabolism is proportional to body mass in small organisms but follows Kleiber's three-quarter-power law in larger animals. We derive both regimes from the Metabolic Holon (MH), a locally optimized capillary-tissue oxygen-supply unit coupling convection, diffusion, and cellular oxygen consumption. Physical similarity predicts that the effective number N of repeated MHs is body-mass invariant within metabolic groups, while independent observations constrain its group-specific magnitude. Without calibration to metabolic-rate or heart-rate data, the theory predicts absolute metabolic rates across 18 orders of magnitude, regime transition, group-specific levels, and heart-rate scaling. One empirical lifetime-heartbeat constraint sets lifespan. Kleiber's law is thus one asymptotic consequence of a general physical theory of organismal aerobic metabolism.

physiology↗

bioRxiv2025

From cells to organism - how natural selection causes metabolic scaling

The cell is the power station of life. Surprisingly, to date there is still no metabolic scaling theory that links cellular respiration to organismal metabolism and predicts the mouse-to-elephant curve, also known as Kleibers law, in an approach that is consistent with physicochemical principles. This paper shows that for a consistent model, the novel concept of the optimised Metabolic Module (MM) is the missing link between cell and organism. It is shown how evolutionary selection under resource scarcity optimises the MM towards (a) lightweight design and (b) resource efficiency. Thus, Darwins evolution by natural selection is simulated by model-based optimisation. The final general model presented is complete (for the entire mass range of the organism of different taxonomic classes), concise (it uses only five scale-invariant physicochemical constants), clear (it predicts all metabolic rates within the uncertainty range of a scale model observed in measurements) and consistent with Murrays law of capillary blood flow and cell metabolism. The model features observed asymptotes for both small protists and large endotherms. It predicts the mass-dependent metabolic rate of protists, planarians, ectotherms and endotherms with the usual uncertainty of any scaling theory. It finally turns out that Kleibers law is an asymptote of the derived general model, namely for the case of diffusion-limited cell metabolism.

physiology↗

bioRxiv2025

General Theory of Metabolism related to Animal's Taxonomy and Size

Each mammal has a budget of approximately one billion heartbeats after birth. This is consistent with their heart rate and life span, which scale with their mass to the power -1/4 and 1/4 respectively, given a complex cardiovascular system. However, the underlying empirical law, i.e., Kleibers law, according to which the metabolic rate scales with the mass to the power of 3/4, applies to all animals: for instance, flatworms with a most simple vascular system and a size slightly above the diffusion limit on growth show the same metabolic scaling as mammals. To date, there is no concise theory that is consistent with cell metabolism and compatible with physiological laws, e.g., that the volume flow scales with the capillary diameter to the power of three (Murrays law). In this paper we present how cell metabolism determines the scaling of the organisms metabolic rate via the Metabolic Module (MM), a cylinder formed by the organisms cells with a concentric capillary - sized and shaped with scarcity. Evolutionary changes from one taxonomic class to the next led to an unsteady increase in the number of MMs: the metabolism of protists and planarians, e.g., flatworms, is given by one MM only; for ectotherms, i.e., cold-blooded organisms, one thousand and for endotherms, i.e., warm-blooded organisms, nearly one hundred million MMs working together. Special cases, such as diffusion-limited metabolism and the 3/4 power law are asymptotes of the presented general theory. The presented general theory of metabolism offers valuable insights for the targeted development of artificial tissues.

physiology↗